NBSIR 75-677

Hazard Assessment of Aluminum

Electrical Wiring in Residential Use

Elaine D. Bunten, John L. Donaldson, Eugene C. McDowell

Product Systems Analysis Division

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

December 1974

Final Report

Prepared for U. S. Consumer Product Safety Commission

Washington, D. C. 20207

NBSIR 75-677

HAZARD ASSESSMENT OF ALUMINUM

ELECTRICAL WIRING IN RESIDENTIAL USE

Elaine D. Bunten, John L. Donaldson, Eugene C. McDowell

Product Systems Analysis Division

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

December 1974

Final Report

Prepared for U.S. Consumer Product Safety Commission

Washington, D.C. 20207

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

TABLE of CONTEOTS

Page

Acknowledgements iv

Abstract v

1. Introduction and Executive Summary 1

1.1 Problem Statement 1

1.2 Purpose of this Document 1

1.3 Report Highlights 2

2. Background 3

3. Data Requirements and Data Characteristics 6

3.1 Data Requirements 7

3.1.1 Data Required to Determine Nature and

Extent of Use of Aluminum Wiring 8

3.1.2 Data Required to Determine Level of

Risk to Consumers 9

3.1.3 Data Required to Describe the Performance

of Aluminum Wiring in Residences 10

3.2 Characteristics Required of the Data and

Data Collection Procedures 13

3.2.1 Definition of Objectives 13

3.2.2 Sampling Procedures, If Any 14

3.2.3 Potential Sources of Observation Bias 14

3.2.3.1 Nonobservation 14

3.2.3.2 Observing arid Recording Data 15

3.3 Summary 16

i
Contents (continued)

Page

Field Data and Data Sources Examined 17

4.1 Approach 17

4.2 Summary of Data Sources Examined and

Their Limitations 19

4.2.1 Systematic Documentation 19

4.2.2 Fire Investigations 20

4.2.3 Incomplete Reporting of Electrical Failures 21

4.2.4 Biases 21

4.3 Summary and Evaluation of Information Found : 21

4.3.1 General 21

4.3.2 Specific Sources of Information 24

4.3.2.1 Consumer Product Safety Commission 24

4.3.2.2 Underwriters' Laboratories, Inc.

Field Surveys 25

4.3.2.3 American Plan Corporation 29

4.3.2.4 International Association of

Electrical Inspectors 30

4.3.2.5 National Fire Protection

Association 30

4.3.2.6 Prince George's County, Maryland 30

' 4.3.2.7 Washington, D. C. 31

4.3.2.8 Huntington Beach, California 31

4.3.2.9 Summary 31

4.4 State and Local Restrictions on the Use of

Aluminum Wiring 32

4.5 Estimated Numbers of Homes with Aluminum Wiring 36

4.6 Conclusion 38

ii
Contents (continued)

Page

5. Satisfying the Data Requirements 39

5.1 The Macro Study 41

5.1.1 Sample for the Macro Study 42

5.1.2 Data Collection for the Macro Study 42

5.2 The Micro Study 43

5.2.1 Sample for the Micro Study 45

5.2.2 Data Collection for the Micro Study 45

5.3 Summary 48

References 49

iii
ACKN0WLEDGB4Er^S

The authors wish to thank C. W. Hurley and W. S. Williams of the

Technical Analysis Division, NBS, for their direct assistance in this

study. Also, the following NBS staff members' consultations are gratefully acknowledged: L. D. Ballard, R. L. Cilimberg, M. G. Domsitz,

L. S, Joel, S. J. Kim, L. W. Masters, L. Oberlander, J. A. Rockett,

J. R. Sorrells and R, 0. Stone.

Many persons outside NBS provided valuable help. Deserving

special mention are: W. H. King, Consumer Product Safety Commission;

R. H. Hanson, D. I. Siskind and A. F. Young, Bureau of the Census;

T. J. D'Agostino, Underwriters' Laboratories, Inc.; C. L. Duncan,

Huntington Beach (CA) Fire Department; and R. J. Kelly, Washington (D.C.)

Fire Department.

The authors thank the following members of NBS for their typing

services: M. Abbott, P. Droneberg and L. Freeman.

iv
HAZARD ASSESSMENT OF ALUMINUM ELECTRICAL WIRING IN RESIDENTIAL USE

Elaine D. Bunten John L. Donaldson

Eugene C. McDowell

Abstract

In the mid- 1960s, aluminum wire began to be used in

significant quantities for residential branch- circuit wiring.

Reports of problems from various localities in the U.S. raised

serious concern and controversy as to the safety of this application. An official determination on this matter is within the

jurisdiction of the Consumer Product Safety Commission. This

report reviews the history of the use of aluminum in residential

wiring and describes the characteristics essential to data to

be used to evaluate the performance of aluminum wiring in the

field. The examination of existing field data shows that no available data have the characteristics necessary to develop a reliable estimate of the level of risk to consumers associated

with aluminum wiring. Neither can the available data be used

to establish the relative risk of aluminum con^ared to copper

wiring. There is only a gross estimate of the extent to which

aluminum wiring is now in use in U. S. residences. Statistically

sound estimates of risk would be possible only after data

collection on a large scale.

