A111D2 S3fi4bS

NATI INST OF STANDARDS & TECH R.I.C.

All 102538465

i auom r. n«nver/A study of the effects (NASA)

A Study of the Effects of

Carbon Fibers on Home

C. Denver Lovett

R. A. Wise

C. C. Gordon

K. Yee

Center for Consumer Product Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

Issued February 1980

“ QC TMENT OF COMMERCE

lances

100 IEAU 0F STANDARDS

U56

79-1952

1980
—
NBSIR 79-1952 (NASA)

» » • A STUDY OF THE EFFECTS OF

CARBON FIBERS ON HOME

APPLIANCES

NBS

RESEARCH

INFORMATION CENTER

fOO

U 5b

\q2

C. Denver Lovett

R. A. Wise

C. C. Gordon

K. Yee

Center for Consumer Product Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D C. 20234

Issued February 1980

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Executive Summary

At the request of the National Aeronautics and Space

Administration (NASA), the National Bureau of Standards,

Center for Consumer Product Technology conducted an

evaluation to determine the possible effects of carbon

fibers on consumer major and small appliances. An economic

risk assessment to be performed by NASA will weigh the fuel

savings from using ligher weight carbon fiber materials in

aircraft and motor vehicles against the possible dollar loss

of equipment damaged by crash released fibers and any

possible injuries. The NASA program includes avionics in

both aircraft and airports, power stations, computers,

hospital equipment and home equipment including appliances.

This information collected on appliances is a small part of

the data necessary for NASA to complete the economic risk

assessment on the future use of carbon fiber composite

materials.

Available market statistics were used to estimate total

depreciated dollar value in U.S. homes of $50 billion for

major appliances and $10 billion for small appliances.

These corresponding values for 1985 are projected to be

nearly $100 billion for major appliances and $20 billion for

small appliances. The appliance categories (types) that

make up 80% of this estimated value were determined and

specific models of each category which were typical of the

current design and construction were obtained for analysis

and laboratory evaluation. A total of 59 appliances were

examined during the study. The selection criteria was

chosen to allow this limited study to assess the effects of

fibers on the largest possible dollar value of appliances.

The analysis determined potential faults and hazards

that might be caused by fibers infiltrating appliances. In

the 47 non-electronic appliances examined, 23 potential

faults were detected. Twenty of these faults would be of

little significant consequence such as false signals from an

indicator light or a false buzzer signal. The remaining

three faults could result in possible equipment malfunction.

Forty-seven of the 59 appliances were amenable to

evaluation by probe testing and analysis. A diagrammatic

view of the evaluation is shown in Figure ( i)

These 47

appliances collectively contained 732 potential hazards.

However, because of constraints such as fiber length, node

spacing to the nearest conductive surfaces, surface finish

and protective environmental enclosures, only 53 of these

i
nodes pose significant risk of shock hazard. These 53

potential hazardous nodes must be tempered by the type of

power connection. Of the 53 hazardous nodes, 37 represent a hazard only if the power supply ground systems are violated.

The remaining 16 hazardous nodes were found in nine small

appliance models having no provision for grounding. Whether

these 16 hazardous nodes would result in electrical shock to

users would depend on a fiber shorting the node to the case

and the user touching the case and simultaneously touching a grounded conductor with another part of the body. The

probability of these conditions was not evaluated in this

study

.

Sixteen of the appliances selected for evaluation were

not amenable to quantifying the potential faults and hazards

by means of probe testing and analysis. Ten of these 16

models representing several appliance categories were

recommended for carbon fiber chamber testing to determine

faults and hazards. Some of the reasons for selecting these

models for chamber testing are:

1. Initial evaluation of models containing electronic

controls indicated that potential faults were too

numerous to analyze;

2. Some appliances contain internal, bare bus-bar wiring

which have numerous possibilities for fiber connections

as compared with a typical node;

3. Some appliances contain uninsulated heater wires which

are exposed to various amounts of fan or convection

forced air and also have numerous possibilities for

fiber connections; and

4. Some representative models were chosen to quantify the

fiber exposure required to cause a fault or hazard as

an indication of the vulnerability of this appliance

category and others of similar construction.

Many of the potential hazards identified will require

substantial further analysis to quantify the potential risk.

Some of this analysis will be performed as part of the

continuing MBS technial support to the NASA carbon fiber

program

.

ii
47 APPLIANCE MODELS EXAMINED

BY PROBE-TESTING AND ANALYSIS

268 NODES WITH SPACING

GREATER THAN 20mm

If fiber length <20mm

APPROXIMATELY

198 NODES WITH

SPACING OF 5mm

OR LESS

158 NODES

ADJACENT TO BARE

METAL SURFACES

53 NODES IN AN

OPEN OR FAN- FORCED AREA

16 NODES

SUSCEPTABLE

TO GROUNDING

VIA FIBER

If fiber length 5 5 mm

40 NODES ADJACENT TO PAINTED

OR ENAMELED SURFACES (If coated surface

provides electrical insulation

105 NODES IN AN ENCLOSED AREA

(If transfer function into enclosed area is low)

37 NODES LOW PROBABILITY

OF HAZARD (If properly grounded]

9 Portable appliance hazards not affected

by grounding system

Figure i. Diagram of potential shock hazards.

iii

\
Table of Contents

page

Executive Summary , i

1.0 Introduction 1

1.1 Background ........... 1

1.2 Scope ....... .... 1

2.0 Approach 3

2.1 Appliance Selection . 3

2.2 Laboratory Evaluation 3

3.0 Appliance Selection 5

3.1 Objectives for Selecting Categories .... 5 3.2 Value of Appliances in Households in 1977 . 5 3.2.1 Saturation 6

3.2.2 Economic Life 6

3.3.3 Cumulative Value ..... 10

3.3.4 High Growth Rate 10

3.3 Selection of Appliance Categories for

Laboratory Evaluation 13

3.4 Future Market Trends and Technology Changes 17

3.4.1 Predicted Saturation 17

3. 4. 1.1 Major Appliances 17

3. 4. 1.2 Small Appliances ...... 22

3.4.2 Units-in-the-Field 22

3.4.3 Cumulative Value 25

3. 4. 3.1 Major Appliances 25

3. 4. 3.

Small Appliances 25

3.4.4 Technology Change 25

3.5 Selection of Makes and Models for Laboratory

Evaluation 28

3.5.1 Criteria . 28

3.5.2 Method 29

3.3.3 Appliances Evaluated 29

iv
page 4.0

Test and Analysis £5

4.1 Introduction 65

4.2 Standard Product Analysis 65

4.2.1 Appliance Hazard Evaluation ..... 55

4. 2. 1.1 Analysis 70

4.2. 1.2 Test Procedure 74

4. 2. 1.3 Suggested Data Evaluation . 84

4.2.2 Appliance Fault Evaluation ..... 86

4. 2. 2.1 Output Devices 86

4. 2. 2.Control Devices ...... 90

4. 2. 2. 2.1 Primary Controls 90

4. 2. 2. 2.

Secondary Controls 93

4. 2. 2. 2.

Auxiliary Controls 94

4. 2. 2.

Test Procedure 95

4.3 Small Appliances Evaluation 98

4.3.1 Hazard Evaluation 98

4.3.2 Fault Evaluation 101

4.4 Electronic Controls Evaluation 101

4.4.1 Clothes Dryer , 103

4. 4. 1.1 Hazard Analysis 107

4. 4. 1.2 Fault Analysis . 109

4.4.2 Clothes Washer , . . , . , , , . . , 110

4. 4. 2.1 Hazard Analysis ...... 114

4. 4. 2.Fault Analysis . 114

4.4.3 Dishwasher 115

4.4.4 Cooking Range 115

4.4.5 S elf -Cleaning Oven 118

4.4.6 Microwave Ovens , , . , 122

4. 4. 6.1 Hazard Analysis ...... 122

4. 4. 6 .Fault Analysis ...... 125

4.4.7 Blender 125

4.4.8 Test Method Analysis 127

4. 4.

8.1

Proposed Test 129

. 4, 4, 8 ,

Test Analysis , 130

v
page

4.4.9

Other Electronic Products (Smoke

Detectors) . , 130

5 .

4.5 Future Product Design Trends ±J 3

4.6 Recommended Chamber Tests 136

General Summary of Faults and Hazards , 139

5.1 Refrigerators Summary

5.2 Clothes Washers Summary

5.3 Electric Ranges Summary , . . 5.4 Freezers Summary

5.5 Dishwasher Summary , . , , . 5.6 Clothes Dryers Summary ...........

5.7 Microwave Ovens Summary ..........

5.8 Small Appliances

5.9 Vacuum Cleaners Summary . . , 5.10 Hand Irons Summary . , , , , 5.11 Toasters and Toaster/Ovens Summary , . , , . 5.12 Food Mixers , , . . 5.13 Fry Pans Summary

5.14 Coffee Makers Summary ...........

5.15 Electric Blanket (Bed Covers) Summary , , , 5.16 Food Blender Summary , . 5.17 Can Openers Summary . . . 5.18 Heaters . , , , 5.19 Smoke Detectors ..............

143

1*45

£48

150

151

155

157

159

159

162

164

165

167

167

171

171

173

175

175

i

vi
List of Tables

P a g. e. Table 3.1 1977 Saturation, by Appliance Category

and Number of Appliances in the Field

7 Table 3.2 Economic Life and Depreciated Value of

of Clothes Washers in the Field in 1977

8

Table 3.3 Estimated Appliance Economic Lives 9

Table 3.4 Saturation by Year for Microwave Ovens 14

Table 3.5 Projected Annual Sales, Depreciated Value

Retail Value of Toaster Over 12 Year

Economic Life

20

Table 3 .Major Appliances —A comparison of

estimated appliance statistics for

1977 and 1985

16

Table 3.7 Small Appliances —A comparison of

estimated appliance statistics for

1977 and 1985

24

Table 3.8 Major Appliance Manufacturers 30

Table 3 .Small Appliance Manufacturers Market Share

and Ranking

32

Table 3.10 List of Major Appliances Evaluated 34

Table 3.11 List of Small Appliances Evaluated 37

Table 5 .

Summary Table of Findings--Appliance

Categories Examined

142

GRAPHITE FIBER HAZARD AND FAULT SUMMARY TABLES BY PRODUCT

Table 5 .

Refrigerator-Freezers 144

Table 5.2 Clothes Washers 146

Table 5.3 Ranges 149

Table 5.4 Fr eez er s 152

Table 5 .

Dishwashers 153

Table 5 .

Clothes Dryers 156

Table 5.7 Microwave Ovens 158

Table 5 .Vacuum Cleaners 160

Table 5.10 Hand Irons 163

Table 5.12 Food Mixers 166

Table 5.13 Fry Pans 168

Table 5.14 Coffee Makers 170

Table 5.15 Electric Blanket 172

Table 5.17 Can Openers 174

Table 5 . 18 Portable Heaters 176

vii
List of Figures

page

Figure i

.

Diagram of potential shock hazards iii

Figure 3.1 Cumulative Values of Major Home Appliances

in the Field in 1977

11

Figure 3.2 Cumulative Value in Billions($) for

Small Appliances in the Home in 1977

12

Figur e 3 .3 Flowchart for Estimating Future

Saturation Levels for Ranges, Dryers,

Freezers, and Disposals

18

Figure 3.4 Flowchart for Estimating Future

Saturation Levels for Method for

Projection: Dishwashers, Clothes Washers

Microwave Ovens

21

Figur e 3 . 5 Projected Product Saturations (1978-1985) 15

Figure 3 . 6 Projected Small Appliance Saturation

Versus Year

23

Figure 3 . 7 Project Cumulative Values of Major Home

Appliances in the Field in 1985

26

Figure 3 . 8 Projected Cumulative Values in Billion($)

for Small Appliances to be in U.S, Homes

in 1985

27

PHOTOGRAPHS OF TESTED MODELS

Figure 3 .

9

Refrigerator RF-1 39

Figure 3 .10 Refrigerator RF-2 39

Figure 3 . 11 Refrigerator RF-3 40

Figure 3 .12 Clothes Washer CW-1 40

Figure 3 .13 Clothes Washer CW—

2

41

Figure 3 .14 Clothes Washer CW-3 41

F igu r

e

3 . 15 Clothes Washer CW-4 42

Figure 3 .16 Electric Range RA-1 42

F igur

e

3 . 17 Electric Range RA—

2

43

Figure 3 . 18 Electric Range RA-3 43

Figure 3 .19 Dishwasher DW-1 44

Figure 3 .20 Dishwasher DW-2 44

Figure 3 . 21 Dishwasher DW-3 45

Figure 3 . 22 Freezer FZ-1 45

Figure 3 . 23 Freezer FZ-2 46

Figure 3 . 24 Clothes Dryer CD-I 46

Figure 3 .25 Clothes Dryer CD-2 47

Figure 3.26 Clothes Dryer CD-3 47

Figure 3 .27 Clothes Dryer CD-4 48

Figure 3 . 28 Mic rowav e Oven MOV-1 48

Figure 3 .29 Microwave Oven MOV-2 49

viii
Figure 3.30 Vacuum Cleaners VC-1 49

Figure 3.31 Vacuum Cleaner VC-2 50

Figure 3.32 Vacuum Cleaner VC-3 50

Figure 3.33 Hand Iron HI-1 51

Figure 3.34 Hand Iron HI-2 51

Figure 3.35 Hand Iron HI-3 52

Figure 3.36 Hand Iron HI-4 52

Figure 3.37 Toasters T0-1 53

Figure 3.38 Toasters T0-2 53

Figure 3.39 Toasters TO-3 54

Figure 3.40 Toasters TO-4 54

Figure 3.41 Toaster Ovens T0V-1 55

Figure 3.42 Toaster Ovens T0V-2 55

Figure 3.43 Toaster Ovens T0V-3 56

Figure 3.44 Food Mixers FM-1 56

Figure 3.45 Food Mixers FM-2 57

Figure 3.46 Food Mixers FM-3 57

Figure 3.47 Fry Pans FP-1 58

Figure 3.48 Fry Pans FP-2 58

Figure 3.49 Fry Pans FP-3 59

Figure 3.50 Coffee Makers CM-1 59

Figure 3.51 Coffee Makers CM-2 60

Figure 3.52 Coffee Makers CM-3 60

Figure 3.53 Coffee Makers CM-4 61

Figure 3.54 Coffee Makers CM-5 61

Figure 3.55 Bed Covers (Electric Blanket) EB-1 62

Figure 3.56 Blenders FB-1 62

Figure 3.57 Can Openers C0-1 63

Figure 3.58 Can Openers C0-2 63

Figure 3.59 Smoke Detectors SM-1 , SM-2 , SM-3 , SM-4 64

Figure 3.60 Smoke Detector SM—5 64

Figure 4.1 Length Factor Hazard Analysis 71

Figure 4.2 Circuit Configurations & Hazard Matrix 73

Figure 4.3 Open Wire Heaters Hazard Analysis 78

Figure 4.4 Open Wire Heaters Hazard Analysis 78

Figure 4.5 Fault Analysis Output Devices —Single 87

Figure 4.6 Output Devices —Series Fault Analysis 89

Figure 4.7 Secondary Controls Fault Analysis 92

Figure 4.8 Secondary Controls Fault Analysis 92

Figure 4.9 Clothes Dryer Electronic Control CD-4 104

Figure 4.10 Electronic Clothes Dryer Control 105

F igur e 4 . 11 10 6

Figure 4.12 Clothes Dryer — Pencil at TP-1 108

Figure 4.13 CW-4 Electronic Control Clothes Washer 111

Electronic Power Circuits

Figure 4.14 Electronic Control Clothes Washer 112

Electronic Input Circuits

Figure 4.15 Tech Sheet--Reta in for Service Technician 113

ix
Figure 4.16 Installed in Dishwasher 116

F igur e 4.17 Soldered Sides 116

Figure 4.18 Component Sides 116

Figure 4.19 117

Figure 4 .20 Electronic Control Range Circuit Board 119

Figure 4 .21 RA-1 Electronic Range Control 120

Figure 4 . 22 RA-1 Electronic Control Range 121

Figure 4 .23 Electronic Control Left Cleaning Range 123

Figure 4 . 24 Self Cleaning Range 124

Figure 4 .25 Appliance Electronic Control Circuits 126

Figure 4.26 Blender Circuit Board 126

Figure 4.28 Battery Operated Smoke Alarm 131

Figure 4 .29 Photoelectric Smoke Detector Schematic

C ir cu i

132

X
A STUDY OF THE EFFECTS OF

CARBON FIBERS 1.0 ON HOME APPLIANCES

Introduction

1 . 1 B ackground

Carbon fibers are being used in a new generation of

composite materials. These carbon fibers are finer than

human hair, fairly good electrical conductors and virtually

indestructable . They are so light and millions are

contained in a gram mass. The composite materials have

opened a wealth of opportunities in structural engineering

application for many products including consumer products

(skis, fishing rods, golf clubs, tennis rackets, etc.) motor

vehicles and aircraft. The potential benefits of carbon

fibers are many-fold including high strength and light

weight. Use of these new materials in military and

commercial products are expected to result in energy savings

and increased safety. In the next decade, composites may

become as important to the United States economy as the

steel and aluminum they replaced.

Unfortunately, these benefits are not without possible

risk. With the expected rapid growth in the use of carbon

fiber material in aircraft and automobiles, vehicle

accidents followed by fires could become a possibly

substantial source of fiber release. If released into the

air, fibers can easily be transported by winds. If these

fibers come in contact with electrical devices, they can

create undesirable conductive circuits or initiate arcs. A

variety of actual incidents have occurred supporting the

hazards carbon fibers pose to electrical equipment. These

fibers may cause improper operation of a device or they may

cause potentially lethal voltage to be present on the device

case. The National Bureau of Standards (NBS) , in support of

National Aeronautics and Space Administration (NASA) Langley

Research Center, has performed tests and analysis to

determine what adverse effects could occur if carbon fibers

infiltrate the electrical circuitry of home appliances.

1 . 2 S cope

The Product Performance Engineering Division, Center

for Consumer Product Technology (CCPT), National Bureau of

Standards, followed a work plan as agreed to with personnel

of NASA Langley Research Center (LaRC). This work plan was

designed to accomplish the following:

1
1. Evaluate present appliance design which might be

susceptable to harmful effects from carbon fibers and

estimate the value of existing products in homes.

2. Test representative samples of current production for

susceptability to carbon fibers.

3. Estimate future sales trends and design technology.

The scope of this work does not include an assessment

of the risk of disseminating carbon fibers from an accident

source into the circuitry of household appliances, but

rather, the intent of this study is to document what may

happen if carbon fibers should enter the electrical

circuitry of household appliances.

The results of this evaluation will be used by NASA as

a part of an economic risk assessment as to the expected

future dollar loss of product/equipment due to carbon fibers

and to make trade-off decisions between anticipated benefits

and potential risk caused by accidental fiber dissemination

inherent with the extensive use of carbon fiber composite

material

2
2 .

Approach

2 . 1 Appliance Selection

To provide NASA with useful data for an economic risk

assessment, a market survey was made to select appliance

categories (types) accounting for 80$ of the total dollar

value of appliances currently in U.S. households.

To obtain this estimated 80 $ of total dollar value,

appliance statistics were examined to ascertain or estimate

1) saturation levels, 2) saturation growth trends, 3) annual

sales, 4) forecasted annual sales, 5) average unit cost, 6)

inflation trends and 7) estimate economic life. Appliances

were ranked by estimated dollar value in household based on

saturation and average unit cost. Two lists were compiled.

One list consists of electrical major appliances which

account for 80$ of the total dollar value of all major

appliances in U.S. households. The second list consists of

small (or portable) appliances which account for 80$ of the

value of all small appliances currently in U.S. households.

The two final lists of selected appliances to be evaluated

in this program were approved by NASA.

Since the cost and time required to evaluate each model

within every selected appliance ctegory is not economically

justifiable, at least three models from each category that

are representative of the technology used in most of the

current appliances in that category found in U.S. households

were selected for evaluation. To give adequate

consideration to both expected future dollar loss and future

vulnerability, rapid growth appliances and appliances having

technologies, which are susceptible to adverse effects of

carbon fibers, were selected for evaluation, respectively,

regardless of the current market share. For each selected

category the projected saturation and the projected dollar

values of appliances expected to be in the field by 19 85

were estimated. These values will assist NASA inmaking an

economic risk assessment as to the cost of failure of

appliances due to carbon fibers.

2 . 2 Laboratory Evaluation

Major and small appliances were evaluated for faults

and electrical shock hazards due to node-to-node and nodeto-case electrically conductive paths. The evaluation

included both an analytical evaluation of control circuitry

and actual probing of the circuits with a test instrument

3
which simulates the electrical properties of a carbon fiber.

All circuits, with the exception of some electronic controls

were analytically evaluated to identify those nodes where

probing for faults would yield useful information. Each

circuit which was probed was also evaluated analytically to

determine if there were any improper operations not

detectable by probing with the carbon fiber simulator.

Data necessary to determine potential shock hazards

were evaluated by measuring the spacing to ground for all

uninsulated parts and by evaluating the ground integrity of

all touchable metallic parts. The coating of these surfaces

were noted and also the environment around the potentially

hazardous nodes, including the expected air currents, and

the degree of protection to infiltration of carbon fibers.

Appliance circuit diagrams were reviewed to ascertain

the number of nodes and the amount of included electronic

circuitry. If the number of nodes exceeded 100 or if the

electronic controls were judged to be too complicated for

probing with the carbon fiber simulator, that appliance was

recommended for chamber testing by NASA. The results of the

identified faults and shock hazards are to be used by NASA

in combination with the transfer function data, developed in

the chamber to assess the level of risk.

4
3 . 0 Appliance Selection

j

3 . 1 Objectives for Selecting Categories

The objectives for category selection are:

1. to identify two lists of appliances which,

separately, account for 80% of the total

depreciated dollar value of major appl iances and

small appliances currently found in U.S.

households

.

2. to identify appliance categoreis having

significant growth trends which indicate a substantial future saturation. These identified

categories were included regardless of their

current saturation levels.

These objectives were established to be compatible with

the overall objective of making an economic risk assessment.

3 . 2 Value of Appliances in Households in 1977

The value of appliances in U.S. households is

determined by 1) the actual age of the appliance, 2) the

estimated economic life and 3) the retail price at the time

of purchase. Any appliance which remained in service, but

had an age greater than the estimated economic life, was

assumed to have no economic value. Also any appliances

which may have been removed from service before the

completion of their service life were not deducted from the

existing appliance stock. The value of appliances in U.S.

households is an estimate based on a systematic analysis of

readily available appliance statistics. There was no

attempt to refine the analysis for second order factors

which have a minimal effect on estimated value.

A nonrepair able failure of an appliance will not result

in a loss equivalent to the current retail price of an

appliance nor will such a loss be equivalent to the initial

purchase price. The economic value of an appliance at any

age is assumed to be the book value as determined by the

"straight line depreciation method."

Eighty percent of the total dollar value of appliances

in U.S. households is based on the cumulative depreciated

dollar value of all electrical major and small appliances

sold during the years prior to the evaluation year for a

5
number of years equal to the economic lifetimes of the

various appliance categories.

3-2.1 Saturation

Saturation is the percent of households having a particular appliance. Appliance statistics from

"Merchandising" magazine were reviewed to ascertain

those appliance categories with high i saturation

values. An appliance category having high saturation

values in conjunction with high, average unit cost are

significant contributors to the total estimated value

of major appliances in U.S. households. Major

appliances and small appliances were ranked separately

according to high saturation and high unit cost to

identify those appliance categories that are the most

significant contributors to the total value of

appliances in U.S. households. The saturation of

appliances and the number of units in the field for

both major and small appliances are shown in Table 3-1.

3.2.2 Economic Life

Before the total dollar value of appliances in

U.S. households could be estimated, some reasonable

estimate of economic life for each appliance category

was necessary. The following computational procedure

was developed to estimate the economic life for each

category

Starting with 1977 annual sales data, the number

of units sold annually for each particular category

were summed until the cumulative number of units sold

matched the estimated total units in the field in 1977.

The number of sales years required for cumulative sales

to equal this total defined the economic life of the

particular appliance category. An example of this

summation for clothes washers is shown in Table 3-2.

Using the above procedure, the economic life of

each appliance category was estimated and is shown in

Table 3-3. Any appliance remaining in service beyond

its economic life as defined above was assumed to have

no economic value for the purpose of this study.

6
Table 3 ,1

1977 Saturation, by Appliance Category

and Number of Appliances in the Field

Major Electrical Appliances

Units

in Field

(million)

1977 Saturation

(%)

1 . Refrigerators 75.8 99 . 9

2 . Clothes Washers 55.8 73 .3

3. Electric Ranges 41.4 5 5.8*

4. Freezers 28 . 9 38 .

5. Dishwashers 28 .37 . 0

6. Clothes Dryers 32.1 42.3*

7 . Room Air Conditioners 25 .

33 . 0**

8 . Microwave Ovens 6.2 8 . 2

9 . Disposals 22.3 29.5

Small Appliances

1

Vacuum Cleaners 75.8 99 . 9

2 . Irons 75.8 99 . 9

3 . Toasters 75.4 99 .

4 . Food Mixers 69.1 91 .

5 . Fry Pans 48 .

63 . 6

6. Coffee Maker

75.4 99 . 4

7 . Bed Covers 44.5 58 . 6

8 . Blenders 36.1 47 . 6

9 . Can Openers 42.8

' 56.4

1 Source: Merchandising, the 56 statistical issue and marketing

report, March 1978.

* Source: Merchandising, March 1978, based on utilities' estimates.

** Sears, "Department of Energy / S ear s , Roebuck and Company Meeting,"

July 20, 1978.

7
Table 3,2

Economic Life and Depreciated Value

of Clothes Washers in the Field in 1977

Saturation: 73.3%

Year

Units in Field:

Economic Life:

Units Shipped Average Cost

(Millions) per Unit ($)

55.5 Million

12 yr s

Depr ec iat ion

Fac tor

Depreciated

Value ($ M)

1966 4.446 228 1/12 84 .

1967 4.323 235 2/12 169.3

1968 4.482 239 3/12 267 .8

1969 4.379 238 4/12 347.4

1970 4 .094 234 5/12 400.87

1971 4 .609 234 6/12 538 .

1972 5 .107 237 7/12 706.0

1973 5 . 504 245 8/12 8 99.0

1974 4.948 257 9/12 953 . 7 1975 4 .228 318 10/12 1120.4

197 6 4.492 348 11/12 1433.0

1977 4 . 933 363 12/12 1790.6

TOTALS 55.5 8711 . 57

Cumulative value o f retail sales over the last 12 years:

$11,366 billion.
Table 3 .3

Estimated Appliance Economic Lives

Major Home Appliance

Refrigerator

Clothes Washer

Range

Freezer

D i shwa sher

Clothes Dryer

Room Air Conditioner

Microwave Oven

Disposal

Economic Life (yrs)

15

12

18

20

10

15

6

8

9

Small Home Appliance

Vacuum Cleaners

Irons

Toasters

Food Mixers

Fry Pan

Coffee Makers

Bed Covers

Blender

Can Openers

Economic Life (yrs)

9

10

12

15

7

7 10

8

8

9
3.2.3 Cumulative Value

The cumulative sales values were based on a double summation. First, the annual retail dollars

were summed for each sales year that was within the

economic life of the particular appliance category.

Secondly, these resulting totals were summed over each

appliance category to obtain the cumulative sales

value

The cumulative depreciated value of the appliance

was based on straight-line depreciation using the

procuct of the annual retail sales and the ratio of

remaining life to the estimated economic life and the

average unit cost. The resulting depreciated values

were summed for each sales year within the estimated

lifetime of the particular appliance category. The

cumulative depreciated value was obtained by summing

these totals for each appliance category. The

cumulative depreciated values or major appliances range

from about 50 % to 65 % of the cumulative retail values.

Figures 3.1 and 3-2 show the cumulative dollar

values of the most significant electrical, major and

small appliances in U.S. households. The cumulative

depreciated value of these appliances is estimated to

be $46.5 billion and $10.5 billion for the major

electrical appliances and small appliances

respectively. If additional major electrical appliance

and small appliance categories were considered, the

cumulative depreciated values would approach but

probably not exceed $50 billion for the major

electrical appliances and $11 billion for the small

appliances.

The dotted line in Figures 3.1 and 3.2 represents

the cumulative retail values of the electrical major

appliances and the small appliances purchased during

the economic life of the respective appliance. Neither

the cumulative retail values nor the cumulative

depreciated values are adjusted to 1978 dollars, since

the adjustment would not change the appliance

categories selected.

3.2.4 High Growth Rate

Since the output of this study will be used to

assess the future dollar loss to appliances due to

adverse effects of carbon fibers, it is essential that

appliance categories having significant growth trends

10
IN

THE

FIELD

IN

1977

09

093 09

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jo;eja 6 ujay

$ uojjiiy ui san|BA aAjiBjnuinQ

li

Major

Home

Appliances
CUMULATIVE

VALUE

IN

BILLIONS($)

FOR

SMALL

APPLIANCES

IN

THE

HOME

IN

1977

09

09

IX + Sjaddoj ujoq

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Al + suej Aj^

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12

Small

Appliance

Categories
to be identified such that their contribution to the

total dollar value of appliances expected to be in the

field by 1985 can be quantified. Appliances which have

significant growth rates and are predicted to have

significant saturation by 1985 were selected for test,

although the dollar value of the particular category of

appliance presently in the field may be small compared

with other appliance categories. Appliances which meet

these criterion are microwave ovens and smoke

detectors. Table 3.4 shows the saturation of microwave

ovens between 1971 and 1977. The projected growth in

saturation can be observed from Figure 3.5. Although

the present (1977) saturation is less than 10%, it is

expected to reach a saturation level of approximately

45% by 1985. This projected growth for microwave ovens

is based on sales forecasts obtained from the

"Appliance" magazine (January 1978). Microwave ovens

are expected to contribute about $5 billion out of a total of $100 billion projected depreciated value for

major appliances in 1985.

Annual sales data for smoke detectors for 1977

was 6.4 million units and the projected sales are 8 and

8.8 million units for 1978 and 1979, respectively.

Many county cooes are rapidly legislating smoke

detectors into use and there is a rapid growth in

public awareness of protection which smoke detectors

provide. Its saturation is expected to be significant

by 1985.

3 . 3 Selection of Appliance Categories for Laboratory

Evaluation

The selection of appliances for laboratory evaluation

consisted of identifying those appliance categories which

satisfy the selection criteria discussed previously. The

major electric al appliance categories collectively

satisfying the criteria of significant ( 80 %) dollar value

were identified by the use of Figure 3.1. These appliance

categories are: 1) refrigerators, 2) clothes washers, 3)

electric ranges, 4) freezers, 5) dishwashers, and 6) clothes

dryers. Although total dollar value of microwave ovens

currently found in U.S. households is presently low in

comparison with other major household appliances, microwave

ovens has been selected for evaluation because of the

projected growth in saturation. As shown in Table 3.6, the

total depreciated dollar value for microwave ovens is

expected to approach the $10 billion level by 1985.

13
Table 3.4

Saturation by Year for Microwave Ovens

Year Saturation

1969 —

1970 —

1971 0 . 2 1972 0.6

1973 1.2

1974 2.2

1975 3 . 2 1976 5 . 1

1977 8,2

Same as 111 •

14
PROJECTED PRODUCT SATURAT10 NS (1978-1985)

15
Estimated

Appliance

Statistics

for

1977

and

1985 ' 3o m tH

H 33 0 0 pH CN r*.

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a) pH pH cn CN pH rH rH rH 3 H

pH 32

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pH

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16 1
Small appliance categories satisfying the criteria of

significant (80%) dollar value were identified by the use of

Figure 3.2. The 80% line drawn on Figure 3.2 results in the

selection of sevn appliance categories which are estimated

to account for 80% of the total depreciated dollar value of

appliances currently found in U.S. households. These seven

appliance categories are 1) vacuum cleaners, 2) irons, 3)

toasters, 4) food mixers, 5) fry pans, 6) coffee makers and

7) electric bed covers. Smoke detectors exhibited

significant growth in annual sales and were selected

regardless of their present contribution to the total dollar

value of small appliances currently found in U.S.

households

3 . 4 Future Market Trends and Technology Changes

Since one of the overall objectives of the carbon

fiber program is to make an economic risk assesment as to

the probable future dollar loss of household appliances due

to adverse effects of carbon fibers, an assessment as to the

future dollar worth of appliances and the future category

mix is necessary. Otherwise one may spend time and effort

evaluating an appliance which is obsolete and has not future

market sign if icancy . To select and evaluate appliances

which have relevance to the economic and hazard

vulnerability of future appliances, saturation growth trends

were plotted and technology advances were noted.

3.4.1 Predicted Saturation

Various methods were used to estimate future

saturation values. The availability of data and the

potential contribution of the particular appliance to

the expected total value were primary considerations in

developing the various methods for estimating future

saturation levels.

3. 4. 1.1 M ajor Appliances : Figure 3.3 shows a flow diagram of the method used to estimate

saturation by year for ranges, clothes dryers,

freezers, and disposals. The basic data that

were used to estimate the annual saturation were

the projected households and the extrapolated

values of the 1975 saturation levels. The

product of the number of projected 1985

households and the extrapolated, 1985 saturation

is the estimated number of units that will be in

the field by 1985. The difference between the

17
FLOWCHART FOR ESTIMATING FUTURE SATURATION LEVELS

FOR RANGES, DRYERS, FREEZERS, AND DISPOSALS

Figure 3.3

18
total number in the field in 1977 (with economic

life extending into 1985) and the number in 1985

gives the estimated total units to be sold

between 1977 and 1985. The projected average

annual sales were obtained by dividing the total

estimated sales between 1977 and 1985 by eight,

the number of sales years between 1977 and 1985.

A sample calculation of the average projected

annual sales for toasters is shown in Table 3.5.

Each year's appliance stock (total units in

U.S. households) is equivalent to the summation

of the annual units sold during the number of

previous years equal to the economic lifetime of

the particular product. Therefore, the future

appliance stock was calculated by adding the next

year's annual sales to the current year's

appliance stock and deducting the units sold for

the sales year which is just beyond the lifetime

of the product. The annual saturation levels

were obtained by dividing the estimated future

appliance stock by the corresponding projected

households

A slightly different method was used to

predict the saturation levels for refrigerators,

dishwashers, clothes washers, and microwave

ovens. This method was formulated to effectively

use the forecasted sales published in the January

1978 issue of "Appliance" magazine. The forecast

covers the five-year period between 1977 and

1982 . Figure 3 • ^ shows a flowchart of the

procedure used to estimate the future annual

saturation values. The future appliance stock

was calculated by adding the next year's

forecasted sales to the current appliance stock

and deducting the units sold for that sales year

which is one year beyond the economic lifetime of

the particular product. The yearly calculated

appliance stock was divided by the future housing

stock to obtain the projected annual saturations

between 1977 and 1982. Saturations between 1982

and 1985 were obtained by extrapolat ion

The projected annual saturation values

calculated by the above procedure are shown in

19
Table 3.5

Projected Annual Sales, Depreciated Value,

Retail Value of Toaster Over 12 Year Economic Life

Numb et

Shipped

Year (Million)

Retail

Value

( $ Billion)

Fractional Depreciated

Cost per Remaining Value

Unit ($) Value ($ Million)

1972 6. 650 .1130

1973 6.845 .1164

1974 7.177 . 1435

1975 6.204 .1438

1976 7.397 . 1767

1977 7 .400 .1895

1978 7 . 53 .203

1979 7 . 53 . 218

1980 7 . 53 . 233

1981 7 . 53 .248

1982 7 .53 . 271

1983 7 . 53 . 286

1984 7 . 53 .308

1985 7 . 53 .331

TOTAL 2.751

Product Category

Toasters

Projected Saturation: 99%

Projected Units in-Field: 88.4

Estimated Economic Life: 12

7% Inflation Rate

Average Projected Annual Sales =

18 . 51

17 . 01

19.99 1/12 *12

23 .18 2/12 24

23.89 3/12 44

25 . 61 4/12 63

27 .00 5/12 85

29.00 6/12 109

31 . 00 7/12 136

33.00 8/12 165

36.00 9/12 203

38.00 10/12 238

41.00 11/12 282

44 . 00 12/12 331

1772

88.4 - (7 .17 + 6.2 0+7 .4+7 .4)

1983 Retail Value of Units Sold Over Lifetime of the Product:

$2,751 Billion

1985 Depreciated Value of Units in the Field: $ 1.772 Billion
FLOWCHART FOR ESTIMATING FUTURE SATURATION LEVELS

FOR METHOD OF PROJECTION:

DISHWASHERS, CLOTHES WASHERS, MICROWAVE OVENS

ADD ANNUAL

FUTURE SALES

PREDICTION

PROJECTED UNITS

IN FIELD BY YEAR

FUTURE HOUSING

STOCK PROJECTION

BY YEAR

SATURATION

BY YEAR

DEDUCT UNITS THAT

ARE ONE YEAR

BEYOND THEIR

ECONOMIC LIFE

Figure 3.4

EXISTING UNITS

IN FIELD

21
Figure 3.5. A comparison of the projected 1985

saturation values with the 1977 saturation values

for each appliance category is shown in Table

3.6.

3. 4. 1.2 Small Appliances : The projected

saturation values for blenders, can openers,

electrical bed coverings, and fry pans were

estimated by averaging for each product, the

growth rate in saturation of the five years prior

to 1977 and projecting this constant growth rate

over the next eight years. These saturation

values are plotted in Figure 3.6. The saturation

growth rate for these four products range from 1 %

for fry pans to 1.7% for blenders.

For food mixers which have a higher

saturation, one half of the saturation growth

rate for the five years prior to 1977 was

projected over the next eight years. The

estimated, average projected growth rate over the

next eight-year projection period is 0.7% per

year. The projected saturation values for food

mixers are also plotted in Figure 3-6.

A constant saturation of about 99% is

projected for vacuum cleaners, toasters, irons

and coffee makers. A comparison of the 1985

projected saturation values and the 1977

saturation values are shown in Table 3.6.

3.4.2 Units-in- the- Field

An estimated number of units expected to be in

the field in 1985 is essential to an economic risk

asessment as to the probable dollar loss of appliances

due to adverse effects of carbon fibers. Such an

estimate is the product of the projected 19 85

saturation levels and projected 1985 households. The

number of projected households was obtained from the

U.S. Department of Commerce report, "Projection of the

Number of Households and Families 1975 to 1990." The

number of households in 1985 is estimated at 88.5

million. For each appliance category the total units

estimated to be in the field by 1985 is shown in Table

3.6 for major appliances and Table 3.7 for small

appliances. Also these projected cumulative values for

1935 are compared with the corresponding estimated

22
%

Saturation

PROJECTED SMALL APPLIANCE SATURATION VERSUS YEAR

23
Small

Appliance

A

Comparison

of

Estimated

Appliance

Statistics

for

1977

and

1985

24
cumulative values for 1977, which are shown in Tables

3 . 6 and 3.7.

3.4.3 Cumulative Value

3. 4. 3.1 Major Appliances : The 1985 projected

cumulative sales and the 1985 projected

cumulative depreciated values for major

appliances are shown in Figure 3-7. The

cumulative retail values approach the 160 billion

dollar level while the cumulative depreciated

value approaches the 100 billion dollar level.

These cumulative values were determined according

to the procedure previously described for the

1977 cumulative values. The projected annual

sales derived as part of the saturation

prediction and an annual inflation rate of 7% per

year for the unit cost were used as a basis of

estimating the cumulative retail value and

cumulative depreciated values.

3. 4.3.2 Small Appliances : Projected cumulative

dollar values for small appliances approaches 32

billion dollar for the cumulative retail value

and approaches about 20 billion dollar for the

cumulative depreciated value. These cumulative

values are shown in Figure 3.8.

3.4.4 Technology Change

The most prevalent advanced technology

incorporated in appliances currently being sold is the

electronic control system. Electronic control in

appliances range from the simple inclusion of a solid

state rectifier (diode) in an otherwise

electromechanical system to ul trasophist icated large

scale integrated circuitry including microprocessors.

Because of relative low voltage and current levels

found within electronic controls, infiltrated carbon

fibers may conduct enough current to randomly activate

devices such as switch solenoids and diodes which may

adversely effect normal operation or result in a permanent failure. Electronic controls are the only

identified example of advanced technology that may have

high vulnerability to carbon fiber infiltration.

However, many appliances which incorporate electronic

controls also have capacitance type, smooth touchsurface switches for activating various cycles. This

25
Cumulative

Values

in

Billions

($)

PROJECTED CUMULATIVE VALUES OF MAJO R HO ME_APPLIANCES

IN THE FIELD IN 1985

O

p3£

7

V)w

0) 7

S >

to + >

+

to

03 >

+ > >

M

33ene

ta cc

«c

to

CQs i * s i

5 o

tO£

**Qi

0)w

CJ

to

09>•

tea o

+

cJ<

+

yi(S(AO Q u. cc =L

Vi b

T! X — W — V >

JJ + T 5; = > —

5 s

CJ .e

to

(Q

Figure 3.7

26
PROJECTED

CUMULATIVE

VALUES

IN

BILLION

($)

FOR

SMALL

APPLIANCES

TO

BE

IN

U

S.

HOMES

IN

1985

L

o to

co09 H—

i

iL.

i

iL..

CM

c*» CM CM CM

CM

sjauado ueg

sjapuaig

sja/vog pag

sued Ajj

\ + sjax;|/\| pooj

III+ sjajseoi

||+ SUOi|

|+ sja^eyy aajpg

sjaueaig wnroe/\

($) uoi||;g u; an|e/y a/ujeinumg

27

Small

Appliance

Categories
feature may offer some protection against infiltration

of carbon fibers because there is an absence of

pushbuttons and associated crevasses that enhance

carbon fiber intrusion.

The interaction of any added protection against

carbon fiber intrusion and increased susceptability due

to low current and voltage characteristics of

electronic control systems must be evaluated to

adequately assess the risk of advanced technology

appliances to carbon fibers.

Appliances selected as representative of advanced

technology and examined, incorporate various degrees of

electronic controls from the simplest to the

ul trasophi st icated . The barriers to carbon fiber

transfer range from a button type control panel with

many openings to a smooth, plastic film touch surface

with negligible infiltration paths for carbon fibers.

A dishwasher (DW-3), clothes dryer (CD-4), blender (FE1) , and range (RA-1) were selected as representative of

this changing technology. The range, the dishwasher,

and the clothes washer incorporated finger touch

controls (no buttons) without openings.

3 . 5 Selection of Makes and Models for Laboratory Evaluation

Evaluation of all makes and models within each selected

category was not economically justifiable under the timing

and funding constraints of this study. Therefore selection

criteria we established for identifying makes and models for

laboratory evaluation.

3.5.1 Criteria

Three factors formulated the selection criteria

for makes and models within an appliance category.

First, the selected appliances were to be

representative of at least 75 % of each category of

appliance recommended for testing. Secondly, at least

three models were to be evaluated provided that this

number was consistent with the time and manpower

allocated. Thirdly, models were to be included that

are representative of changing technology which is

likely to account for a significant portion of

appliances in the field by 1985 regardless of the

current saturation levels.

28
3.5.2 Method

Industry sales profiles from "Appliance” [4,5,6]

magazine were examined to identify companies that

collectively accounted for about 75% of the market

sales. These companies are identified in Table 3.8 and

Table 3.9. The sales managers for these companies were

contacted to ascertain their best selling models. Most

sales managers readily divulged their model numbers

which accounted for the largest percent of their sales,

but the exact numerical percentage was not divulged.

In most cases the sales managers indicated that several

models would have to be included to account for 75% of

their sales. An evaluation of several models from each

company would vastly exceed the time and manpower

constraints for this study. Therefore, in most cases,

one model accounting for the highest percent of sales

for each company that collectively make up 75% of the

total sales was selected.

3.5.3 Appliances Evaluated

The availability of models, time and manpower

constraints limited the laboratory evaluation to those

models listed in Tables 3-10 and 3.11 by category and

identifying code numbers. A brief description of the

basic features of each model is given in these tables.

Photographs of each model are shown in Figures 3-9

through 3.60.

29
Table 3.8

Major Appliance Manufacturers

Appliance Percent of Market

1976 1977 1978

Refrigerators

S' r

GE/Ho tpo int 28

Whirlpool 22

< 80 < 85

Whit e-West ing house 18

Frigidaire 9 L

Washers r r Whirlpool 40

GE/Ho tpo int 18 < 80 * 75

Maytag 13 L

Rang es GE 33 r r

White-West inghouse 12

Magic Chef 10

< so

< 80

Roper 10

Tappan 9 L

Dishwasher s r s'

Design & Mf r

.

35

GE 23 < 85 85

Hobart 18 V

Sources [4,5,6]

.

30
Table 3.8 Cont

Major Appliance Manufacturers

Appliance Percent of Market

1976 19 77 1978

Dryers ( elec .

)

Whirlpool 40

r r

GE/Hotpoint 20

4, 80 < 85

Maytag ll

Whit e-Wes ting house ll

Freezers

Wes t inghous

Whirlpool

Revc o Admiral

31
Table 3 .

Small Appliance Manufacturers Market Share and Ranking

1976 1977 1978

% of % of % of

App 1 ianc e Company Mar ke t Rank Market Rank Market Rank

Vacuum Cleaners Hoover 23 1

NUE (Eureka) 17 2 80 Electrolux 12 3 Whirlpool 10 4 80 ( include

Sub earn exc lud e Gen. Signal 8 5 ( include

Scott&Fetzer 7 6 Sunbeam) Scott&Fetzei

Irons Gen . Elec

45 1 90

Sunbeam 19 2 ( inc lud e 80

SCM (Procter 18 3 Scovill)

S ilex)

Toast ers Gen . Elec

1

SCM 2 McGr aw -Ed is on 3 Sunbeam 4

Food Mixers Gen . Elec

1

(portable) Scovill 2

S unb earn 3

Dynamic (faring) 4

Food Mixers Sunbeam 1

( stand) Scovill 2 Gen . Elec

3

Dy nam ic 4

Fry Pans Presto 1

Dart (We st bend) 2 Gen. Elec 3

McGraw-Edison 4

Hoover 5 LCA 6

Mel ita 7 Nat ' 1 Presto 8 Regal Ware 9

Scovill 10

Sources [4,5,6]

32
I

Tab 1 e 3 . 9

'

( Con t .