Key words: Aluminum wire; consumer product safety; electical

failures; electrical fires; electrical wiring;

fire hazards

V

Hazard Assessment of Aluminum Electrical Wiring in Residential Use

1. Introduction and Executive Summary

1.1 Problem Statement

Under contract with the U.S. Consumer Product Safety Commission

(CPSC) , the Technical Analysis Division (TAD) of the National Bureau of

Standards initiated a four-phased program of work concerning aluminum

wiring in U.S. residences. The objectives of this work can be summarized

as

Phase I: Identify, evaluate, and analyze existing field

data to determine accessibility, validity, and

reliability as a prerequisite to their being used

to evaluate the use of aluminum electrical wiring

in U.S. residences.

Phase II: If existing data are found to be inadequate to

perform the evaluation cited above: identify

additional data required, then design and carry

out data collection with the concurrence of NBS

and CPSC.

Phase III: Using existing and/or additionally collected data,

estimate the extent of use of that wiring in U.S.

residences and the level of risk* to the consumer

associated with its use.

Phase IV: If the CPSC determines that aluminum electrical

wiring presents an "unreasonable risk" to the

public, examine and evalute alternative approaches

for reducing the level of risk.

Phase I and parts of Phase II have been conpleted. The project was terminated by the CPSC before the remaining phases could be performed.

1.2 Purpose of this Document

This document is a final report summarizing the work that was

conpleted. The report deals primarily with the data and data sources which were considered to have possible merit with regard to an assessment

of the use of aluminum wiring in the field (i.e., reports of its performance as actually installed in U.S. housing). It presents and dis- cusses inherent characteristics of aluminum wiring only in order to

clarify the evaluation of existing sources of field data, or to explain

additional data requirements. Included in the report are

*"Level of risk" refers to the likelihood of a hazardous outcome
• A brief history o£ the use of aluminum electrical

wiring in the United States;

• A brief resume of events and actions affecting the use

of aluminum electrical wiring;

• A description of the characteristics essential to data

to be used to evaluate the performance of aluminum wiring

in the field;

• A general discussion of the adequacy of the existing data

relative to the data requirements

• An evaluation of certain specific sources of available

field data;

• Identification of additional data requirements; and

• Recommendations and a general plan for additional

data collection.

1.3 Report Highlights

The items included in this report result in the following observations

• An examination of the history of events associated with

the use of aluminum electrical wiring in U.S. residences

supports the view that the use of aluminum conductors

in residential applications has resulted in problems.

• The data which would be required to determine the nature

and extent of any hazard associated with the use of

aluminum conductors are identified and the requirements

- are used to evaluate existing field data.

• The examination of existing field data shows that no available data have the characteristics necessary to

develop a statistical estimate of the level of risk

to consumers associated with aluminum wiring. Neither

can the available data be used to establish the relative

risk of aluminum conpared to copper wiring.

• Existing data cannot be used to establish that aluminum

wiring presents no substantial hazard to consumers.

• Existing data can be used to provide only a very gross

estimate of the extent to which aluminum wiring is now in

use in U.S. residences.

• It would be possible to continue with Phase III of the

current project only after a significant data collection

effort has been undertaken.

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2 . Background

Currently, aluminum and copper are the only commercial metals

vdiich are both available in sufficient quantities and have the necessary

characteristics for general use as electrical conductors. (Sodium,

niobium, silver, etc. are sometimes used as electrical conductors for

special applications.) Copper was the first, and for many years the only

metal used as an electrical conductor. (1)* Aluminum conductors were first

formally recognized in the 1901 edition of the National Electrical Code

(NEC). It was not until 1946, however, that Underwriters' Laboratories,

Inc. (UL) labeled aluminum conductors. (Users of electrical equipment

often use UL tests and certifications in their buying decisions.)

Subsequent to the 1946 UL listing, (equipment is "listed" as it is

approved) production and use of aluminum electrical cables in the larger

(AWG #8 and larger) sizes became increasingly common. (2)

In the early 1950s UL undertook an examination of aluminum building

wires and connectors because of "...anticipated development in the

aluminum wire industry...". The san^jles for this investigation "...represented the first efforts of wire manufacturers to utilize aluminum for

building wire". (3)

In February 1957, UL recognized nonmetal lie- sheathed aluminum wire

(the kind commonly used in much house wiring) and invited manufacturers

to apply for labeling approval. Despite this, there appears to have been

little production or use of aluminum electrical wire for use in residences

prior to the 1960s, with 1966 generally being regarded as the year in

which there was a significant increase in the production of aluminum

electrical wire for use in homes. (2) Based on estimates by The Aluminum

Association, approximately 23 million meters of aluminum cable in housewiring sizes were produced in the period 1960 through 1965; in 1966,

approximately 36 million meters of such cable were produced; and from

1966 through 1971 approximately 737 million meters of such wire were

produced. (4) (See Section 4.5 for a discussion of these estimates.)