)

Small Appliance Manufacturers Market Share and Ranking

Appliance Company

1976 1977 1978

Z of

Market Rank

Z of

Market Rank

Z of

Market Rank

Coffee Makers N . A . Sy s t ems 33 1

(drip) N.A. Philips 17 2 Dart 14 3 75 75

SCM 7 4

Sunbeam 5 5 Coffee Makers Regalwar

1

(percolator) Gen . Elec

2

Dart 3

SCM 4

Sunbeam 5

Corning 6

Cornwall 7 LCA 8

Lake Center 9

McGr aw -Ed ison 10

Bed Covers Sunbeam 1

Essex 2

Manufacturer - Brand Name

Dart — Rockline, Westbend

Dynamics - Waring

General Signal - Regina

Hoover - Knapp-Monarch, Nesco

LC A - Faberware, Rexair, Spartus

NUE - Eureka

NA Phillips 'Norelco

NA Systems - Mr. Coffee

SCM - Procter Silex

Scott & Fetzer - Douglas, Kirby

Scovill — Hamilton Beach, Dominion

Sunbeam - Northern Electric

33
List

of

Major

Appliances

Evaluated

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34

continuous

water

level

control,

dispenses--

bleach,

softener,

detergents.

Finish:

top,

lid,

and

tub;

porcelain;

Cabinet

is

baked

enamel.

Selected

as

representive

of

changing

technology

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List

of

Major

Appliances

Evaluated

ft

D

4-1 •• 4-1 14

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d 44 44

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t-i £3

u o • •H

O CO cnD • rH

44 •H -a 4-1 >> 3 CO

D •» }4 3 44D c rH O O c H 1 d H •d H •d o >44 cn <u CO o ca 14 "d cn D D D CO- £ o X a> CO rH 14 X E • a £ •H •» o Qu cn td 0S CO •H 44 o 44 3 •H o 14 ca d O 3 CD 4J o CJ 3 •H 44 44 CJ 44 o 4-1 4-1 ca 4-1 6 iH •H •H CT D 44 CO CO o rH M cn -h o 4-1 S-i D 3 3 as E c 0) o X 3 4-1 > CO 4—1 H 42 • 43 o rH > •• o E CJ U 43 O X a

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H CO

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D

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4-1 •a

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36 :

MOV-2

Manual

dial,

solid

state

components

variable
Table 3.11

List of Small Appliances Evaluated

Discr iption/

Appliance Type/NBS Code Comments

Vacuum Cleaners VC-1

VC-2

VC-3

upright

upright

canister

Hand Irons HI-1 spray s team d ry plastic body

HI-2 spray steam dry with light

HI-3 spray steam dry take apart

HI-4 spray steam dry standard

Special IR Sensor & Toasters TO-1 Auto . lowering

TO-2 Sensor Control

TO -3 Heatup /Coo Id own Control

TO-4 S td . four slice

Toaster Ovens TO V -

1

large four slice model

TOV-2 two slice model

TOV-3 large model, sensor

Food Mixers FM-1 hand , low end unit

FM-2 hand y model speed control

FM-3 stand model -metal case

Fry Pans FP-1 small & plastic enclosed

FP-2 standard d iecas t FP-3 standard brazed heater

Coffee Makers CM-1 high volume unit. drip

CM-2 high volume-3 conductor cord

CM-3 plastic percolator low end

CM-4 party percolator (large)

CM-5 high volume unit

,

percolator

37
Table 3.11

List of Small Appliances Evaluated

Appliance Type/NBS Code

Elec. Bed Covers EB-1

Food Blenders FB-1

Can Openers CO-1

CO-2

Smoke Detectors SM-1

SM-2

SM-3

SM-4

SM-5

Discr iption/

» Comments

similar to all others

high technology,- solid

state circuit

standard low end model

automatic turn off

high vol, private brands

std. unit --bat t ery

industrial manufacturer

line power

line power & photoelectric

38
REFRIGERATORS

RF-1

RF-2

39
REFRIGERATORS

RF-3

CLOTHES WASHERS

CW-1

40
CLOTHES WASHERS

CW-2
CLOTHES WASHERS

CW-4

ELECTRIC RANGES

RA-1

42
ELECTRIC RANGES

43
I

DISHWASHERS

DW-1

DW-2

44
DISHWASHERS

FREEZERS

FZ-1

. . ___ ....

45
FREEZERS
CLOTHES DRYERS

47
r

MICROWAVE OVENS

MOV-1

48
MICROWAVE OVENS

49
VACUUM CLEANERS

VC-3

50
HAND IRONS

HI-1

HI -2

51
HAND IRONS

HI-3

HI-4

52
TOASTERS

TO-1

TO-2

53
TOASTERS

TO3

TO-A

54
TOASTER OVENS

TOV-1

TOV-2

55
TOASTER OVENS

TOV-3

FOOD MIXERS

FM-1

56
FOOD MIXERS

FM-2

FM-3

57
r

FRY PANS

FP-1

FP-2

^/TtejuaEne 330 - rwn 373 • i>orx onova

58
FRY PANS
COFFEE MAKERS

CM-2

CM-3

ii

60
COFFEE MAKERS

CM-5

6l
BED COVERS

(ELECTRIC BLANKET)

EB-1
CAN OPENERS

CO-1

CO-2

63
SMOKE DETECTORS

SM-L SM-2

SM-3, SM-4

SM-5

i

i

64
4 . 0 Test and Analysis

4 . 1 Introduction

This phase of the NBS carbon fibers program was to

evaluate hazards and faults and it consisted of a review of

the conditions that could generate hazards and an analysis

of the electrical circuit configurations generated by

possible carbon conductive paths that would cause faults.

The original NASA test procedure was tried and evaluated by

NBS and a new test procedure was proposed to NASA and

accepted. The analysis of hazards together with the test

procedure used will be discussed first; then, the fault

analysis and its test procedure will be given. Small

appliances and electronic controls will be covered

separately. All evaluations were based on data from NASA at

the beginning of work that indicated the longest fibers of

significance as 20 mm in length. Later data indicates that

more than 95% of the fibers released are 10 mm or less and

85% of the fibers released are less than 5 mm in length [7].

Data on fiber characteristics [10] indicates they appear as

a resistor, with a constant resistance per unit length until

burnout current or temperature is approached, plus two

contacts at the ends which are nonlinear with a 1 to 2 volt

drop. For short high current pulses fibers burn out at

about 100 millijoules [10]. The resistance per unit length

for most fibers varies from about 500 fi/cm to 3000 fi/cm.

The burnout current ranges from about 10 mA to 33 mA for

most fibers and the burnout power dissipation from about 0.3

W/cm to 0.8 W/cm [11], Therefore since most fibers are one

centimeter or less in length, continuous currents conducted

will be no more than about 33 mA and continuous power

dissipations no more than about 1.6 W. All fibers 20 mm or

less will burn out if directly connected across power line

voltages of 120 V or 240 V.

NASA has the facilities for chamber testing products

with various fiber lengths and exposures. Appliances not

suitable for analysis have been recommended for chamber

testing

65
4.2 Standard Product Analysis

4.2.1 Appliance Hazard Evaluation

Aside from the potential hazards associated with

appliances in normal use, three possible hazard modes

could be generated by carbon fibers. These are

discussed in order of importance.

1. Electrical Shock

The only way one can get an electrical shock

from an appliance is to simultaneously touch an

uninsulated metallic part of the appliance that has a differing electrical potential than another touched

electrical conductor (not necessarily part of or

connected to the appliance)

If an uninsulated, ungrounded, metallic part of

an appliance can be touched, and if it is connected to

an electrical voltage through a carbon fiber,

sufficient voltage (120 volts) and current (up to

about 33 mA ) are available to cause a serious electric

shock when another part of the body is touching an

electrically-grounded conductor.

It should be noted that the shock hazard is less

than the hazard caused by a direct line short since

the fiber resistance will be in series with the body

resistance resulting in a lower current level. If the

fiber plus body resistance are low enough to allow

current greater than the 33 mA , the fiber will burn

out when it has dissipated 100 mJ which should occur

in no more than 50 ms. Carbon fibers carrying

currents of 33 mA or more will burnout prior to the

time likely to result in electrocution. Currents

below 33 mA will not likely result in electrocution

(stoppage of the heart) [12]. The likelihood of death

occurring from carbon fiber aided electric shock,

therefore, appears to be small. It should be noted,

however, that burnout will not prevent a person from

feeling the shock. If multiple carbon fibers bridge

the gap from ungrounded conductors to the frames of

ungrounded appliances, problems are forseen.

Since virtually all major appliances are

Underwr i ter s

’ Laboratory (UL) Listed, they have passed

tests to assure that accessible electrically

66
conductive parts are either insulated or are

constructed so they may be electrically grounded.

Thus, when properly manufactured, installed, and

grounded, there is little probable shock hazard

generated by carbon fibers. Should a carbon fiber

touch an uninsulated electrical part whose voltage is

above ground and connect it to a grounded uninsulated

chassis part, the fiber cannot raise the voltage

because of the ground connection. The fiber may burn

out but burn out is not a hazardous occurrance. In

all known major appliances, the few electrically

isolated parts (usually plated knobs or escutcheons)

have no connecting pathway to energized nodes that

could be formed by carbon fibers. It is possible that

fibers completing a circuit to ground may cause a ground fault circuit interrupter (GFCI) to trip, even

if the fiber would burn out. GFCI’s may trip faster

than a fiber will burnout. This nuisance tripping is

not likely to be a significant problem for appliances

since GFCI’s are currently required by the National

Electric Code in outdoor, bathroom and garage outlets

which are not the normal locations for appliances.

Because of the above, there is no need to

analyze the electrical shock effects of carbon fibers

on effectively grounded appliances either operating or

not (device "on” or device "off").

There is a need, however, to inspect all

touchable metallic surfaces and the bonding between

such surfaces to evaluate the integrity of the ground

connection. The UL requirements permit considerable

latitude in the means for making the connections;

hence long term integrity should be evaluated. Thus a listing of all metallic surfaces that may be touched

by the user was proposed by NBS and accepted by NASA

as a part of the hazard evaluation. This listing

requires inspection of all touchable conductive

surfaces to classify the integrity of the ground

connection

.

If the chassis of an appliance is not grounded,

two types of electrical configurations must be

considered

Type 1. 120 volt plug-in appliances with or

without a ground wire such as refrigerators and

67
240 volt devices with no need for a neutral wire

connection such as water heaters.

Type 2. 240 volt appliances with neutral third

wire that may carry current (e.g. ranges,

clothes dryers)

.

In Type 1 appliances, it must be assumed that

any uninsulated electrical connection within the

device can be at a potential above ground. This is so

because with 120 volt appliances, the current carrying

circuits that are normally connected to the electrical

neutral source may be incorrectly connected to the

high potential source and vice versa (plugged into

unpolarized or incorrectly wired outlet either way)

.

Even though a three prong grounding type plug is

furnished for major appliances, it is possible for the

user to remove the grounding prong, thus defeating its

purpose. Also, 240 volt appliances without electrical

neutral have all current carrying circuits connected

to power sources that are 120 volts above ground

electrically so a carbon fiber connecting either line

to an ungrounded touchable conductive surface raises

its voltage to 120 volts.

Because of the above, all uninsulated electrical

connectors (nodes) must be evaluated for spacing from

ground since for spacings less than 20 mm a carbon

fiber could cause a hazardous condition. For this

evaluation, the "Fiber Simulator" which tests for

burn-out is not needed since, when the chassis is

ungrounded, the fiber obviously cannot burn out

because no current can flow.

Type II appliances that have 240 volt input but

that require a neutral to function properly may have

some nodes that need not be evaluated for hazard

potential. These nodes are the ones that must be near

ground potential at all times since they are connected

to neutral. Such nodes of course could not generate a hazard condition even with spacing less than 20 mm.

However, all uninsulated electrical connections

(nodes) of Type II devices except those directly

connected to neutral must be evaluated for spacing

from the chassis or other accessible metallic part.

Again, electrical test for burn out is not needed.

68
Open Wire Heaters

Open wire heaters are a special case of

possible shock hazards that is not adequately

evaluated by measuring the spacing of

uninsulated nodes to ground, because the hazard

condition can exist along a long length of wire.

In some appliances, notably clothes dryers, high

wattage high temperature heaters are constructed

of high resistance (compared to copper)

uninsulated wires. Typically these wires are

mounted on ceramic insulators which in turn are

mounted to a grounded (chassis) bare-metal

surrounding support structure. They are

usually, but not always, located in a forced air

flow environment.

In _no case can a node to node fault caused

by a carbon fiber cause an electrical shock

hazard with connector nodes or with open wire

heaters. This is so because node to node

connectors connect only electrical parts to

electrical parts. Since these are all either

electrically insulated from ground or already at

ground potential, connecting one to another

cannot expose the user to any elevated

electrical voltage when the chassis is touched.

In any case, node to node fiber connections are

sufficiently evaluated for hazard potential

since each node is separately tested by

measuring its clearance from touchable metallic

parts

.

2. Fire

Since a carbon fiber can dissipate about 100 rr.J before burnout, this low energy level is not likely

to initiate a fire or cause carbonization of high

temperature electrical insulating parts. The maximum

continuous circuit power dissipation due to fiber

connection would be 33 mA times 240 volts or 7.9

watts, but no more than 1.6 watts of this can be

dissipated in the fiber without burnout. The

remainder must be dissipated by other current limiting

circuit components. In our judgement, this low power

level in free air will not generate enough heat to

ignite nearby objects. If the fiber were against an

insulator, the heat generated from the one watt may

69
cause serious carbonization over a long period of

time, but again the likelihood of fire is very remote,

using UL prescribed insulation. Some electronic

products or electronic applications in major

appliances may be designed such that long term

carbonization could establish fire potential

conditions. Such possibilities cannot be evaluated

with a single measurement using the Electric Fiber

Simulator. Only long term (hours, days, or weeks)

tests could be used to determine potential fire hazard

for such designs.

Besides considering heat generated by a fiber,

there is also the possibility of the fiber conducting

current to a resistive load within the appliance to

generate heat in the load (e.g. a fiber conducting

across open switch contacts (nodes)). The 33 mA in

any load is judged to create a very remote possibility

of a fire hazard.

A final consideration is the possibility of the

fiber making a conductive path to a secondary control

device (i.e. relay coil). The four watts available

may be sufficient to close a relay or turn on a solid

state electronic switch which in turn could start a motor, turn on a lamp or apply voltage to a heater.

All of these devices are of course designed to be

turned on without fire hazard and are protected by

thermal devices should excessive temperatures be

attained, particularly if left running continuously.

This too is a UL requirement.

The only exception found to date is in an electronically controlled dishwasher which does not

have a back-up safety thermostat. This possibility is

discussed under "Electronic Controls."

Thus, though the probability must be considered

during analysis, it may be concluded that there is

little possibility of fire hazard associated with

carbon fibers for appliances.

3 . Physical Harm

Because of the power limitation discussed above,

it is our judgment that no physical harm is likely to

result to the appliance's user caused by electrical

connections through carbon fibers to operating

70
devices. Motors cannot run and/or heaters will not

heat with the relatively high carbon fiber resistance

in series with them and the associated four-watt

limitation. Even with a burn out, the higher power

would be applied for such a short period of time that

no damage could be done. The only known possible

hazard is if a fiber were to cause a secondary control

device to turn on which in turn would turn on a motor

or heater. A motor running or a false cycle of a timer controlled appliance is considered a fault

condition, not a hazard. A heater turned on might

represent a burn hazard, particularly in an electric

range but such hazards exist even without the exposure

to carbon fibers. Such conditions will be covered in

the notes section of the hazard analysis.

4. 2. 1.1 Analysis

In analyzing the probability of hazard in

appliances, it has been determined that except

for a remotely possible fire or burn hazard

related to secondary control devices (discussed

in the Fault Evaluation section), only electric

shock need be considered and then only if the

appliance is ungrounded. Spacing is the prime

consideration because if the distance is over 20

mm, the likelihood of a hazard is negligibly

small due to the anticipated fiber length

distribution. The hazard potential varies

inversely with spacings less than 20 mm.

Four other factors effect the probability

of hazard and each will be discussed

separately

1. Exposed Surface. The likelihood of a carbon fiber connecting a node to ground is not

only related to spacing but also to the contact

surface exposed to fibers. Figure 4.1

illustrates this condition. From the figure it

is obvious that there is greater potential for

fiber connections with the uninsulated terminal

than with the insulated one and that this

difference is roughly proportional to the length

and width of the exposed surface. Probability

analysis can perhaps be used to quantify this

factor so a measurement was taken of the other

dimensional parameter-exposed conductive surface

less than 20 mm away from a grounded surface for

later use.

2. Some grounded surfaces are electrically

conductive, others are painted and so may or may

not be insulated depending upon the integrity of

the coating. Some surfaces may be coated with a 71
UNINSULATED

TERMINAL

INSULATOR

CARBON

FIBERS

D=DISTANCE

L=LENGTH

FIGURE 4.1

LENGTH FACTOR HAZARD ANALYSIS

71-a
high temperature fired porcelain enamel which is

an even better insulation than paint but still

not necessarily sufficiently reliable to be

considered as acceptable insulation. The

presence of a coating material should be noted to

permit its inclusion in evaluating the overall

hazard potential of a conductive surface less

than 20 mm away from one exposed electrical

conductor

3. Switch position can effect the hazard

evaluation only from a statistical point of

view. The position of various electrical

switches (on-off, timed cycle, light, etc.) will

not affect the existence of a shock hazard since

any electrical conductor with less than 20 mm

spacing may _at some time during the operation of

the device be at an elevated voltage (depending

upon grounding and upon the polarity of the input

wires) . Some nodes are directly connected to the

power source so a fiber connecting these to

ground would produce a hazard at all times.

Other nodes are only connected to electricity

when a switch is closed so a hazard would exist

only while the appliance is operating and in some

cases for only a short period of time during an

operating cycle. In other cases, the node is not

a hazard when the appliance is running but may be

a hazard when the appliance is off. Figure 4.2

shows the possible circuit configurations and

hazard matrix. Because of the above, the type of

hazard condition switched or not switched needs

to be known to complete a statistical analysis

of hazard probability.

It is perhaps as probable that an

ungrounded appliance will be connected with

reverse polarity as for it to be connected

correctly. This is so because if the ground pin

is cut off the plug or if a "cheater” adapter is

used, the plug or "cheater" can be inserted into

the outlet either way. Thus, consideration need

not be given as to which side of the incoming

power lines the node is connected, or whether

permanently or switched. In any case there is a chance that a carbon fiber connection to ground

will cause a hazard. In Type II appliances any

fiber connection to an ungrounded touchable

72
Circuit Configurations

r

Note: 1. Node numbers, loads j and switches same . locat ions on all figure

2. Loads energized only or circuits B and F

3. R1 and R2 can be a single load

4. Either or both switches may be used

5. L = Switch is (normally) line side of incoming power

6. N = Switch is (normally) neutral., side of incoming power

Hazard Matrix

Hazard — = None

X = Continuous

R = When runnir

0 = When off

Figure A B C D E F G H

Polarity N o rma

1

Rever s ed

Neutral Switch Closed Open Closed Open

Line Switch 0 C 0 C 0 c 0 C

Node

1 X X X X - - - -

2&3 - R - 0 0 - - -

4 - R - 0 0 R - -

5&6 - - - 0 0 R - -

7 - - - - X X X X

Figure 4.2

73

L
metallic surface will cause a hazard but in these

devices the probability of the appliance not

being grounded is low.

4. The last effect on hazard probability

relates to the condition of the air surrounding

the node under question. If the node is

completely insulated or hermetically sealed,

there is no hazard involved. If the node is in a confined volume of air with only small holes or

openings offering passage to fibers from the

ambient air, there is a little chance for a carbon fiber hazard. Many terminals are in

physically inaccessible locations but have large

and numerous connecting passage ways to outside

air. These terminals are considered to have a "normal” (unrestricted) chance for a fiber to

cause a potential problem. Terminals located in

a forced air passage with a fan blowing air

across them have a somewhat better chance of

carbon fiber deposit but also have a better

chance for the fiber to be blown away. Thus the

overall effect may be an only slightly higher

than normal probability of hazard. The worst

case is those node locations where a slow but

steady one way flow of air is passing over the

exposed connection. A hot air chimney effect or

the venturi effect of nearby high air flow could

create this condition. Here the air is flowing

by to increase the exposure to possible fibers

but the movement is not great enough to blow

fibers off of the terminals. Thus, the

surrounding air status needs to be evaluated for

all hazardous node locations.

4. 2. 1.2 Test Procedure

Based on the foregoing discussion, the

following test procedure was proposed to NASA,

accepted, and utilized in evaluating all of the

purchased appliances.

The test procedure uses three "Hazard

Analysis" record taking sheets, samples of which

are on the following pages. The steps to be

followed in data taking after filling in the

general information on Data Sheet I are as

follows:

74
/ ) DATA SHEET 1

GENERAL INFORMATION

TABLE A .... • 4 .TYPE_OF EOU I PfSENT

MANUFACTURER

KODELI NUMBER

-i SERIAL NUMBER

'

operating VOLTAGE

CIRCUIT DIAGRAM REF NUMBER

GRAPHICS REF NUMBER

TABLE B VENTILATION TYPE * REMARKS

FORCED AIR

CONVECTION

WATER 1

i OTHER I FILTER DATA n

FILTER TYPE j j FILTER P/N | VENTILATION SKETCH

TABLE C

CONTROL UNIT TYPE REMARKS

MECHANICAL

ELECT/KECK

tLtL 1 KUiWL I

I OTHER

SEALING MECHANISMS

NONE

COATINGS

ENCLOSED

DATA TAKER (INITIALS) Date

75
1. Number all nodes on an electrical schematic

or wiring diagram.

2. Fill in the product identification and node

numbers on Data Sheet II.

3. Disassemble the appliance sufficiently to

inspect all electrical connections (nodes).

4. Measure the distance from each exposed node

to the nearest chassis (mechanical ground) or

electrically conducting structure that is

connected to chassis ground. If greater than 20

mm, put a check mark in the space "D" column in

Data Sheet II. If the node is totally insulated

put a zero in that column. If not, record the

distance (to the nearest mm) in the "D" column

and then proceed with the following steps

recording the information in the appropriate Data

Sheet II column:

a. Measure the length of the exposed

metallic electrical conductor (node).

Since open wire heaters are generally

coiled with the ceramic support encircling

the coil, specifying the millimeter

dimensions of the electrically-energized

surfaces to the ground surfaces is

difficult. To provide some relative

measure of the potential hazard involved,

the measurements illustrated in Figures 4.3

and 4.4 may be utilized.

Figure 4.3 shows a case where the

coiled heater wire is more than 20 mm away

from the nearest ground surface except near

the ceramic support structure. In this

case some of the heater wires are close to

a ground point, Dl, and some are near the

maximum fiber length distance, D2, so an

average of these two values is a reasonable

estimate of the spacing, D.

While it might appear that the length

of the exposed conductor would be the total

stretched out length of the coiled wire, a better measure would be to consider the

76
Data Sheet II

Hazard Analysis

Product Mfgr. Code //

Node

#

Spac

D mm >o

e(mm)

Lmm

Coat

B,P,E

Air

E,N

FC, FF

SW

c,s Total Notes

Node

it

Spac

D

mm> o

e(nnn)

Lmm

Coat

B,P,W

Air

E,N

FC, FF

SW

C,S Total Notes

- — -

• -

•

-

- i I

- .

* ;

-

"1

-

*

Totals Totals

Remarks

77
D2 =20 mm

D1+D2

D2 = 1 0 + Dj

2

L=2D2 =40 mm

vJUUULOJUUUU JUUUUUUUUUbL

X //////f?7//////// /

T

°1

*

GROUND

7

02

1

FIGURE 4.4

OPEN WIRE HEATERS HAZARD ANALYSIS

78
coil as a solid structure and thus the

measure would be the length of the exposed

coil. In the illustrated case, this would

be L=2D2* This measure seems consistent

with the length measurement used with

normal nodes or terminals.

Figure 4.4 illustrates a heater coil

running parallel to a ground surface and

the measurements (D&L) used are shown.

The configurations likely to be used

for heaters are many and quite varied so

while the figures adequately specify a measurement system for the illustrated

designs, variations will have to be

considered individually. For instance, a coiled heater between two flat ground

plates could be considered as 2L but if the

plates are not equally spaced from the

coil, the heater would be considered as two

nodes, with equal L's but different D's.

Also, a straight line heater centered in a cylindrical support structure with less

than 20 mm spacing might be a larger

multiple of L.

b. Note whether the ground or chassis

part is bare metal, coated with paint, or

coated with a baked porcelain enamel.

c. Note the type air circulation around

the node using the following definitions:

E = Node is in an enclosed

compartment with no way for carbon

fibers to get into the node area

except for small holes or air gaps at

the joints of the protective cover.

N = normal, large room area air

accessibility through louvers or

other such means.

FC = Forced air flow by the node

either by hot air chimney effect or

venturi effect.

79
FF = Air forced over the node by fan.

5. Analysis of the circuit diagram is done to

provide the appropriate value for the switch

column of Data Sheet II. This evaluation is to

determine the need for a switch contact to be

closed in order to create a shock hazard or

whether the node may always be connected to the

high voltage line. Use the following

definitions

C = Always connected to one side of the

incoming power line or the other

side

S = Connected to an incoming power line

conductor only when a switch is

closed

6. The columns labeled "total" are filled out

as described in a later section of this report

under "Data Evaluation."

7. The columns labeled notes refer to note

numbers of notes listed on Data Sheet IV of the

analysis (see attachement) . The notes describe

any peculiarities associated with the node or

product under evaluation.

8. On Data Sheet III, list by an appropriate

name all of the metallic parts of the appliance

that could be touched by the user (coated or

uncoated, plated or chrome color plastic, etc.).

Parts that are welded together are considered as

one part. Proceed with the following steps

recording the information in the appropriate Data

Sheet III column:

a. In the first column, note the

approximate (visual estimate) area of the

surface of the part: use "S" if under four

square inches; use "M" if four square

inches to one square foot; and "L" if more

than a square foot.

b. Measure the resistance of the part to

the ground terminal of the appliance. (Rxl

ohms range of a Simpson 260 multimeter)

80
1

Page

Data Sheet III

Hazard Analysis

Ground Integrity

Product Mfg. Code //
Light scratching to break through

noncoating barriers is acceptable.

c. Note whether the touchable surface of

the part is conductive, paint insulated, or

baked procelain enamel coated.

d. If the resistance of the part

connection to ground is over one ohm or

marginally connected (See e 3&4), measure

its distance to the nearest node. Record

the distance if less than 20 mm.

e. Note the method of connection to

ground using the following definitions:

1. Wire or strap connection, metalto-metal contact or lock/star washer.

2. Wire or strap connection,

connection mostly through screw

threads

3. Connection from the part to

another grounded part through

stationary surface to surface contact

(may be screw or bolt connected).

4. Connection from the part to

another grounded part through a moving mechanical connection (hinge,

bearing , etc. )

5. Isolated, no electrical connection.

In order to record the heater hazard, D and

L values as shown in Figures 4.3 and 4.4 may be

used and placed in the proper columns of "Data

Sheet II." In this case, however, if there are

multiple identical support structures, instead of

just a node number, write in the number of heater

nodes with an appropriate note. Also on this

line should be a note number referring to a description on "Data Sheet IV, Notes" of the

heater and how the hazard was evaluated.

82
Data Sheet IV

Hazard Analysis

Notes

Product . Mf g

.

Note

i

f

83
4. 2. 1.3 Suggested Data Evaluation

The foregoing test procedure includes

several factors that affect the statistical

analysis of the probability of hazards being

generated by carbon fibers. Since the evaluation

of probabilities was not part of the NBS work

plan, no action was taken on the subject.

However, to indicate the reasons for suggesting

the type of data to be taken in the hazard

analysis, a possible formula for combining the

effect of the five factors effecting hazard is

given as follows:

HF L x AF

D

2

x CF x SF

where HF= hazard factor

L = length of the exposed node in mm

D = distance of node to ground in mm

AF = air flow factor

CF = coating factor

SF = switch factor

Possible values for the factors affecting

the hazard factor could be:

AF = .5 = enclosed

1 = normal exposure

10 = chimney or venturi forced flow

3 = fan forced air flow

CF = 1 = base metal

4 = paint coated

10 = enamel coated

SF = 2 = unswitched node, Type I appliance

84
10 = unswitched node, Type II appliance

4 = switched node, Type I appliance

15 = switched node, Type II appliance

Of course the above proposed formula and

factors are for illustration only and are only a suggested analysis. They are not the considered

opinion of a knowledgeable group of experts or of

experimental quantification. Further

consideration should be given to improving the

data base before finalizing each of the factors.

Regarding open wire heaters, it is apparent

that the voltage applied f rom a heater wire to a nongrounded structure by a fiber will vary

depending upon the position along the heater that

is contacted. At some places the resultant

structure voltage may be full line voltage (120V)

and at others the voltage could be zero or at

least less than 30 volts and therefore

nonhazardous . This effect is only realized when

the heater is "on." The hazard evaluation

differs with 240 volt type II appliances (i.e.,

clothes dryers) and type I devices. On type II

appliances, it would be reasonable to multiply

the L/D factor by 0.75 to compensate for the

nonhazardous portion of the heater wire. On type

I appliances, the same factor would apply only

during the time that the heater is connected to

both sides of the line (switched "on"). At all

other times, one side of the heater rnay be

solidly connected to the neutral wire so with

reversed polarity the entire length of heater

wire could be at full line potential. This would

result in a 0.5 factor for the off condition.

Some appliances disconnect both sides of the

heater when it is off so that no hazard exists

during these periods.

The totals column was included on the

Analysis Data Sheet II to provide work space for

making an individual and total calculation of a hazard factor should this method be pursued.

85
Ground integrity was not incorporated in

the hazard factor formula since this is a subjective evaluation. The secondary control of

ranges was also not evaluated because there is

only one electronic range known that might

evidence such hazard. It will be discussed in

the electronics section of this report.

4.2.2 Appliance Fault Evaluation

Fault analysis relating to carbon fibers is

needed to evaluate what the effects of the fibers would

be on the performance of electric appliances.

Performance can be considered affected if an

objectionable difference in appliance operation is

noticed that would be sufficient to generate a service

call for repair or to initiate owner dissatisfaction or

owner repair action. Such action can occur if there is

a malfunction of a component in either of the two major

electrical system classifications: output and control.

Each will be discussed separately.

4. 2. 2.1 Output Devices

An output device is a component that

performs some function of use to the user. Some

general types are:

motors

heaters

solenoid valves

lights

clocks

With a few minor exceptions, all such

devices in appliances are designed to operate

with 120 or 240 volt ac power input. The

exceptions are the few devices that are designed

for low voltage operation. These must have

another device in series with them to drop the

line voltage down to their operating voltage. In

appliances, transformers are generally used only

in control circuits due to cost.

Figure 4.5 is a simplified circuit diagram

of a power source applied to a number of

operating devices. The X’s on the figure

86
I

I

LI = L 2 N

G

Ml

M2

M3

SL

HI

H2

T

X

0

Power Input Terminals, 120/240 Volts

Power Input Neutral

Chassis Ground

Mo tor , 120V

Mo tor , 240V

Start Winding Type Motor

Solenoid

Lamp

Heater, 120V

Heater, 240V

Clock Motor

Carbon Fiber

Conductor

Control Switch

Terminal or Node

Fault Analysis

Output Devices - Single

Figure 4.5

87
represent the control devices that will be

discussed later. The dotted lines represent

carbon fibers. It is obvious that all of the

carbon fibers (except the three that connect the

power neutral to chassis ground) will have line

voltage applied to them, either 120 or 240 volts.

It is also obvious that this voltage will cause

the fiber to heat up and possibly burn out. In

any case, the very low current flow through the

fiber will not effect the operation of the

device. Any burnout will occur either

immediately or as soon as the voltage is applied

to it. If the fiber does not burn out, it is

only adding a maximum of a 33 milliarnpere load to

the line and so will have negligible effect.

Between one pair of devices, S and T, of

Figure 4.5, are shown four of the many other

fiber connections that could occur between

terminals of different devices. It can be seen

that all such interconnections would place the

fiber across 120 or 240 volts or would be across

lines of equal potential. None of these

connections could effect operation of the devices

except the one labeled #1. This connection goes

to a switched clock motor with low wattage. The

clock could operate from the fiber current which

would be a fault. It is unlikely, however, that

a clock would have a switch (X) in its circuit.

With no switch, no problem exists with any of the

possible carbon fiber conductive paths.

Therefore, for fault evaluation, it is not

necessary to test any connectors, terminals,

buss bar conductors or any nodes associated with

power supply conduction circuits or output

devices

The exception to the above that should be

considered is circuits where two devices are in

series. The two heaters across 240 volts shown

in Figure 4.5 indicate two identical units which,

when in series, would have 120 volts across each.

These of course behave identically to other 120

volt devices as far as carbon fibers are

concerned

Figure 4 . 6A shows several configurations of

output devices in series that are not pairs of

88
LI. N, L2, G = INPUT POWER CONNECTIONS 240/120 VOLT

F=FLOURESCENT LAMP

B=BALAST CARBON

H=HEATER H, to H5 FIBERS

R=DROPING RESISTOR R 1 & R2 L=LAMP

A

GENERALIZED CIRCUIT

FIGURE 4.6

OUTPUT DEVICES—SERIES FAULT ANALYSIS

89
identical devices. Only carbon fiber No. 1 is

shown across the combination of two series

components since this and all other such line-toline connections will obviously not effect the

operation of either of the devices.

Figure 4 . 6B shows a simplified circuit of

two load devices in series. When considering the

effect of carbon fibers across one of two devices

in series, it must be noted that the maximum

current a fiber can conduct for extended periods

of time is less than 33 milliamper es

.

This fiber current limits the maximum

additional amount of power that can be supplied

to a load by a fiber in parallel with a second

device in series with the load to less than seven

watts (7.9 W-1.6 W in fiber). Conversely, the

same current limit also results in the maximum

power decrease in a device shunted by a carbon

fiber to about the one watt the fiber can

dissipate. Thus, fibers can only effect very low

wattage output devices. The only known low power

output device in appliances is a clock. (Timers

will be discussed in the control section.)

Clocks would not be connected in series with

other devices so they would not be effected by

carbon fiber conduction paths.

4 . 2 . 2 . 2 C ontrol Devices

Control devices are those components within

an appliance that control the electrical power

flow to output devices. They can be divided into

three groups--primary , secondary and auxiliary.

4 . 2 . 2 . 2 . 1 Primary controls are those that

control output devices ( loads) directly such as:

fuses (thermal, current)

circuit breakers (thermal, current, manual reset, etc.)

manual switch (rotary, slide, toggle, momentary, etc.)

sensor switch (pressure, temperature, position, etc.)

timed switch (normally open, normally closed,

double throw)

relay contact (normally open, normally closed,

90
double throw)

electronic switch (ac, dc, phase controlled)

Figure 4.7A illustrates the basic circuit

of all primary controls. Figure 4.7B shows a series chain that includes one of each type of

primary control; any one of which, when opened,

will interrupt current to the load. The dotted

lines around the devices indicate possible carbon

fiber paths. It can be seen that if the control

device is conducting (closed) a fiber will have

no effect. Except for very low-wattage loads, if

the device is open, the fiber will burn out

unless another control in the series chain is

open. In this case, the fiber will have no

effect until all other switches are closed which

will then cause the fiber to burn out. One of

the many possible fibers is shown drawn from a control device terminal to the line on the

opposite side of the load. All such fibers will

have no effect when the switch is open but will

burn out when the switch (or switches) closes.

Again, there would be no effect on load

operation. Further consideration shows that it

makes no difference whether the primary control

device is in the line or neutral conductor nor

will voltage effect operation. Should the fiber

not burn out, its resistance would prevent enough

current from flowing to cause the controlled load

device to operate. The only exception to the

above would be if the output (load) controlled

consumes less than ten or so watts at normal

voltage. Such light loads are more likely to be

incorporated in electronic products than in

appliances (pilot indicator lights will be

discussed later). Any such low-wattage output

devices must be considered separately for fault

effects

.

In conclusion, fault analysis of primary

controls consists of an evaluation of the loads

controlled. Once assured that all are over 20

watts, i.e. significantly greater than 10 watts,

further evaluation or testing is unnecessary.

Testing with the carbon fiber simulator would of

course be needed for evaluating low power

effects

.

91
PRIMARY CONTROL

LOAD

FIGURE

LOAD

RELAY

CONTACTS

LOAD

*— CARBON FIBER

FIGURE 4.8

SECONDARY CONTROLS FAULT ANALYSIS

92
4. 2. 2. 2. 2 Secondary controls are ones that

control output devices indirectly by means of a second electrical circuit, usually of low

wattage. The types of secondary controls are:

relay (magnetic coil or bimetal heater)

timer (electric motor or electronic circuit)

electronic circuit

indicator lamp

audible signal

The last two devices may be termed

secondary controls in that they prompt the user

to do some action on a primary control such as

turn the device off; turn a heater off, so as not

to be burned; change a selected cycled from one

to another; etc.

Note that all secondary controls are really

electrical loads of some sort. As such they are

controlled themselves by primary devices

identical to those previously mentioned but at a much lower current (and sometimes voltage) level.

Malfunction of a secondary device would be a fault and so all such devices must be tested with

the fiber simulator. From the diagrams of Figure

4.8A and B, it can be seen that carbon fibers

across the secondary control itself as fiber #

1

is cannot produce a fault since the line voltage

will cause the fiber to burn out and the control

will not be affected even momentarily. However,

the low current primary control itself must be

evaluated. This is done by placing the fiber

simulator in series with the secondary device

(lamp, magnetic coil, timer motor, etc.) and the

combination across a 120 volt power source or

other voltage if so designed. If it is found

that the simulated fiber will provide sufficient

current to operate the device without burning out

or if it operates the device momentarily before

burning out, the circuit to the secondary control

load must be evaluated. The circuit is first

checked to see if a high power output device is

always in parallel with the secondary device,

such as Figure 4.8 A & B. If so, the load would

cause a fiber such as #2 to burn out and no fault

condition exists. If there is no parallel output

device as in Figure 4 . 8C , the fiber can cause a

93
fault so the circuit leading to the secondary

control load must be evaluated to see if under

any condition a fiber could be positioned such

that it would conduct current to the device. If

it can, a fault condition possibility exists and

should be noted and explained.

When fault conditions are located by

analysis, a double check may be advisable. The

double check is to connect the appliance to a power source and then simulate the fault with the

fiber simulator connected across the appropriate

nodes. Any questionable possibilities of any

sort should also be tested at this time. During

the test, data should be taken of the test

conditions and effects of the fault and such test

results included with the final report.

4.2. 2. 2. 3 Auxiliary controls are separate

components within the appliance that are used to

effect the operation of a primary or secondary

control. The components known to be used in

appliances are:

resistors (low watts, high watts)

capacitors (phase change, filtering)

transformers (low voltage supplies, lamp ballast)

Most resistors used in appliances are used

to generate heat as an output device for one use

or another. These would generally be over 20

watts and be tested as outputs. The few under 20

watts should be evaluated just as secondary

controls were evaluated. Other resistors are

used as voltage reducing and/or current limiting

devices for secondary controls. These

applications should also be evaluated in the same

manner as secondary controls.

The few capacitors used in appliances are

either used in series with motor windings or as

radio noise suppression devices. They may be

analyzed individually like secondary controls.

Transformers, too, should be evaluated for

potential fault conditions much like secondary

controls. Where trans former- like devices are

used as lamp ballasts, the currents and voltages

94
are sufficiently high that they may be considered

as primary controls and need not be further

evaluated

.

4.2.2. 3 Test Procedure

In order to analyze each appliance for

potential fault conditions, the following

procedure should be performed using the attached

sample data sheets. The procedure assumes that

the hazard analysis is already completed.

1. List on Data Sheet V all electrical

components except primary controls, i.e.,

output devices and secondary control

devices

.

2. Record the wattage if known, or measure the

resistance of all devices suspected to be

high (over say 20 watts) power. Unknown

power or low power devices should be noted

to indicate a test is needed.

3. List on Data Sheet VI the component numbers

that were noted in step 2 as requiring

further evaluation.

4. Use the carbon fiber simulator to determine

whether the device will operate when in

series with a carbon fiber to 120 volts.

Note the resistance value for burnout in

the second column. If no burnout, so

indicate. Note: If the device is designed

to operate on a different voltage, test

using the design voltage.

5. If the device will not operate in any of

the test positions of the simulator, go to

step 7. If the device does operate, list

in column 3 the node numbers (terminals) of

the device.

6. By inspection of the circuit diagram,

determine what primary control or controls

supply power to the low power device.

95
Data Sheet V

Page

Fault Analysis

Component List

Product Mfg._ Code II

/

Comp,

0 Name or^T

Comp

II

J Name or~T

*

•

-

•

*

! -

-

-

•

96 *
Data Sheet VI

Page

Fault Analysis

Low Wattage Components

Product Code 0 Burn-
7. If the answer to 5 was no, the "Fault"

column 5 should be marked N. If the answer

is yes, analysis of the circuit must be

made to determine the effect of carbon

fibers on the various nodes listed in 6

(above) of primary devices that could

effect operation. If no problem (effect on

performance) is possible use an "N" in

column 5 otherwise use a "Y."

8. Describe the fault condition (use notes on

Data Sheet VII if necessary.).

4 . 3 Small Appliance Evaluation

The basic difference between small appliances and major

appliances as related to carbon fiber hazards and faults is

that most small appliances do not have a specific power wire

which will always be connected to the electrical power

supply neutral. There are very few exceptions to the above

and even these exceptions may not be relied upon because it

is even more likely than with major appliances that the user

has defeated the third conductor grounding system by cutting

off the third pin on the cordset plug. Also, there are no

240 volt small appliances in the U.S., so none are of Type

II.

Because of the lack of a grounding system, there is no

ground integrity to evaluate on small appliances. The

remaining hazard and fault analysis is essentially identical

with that used for major appliances so the same analysis

system (measurements and forms) was used.

4.3.1 Hazard Evaluation

Although many small appliances are completely

enclosed by an insulating plastic housing, in almost

all cases there are metal parts that can be touched and

these are frequently interconnected through other metal

parts to internal structures that are in close (less

than 20 mm) proximity to exposed electrical connectors

or nodes. The external metal parts then may be

potential shock hazards and so must be evaluated.

Since one of the two power supply connectors is neutral

or at ground potential, a 50% chance exists that a fiber connecting a node to an exposed, touchable,

metallic part will create a hazard. Each insertion of

the plug into an outlet creates another opportunity to

98
r

Page

Data Sheet VII

Fault Analysis

Notes

Product Mfg Code //

99 •
change a nonnazardous connection into a hazardous one.

Thus, once a fiber has created a hazardous condition,

the only safety factor relates to the mechanical

vibrations associated with the movement of small

appliances which may dislodge a fiber and cause it to

move to a nonhazardous location. Except for the

exposed heaters of electric room heaters, toasters,

some older hot plates, etc., the electrical parts of

small appliances tend to be more enclosed (less

accessible to room air) than major appliances. There

are ten nodes in what would be considered "normal"

(unrestricted) locations as defined in the analysis of

major appliance hazards, but many are either enclosed

or in a moving air environment (FF or CF).

The discussion of the types of hazards relating

to carbon fibers in major appliances also holds for

small appliances in that electric shock is the only

hazard involved. Fire, flood, or physical harm are not

likely eventualities.

Special Case

In some cases, small appliances are

constructed using uninsulated conductors (stiff

wire or sheet metal "bus" I bars) . Such designs

are used where very high temperatures exist in

the compartment containing the wiring. Because

of the heat there is usually an air vent or vents

associated with such compartments to supply some

convective air cooling. Toasters, toaster ovens,

heaters, and to some extent hand irons are

typical of such construction. Because of the

many measurements and varied configurations, it

is not possible to analytically evaluate the

hazard potential of these devices. Two of the

above products, toasters and heaters, also have

exposed wire heaters. These heaters do not lend

themselves to the same analysis proposed for

similar heaters in major appliances since they

are not surrounded by grounded bare metal support

structures. The above restrictions limited the

activity of this project on toasters and heaters

to pictures and descriptions only. Hazard

evaluation will have to be done through actual

chamber testing of typical product designs.

100
4.3-2 Fault Evaluation

As in major appliances, carbon fibers cannot

cause a fault condition in a device which consumes over

about 20 watts. This is so because if a fiber is

across open switch contacts, it will either burnout

without supplying sufficient current to the device to

cause it to operate or it might not burn out but then

would supply even less power to the device

(insufficient to cause the device to operate). Fibers

across 120 volt terminals will only act as a negligibly

small additional load or they will burn out, either

case having no effect on the device. The only effect

fibers could have would be to turn on a gas discharge,

low wattage indicator light when it should be off.

This can only happen if there is no higher wattage load

in parallel with the light. Two known situations of

this type are an electric blanket with the blanket

disconnected from the control and a fry pan with its

control unplugged from the pan; both are minor faults

not likely to generate repair action.

Secondary control devices (relays, timers, etc.)

are seldom used in small appliances and when they are,

as in some toasters, the power used by the secondary

control is so great that carbon fibers will not operate

them

Thus, with one minor problem, small appliances

are not susceptable to carbon fiber caused faults.

Nevertheless, in order to verify this conclusion, all

of the test appliances were evaluated for fault

conditions and data sheets completea.

The combination of small appliances with

electronic controls will be covered in the electronics

section of this report.

4 . 4 Electronic Controls Evaluation

Electronic circuits in appliances range from the simple

inclusion of a solid-state rectifier (diode) in an otherwise

electromechanical system to ultra-sophisticated large-scale

integrated circuit including microprocessors. Diodes are

used for power reduction in heaters or lights, for

rectification in battery chargers for DC operation of

electromagnetic devices and for power supplies to other

electronic devices. Other than diodes, electronic circuits

101
are included in appliances, major and small, to provide

control functions, not just to replace switches. Complex

control functions are accomplished with large scale

integrated circuits (IC) which contain input and output

circuits as well as clock circuits to provide a time base.

Some connections to the IC serve a dual function as both

input and output signal lines; the IC constantly switches

such lines from input to output. All of today’s control

electronics are solid state and may use transistors, or

thyristors as switches to control the a.c. power circuits.

However, when the controlled functions use very high power,

i.e. clothes dryer heater, clothes washer motor, etc.; the

electronic control operates a secondary relay whoes contacts

provide a mechanical switching function. Lower power

devices or short time operation devices are directly

controlled by electronic switches. Control inputs to the

electronic circuit may be either mechanically operated

devices, i.e. pushbuttons or water level switches, or they

may be electronic sensors sensing the proximity of a finger

or the resistance of a damp clothes load, etc. Power input

to electronic circuits is usually supplied by a stepdown

transformer with associated rectifiers, capacitors, and

regulators. In some cases, a step-up or a high voltage

secondary winding is also used on the transformer to supply

other circuits, i.e. clothes sensor, gas discharge type

display, etc. A transformer is not always used since low

voltage can be obtained by using a dropping resistor. A

blender circuit was found that used this system.

In most cases the control system controls the timing of

operations and switches them sequentially in a selected

cycle. In many appliances the control is complicated by the

addition of separate sensors which modify the timing of the

selected cycle.

Six electronically controlled appliances were obtained

and inspected as follows:

1 . c lothes dryer

2. c lothes washer

3. dishwasher

4.

5.

cooking

blender

range

6. microwave oven

The electrical circuit of a several-year old electric

self-cleaning oven range was obtained and as much analysis

as possible was done on this limited material.

102
The clothes dryer circuit was analyzed extensively.

The clothes washer circuit was traced but the analysis was

limited to a comparison with the clothes dryer. Portions of

the cooking range circuit were traced and analyzed.

The dishwasher, blender, and microwave oven circuits

were physically compared to the others with only the power

input circuits evaluated.

4.4.1 Clothes Dryer

The clothes dryer was disassembled and a standard

analysis was made of all parts other than the

electronic circuit. The electronic circuit is selfcontained, see picture Figure 4.9, and consists of a single-sided printed circuit board, approximately 10 x 15 cm, with three multiconnector terminals, a power

supply transformer and the electronic components

mounted on it. Separately attached to the board is a 10-pushbutton switch assembly with its own printed

circuit board and connector. A wiring harness

interconnects the two boards and a second harness

connects the main board to a relay assembly having

three relays in one assembly. One of these relays can

only be closed by manually depressing its armature with

the "on-off" switch button. Once depressed, the closed

relay contacts apply line power to the dryer and its

electronic circuit which in turn supplies current to

the relay coil to hold it closed. At the same time,

current is supplied by the electronic circuit to the

other two relays to close them (magnetically) . One of

the relay's contacts supplies 120 volts to the motor

that turns the dryer drum. The other relay supplies

240 volts to the heater. The heater however cannot be

energized unless the motor is running since a centrifugal motor switch is in series with the heater.

The heater can also be turned off by a separate

(nonelectronic) temperature control thermostat switch

or by a safety temperature limit thermostat.

The board of the printed circuit was traced and a schematic diagram was drawn, see Figure 4.10. The type

of discrete solid state devices was not known, so an

assumption was made in each case. Correctness of the

assumptions will not appreciably effect the analysis.

Figure 4.11 is a copy of the dryer power circuits that

was part of the service data included with the dryer.

103
Clothes Dryer Electronic Control

CD4 (at top)

Figure 4 .

104
Electronic

Clothes

Dryer

Control

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WARNING Disconnect from Electrical Supply Before Servicing Unit

POWER SUPPLY

120/240 Volt 60 Hz.

3- Wire

MOTOR

350 Watts No Load

Speed - 1740 RPM CCW

HEAT ELEMENT

5200 Watts

at 240 Volts

DRUM

Size — 6.9 Cubic Feet Speed - 45 t 3 RPM CCW

WRINKLE GUARD III (This is an option that allows the operator

to select or omit the wrinkle guard feature

for any load.)

Complaint

LONG DRYING TIME -

Possible Cause

Improper cycle selection.

Filled lint screen. Too long or faulty exhaust system.

Defective heat element.

Defective thermostat. (See test procedure.

Customer using cold water rinse. Customer overloading dryer.

Incorrect tumble speed.

Dryer installed in cold area. Defective relay.

Defective sensor. Defective 1C control.

The laundry is tumbled without heat for

several seconds every 5 minutes. This tumblewait action is repeated for about 2-1/2 hours

unless the dryer door is opened sooner.

WONT SHUT OFF -

Note: Wrinkle Guard III is selected when

this button is in the depressed position. It will remain depressed until it is pushed again

which allows it to move back out which will omit the Wrinkle Guard cycle.

TOUCH-UP CYCLE

This cycle is used to remove wrinkles from

permanent-press garments that are otherwise

clean but wrinkled. Set the Fabric Selector to TOUCH-UP and push the 20 minute (TOUCHUP) pushbutton. This setting provides 15 minutes of heated tumbling followed by 5 minutes of cool down.

WON'T RUN -

STARTS. BUT WILL - ONLY RUN AS LONG

AS "PUSH-TO-START"

BUTTON IS HELD

CLOSED.

106 1

Defective sensor. Defective 1C control. Defective relay.

(See Page 2 & 3

of this Tech

Sheet.)

Defective 1C control. Defective relay.

Door not closed. Door switch contacts D1-D open.

Defective drive motor.

Dryer in "Wrinkle Guard" part of cycle.

Dryer selector switch in "Off” position.

Defective relay.

Defective 1C control.

Figure 4.11

689593
4 . 4 . 1 . 1 H azard Analysi s One conceivable hazard condition that

arises whether or not the chassis is grounded is

related to the clothes wetness sensor. From the

circuit it can be seen that if TP1 (line voltage)

is connected by a fiber to YR, 120 volts a.c.

would be applied to one of the sensor contacts.

The fiber would not burn out due to the high

resistance to ground through the resistors (47k ft,

27k ft and 18M ft) on the electronic circuit

board. YR connects to a bare metal exposed

contact surface (about 3 mm x 55 mm in area)

mounted on a plastic part on the rear wall of the

drying drum or tub. Inspection of the circuit

board shows that there is a location where a fiber of 19 mm length might make the above

connection. The situation however is not

hazardous since TP1 is disconnected when the door

switch is opened and the door must be opened to

access the sensor contact.

All other hazards related to the electronic

circuits are limited to locations where a fiber

could connect a node connected to a power line to

the chassis (not electrical neutral). Such

hazards could only exist if the green wire

chassis ground located at the input power line

terminal board were disconnected--a very unlikely

eventuality and particularly so since in all

probability the moisture sensing system would not

function properly without the connection.

However, should the disconnection occur, the

chassis can be raised above ground potential when

carbon fibers connect TP1 on the electronic

circuit board to a chassis structure part. Since

terminal TP2 is already connected to the

electrical neutral, fibers connecting it to

ground would not create a hazard.

Observation of the circuit board shows 14

possible fiber connections from TP1 to other

nodes. In Figure 4.12; the pencil points to TP1.

One of these 14 possibilities, a connection to

TP2, would be a nonhazardous burnout or

nonhazardous load. Three would be directly to

ground and potentially hazardous. Five

connections could connect to ground through the

107
Clothes Dryer - Pencil at TPl

I Figure 4.12

108
integrated circuit. These latter may or may not

constitute a hazard depending on the withstand

voltage of the IC. Only potentially destructive

tests could determine the hazard factor. Two

connections would be to a solid state device

connection which would also require potentially

destructive testing to evaluate. One possible

node to node connection would be through a 27k ^ resistor and then through the device input to

ground .

A connection to the junction between the

47k 0, resistor and the diode D9 would not be

hazardous

.

4 . 4 . 1 . 2 Fault Analysis

There are four functional areas of the

circuit that might be affected by carbon

f iber s

:

1. power circuits

2. output (relay) circuits

3. input circuits sensor

4. input circuits selection

Each of the functional areas was reviewed

for possible faults due to carbon fiber

connections. To attempt to itemize all of these

possibilities would require a list many pages

long. Many, if not most, possible fiber

connections would cause fault conditions of one

description or another. None of these

connections appear to cause a hazardous condition

to arise.

Illustrative of the complexity of listing

and analyzing possible fiber connections is the

following list of connective paths from the "X"

input terminal of the IC to other terminals:

109
No. of Possible

Fiber Connections

X to terminals connected to ground 3

X to grounded switch structures 3

X to Z 4

X to W1 1

X to Y 2

X to P8 (input dc power lead to IC) 2

X of P7 (gate to heater transistor) 1

X to collector of IC voltage regulator 1

X to base of IC voltage regulator 1

X to sensor gas discharge lamp (diode side) 2

TOTAL 20

There are about the same number of possible

fault connections for each of the other timing

control input circuits (Y, Z, and W).

The possible fault conditions that could

arise range from very simple ones such as the

dryer will net turn "on" (grounded base of SI

relay transistor) and will not turn off (base of

SI connected to CS2) to very subtle fault

conditions. Subtle ones would be a change in

timing which would affect only the heater "on"

and motor "run” timing after the dryness sensor

has initiated the termination of the drying

cycle. Such faults would arise from fiber

interconnections of the XYZ and W circuits.

4.4.2 Clothes Washer

The electronically controlled clothes washer was

also analyzed by making a schematic circuit diagram of

its electronic circuit, see Figures 4.13 and 4.14.

The circuits do not necessarily correctly indicate the

type of three terminal solid state devices used since

this information was not available. Analysis of the

circuit, however, is not dependent upon the device

type. The basic functional areas can be broken into

the same groups as the clothes dryer and similar

analysis was made for hazards and faults. The circuit

board is approximately 13 x 20 cm in size and single

sided. Figure 4.15 is a copy of the circuit supplied

with the washer by the manufacturer.

110
Ill

Figure

4.13
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Electronic

Control

Clothes

Washer
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113 Figure 4.15
4.4.2. 1 Hazard Analysis

Since the clothes washer is a Type I appliance, circuits connected to either side of

the line must be considered potential hazards

with a 50/50 chance of being above ground

potential. Inspection of the circuit shows that

no part of the electronic circuit is directly

connected to ground so any carbon fiber making

contact to the chassis structure to almost any

conductor on the electronic circuit board could

constitute a hazard condition. Physically, there

is only one location on the board that could be

connected to the chassis structure with a carbon

fiber. This is from the heat sink of the voltage

regulator to a mounting bolt on the indicator

lamp housing (13 mm). A fiber from this point

(voltage regulator transistor collector to

ground) would apply line voltage to ground

rectified by two sets of series rectifiers in

parallel (the power supply full wave rectifiers.)

All other uninsulated electrical connections are

more than 20 mm spacing from chassis structure.

4. 4. 2. 2 Fa ult Analysis

The functional areas of the electronic

circuitry for the clothes washer are the same as

for the clothes dryer. The only external input

circuit sensor in this case is the water level

switch which is the same as that used on

nonelectronic control types. As with the dryer,

the number of possible carbon fiber locations

that could cause fault conditions is very high--

hundreds or thousands of node-to-node

possibilities- -so an analysis of each would be

meaningless. It should be noted that whereas the

dryer had only three output circuits, the washer

has 10 circuits that control relays and/or

solenoids. Each of these circuits has a threeterminal solid state output device (transistor or

thyristor) that can be turned on, turned off or

burned out by various fiber connections. Also,

the dryer has 10 pushbutton switches that affect

five input circuits. The washer has 12 switches

affecting 10 input lines and these input lines

provide signals to the lamp and control IC’s as

well as the main program IC.

114
Several possible fault conditions could

keep the hot or cold water solenoid energized

which would cause the water to continue flowing

into the tub during the entire wash cycle. This

could overflow the tub and cause water to flow

onto the floor of the laundry room. Depending

upon the definition used this might conceivably

be termed a hazard condition.

4.4.3 Dishwasher

No schematic circuit diagram was made of the

electronic circuits of the dishwasher. Pictures 4.16,

4.17, and 4.18 however show the boards and components

and Figure 4.19 shows a copy of the electrical

schematic diagram supplied with the unit. Both printed

boards, each about 10 x 25 cm in size have a direct

connection to electrical neutral and one has a directto-power line input. There are eight output circuits

to relays, solenoid, blower motor, and thermal actuated

operators that could be turned on or held off by

carbon fiber connections. Also, there are two input

sensing circuits--a thermostat and a float switch.

Since the float switch is in series with the water

valve solenoid, there is little possibility of a flooding situation caused by the electronic circuitry

as there was in the clothes washer.

There is a potential hazard associated with the

heater because there is no backup thermostat overheat

protector. If a fiber-created circuit were to hold the

heater relay closed, the heater would stay on as long

as the door switch remained closed. Hazardous interior

temperatures might be developed with such a fault.

There are nine input circuits that control the cycles

and cycle timing. Also incorporated into the

dishwasher is an LED type numerical display device. The

two digits of the display each have seven input

circuits, any one of which might be made inoperative

by carbon fiber connections.

4.4.4 Cooking Rang e The electronically-controlled cooking range had a capacitance type finger presence detector (as opposed

to mechanical displacement type pushbuttons) and was

the only appliance found to use a planar gas-discharge

type numerical display device. The printed circuit

115
DISHWASHER

ELECTRON IC

CONTROL

Figure 4.16

Installed in

Dishwasher

Figure 4.17

Soldered

Sides

kw A

Figure 4.18

Component

Sides

116
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Figure 4.19

117
board in the range is a large one, about 12 x 58 cm.

See Figure 4.20. On this board are mounted all of the

electronic circuits, displays, spring contacts to the

finger sensing pads, and transformer. A schematic

diagram of some of the electronic circuits was drawn

and is shown in Figure 4.21. Figure 4.22 is a copy of

the power circuits supplied with the range. The

transformer on the circuit board has a high voltage

winding needed for the displays as well as a low

voltage isolated winding to supply the logic circuits.

This low voltage is connected to the neutral line

through a voltage regulating power transistor. Because

of the use of a stepup transformer, many of the

circuits on the electronic printed circuit board must

be considered potentially hazardous as related to

carbon fiber connections less than 20 mm to structural

conductive parts. The product is a Type II device and

as such the likelihood of a floating chassis (ground

connection removed) is minimal. Also, the circuits

connected to the neutral incoming power connector (N)

cannot be made hazardous. This is so because the range

would be otherwise inoperative if either of the line

voltage power connectors were inadvertently connected

to the neutral terminal. A limited measurement of node

to ground distances showed more than 20 locations on

the board that were less than 20 mm from ground and

thus might constitute a hazardous condition. As with

the other electronic products, the fault possibilities

are too numerous to itemize or analyze. Mechanical

interlocks and an overlimit thermostat provide adequate

protection from hazardous oven temperatures. A hot

surface warning pilot light provides protection from

unsuspected hot surface units should the electronic

circuits cause them to turn on unexpectedly. The

possibility does exist that combustable items could be

left on an unattended surface unit at the time that a fiber causes the heater to go on. This is a potential

hazard but such a hazard would also exist with

nonelectronic type ranges since carbon fibers are not

the only way the hazards could develop. This

electronically controlled model range has been reported

to be no longer manufactured.

4.4.5 Self-Cleaning Oven

Some of the early self-cleaning oven ranges used

electronic oven temperature controls which also

provided the turn-off signal for the self-cleaning

118
Electronic Control Range

Circuit Board.

Component Side (Note Displays)

Soldered Side

Figure 4.20

119
120

It

32032

Control

Circuits
KA1

Electronic

Control

Range

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121
cycle. No range was obtained for inspection but a circuit diagram Figure 4.23 was found that shows the

circuits involved. These circuits were simplified in a schematic diagram Figure 4.24 to help in the analysis.

Since the electronics are completely isolated from the

power circuits by an isolation stepdown transformer,

the electronic portion of the range should add no

additional shock hazard potential. Carbon fibers

making node to node connections on the electronic

circuit could cause relay HW to close or prevent it

from closing thus effecting oven temperatures (a fault)

but would not generate a hazard due to the NAK

temperature limiting thermostat.

4.4.6 Microwave Ovens

Two countertop microwave ovens were examined

which both had electronics in the control systems in

addition to the inherent power output componentsmagnetron, high voltage rectifier, capacitor,

transformer, etc. One model has an electronic timer

and control system with finger sensing switches. The

second model has a mechanical timer but also has an

additional electronic controller, which incorporates a temperature sensing circuit (meat probe) that switches

the magnetron power circuit. Complete circuit diagrams

were not obtained. A diagram of the power circuits but

not the controls was provided with the model with the

mechanical timer. No schematic was made of the

electronic controls.

4. 4. 6.1 Hazard Analysis

Countertop microwave ovens are Type I appliances, so circuits connected to either side

of the line are potential hazards. The power

supply for the electronics and the high voltage

for the magnetron are isolated from the power

line by transformers in both models examined.

These circuits should not add potential shock

hazards.

Possible operation of the magnetron,

described in the following fault section, due to

fibers is probably not a hazard since door

interlocks still function to protect operators,

thermal cutouts prevent overheating and fires in

the microwave p ower circuits and any burned food

122
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FIGURE 4.24

SELF CLEANING RANGE

124
would be contained in a totally enclosed metal

cavity

.

4. 4. 6. 2 Fault Analysis

Both models have what appears to be a thyristor which switches power to the magnetron.

It is likely that a fiber can turn on the

thyristor directly or solid-state drivers could

be made to turn the thyristor "on.” This would

turn on the magnetron. For the model with the

mechanical timer, the power will still be

controlled properly by the timer but will be on

all the time when the meat probe is used. This

operation is unlikely to be a hazard since the

oven has thermal sensing and current sensing

overload protection.

The meat probe will turn the oven off at a temperature below the setting if the sensor is

shunted by a fiber's resistance. The probe

examined is 50k ft at room temperature and about

5-10k ft in the range of cooked food temperatures.

There is a possibility of a fiber

initiating an arc in the high voltage circuit.

One oven was found to produce a 4kV peak square

wave. One oven has a node 10 mm from the chassis

and the other oven has a node 17 mm from the

chassis. These distances are in the range of

possible arc maintenance. The arc would short

circuit the magnetron high voltage probably

preventing any microwave output.

The circuits were not probed or subjected

to fibers to test the possibility of arcing.

4.4.7 Blender

The only electronically controlled small

appliance examined was a blender whose electronic

circuit controlled both speed and time of operation of

the motor. The electronics also provide a calculating

function to perform English/Metric units conversions.

No circuit diagram was drawn but pictures were taken.

Figure 4.25 shows two major appliance circuit boards

along with that of the blender to indicate the
1

Applianc e Elec troni c Control i CD-4 Clothes Dryer

CW-4 Clothes Washer

FB-1 Blender

Figure 4*25

Blender Circuit Board

(Switch Assembly on Left)

Figure 4.26

126
comparative size. Picture 4.26 is a closeup to

show the circuitry involved.

There are no shock hazards involved with the

blender since there are no exposed (touchable) metal

parts that are within 20 mm of an electrical part . Neither is a physical hazard likely since more than one

operation must be made before the blender motor will

run (turn mechanical on-off switch on, select speed by

pushing a button, start motor by pushing the "start"

button). Observation of the electronic circuit board

shows that the likelihood of a fault due to fiber

interconnections on input, output display or power

circuits is high. In this appliance, fault conditions

are aggravated by the air flow arrangement which causes

the motor cooling air to flow by (partially over) the

electronics. Also the very close spacing of the nodes

makes many interconnections with a 20 mm fiber

possible

.

4.4.8 T est Method Analysis

The shock hazards associated with electronic

circuits vary from none to many (over 20). Because of

the extreme variation in circuits and construction, and

because the electronic components configurations do not

lend themselves to physical spacing measurements

(millimeters) or fiber simulator testing the only way

to evaluate electronically controlled appliances is to

actually test them with exposure to a carbon fiber

environment. A possible comparison could be made by

testing two clothes dryers simultaneously, CD3 and CD4

,

since they are similar except for the control circuits.

The test would need to separate any measured shock

hazard conditions into those associated with the

control circuits vs. power circuit hazards. Similar

tests could be run on the other electronically

controlled appliances.

However, it is not felt that testing all of the

electronically controlled appliances examined would be

meaningful since these designs are but early examples

of many that will be available in the future.

Undoubtedly these future products (and improved or

updated designs of the present ones) will differ

significantly from the now available ones (for example,

in number and type of IC). These variations make an extrapolation of test data taken now no better than

assuming that a test on a single clothes dryer is a rough measure of hazard sensitivity of all major

appliance electronic control designs. Though

127
availability of various designs of electronically

controlled small appliances is practically nill,

experience indicates that the number of possible

hazardous conditions is not likely to be much different

than with stand arc nonelectronic designs.

Faults in the electronic controls of appliances

can occur in any of the following functional areas:

1. power supply

2. output controls--r elays , solenoids, etc.

3. output signals--lamps , alphanumeric displays, sounders,

etc

4. input sensors--temperature , water level, etc.

5. input selectors—pushbu ttons , finger sensor, etc.

Carbon fibers can cause faults by making

electrical interconnections within any of the above

functional areas. These faults can range from

catastrophic (appliance no longer functions at all) to

subtle faults not easily observed but still a likely

cause of customer irritation resulting in a service

call

It has been concluded that tests for either

faults or hazards in a carbon fiber environment of any

of the electronic control appliances per se would not

be productive. This is partly because the very first

fault may be destructive so that other faults or

hazards could not then be detected. Second, and most

importantly, the only way many faults can be detected

is by running the appliance through all of the possible

cycle combinations and closely observing the operation.

For instance, if the dryer were exposed ana a fiber

connected Y to Z , the only way this could be detected

would be to run the dryer with a standard damp load of

clothes with the 4th from left pushbutton depressed.

The total drying cycle could then be compared to the

time required by the same test (prior to fiber

exposure) drying cycle time with the 4th from left

button depressed and with the 2nd button depressed.

This particular fault would also be detected by

comparing tests run before and after on the 60 minute

timed cycle vs. the 60 and 40 minute cycles prior to

exposure

It can be seen that a set of six runs with a standard clothes load plus one with the wrinkle guard

128
"on" and three runs without clothes load plus one with

wrinkle guard "on" to check the "time only" cycles

would be needed prior to exposing the unit to carbon

fibers. These 11 standard cycles with a record of the

sequence of operations and cycle times would then be

compared with the same runs after exposure. During

these runs the motor, heater, ana indicator lights

would have to be observed to assure that they were

functioning correctly. The above set of 22 tests could

be run but a catastrophic fault might well abort the

test during or at the very start of the first run with

chamber fiber exposure. The only way to circumvent

this would be to insulate the connections that lead to

catastrophic failure, but this would then prevent the

test evaluation of the worst case failure mode.

Furthermore, testing of the dishwasher would not give

results that could be directly ex tr apol at able to other

electronic controlled appliances because the circuits

and systems differ so greatly that a fault in a dryer

timing cycle could well not be comparable to a fault in

a clothes washer cycle. Thus, each would have to be

tested individually. Because of the above the

following recommendations are made.

4 . 4 . 8 . 1 P roposed Test

In order to evaluate the probability of a carbon fiber causing either a hazard or a fault

in electronic circuits, it is proposed that an electronically controlled appliance (preferably

clothes dryer CD4) be tested in an environmental

chamber exposing it to carbon fibers with the

following modifications having been made.

1. Disconnect the electronic circuit board

multiwire connectors.

2. Connect external wires to the control

relays and bring them outside the chamber.

Provide external power to these wires so that the

dryer motor and heater can be controlled to

permit either running the unit or not during the

fiber exposure.

3. Disconnect the ground strap so that the

chassis voltage to neutral may be measured during

the test.

129
4. Modify the electronic circuit board. Using

multiconductor cable, connect a wire to each of

the separate circuits on the circuit board.

Connect the cables to a scanning multimeter (or

data logger). Since the side of the circuit

board opposite the electronic components is

insulated with a nonconduct ive transparent

coating, the connections can be made to this side

and reinsulated so as not to change the fiber

exposure conditions.

5. Using the scanner, monitor the resistance

of each circuit to every other circuit and to

ground during the fiber exposure period. Record

any changed resistance values.

4 . 4 . 8 . 2 T est Analysis

The results of the above test will provide

information as to the number, time, and location

of fiber connections during the exposure period.

This information will permit statistical

evaluation providing probabilities for faults

and/or hazards in the five sections of electronic

circuit boards. These probabilities can be

combined with a count of input/output circuits

and controlled functions, circuit board area of

uninsulated printed circuitry, component density,

etc., to result in an overall probability of

fault and hazard for any electronically

controlled appliance. The probability can be

applied to the various presently available

circuit boards and also will assist in

estimating the future carbon fiber related

problems that may arise as the use of electronic

controls increases.

4.4.9 Other Electron ic Pr oducts (Smoke Detectors)

Although not considered in the small appliance

category, several smoke detectors were obtained for

carbon fiber effect analysis. The units were partially

disassembled and inspected. Simplified electrical

schematic diagrams were drawn for two of the units, see

Figures 4.28 and 4.29, one of which was a batteryoperated, ionization type, and the other a photo

electric, line cord powered type. Inspection of the

units shows that they can range from very simple with
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few nodes to very complex with many nodes and

components. Because of the complexity and because a test would be simple to perforin with little difficulty

in evaluating faults (false alarm, no alarm or short

battery life), it is proposed that no physical or

electrical analysis be performed but rather that the

units be tested in a chamber fiber exposure experiment.

There are no shock hazards related to these products

(no exposed touchable metallic parts), but the hazard

evaluation instead is directly proportional to the

fault probability.

It should be noted that the term electronic or

solid state has been used by manufacturers to apply to

devices incorporating only a diode as the sole claim to

the term. Other products utilize electronics to

control only one function with one input (lamp dimmer,

drill speed control, range temperature control, etc.).

Such devices make better claim to the term

"electronic." The potential for fault or hazard is

greater than for the nonelectronic equivalent, i.e.,

perhaps two to four fault modes and two additional

hazard inodes for each such application. Ho testing is

proposed for such products.

4 . 5 Future Product Design Trends

In the past 20 years or so only two new major

appliances have been introduced, the trash compactor and the

microwave oven and only the latter appears likely to be a significant factor in the future. Two major appliances have

shown large market saturation gains during these years; the

dishwasher and the clothes dryer but their basic designs

have not changed significantly. While load capacities of

appliances have tended to increase and styling has evolved

slowly from rounded to square corners, there have been no

changes that would effect their susceptabi lity to carbon

fibers. Design changes have been toward lower costs and

additional features, i.e., permanent press drying cycle, ice

cube dispensers, srnoothtop ranges, etc. Electrical design

changes have been toward the use of more insulation and

consequently lesser carbon fiber hazard potential.

In considering new technologies and their impact on

either appliance designs or the function of the appliances,

only the use of electronics is likely to be a major factor.

Food technology, fabric technology, energy related

133
technology, materials technology (including carbon fiber * reinforced plastic parts) all may cause changes in product

or product functions but none would seem to change the

hazard or defect su sc ep t ability of appliances due to a possible increase in airborne carbon fibers.

i When evaluating the probable future growth of

electronic controls in appliances, past progress is

illuminating. The availability of silicon controlled

rectifiers (SCR's) started in the late 1950's and these

devices made possible the control of sizeable amounts of

power with solid state devices. In the intervening 25 to 30

years, little has been done in incorporating electronics

into appliances for three reasons: 1) Costs were high and

have only recently approached a breakeven position; 2)

Electronics provided no additional function or features that

were not already readily accomplished by electromechanical

systems (Only the magic of the word "solid state" and

possibly some reliablity improvement were potentially

saleable advantages); 3) Electronic controls do not have the

inherent time or cycle display available with timer-motor

electromechanical controls. A display is desirable since

it is frequently necessary for the appliance user to be able

to visually determine the point in the operating cycle

(i.e., how much longer until the wash cycle is done?).

The next ten or so years will certainly see a large

growth of electronics in appliances because all three of the

earlier restraints have lessened. The cost of electronic

controls has fallen drastically so that now equivalent

electronic systems cost only one and a half to five times as much as the electromechanical counterpart as opposed to the

10 to 20 times as much a few years ago. While electronics

are not likely ever to attain a post breakeven point, the

additional benefits discussed below might outweigh a modest

cost premium.

The advent of large scale integrated circuits including

the microprocessor at reasonable cost permits the design of

control circuits that improve the performance of products.

The additional electronic computational and complex logic

capabilities can be used to provide more precise control

with greater flexibility than possible with

electromechanical devices. This improvement usually

requires the addition of sensors or transducers, however,

which adds to the cost and complexity. Whether the benefits

of electronic controls can be "sold through" to the consumer

134
will largely determine the actual growth pattern of this

technological advance.

Display devices have also seen drastic price reduction,

due largely to the high volume of units used in applications

other than appliances. Numeric or alphanumeric displays can

reduce the problem of the lack of a visual point- in-cycle

reference which was the third major obstacle.

All of the above indicates a certain growth in

electronic controlled appliances, the question is how much.

Ho sure answer can be given but an educated guess would be

that in 10 years, electronic controls will constitute about

25% of the sales volume (units) in appliances. This would

mean that perhaps 10% of appliances in use by 1988 will have

advanced electronics control systems.

This growth must be considered when evaluating the

potential harmful effects of a growth in the use of carbon

fiber materials.

Of course the major exception to the above is the

microwave oven whose power circuits are all 100% electronic.

The control systems for microwave ovens are now probably

about 60% electromechanical and 40% electronic, but this

ratio will probably invert in the next 10-year period.

While this discussion has been directed toward major

appliances, it is just as valid for small appliances. The

exception is that the 10-year growth of the use of

electronic controls is likely to be much less. This is

because even slight cost/price increase in the small

appliances marketplace is less likely to meet public

acceptance. Two areas, entertainment and/or communication

devices and security products, are likely to continue their

extraordinary growth rate. Whether such products can be

considered appliances is subject to question but since their

useful output is not power, their relationship to carbon

fibers is in a different category. Indicative of the growth

expected is the recent announcement of two new electronic

small appliances at the January 1979 Housewares Sho« , a Yogurt maker and an electric blanket. No reason is given in

aover ti sements for the solid state application in the Yogurt

Maker (probably a heat reducing diode) and the claim for the

blanket circuit is silent operation. At the other end of

the spectrum are a blender and food processor presently on

tne market that have very complex electronic circuitry to

provide speed control, cycle time control and LED numeric

135
readout display. A dual use for the electronics on these

products is the provision for a simple computer mode to

allow a few English-Metric units conversions.

4.6 Recommenced Chamber Tests

It is recommended that the following products be tested

in a carbon fiber chamber to measure the exposure required

to cause any faults or hazards:

1. CD3 Clothes Dryer

2. CD4 Clothes Dryer, electronic control

3. T02 Toaster

4. T0V1 Toaster Oven

5. T0V3 Toaster Oven

6. H I 4 Hand Iron

T. SM3 Smoke Detectors

8. H3 Heater

9. M0V1 Microwave Oven

10. M0V2 Microwave Oven

The above product list should suffice to evaluate the

general population of appliances and is based on the

assumption that purging of tested appliances is possible so

that each can be tested several times with essentially no

carbon fibers present at the start of each test.

The reasons for selecting each of the above appliances

are as follows:

1. CD-3 Clothes Dryer--"Typical " major appliance

construction. The construction of ail major appliances,

from an electrical circuitry standpoint, are quite similar--

insulatea wires interconnecting components with quick

disconnect flag type terminals. This similarity permits the

test results from one tested appliance to be used in

evaluating all other appliances using the data taken by this

NBS study. What is required is to know how many carbon

fiber generated electrical circuits occur under a known

fiber exposure. This figure can then be applied to the

"susceptability" information on each of the other appliances

that were studied. The tested appliance will have a known

number of nodes having a known combined "D" x "L" factor in

136
each of the types of environment, i.e., enclosed, normal,

fan forced, convection forced. The fault and hazard

occurency during standby and operating status of the tested

appliance can provide the basis for evaluating most other

appliances except those recommended for chamber testing.

There is no known method of evaluating the integrity of

the ground system or of evaluating the probability of fibers

making connection through noncontiguous paint or enamel

insulation. The hazard factor of such barriers will have to

be estimated.

2. CD-4 Clothes Dryer with electronic control. The test

for susceptability to hazards and faults will be difficult

to measure ana to generalize for extension to other

electronic controlled appliances. See section 4.4.8 of the

main report for a proposed test method to be used for

electronically controlled appliances.

3. TO-2 Toaster. Due to the "bus-bar" type construction

and the open wire heaters of most toasters, the hazard

susceptability of these devices cannot be analytically

determined. See section 4.3.1 Special Case for a discussion

relating to this product. Chamber testing must be done for

this evaluation. Toasters are not susceptable to carbon

fiber created fault conditions. Experience shows that the

construction of most (if not at all) toasters is so similar

that the test on one can be extended to all.

445. T0V-1&3 Toaster Ovens. Although toaster ovens do not

use exposed heater elements, the electrical interconnection

circuits are similar to toasters and cannot be analytically

evaluated. Two units are proposed for testing since they

represent well over 75% of the units in existence and they

are quite dissimilar both in control circuitry and in heater

construction

.

6. HI-4 Hand Iron. The proposed iron is similar in

construction to a majority of all irons now in use. The

electrical construction is somewhat similar to toaster ovens

but the similarity is not sufficient to permit extrapolation

so a test is proposed.

7. SM-3 Smoke Detector. See section 4.4.9 for a discussion as to the reasons for selecting these products

for testing. It is felt that the unit selected is "worst

case" for potential fault conditions and the test results

137
I

can easily be used to provide a reasonable estimate of

suscep tability of otner types.

8. H-3 Heater. This product was also aiscussed in section

4.3-1 of the main report. The construction of the

recommended unit is quite similar to most other portable

electric room heaters so the results can be generalized.

The product is most interesting due to its susc eptabi lity to

hazards from convective air currents.

9&10. M0V-1&2 Microwave Ovens. See section 4.4.6 of the

main report for a discussion of the reasons for testing

these units. The results relating to extra high voltage

with the possibility of sustained arcing is of great

interest with this product type.

138
5 . 0 General Summary of Faults and Hazaras , General . Major electrical appliances were purchased on the

open market to evaluate their susceptability to possible

graphite fiber generated hazards and faults. The models

were from the largest manufacturers and were their highest

selling models. A review of the descriptive features and an

inspection of these models indicates, with the exception of

electronic controls, that they all are quite representative

of appliances sold in the past 20 years, differing merely in

styling and in the additions of special cycles. For example

current laundry products incorporate additional cycles for

handling new, synthetic fibers, ana dishwashers incorporate

special cycles for handling various dish loads; there may be

a cycle for extra difficult loads.

Analysis and testing on all major electrical appliances

indicate that the potential hazards are numerous and the

potential faults are minimal for all major appliances which

do not incorporate electronic controls. While the inclusion

of electronic controls does not substantially change the

number of hazards, the number of potential failures are too

numerous to determine either by analysis or by direct

probing of the circuitry with the carbon fiber simulator.

A potentially hazardous node is one with a spacing or

20 mm or less from the chassis or any touchable conductive

surface. The number of hazardous nodes typically represents

50 to 75 percent of the total number of nodes. The number

of potential hazards are about 40 per major appliance.

These potential hazards must be tempered by hazard

type, environmental enclosure, ground integrity and relative

spacing. Each of these are discussed below.

Environment Enclosure. The environmental description gives

a rough gauge of difficulty for carbon fiber intrusion. The

three classes of environmental enclosures are:

1. Enclosed (E)--This is an enclosure which has a few

small openings which make it difficult but not

impossible for carbon fiber intrusion.

2. Normal (M)--This is a semi-enclosed area having many

accessible openings.

3. F/C--This is an area which is exposed to fan-forced air

or convection forced air.

139
Hazard Type. There are four hazard types which are

described by the finish of the nearest surface in the

vicinity of a particular node and whether a particular node

is continuously electrically active or whether a particular

node is switched to be active during certain parts of the

duty cycle. The four hazard types are described below.

1. Continuous Bare (CB): This is a node which is

continuously electrically active and has a spacing 20

mm or less to a bare metal surface.

2. Switched Bare (SB): Ths is a node which during certain

phases of the duty cycle is switched to be electrically

active and is 20 mm or less to a bare metal surface.

3. Continuous Painted/Enamel (C P/E): This is a node

which is continuously electrically active and has a spacing of 20 mm or less to a painted or enameled

surface

.

4. Switched Painted/Enamel (S P/E): This is a node which

during certain phases of the duty cycle is switched to

be electrically active ana has a spacing of 20 mm or

less to a painted or enameled surface.

Spacing . The spacing between an active node and the nearest

conductive surface is one of the parameters that will

determine the probability of a particular length fiber

making a connection and the resistance to current flow from

an active node through fiber to a conductive touchable

surface or to the chassis. The smaller the spacing, greater

the possible current flow due to lower fiber resistance.

Spacings were measured between noaes and conductive

surfaces. Four spacing groups were determined as follows:

<5 All spacing which

millimeters

.

measured less tha n 5.9

6-9 All spacing which measured 6 to 9.9 millimeters

.

>10 All spacings which

less than 20.1 min.

measure at least 10 mm but

Ground Integrity . Ground integrity for each appliance was

not quantitatively evaluatea but a review of the data taken

ana inspection of the appliances evaluatea does not indicate

a significant likelihood of hazards due to disconnected or

poor grounds between accessible touchable parts, either due

140
to manufacturing defect cr due to probable degradation of

connections during the life of the product.

Faults and Hazard Statistics . A total of 59 appliance

models were evaluated. However 16 of these appliances were

not amenable to a complete evaluation by analysis and probe

tests. Ten of these 16 models are being recommended for

chamber testing because 1) some contain electronic controls

and 2) some contain internal bare-bus bar wiring or

uninsulated heater wires which presented an unwieldy number

of possibilities for carbon fiber shorting and 3) some are

r epr esentative models chosen to quantify the fiber exposure

required to cause a fault or hazard as an indication of the

vulnerability of a particular appliance category and others

of similar construction.

Forty-seven of the 59 appliances were amenable to a complete or partial evaluation by probe testing and

analysis. Table 5.0 shows a summary of hazard statistics.

The 47 appliances examined collectively contained almost

1000 nodes of which 732 were determined to be potentially

hazardous nodes. However, these potentially hazardous nodes

must be tempered by the expected fiber length, node spacing

to the nearest conductive surface, and the type of

environmental enclosure.

According to the China Lake Barrel Eurn Test results

published in NASA conference publication 2074 C7], most of

the fibers are less than 5 mm in length. Therefore, nodes

having spacing greater than 5 mm to the nearest conductive

surface would require multi-fibers to bridge the gap between

a node and the surface. Additionally, tests conducted for

NASA to determine "the vulnerability of quick disconnectconnectors to carbon fibers" indicate that when the fiber

length is less than the space between the node and the

conductive surface, the exposure required to bridge the

spacing with multi-fiber bridges is orders of magnitude

greater than when the fiber length to spacing ratio is greater than unity [8], If this is a valid conclusion, then all

nodes with spacing greater than 5 mm are significantly less

susceptable to capturing fibers as compared with nodes which

have a spacing small than 5 mm.

Of the 732 potentially hazardous nodes, 158 have

spacings less than 5 mm to the nearest conductive surface.

About 66$ of these 158 nodes are located in an enclosed

area, which greatly impedes carbon fiber intrusion. A

Bionetics fiber chamber test on a clothes dryer [91

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indicates that the transfer function into an enclosed area

is more than two orders of magnitude smaller than the

transfer function into a normal area. These nodes should

have a lower likelihood of causing a hazardous electrical

shock condition.

The remaining 3 4% of the hazardous nodes are loacted in

a normal or a fan forced area which is susceptable to carbon

fiber intrusion. Therefore, after considering vulnerability

restraints such as fiber length, spacings to nearest

conductive surface, protective surface coating and

environmental impedence, about 53 nodes out of 732 nodes may

pose significant potential shock hazards if the appilance is

not properly grounded. However, 37 of the 53 nodes were

found in 120 volt or 240 volt, 3-wire appliances and if

these appliances are properly grounded these nodes would

present low probability of electrical shock hazard. The

remaining 16 nodes were found in nine portable appliances

(120 volt, 2-wire) in which the electrical shock hazard is

not affected by the grounding system. These 16 nodes are

potentially hazardous.

5 . 1 Refrigerators Summary

Three refrigerators were evaluated, see Table

5.1, to assess their susceptabili ty to possible carbon

fiber generated hazards. Inspections of three

refrigerators revealed that most electrical components

are either located in a fan-froced air path or fairly

well enclosed by interior panels. Those electrical

components which are located in a fan-forced air path

are routinely exposed to lint accumulation ana other

airborne particles, and therefore must be appropriately

aesigned for this type of harsh environmental

conditions

Hazardous Nodes : The three refrigerators evaluated

collectively contained 48 nodes. Twenty-nine or 60.4

percent of these nodes were determined to be

potentially hazardous nodes. The nodes were not

equally distributed between the three r ef r igerators

that is; RF-1 had a total of 23 nodes which includes 14

hazardous nodes, RF-2 has a total of 21 nodes which

includes 13 nazaraous nodes, and RF-3 has a total of

four nodes which included a hazarous node. Although

the circuit diagram for RF-3 shows more than four

nodes, these other nodes are either completely enclosed

143
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or substantial disassembly of components would be

required to attain accessibility.

Hazard Types: The 48 hazardous nodes are classified by

hazard type which (1) describes the coating or finish

of the conductive surfaces within a 20 mm spacing from

nodes and (2) whether the nodes are continuously

electrically active or switched to be electrically

active during certain phases of the duty cycle. Of the

48 hazardous nodes, six nodes were of the "continuousbare” type; seven nodes were of the " switched- bare"

type, fives nodes were of the "continuouspainted/enamel" type and ten were of the "switchedpainted/enamel" type*

Environment : The 29 potentially hazardous nodes are to

be tempered by the environmental conditions which may

impede carbon fiber intrusion or promote carbon fiber

intrusion. Nine of the 29 hazardous nodes were located

in an enclosed area while the remaining 20 hazardous

nodes were located in a fan-forced air path. The 20

nodes located in a forced air path would be more

readily exposed to an airborne particles such as lint

or carbon fibers.

Spacing: None of the 48 hazardous nodes had a spacing

of less than 6 mm. About two-thiras of the hazardous

nodes had a 6 to 9 mm spacing to the nearest conductive

surface. The remaining one-third of the hazardous

nodes had a 10 to 20 mm spacing.

The three refrigerators evaluated contained 57

touchable surfaces. However 41 of these surfaces had

greater than a 20 mm spacing to the nearest node. One

of the main cabinet surfaces and the freezer

compartment interior wall had a 12 mm spacing to the

nearest node. One wall of the refrigerator

compartments had a 10 mm spacing to the nearest node;

none of the surfaces that were less than 20 mm from the

nearest node were bare-metal surfaces.

Faults . Of the three ref r igerator s evaluated no faults

were detected either through analysis of the electticao

circuits or by probing with the carbon fiber simulator.

5 . 2 Clothes Washers Summary

Hazardous Nodes . The four clothes washers evaluated,

see Table 5.2, collectively contained 155 nodes.

Se venty-three percent (113) of these nodes were

145
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determined to be potentially hazardous nodes. The

hazard nodes as a percent of the total nodes per unit,

range from a low of 37% for CW-3 to a high 90% for CW1. The relative degree of hazard for a particular node

is affected by its environmental condition which can

either impede or enhance carbon fiber intrusion. Out

of a total of 113 hazard nodes about 50% (or 56) of

these nodes were located in an enclosed (E) having very

small openings which make it difficult but not

impossible for fiber to infiltrate. The other 50% of

these nodes were located in normal (N) area having many

accessible openings. None of the potentially hazardous

nodes were located in a forced air path.

Hazard Type . About 19 percent of the potentially

hazardous nodes were continuously electrically active

and were less than 20 mm from bare metal parts. The

second most hazardous type node is one that is

electrically active only during certain portions of the

duty cycle and are within 20 mm of a bare metal part.

Fifty-six percent of the potentially hazardous nodes

fall in this category, the "switched to bare" metal

(SB) . The third most hazardous nodes is a continuously

active node which is located within 20 mm of a painted

enamel insulated surface. Only one of 113 total

potential hazardous nodes of this type was continuous

painted/enamel (C P/E). The fourth hazard level are

those nodes that are switched to be electrically active

during certain portions of the duty cycle and are

within 20 mm of a painted or enamel surface. About 12

percent of the total 113 potential hazardous nodes were

switched and could conduct current through a carbon

fiber to a painted or enamel coated surface.

Spacing. About 12.4 percent of nodes are less than 6

mm away from a conductive surface, 21 percent of the

nodes are between 6 mm to 9.9 mm away from a conductive

surface and the remaining 56.6 percent of the nodes

were within 10 to 20 mm from a conductive surface.

Faults . Only the clothes washer (CW-4) which has

electronic controls was judged to possess potential

faults too numerous to determine by analysis or to

detect using the carbon fiber simulator. Of the three

other clothes washers, only one fault was detected

which would cause a temporary malfunction. With the

exception for electronic controls, permanent or

temporary malfunctions due to carbon fiber intrusion is

147
likely to be minimal. However, the potential for shock

hazard could be numerous depending on many factors

including environmental enclosures, the conductivity of

surfaces adjacent to active nodes, relative spacing

between active and conductive parts and the ground

integrity

5.3 Electric Ranges Summary

Three electric ranges were evaluated, see Table

5.3. Two of the units RA-2 and RA-3 were

representative of current large volume sellers. The

RA-1 unit was an electronic controlled unit using large

scale integrated circuit control chips and other solid

state circuitry on printed circuit boards. This

control technique may be a future design trend. The

other two units are more representative of present

units and older units. The more varied the control

operations on the range the greater the number of nodes

and the greater the potential for hazards and/or faults

from carbon fiber bridging.

The electric ranges operate from a 3-wire, 240-

volt, 60 Hz power source with 120 volts 60 Hz available

for some low heat conditions. Also an electric clock

timer may be supplied. The units incorporate

temperature control of surface, oven and broil elements

with the use of thermal sensory switches, thermal

relays, triacs, and range timers. Operation of the top

surface cooking elements and oven bake and broil

elements is frequently indicatd by pilot lights of 1/3

watt. Oven inspection lamps are usually 40 watts, 120

volts

The printed circuit control board for the

electronic control unit is located at the top and back

of the RA-1 unit which is the location of the controls

for the conventional units. The approach for

determining faults or hazards for this control unit

would be to test this portion in a fiber chamber. The

category summrnary is based upon this approach.

Hazards . The three units contained a total of 193

nodes of which 152 (79$) are classed as potential

hazards of 20 millimeters (mm) or less. Individually

this is 79$ for RA-1, 74$ for RA-2, and 81$ for RA-3-

The hazard types are principally continuous to bare

metal (CB) and switched to bare metal (SB). The

148
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percentages are RA-1, CB = 22% and SB = 73%; RA-2, CB = 30% and SB = 57%, and RA-3, CB = 31% ana SB = 54%. The

remaining hazards types are continuous to either paint

or enamel (C P/E) and switched to paint or enamel (S

P/E) surfaces which act as insulators until

degradation

Hazard Spacing. Of the total number of hazards 16% are

less than 6 "mm, 20% are 6 to 9 mm and 65% are 10 to 20

mm spacing from the nodes to a conducting surface.

A total of 60 bare parts and 28 painted enameled

parts that are touchable during normal operation by a user are identified. Many nodes have spacing of less

than 5 mm but most of thess are in an enclosed

environment.

Environment . All of the nodes on units RA-1 and RA-2

and 40 out of 52 of RA-3 are considered located in an

enclosed environment. The remaining 12 nodes of RA-3

are in a normal environment.

Faults. Analysis of possible fault data indicates no

permanent faults would occur due to fiber bridging

because of' high currents required by the elements

connected to the nodes. If a timer is started by a fiber bridge it activates a high current parallel load

to cause a burnout.

The possibilities for fault from fibers in the

electronic control unit of the RA-1 range were too

numerous for analysis or evaluation with the fiber test

simulator. More reliable information could best be

obtainea in a fiber test chamber.

5 . 4 Freezers Summary

Freezers are very similar to refrigerators in

that both have compartments that are fairly well

enclosed having only interior compartment air

circulation and both also have compartments that

intermittently exchange large amounts of air with the

room environment during a large portion of the day.

While some of the electrical components which are

enclosed by freezer doors, interior panels and

insulation are reasonably well protected from carbon

fiber intrusion, other electrical components located in

a fan-forced air path are routinely exposed to airborne

particles. However, some of the electrical components

150
have covers which enclose all nodes. These covers have

only small openings for the entrance of insulted wires.

Hazardous Nodes : The two freezers evaluated, see Table

5.4, collectively contained a total of 17 nodes 11 or

64.7 percent of these nodes were potentially hazardous

nodes because they are within 20 mm of a conductive

surface. Freezer FZ-1 has 10 nodes of which seven are

hazardous nodes. Freezer FZ-2 has seven nodes of which

four are hazardous nodes.

Environment . Six of the potentially hazardous nodes

were located in an enclosed environment ana the

remaining 5 nodes were located in normal areas. All

electrical components that are located in a fan-forced

air path have nodes that are enclosed and are almost

completely protected from possible carbon fiber

attachment

Hazard Type : The 11 hazard nodes are classified by

hazard type which (1) describes the coating or finish

of the conductive surfaces within a 20 mm spacing from

nodes and (2) whether the nodes are continuously

electrically active or switched to be electrically

active during certain phases of the duty cycle. Of a total of 11 hazardous nodes, only one node is a "continuous bare" type, one node is a "switched bare"

type, six are "continuous painted/enamel" type and

three are "switch-painted/enamel" type.

Spacing : Since spacing between a node and a conductive

surface affects the probability of carbon fiber

connection the distribution of the spacing was noted.

Only one of the nodes had a spacing less than 6 mm.

Six of the nodes had a spacing between 6 to 9 mm and

four of the nodes had a spacing between 10 and 20 mm.

5 . 5 Dishwasher Summary

Three dishwashers were evaluated, see Table 5.5.

These were the largest volume selling models. It is

expected that these units would be representative of

the current and past units. The models cover the low

ena builder's model to- the top-of- the- 1 ine model. This

selection covered differences in spray arms or towers,

dish rack design, detergent dispenses, and special

cycles of light soil, pots ana pans, sani-cycle, and

plate warming. More operations will increase the

151
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153
possible number of nodes and create a greater potential

for hazards and faults.

The household dishwashers are of three types; (1)

undercounter, (2) convertible and (3) portable. The

undercounter is permanently installed and is less

likely to be a hazard or fault problem than the other

two. It is the largest seller on the market. The

portable has the smallest percentage of the market.

All units operate on 120 volt 60 Hz power source. Our

evaluation was on three undercounter models.

All dishwashers now have a three-wire electrical

connection or cordset. Those with plugs (portables or

convertibles) may not be grounded if they are used with

a three-to-two adapter into an ungrounded electrical

receptacle. If any machine loses its case electrical

ground, this increases the hazard potential from the

nodes that are 20 millimeters (mm) or less from

conducting surfaces that can be touched by the user.

Hazards . The total number of nodes for the three

machines is 161 but only 81 are considered potential

hazards. The builders model dishwasher (DW-1) had all

nodes insulated so no fiber could cause a fault or

hazard. The hazard nodes are divided about equally

percentage wise between the other two machines. The

hazard types of classes and percentages are (1)

continuous bare (CB) of 12% , (2) switched bare (SB) of

20%, (3) continuous insulated by paint or enamel (C

P/E) of 15%, and (4) switched insulated by paint or

enamel (S P/E) of 50% (percentages are rounded).

Hazard Spacing . The spacing of nodes considered

hazards is 30'% for 5 mm or less, 18% for 6 to S mm, and

50% for 10 to 20 mm for the DW-2 and DW-3 machines.

All nodes of DW-1 are insulated.

The DW-1 dishwasher’s touchable surfaces are all

greater than 20 mm away from current carrying nodes.

On DW-2 and DW-3 the minimum distance between a node

that could be a potential hazard is 6 mm and 5 mm

respectively. There are a total of 73 touchable

surfaces for the three units. Only 26 bare metal and

12 painted or enameled metal are considered as

potential, but remote, hazards from fibers.

154
Environment . All of the nodes in the DW-3 dishwasher

are in a normal environment while those in the DW-1 and

DW-2 units are equally divided between enclosed and

normal. Only one node in any machine is considered in

a forced fan or convection air current location.

Faults . The DW-2 dishwasher is the only machine where

a fiber could cause a fault. This is in eight

locations. The type of fault is bridging of nodes

causing false indication of portions of the cycle

sequence or false running of the program timer or rapid

advance timer.

Due to the fact that a large percentage of

dishwashers are installed under a counter with only the

front door and bottom panel as exposed surfaces, hazard

and fault probability due to fibers is less than for

fully exposed appliances like clothes washers and

dryers

5 . 6 Clothes Dryers Summary

Four clothes dryers were evaluated, see Table

5.6. One of the four dryers, CD-4, incorporated

electronic controls. Since most dryers are 240 volt

appliances, they are either directly wired to the

electrical power source or plugged in with a special

three-wire cordset. Because of this and because there

is always a f actory- ins tailed grounding strap, the

likelihood of a dryer not being grounded is extremely

remote. In the case where the ground is disconnected,

the hazard nodes show in Table 5.6 were identified.

Hazardous Modes . The four clothes dryers collectively

contained 191 noaes. About 3 3% or 158 of these nodes

were determined to be possibly hazardous nodes. The

hazardous nodes as a percent of total nodes per unit

range from a low of about 72% for CD-4 to a high of

100% for CD-I. However, the relative hazard of these

nodes must be tempered by their environmental

enclosures. The percentage of total potential

hazardous nodes (158) found in each type of

environmental enclosure are 26.5% for "Enclosed (E)";

41.7% for "Normal ( N

) " ; and 31.6% for "F/C."

Hazard Type . The 158 total potential hazards are

classified by hazard types which 1) describe the

coating or finish of the conductive surfaces within a

155
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY

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156
20 mm spacing from the node and 2) whether nodes are

continuous electrically active or switched to be

electrically active during certain phases of the duty

cycle. Of the 158 hazardous nodes 11.4% were

"continuous-bare (CB)" type; 6.3% were "continuouspainted/enamel (C P/E)" type; and 9.5% were "switchedpaintea/enamel (S P/E)" type.

Spacing . About 66.4% of the hazardous nodes had a 10

to 20.1 mm spacing to the nearest conductive surface.

Approximately 15.2% of the hazardous nodes had a 6 to

9.9 mm spacing. The remaining 18.4% of the nodes had

spacings to the nearest conductive surface of less than

5 mm

.

Faulzs . The likelihood of faults in clothes dryers due

to carbon fibers is low. The possible faults consist

of a false cycle due to a fiber causing the cycle

control tinier motor to run when it is not supposed to

or an audible alarm to operate at the wrong time. As

can be seen from the summary table for clothes dryers,

there is a total of six possibilities of this fault

occurring in the units tested.

5 . 7 Microwave Oven Summary

Two microwave ovens were evaluated, see Table

5.7. Both had electronic control systems which were

not evaluated. One has a mechanical timer. The

microwave generating circuit and power wiring were

evaluated. The ovens are 120 VAC powered and have a three-wire grounding cord but have potential hazards if

the ground circuit is not connected.

Hazards . The two ovens have 78 nodes of which 54 or

69% are potential hazards.

Hazard Type . Of the potential hazards 4% are

continuously energized and connection to painted or

enameled surfaces C-P/E; 31% are continuous to bare

surfaces CB; 4% are switched and to painted or enameled

surfaces S-P/E; and 61% are switched and connections to

bare surfaces.

E nvironment . Of the nodes which are potential hazards

are in enclosed areas and 57% are in fan forced or

convection forced areas.

157
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY

Microwave

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Spacing. Of the potential hazards, 35 % are less than 5

mm from a surface; 13% are between 6 - 9 mm and 52%

are greater than 10 mm.

Faults . Each oven has a potential for fiber initiated

arcing in the magnetron high-voltage power supply. One

model has 2 nodes less than 20 mm from the case and the

other model one node. An additional potential fault in

each oven was identified in the electronic control

system and is described in section 4 in Electronic

Controls

5 . 8 Small Appliances

General . A total of 39 different models of small

appliances were evaluated to assess any adverse affects

of carbon fibers with respect to generating hazards and

faults. In general, these models are the best selling

models of the four largest companies with respect to

sales volume. In contrast with major appliances, these

small appliances generally have fewer nodes by a factor

of ten. The number of nodes range from a low of two

nodes to a maximum of 13 nodes. But, almost all of

these nodes were determined to be potentially

hazardous. However, extensive use of plastics as exterior housings of small appliances provides some

protection against potential shock hazards. Still

there are some hazards associated with small exterior

metal parts, even though the exterior housing is

predominately plastic. Many of the total nodes per

appliance were found to be within 20 mm of a conductive

metallic surface which were connected to exterior metal

parts. Therefore, casings that are predominately

constructed, see Table 5.9, of plastics do not

completely eliminate all shock hazard potential. Only

one model (FB-1) of 39 models of small appliances

incorporate electronic controls. The faults identified

in the summary tables are exclusively of possible

faults associated with the electronic controls. Out of

39 appliances, five faults were identified. Ho more

than one fault in each of the five appliances were

f ouna

5 . 9 Vacuum Cleaners Summary

Three vacuum cleaners were evaluated, see Table

5.9. The two upright cleaners and one tank type model

are representative of the variety of available units.

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160
They are also similar to units that have been in

service for several years.

All vacuum cleaners operate from a 120 volt, 60

Hz power source. Some have an exit port so the cleaner

can be used as a blower by inserting the normal vacuum

hose attachment at another location. The cleaners use

mechanical adjustments on the upright types and

different attachments on the tank types to clean

different surfaces and pile thicknesses of carpets.

These features, therefore, do not increase the number

of electrical nodes. The mechanical adjustments are

such that there is only a remote possibility of

increasing the fault and hazard characteristics of the

cleaners from fibers.

Hazards . The vacuum cleaners have only a small number

of nodes. A total of nine (9) are noted for these

three units. The cleaner VC-1 has two nodes, none are

potential hazards. Cleaners VC-2 with three nodes and

VC-3 with four nodes are all potential hazards for each

machine.

Hazard Types. The type hazard for VC-2 and VC-3

cleaners is in only two of the four hazard categories.

The VC-3 cleaner had two continuous to bare metal (CE)

and two switched to bare metal (SB) hazards. The only

other hazards of 20 mm or less are three (3) switched

to bare metal (SB) for the VC-2 cleaner.

Environment . The nodes located in cleaner VC-1 are not

of interest due to the spacing. Three (3) nodes in V C2 are in a normal (N) environment and all four nodes of

VC-3 are in a fan or convection forced air (F/C)

environment

Hazara Spacing . The node spacings on VC-1 are all

greater than 20.1 mm. On the other two cleaners four

nodes are spaced 5.9 rnm or less to a conductive part

and three nodes are spaced 6 to 9 mm to a conductive

sur f ace

A total of 23 separate surfaces are identified as

touchable by the user of these cleaners. These are

bare metal (11 places) and paint or enamel (9 places)

with the balance plastics. Due to construction

techniques all are greater than 20 mm away from any

node

161
Faults . Due to the manufacturing techniques used for

this category of appliance, the absence of low wattage

components and node spacing, no faults or temporary

false operation should occur from carbon fiber

bridging

5.10 Hand Irons Summary

A total of four hand irons were evaluated, see

Table 5.10. These irons were basically the largest

volume sellers. In addition to the basic function they

had spray, steam, and/or dry features. These features

could increase the number of electrical nodes for

possible exposure to fiber contamination. The irons

operate from a 120 volt 60 Hz power source. Their

power ranged from 700 watts to 1200 watts. The iron

controls and indicators are mainly a thermostat with

adjustment for fabric temperature selection, steam

button, and ready and/or on indicators light.

Hazards . Three of the irons had four nodes and the

other (HI-3) had six nodes. All nodes are classed as

potential hazards (20 mm or less) in all irons except

HI-3 which had four of the six nodes classed as

potential hazards.

Types of Hazards . Only two types of hazards were

present in the four irons. They were continuous bare

(CB) and switched bare (SB). Each iron contained two

of each of these.

Hazard Spacing . The spacing between electrical nodes

and metal surfaces was concentrated in the less than 6

mm range for a total of 15 locations ana with one

spacing of 10 to 20 mm and none between the 6 and 9 mm

range. There were 32 touchable separate parts with a spacing range of 1 to 3 mm that could be potential

hazards. Only 10 of these are bare metal (B) and three

are paint or enamel (P/E) surfaces.

Faults . The hand irons are fault free due to the high

wattage required except in the case of HI-2 where a fiber could bridge nodes to cause false operation of

the ready light.

162
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY

H

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5.11 Toasters and Toaster/Ovens Summary

A total of four household electric toasters were

examined to determine if they could be analyzed for

potential faults and hazards caused by carbon fibers.

The basic toaster contains a resistance heater supplied

by a 120 volt 60 Hz power source. The toasters covered

the range of 700 to over 1400 watts of power

consumption. Basically the units contain a resistance

heater, thermal sensing element to adjust for toast

darkness, thermostat to cut off unit, and the

mechanical lowering and raising mechanism controlled by

the thermostat and toaster selection control. All have

a two-wire coraset without a ground wire.

After disassembly of the units and visual

examination of the design layout used for these

appliances, it was concluded this appliance category

should be tested in a fiber chamber for the following

reasons. Many areas along the heater element/elements

could be classified as nodes being less than 20.1 mm

away from metal surfaces. The operation of the

darkness toast lever and the position of the toast,

when lowered, changes the possibilities for fiber

bridging. Therefore, the procedure used for node

determination, hazards and faults for the other

appliances seemed cumbersome and non-productive. In a fiber chamber test, these toasters would be exposed to

the various expected lengths and concentrations of

carbon fibers and the results could be more conclusive.

The toaster/ovens are in the same category as the

toasters but perform more cooking functions. In

addition to making toast these can be used to bake,

broil, brown, thaw, and warm in the preparation of home

prepared and convenience foods. They are larger than

toasters and have more temperature selections and

variety of preparation features. These increase the

number of electrical control nodes as compared to a toaster. The heaters on the toaster/ovens are

resistance elements enclosed in cylindrical hollow

rods. The resistance elements are insulated from the

encasing rods. The greatest danger from the heaters is

burns and there is only remote possibility of an electrical hazard should a heater become connected to

the rod case.

The three toaster/ovens usee for this evaluation

are 120 volt 60 Hz powered and range from 1350 to 1500

watts power consumption. The visual inspection of each

164
unit after disassembly indicated a large number of

movable metal arms, levers, springs, cams, etc.

Like the toasters it was concluded that analysis

of faults or hazards from fibers would be cumbersome

and inaccurate for the toaster/ovens. Therefore, it is

recommended that a representative group of these be

evaluated in the fiber test chamber.

5.12 Food Mixer s Hazardous Nodes . The three food mixers evaluated, see

Table 5.12, collectively contained 23 nodes. Fifteen

of these nodes were classified as potentially hazardous

nodes. All of the hazardous nodes were contained in

Food Mixers FM-2 ana FM-3. All of the nodes contained

in FM-1 were totally enclosed in the motor housing.

Therefore, there are no possibility of hazards due to

carbon fiber infiltration into food mixer FM-1.

Types of Hazards . Out of a total of 15 potentially

hazardous nodes, eight nodes were "continuous bare"

type, two nodes were "switched bare" type, two nodes

were "switched to painted/enamel type" and three were

"continuous to painted/enamel" type.

Environment . All of the hazardous nodes are located in

a fan or convection forced environment.

Hazard Spacing . Eight of the 15 hazardous nodes had a spacing of less than 6 mm. Only one node had a spacing

between 6 and 9 mm, and six hazardous nodes has a spacing within the 10 to 20 mm range.

The three food mixers evaluated had 21 touchable

surfaces. One of these surfaces has minimum spacing to

the nearest node of 2 mm. AL1 other touchable surfaces

are greater than 20 mm away from the nearest node. The

one touchable surface that is located 2 mm from the

nearest node is a painted surface with high resistance.

Faults . No faults were identified either by probing

with the carbon fiber simulator or from analysis of

circuit diagram.

165
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY

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CJ ii o oo on

COwaox s

<dM3 o CO 15 -

rOTAL oo co CO

CN

a o* H 2 FM1

CN §

01IH

ai

4-J 0) 01 £ 01 4J rH •H 4-J 1h a; rH (-1 cd E

p-H cd cu cd

01

H CU 3 p £ e i—i a

<u ai

g cd 4J 01 i—I ! ( 4-J

p

01 1-1 • rO 3 CU o

0) o cd •rH E

4-J CN sz 4-1 rH 0) a 00 ai 3

pH E 3 3 3 l-i -H

iH •H cd

O tH cd cd E i—1

pC 4-J CJ -o CL, i—!

4-J cd

01 rH «4H CU <4-4 <4-4 01 £ 01 o 01 o o

oi 01 rH cr« a) ?H 4-J lH

p • i—i

(U 0) ai a) P a-c HP 01 -Q H3 O P E o E E o o

•• 3 1—1 3 3

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u

u

n

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u cd PH

V 1 i-H 4-J o cu cO A c H cn

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60 • C c

•rH 3 •rH CJ 3 z

cdcu co oPo

CJ

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cn

p cn a a) >> rH p P . 01

01

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CJ -C

4J 4-1 0) o o h n csi O 01 33 p v./ 31 <4-4 01

ai o o 4-J >> n 3 cd P cn rH

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CJ

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01

O c

oi

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4-1 P 3 ”3 rH o 01 O 01 01

p-H H3 CJ 4-1 E O 01 cd cn

cd 4-J rH c * 3 01 3 01 01 P 01 01 3

<u 01 .e 3 o p

.3 01 co -h 3 0) o

01 H= •h e 3 HP

cd 4-1 H3 •H

O 4-J 3 O 4-J 4-J 3

p-H

a

a e •H •H

01

a o 3

01 N—P ,—i a 01 CU

HP cd •

4-1 CN 4-J

N it

n 9 o o 03 rH Z H fr*. CJ cn W a CJ

Pp

u

n .. +J .. UH 0 • 0 TD 3 0 cn p V z OJ m cd 0 1g CU n p Q 0 jp Cd CU H z E z 166 B

=»

base

metal

insulated

parts

Environment, ^ir

circulation :

Faults

No. =

number

of

possible

fault

conditions E=

Enclosed.. N=

Normal

F/C

Fan

or

convection

forced
5.13 Fry Pans Summary

Three electric fry pans were evaluated, see Table

5.13. All units are very similar in construction.

They contain a heating element, a thermal switch for

temperature selection, and a neon lamp to indicate when

the unit is heating. One unit contained a thermal

fuse. All units operate from a 120 volt 60 Hz power

source. They all use a two-wire cordset, without the

third ground wire. The power required for these fry

pans ranged from 450 watts to 1300 watts.

Hazards . A total of 16 nodes are present in the three

fry pans. All nodes are potential hazards since they

are 20 mm or less from another node or to another

conductive part. Fry pans FP-2 and FP-3 each have six

hazards and FP-1 has four hazards.

Hazard Types . All three fry pans each have three

continuous bare (CB) type hazards. Units FP-2 and FP-3

each have three switch bare (SB) type hazards and FP-1

has one of this type.

Environment. A total of 14 of the hazards are in an

enclosed environment. The remaining two on FP-2 are in

a normal environment.

Hazard Spacing . Out of a total of 16 hazardous nodes

seven are less than 6 mm, five are spaced between 6 to

9 mm and four are spaced from 10 to 20.1 mm.

Fry pan FP-1 has a minimum spacing of 2 rnrn between a node and a touchable part that could be a personal hazard. All the other nodes are spaced

greater than 20 mm. A total of 13 significant

touchable parts were identified with seven being bare

(B), two paint or enamel (P/E) and the others

insulators.

Faults. The FP-1 and FP-2 pans could have a false

indication of heating from a fiber activating the neon

lamp. A fiber in the cordset of FP-3 when it is

unplugged from the pan could cause the heating neon

indicator to turn on.

5.14 Coffee Makers Summary

Coffee makers are not only common in the homes

but are very popular and numerous in other locations

such as small business offices, individual offices,

167
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY tII!t 33a

P-rtnu

tilHa

z>oo

Pi

fXr

REMARKS

false

signal

false

signal

see

note

2,3

Totals

FAULTS NO. pH rH rH CN

>H

£h

Kt

P/E 0 rH 1—1

CN

Pi - Ow

EhZ

ca CN CM cn

M .

33zz

_*_L z c M P-i 2: cn

CM . A

A CN . t . o

Pio TOTAL <r

m 13

SPACING 0

rHA 0 rH cn <r

cn1 NO

rH cn rH LO

<5

cn CM CM

ENVIRONMENT

F/C 0 0 0 0 z 0 CN 0 CN w NT Mf vO

rH

TYPE

HAZARD

SB rH

D cn

w

p-icn

O

O 0 0

ca0

cn cn cn - - s

/a0 0 0 0 O

NODES £

<iN3

<T vO NO 16 3HOC_.

vO vO 16

Ha

d£

FP1

FP2FP3

co3o

•H

VJ

01 •H

5h 33

ai 3

v>

O

41 cn CJ e 01 4J pH 3 VJ V4 3 VJ rH 5h cd £ d rH cO Oh 3 3

ca *H a. 3 3 u £ E r—!

4) Mh

a) 41 E cd u tn rH rH -U Jh 3

a) 5n -O 3 <D

O <-1

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4) VJO

CM

(0 z

-H 0 -3

VJ 01 tH rH 41 a 00 a) C vj tn H £ C 3 3 P H H 01 •H •H cd O -H cd 3 3 0 g rH VJ 3 .0 3 3 3

rH 4J

a

cn •H UH D. <4H «H 3 'W

cn E cn

O cn 0 0 <3 0

<v cn VJ rH cn 4) 5n«W

VI 5haw 5-13 5-1 «i 1 <iv

u ON cn -o' -O 3 -O O u £ O 6 E tn E O 0 • • 3 T—! 3 3 3 3

ONU 3 0 3 3 -H 3 • 0 >

to \0 rH ±Ja

a

a

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un cn o a> v>

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w

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cn

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tH 3 3 3

tn rH

5-t 33 5hO - cn

a)

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rH 3 CN » a 3 "O 1H 33 <VH a) 3 0 O

tn cn 3 cd u 3 rH

33 0 <IH 3 O 0 O 31 cn

cn4) .c

5h 3 3d rH 3 0 3 3 •• X O Vi B 3 3 3 C 3 VJ iH 3 0 J 3 O 3 3 r—1

•H 3 3 3 cd i-i 3 -D C O 33 5h -u cd 3 00 -H 3 3 O a) rH J3 •H C 3 .3 0 0

cn

pHin

a) rHsEh

CO

u > 9 ^ :=> rH I a

cn o

4J > / ZVi CN O

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•H

cn 3 <u H cn <0 a

a. -a

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a

a i d o <o Eh Z U V) W

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rH •H1

168
trade shops, etc. A total of five units were

evaluated, see Table 5.14. They are considered

representative of currently available types and tose in

use

.

The coffee makers operate from a 120 volt 60 Hz

powersource. The construction techniques make use of a variety of plastics to mold the parts which provide

electrical insulation but also could melt and/or catch

fire if subjected to overheating from electric

malfunction of the unit.

The basic coffee maker uses a heater and a thermostat that functions when the coffee is ready.

The costlier models have additional features such as

brew switch, brew light, warm switch, warm indicator

light, and warm heating element. These increase the

number of nodes and potential hazards.

Ha

z

a rds . The number of nodes per coffee maker for four

of the five units ranged from 3 to 6 with CM-2 having

13 because of more brewing features. The total node

count is 31 ana the potential hazards count (31) is the

same . Hazard Types . A total of 16 continuous to bare metal

( CB) and 13 'switched to bare metal (SB) were defined.

Only two switched to paint or enamel existed.

Environment. All of the nodes of 20 mm or less spacing

for the five coffee makers are considered to be in an

enclosed environment.

Hazards Spacing . Twenty-six (84%) of the nodes are

spaced such that a fiber of less than 6 mm could bridge

from an active node to another node or a conductive

part. The other five nodes (16%) are spaced 6 to 9 mm

away from contact points.

The five coffee makers have a total of 25

touchable parts which could be a potential hazard to a user. Only nine of these parts are bare metal and the

spacing to a potentially active node ranges from 1 to 8

mm.

Faults . Of the five coffee makers evaluated only one

had a potential fault that could occur with a fiber.

The unit CM-2 could give false indication of being on

169
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY

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<P

U-Jou

Hazo0

01

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REMARKS

See

Notes

1,2,3

See

Note 1

Totals 1

FAULTS NO. o rH o o o rH

>>

ki

P/E o o o o o o

PiOWHZ

PQ

r—1

CN CN CN CN* ON ; Mozz

MIN.

SPAC. 00 cn rH CN 18 o

c£o TOTAL <r

m m. NO LO 25

>10 o CN o o CN NT

SPACING

on1 v£> o rH o o o rH -

<5 -O' 10 cn NO cn 26

ENVIRONMENT

F/C o o o o o o z o o o o o o w

<r 13 cn i£>

m 31

SB on rH CN rH 13

TYPE

HAZARD

w

p-.ca

CN o o cb o

CN

CB CN CN <r cO

rH

w

CPo O o o o o o

NODES

!LAZARD <r 13 cn NO

m

31

TOTAL <T 13 cn i£5

m 31

a o’ M Z

rH5 CM2 —5 CM4 0" 2L! g3o

-HP g •H p "3 G a p o G G G a

cn P t—t p P G P

rH P G £ rH rH ca cu G 3

cn •H cuC

G P B rH G ip G G § G P cn rH rH P P G G P • Z 3 G O rH S G

i_> oCN

GZ

•H s p o z•H

r—l G

G CO

G 3 h

G

rH

B c 3 3 P •H P G

•H •H

G

O -H

G

G

GO

B i—l X P G Z CL, Cu cu rH P G

cn

H • ip Cu *P <P ”3 <p

jn

B cn o cn

OO

G o G cn P

rH ON

G

p -U P p

Gp • i—( G 0) G G rH G P ON Z cn Z Z 3 Z o P e o £ e g B o o 3 rH 3 3 3 3

ON

p 3 O 3 3 -H 3 • o m nO rH •U 3 a a R R a a n P rH • « DJ CO G G

in on o G P a p-c v t rH P O CU • NO A 3 H cn o • - M z

CO • 3 ”3 3 G

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cn

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G P 3 •H Z /“N 3 3 P P 3 3 rH O O G O G G •• •H rH Z G P £ P G G G G 3 G G P rH 3 O G • b G 3 G G r—I

•H > P G G 3 G P 3 G G X. 3 O *3 P P G O

.3

G CO -H 3 G

O

G rH

G

G .3 •H 3 3 J= £ 3 G3 G P Z -H G P G G P 5 O P P 3 G P G rH O

rH 0 n 3 •H •H

G •HOG

G

GO 5 G

G o r

—t B 3 G rH G G a, z G w G Z cti • p 3 O Du, P CN iJ N n a n a -H W Z O O <0 H Z H =0 G O u cn w e s J 3 pT H w Z ao

4JBow

a!

h z

LD

cu rHs

E-t

170
or it could indicate false operation of the warm

heating element.

5.15 Electric Blanket (Bed Covers) Summary

A single electric blanket was evaluated, see

Table 5.15. This unit was considered typical of the

majority of electric blankets presently available. It

operates from a 120 volt 60 Hz power source and

consumes 135 watts maximum. This unit had an on-off

switch, neon lamp on indicator and a thermostat heat

selector control. Other thermostats were associated

along with the heating elements.

Hazards . A total of six nodes are present which are

potential hazards. All six of these are less than 20.1

mm to other conductive surfaces.

Hazard Types . The categories of hazard types are two

continuous bare (CB) and four switched bare (SB).

Environment . All nodes are in an enclosed environment

since they are contained in the control for the

blanket

.

Hazard Spacing. The potential hazard nodes are spaced

from conductive surfaces as follows: 1 node at 5.9 mm

or less, two nodes at 6 to 9 rum and three nodes at 10

to 20.1 mm. A total of six touchable surfaces of

potential hazard exists on the blanket control. The

minimum spacing to a hazard for any of these surfaces

is 2 mm. The only hazard surface is one of bare metal.

All others are non- conduct ive

.

Faults . If the blanket is unplugged from the control

but the control is still plugged to the power source a fault could occur. This is a false indication of the

blanket being on if a fiber shorted a node causing the

"on" neon indicator to function.

5.16 Food Blender Summary

A single food blender was included in the group

of small household appliances. Design layout is typical

of a large percentage of these units except this unit

had electronic control of the blending functions. All

operate with a two-wire coraset (no ground wire) from a

171
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY

III : Ii iiiIjIjIIjiIIjiiiii H

CJSOQO

cp

REMARKS ; j

FAULTS NO. f—{

><H P/E o

GROUND

INTEGF CQ

r

MIN.

SPAC. CNI

TOTAL vO

SPACING

>10 cn

6-9 CNJ

<5 i—1

ENVIRONMENT

F/C o

•z o

bJ vO

SB

TYPE

HAZARD

w

cp5 o

CB <N

bJ

CL,CJ o

NODES

JlAZARD MO

TOTAL vO

Mc Q.Z EB1 3p3p3 3Co

•PP

•PcOO £ cn P i—

•P P P 3 P r—

P 3 £ r—

f—

3 CL 3 3

cn •P CL 3 3

i-i £ g 1—

3 <P 3 <u g 3 P cn i—

,—P P 3 3 P • X> 3 3 O r—

$ 3 o a T-l £ XI p CM x= P 3 T-l r—

3 o CO 3 3 p 3 ,—

£ a 3 3 P •P p 3

T-l P CO

O P 3 3 3 O £ r—

4-* 3 xo CL CL CL

r-lp 3

cn T-l cp CL 14-1 LP TO P

cn £ cn

O cn o O 3 O 0) cn P H O <r p 4-1 p P 3 P . r—

0) a) 3 3 1 3 P ON X5 cn X> -O 3 JO O P £ o £ £ 3 E o o

•• 3 r—1 3 3 3 3

O'

p 3 a 3 3 -H 3 • o m \0 F—

p a a n n 0 •P a n a P r—

- « w

CO 3 o -—, m O' o 3 p a CP V i i—

p o CL • NO A c H cn o

••

M z

CO • c “ "a 3 3

T-l c T—

P o 3 S r—( 3 O 3

CL, P 3

bO CJ b< LD

cj p3

/—

3 P 3 3 3

>T ,P P

33 PO * 3 • 3 g a x: g p 0) o o

*—3 CN

*.

a 3 TO

u VP ’3 <P 3

a)

OO

p

>>n c 3 P 3 tP

TO

a cp 3 3

CJ o -a 3 3 o c 3 p e •p

x: /—c p p 3 TO f—

o 3 O 3 3

<p x:

O P E u 3 3 3 3 P rp C • 3 3 3 3 3 T 1 p 3 3 3 CO 3 3 x: c O TO P U

-C 3 CO -T-l 3 3 O <V 3 x: •P c C x: B 3 p x: so •H o P 3 o P p c <u r—

a a c •p •p cn 3 a o 3 3 cd 3 vp ,—

3 3 CL XO • x: 3 p CM P N a a n n o O 3 T—|

c-< SC CJ cn bJ CO

a CJ

CP

iin

-P cp g • •• 0 TJ p 0 CO U V 2 0) OJ 03 0 tg a, N M Q o > 03 04 H s fi SC

CQ

•PP3

rp33p

•P

LD

<D i—

•s

E-i

bJ S'.

•a

<uapoa

<u>coapocS3 b<aCJ

b172
120 volt 60 Hz power source. The power consumption for

this unit is 330 watts.

After disassembly and visual inspection of the

unit, it was concluded that representative units of

this appliance category be tested in a fiber chamoer

for more realistic and accurate evaluation of fiber

effects

5.17 Can Openers Summary

Two household electric can openers were

evaluated, see Table 5.17. These units operate from a 120 volt 60 Hz power source with a two-wire cordset

containing no ground wire. The power required is

approximately 175 watts. The basic circuitry consists

of a small motor and the on-off switch; therefore,

these units have only a small number of nodes.

Hazards . Can opener CO-1 contains four nodes and CO-2

only two nodes. Only the nodes of the CO-1 unit are

hazards due to being 20 mm or less to adjacent

surfaces.

Hazard Types. The hazards of CO-1 are two of

continuous bare (CB) and two of switched bare (SB)

types.

Environment . All nodes (4) of CO-1 and (2) of CO-2 are

in an enclosed environment. A large portion of the

units make extensive use of molded plastic housing

components

Hazard Spacing. The hazard spacing on CO-1 measured

less than 6 mm for three nodes and 6-9 mm for one node.

All nodes for the CO-2 units are greater than 20 mm.

There are 13 touchable surfaces on both can

openers as potential hazards. The minimum spacing of a touchable surface on C0-1 is 2 mm to a hazard node or

other potential conductive surface. The touchable

surfaces on CO-1 are three continuous bare (CB) and

three paint/enamel (P/E) areas.

Faults . No potential faults were noted due to fiber

contamination

173
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY

cnu

0)c3

CL ocg

CJH

CJ

3>QO

OSe

cn

ei

<;sw

ei

173H • c4 O 2 2 <2

><H

K*

PiOWH2

t—

O22O

Pioo2

CJ<2

cnH2WS2O

PiM>2WO

Pic

CMC2W2

>*H

W« 01 • CJ 2 < 2 P-I 2 cn 4<HOC_( Oi—

A

CT»I LO

UlV

CJ2w

cn

cnw

SCL.

CQCJw

CJ2<

CMc

e-o Ma ,92

CM o2

ol2

CM2 8

CM8

cnP3P

cneo2P2

•33o

a; cn CJ s cn 4-J i—

3 4-J P QJ P 2 P c0 £ i—

t—

c0 2 ca 3

cn 2 2 c cO P £ g

»—

GJ <4-4 <u 0) £ cO P cn t—

r—

p P GJ a) P - 2 c <1J O i—

-S

gO C0 2 e 2

4-1 CM 2 P cn 2 2 0) CJ CO GJ c u cn r—

e c 3 c P 2 u cn

1-( 2 cO

O 2 cO C0 03

O

.e i—-

2 4-J

O 2 2 CL 2 2 P C0

cn 2 <4-1 2 <2 <p OD <p

cn £ cn o cnOO 0)

O

0) cn 4J 2 0) p 4-J P P 03 P • i—

0) GJ 0J GJ rH GJ P d 2 cn 2 2 D 2 o P e o £ £ cn £ o o

•• 3 r—

3 3 C 3

O'. P c aCG T1 3 • o Pi Ul 2 1—

4-J

u

a

n

n

u 2 a n n P r—

• « 2 - CO c0 u

Ul Cl o 3 P c0 2 V ( r—

P O 2 • .2 A c H cn o • • M 2

CO • c 2 c cn 2 C 2 p O 3 2 i—

32

cn o

S-i o 3

cO 2

CJ p

<upg2

l-l •3 ~ cn • a) o 2 P P

GJ

O o 2 cn CM » a d) H3 P s—

"3 2 GJ

GJ

O

O P TD

Pi

n 3 cO 3 P cn »—

( a

”3

a <4-4 GJ 3 p

CJ

O •a cn o

cn o c <4-4 GJ - P s 2 2 c 3 p p 3 •a 2 O o GJ O GJ GJ • • 2 2 2 a p £ P

CJ cn c0 ca 3 a

ca

p 2 c O 3 - 5 cn 3 cn GJ r—

2 > p GJ cn 3 3 P 3

GJ cn 2 g

O

u P P 3 O 2 GJ CO 2 3 GJ O 3 »—

a

cn 2 2 3 3 2 £ 3 •a

cO P 2 2 2 o P 3 3 p 5 O P p 3 3 P 3 rH o 2 0 n 3 2 2 3 2 o 03 cn a o 3 3 3 CJ s 3

GJ i—CJ cn 2 2 U

H 3 2 <0 • P 3 o 2 p cm p o o 2 2 H 2 U CJ 2B m n a

cO ~ cj cn 2 cnn 2 w 2 2 4-J 2 G

CJ2 2 0 UJ P p s a) Tj

gj

g •rr| CLi N > HQ S2

>4g

174

ul

<D i-

I
5.18 Heaters

Hazardous Nodes . Collectively, the three portable

heaters evaluated contained a total of 36 nodes. All

except one of these nodes were classified as

potentially hazardous nodes in that they were within 20

mm of a conductive surface. Thirty- three of the

hazardous nodes were located in a fan-forced or

convection forced area. The remaining two nodes were

located in a normal area. Refer to the section on

Heaters to determine the relation between the number of

nodes per heater coil.

Type of Hazard . Fourteen of the 35 hazardous nodes

were classified as "continuous bare" type, 17 nodes

were classified as " switched- bar e" type one was of the

"continuous bare" type and remaining three nodes were

of the "switched painted/enamel" type.

Hazard Spacing . Eight of the 35 hazardous nodes had a spacing of less than 6 mm to the nearest conductive

surface. Sixteen of the hazardous nodes had a spacing

between 6 to 9 mm and 11 hazardous nodes had spacings

between 10 and 20 mm. These three heaters had 15

touchable surfaces. Six of these 15 touchable surfaces

were bare-metal and five were painted/enamel. The

remaining four surfaces were either greater than 20 ram from the neraest node or were constructed of a nonconduction surface.

Faults. No faults were identified either through

probing with the carbon fiber simulator or through

analysis of the circuit diagram.

5 . 19 Smoke Detectors

Five smoke detectors were inspected. Three of

these smoke detectors operate on a 9-volt battery

supply. The other two units operate on 120 volts 60 Hz

supply. These smoke detectors were from the largest

manufacturers and were popular models. Each of these

five units were completely enclosed in a plastic

housing which was intended for either ceiling or wall

mountings. Therefore, shock hazards were judged to be

minimal

Since all five smoke detectors were electronic

devices, the number of potential faults was not

evaluated. All five units are recommended for chamber

testing.

175
GRAPHITE

FIBER

HAZARD

AND

FAULT

SUMMARY iii i

cnU0

-p

toQ) K0X

XI

to -ppo

cuH

CJ2>QO

aC

CP

REMARKS

Totals -

FAULTS NO. o o o o

><

Eh

K=t

w

eu

m CN o m

w

GROUND

INTEGF ca 1—

CN CO VO

-- -_ •> e v r z x X CP Z 00

ro

If >20 N*

TOTAL in uo 15

SPACING

;>xo in CN N*

11

6-9 ro 00 in

16

<5

CN N* CN 00

ENVIRONMENT

F/C CO 14 IT 33 z CM o o CN w o o o O

TYPE

HAZARD i

SB cn 10 N* 17 w

CP . iQ »—

rH rH co

CB in CO CO <riH - w

P-.cj rH o o iH

NODES 1

CN3

10

14 11 35 !1TViOj! 10 15 11 36

Q

O

M Z H1 H2 H3 i |

013oXP

cn

X P X)

<u c p o

a) cn

O 5

cn

p i—

u P 3 P X P 03 E r—

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References

1. "Statistical Issues and Marketing Report," Merchandising,

March 1976, 1977, 1978.

2. "Projection of the Number of Household and Families:

1975 to 1990," U.S. Department of Commerce Bureau

of Census, series p. 25, No. 607, August 1975.

3. "The Saturation Picture," Appliance , September 1978, p. 57.

4. "Analysis of the Appliance Industry Leaders," App 1 ianc

Manufacturer , January 1977, p. 62-69.

5. "Analysis of the Appliance Industry Leaders," Appliance

Manufacturer , January 1977, p. 62-69.

6. "Share of Market or Order of Ranking," Appliance

Manufacturer , January 76, p. 80-833.

7. Vernon L. Bell, "Source of Release," NASA Fiber Risk

Analysis: Conference Publication 2074 , October 31 - November 1978, p. 41-73.

8. Meyers, J.A., "Vulnerability of Quick Disconnectors of

Carbon Fibers," Bionetics Corporation , a preliminary report

not published.

9. Schludge, G, "Appliance Testing Methodology," Bionetics Cor

p

oration : A memorandum report, Feb. 1 , 1979 , not published.

10. Israel Taback, "Vulnerability," Carbon Fiber Risk An a 1 y s i

: NASA Conference Publication 2074, Oct 31 - Nov 1, 1978,

p. 109-123.

11. "An Assessment of the Risks Presented by the Use of

Carbon Fiber Composite in Commercial Aviation,"

Author D. Little Inc., NASA contractor report No. 158989,

January 1979.

12. Dalziel, Charles F., "Electric Shock Hazard," IEEE Spectrum,

Vol. 9, No. 2, pp. 41-50, February 1972.
MBS-114A (rev. 9-78)

U.S. DEPT. OF COMM. 1*1

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBS IR -79-1952

3. R^cigteot' $ Accessor* No*

4. TITLE AND SUBTITLE 5. Publication Date A Study of the Effects of Carbon Fibers on Home Appliances

- - - -

7. AUTHOR(S) 8. Performing Organ. Report No.

C. Lovett. R. Wise. C. Gordon r K. Yee

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, city, state. ZIP) 13. Type of Report & Period Covered —

Ifltllft(

. 15. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200~word or less factual summary of most significant information , If document includes a significant bibliography or

literature survey, mention it here,) At the request of the National Aeronautics and Space Administration (NASA) , the

National Bureau of Standards, Center for Consumer Product Technology conducted an evaluation to determine the possible effects of electrically conductive carbon fibers

on consumer major and small appliances. The information collected is a part of

the data necessary for NASA to complete an economic risk assessment on the future use

of carbon fiber composite materials.

Available market statistics were used to estimate total depreciated dollar values in

U.S. homes for major and small appliances. Models which were typical of the current

design and construction were obtained for analysis and laboratory evaluation. A

total of 59 appliances were examined during the study.

The analysis determined potential faults and hazards that might be caused by fibers

infiltrating appliances. Few potential faults of significant consequence were found.

Some potential electrical shock hazards were identified. Whether these wmld result in

electrical shock to users would depend on a fiber shorting a live contact to the case

and simultaneously touching a grounded conductor with another part of the body. The

probability of these conditions was not evaluated in this study. Many of the

potential hazards identified will require substantial further analysis to quantify the

potential risk.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

/ Appliance failure, appliance hazard, 'carbon fibers, electrical shock

graphite fibers, shock hazard

18. AVAILABILITY I [ Unlimited

[XI For Official Distribution. Do Not Release to NTIS

I | Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

| j Order From National Technical Information Service (NTIS), Springfield,

VA. 22161

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UNCLASSIFIED

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