The substitution of aluminum for copper in electrical (and other)

applications has largely been due to economic rather than technical

considerations. For example, in the early days of its commercial production, the cost per pound of aluminum was much higher than that of

copper and there was no reason to use aluminum in electrical conductors . (5)

The 1940 edition of a well known electrical engineering text, however,

discusses the use of aluminum in high tension transmission lines and low

tension bus -bars, and states, "Because aluminum wires have a greater

diameter for the same conductance than copper wires, the use of aluminum

in insulated wires is prohibited, at the usual prices of both metals,

by the extra cost of insulation. "(6) The National Materials Advisory

Board states that "Aluminum started being used as an electrical conductor

Numbers in parentheses indicate citations listed in the reference

section at the end of this paper.

-3-
when its price on a weight basis fell to about twice that of copper". (7)

A comparison of the prices of the two metals between 1939 and 1970 shows

that except for short periods of time, the price of copper relative to the

price of aluminum has been steadily increasing. As of March 1971, a given

volume of copper was five times more expensive thaa an equal volume of

aluminum. (8) Since it requires a greater volume of aluminum than copper

for the same electrical current carrying capacity and since the larger

diameter of the aluminum wire would cause the cost of insulating aluminum

to be higher, the cost of insulated aluminum wiring for a house at that

time would have been about yi% of the cost of insulated copper wire for

the same house. (5) As of early 1974 the cost of insulated aluminum wire

for house wiring was about 50-60^ of the cost of insulated copper wire

of equal current carrying capacity.

In 1966, UL began listing general use snap switches and attachmentplug receptacles specifically approved for use with aluminum or copper

wire. (9) Prior to this date, based on their earlier investigation, CIO)

UL had considered all general use wiring devices C^xcept for those using

screwless push- in terminals) as acceptable for use with either aluminum

or copper conductors. In 1966, UL stated that wiring devices could be used

with aluminum conductors only when "(1) the terminal is of the wire binding

screw type where the conductor is to be looped around the screw, or {!') on other types of teminals only when marked 'AL-CU'." (9)

At the same time (mid 1960s} that the relative prices of copper and

aluminum led to an increase in the production of aluminum conductors, this same factor contributed toward changing the metals used in the screws and

base plates of the termination devices from brass to plated steel (usually

zinc plated) . Laboratory tests made by Battelle Memorial Institute at a later date indicated that the use of zinc-plated steel with aluminum wire

was not to be recommended since there are basic metallurgical incon^atibilities between the plated screws and the aluminum wire in this application. (11)

By 1968, UL had begun to receive reports of difficulties in the field

associated with aluminum electrical wiring. In 1969, UL and the National

Electrical Manufacturers Association (NEMA) jointly undertook a survey to assess the status of aluminum wire usage in the field. Responses to a questionnaire were solicited from various electrical contractors, electrical

inspectors , manufacturers , and users of electrical control equipment and

related devices. (See Section 4.3 of this report for a discussion of this

survey.) In May of 1971, UL initiated a test program directed toward the

assessment of terminations of aluminum conductors at household duplex

receptacles. (12) In December of 1972, in order to gather field data

about problems with terminations of aluminum wire in residential branch

circuit wiring, UL administered a second questionnaire, this time only to

selected chief electrical inspectors throughout the U.S. In January 1974,

UL administered a follow-up survey to some of the respondents to the 1972

survey. (See Section 4.3 of this report for a discussion of these surveys.)

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Throughout this period, a number of actions were taken which influenced

the use of aluminum wiring and connectors to be used with aluminum wiring.

A number of these are listed below:

• September 1970, UL revised its test specifications for

the labeling of aluminum wire and emphasized the need

for care in making connections with aluminum wire.

• January 1971, at least ten jurisdictions in Orange County,

California had inposed a ban on all direct connections of

aluminim wire to devices of 15 and 20 ampere rating. (13)

(For other restrictions, see Section 4.4 of this report.)

• May 1971, UL required that aluminum wire manufacturers

include precautionary installation instructions on packages of aluminum wire in sizes 8, 10, and 12. (12)

• June 1971, UL again began revising its test specifications

for the labeling of aluminum wire. (12)

• Effective September 1, 1971, UL required that all new

devices eliminate the "AL-CU" marking unless they had

been approved under a new test program. (14) (This

action was announced in a July, 1971, UL Bulletin.)

• March 10, 1972, Leviton, a major manufacturer of devices

sent a bulletin to all of its distributors saying that

all Leviton devices available at that time would be marked

with a notice that they should be used only with copper or

copper- clad wire. (15)

• March 21, 1972, the General Engineering Committee of NEMA

concluded that wiring devices then being sold were suitable

for use only with copper wire or wire having copper or tinplated surfaces, and that those devices should not be used

with other materials until their suitability had been

established by extensive testing. (16)

• June 1972, an Ad Hoc Committee on Aluminum Terminations

was formed with membership from industry and UL. Its

purpose was to study and recommend procedures for improving

the connectability of larger sizes (AWG #12 and larger)

of aluminum conductors. (14, 17)

• June 1972, UL listed the first "CO/ALR" wiring device.

The CO/ALR designation was given to wiring devices

approved for use with aluminum conductors under a new

test program. (17)

-5-
• August 1972, an Ad Hoc Committee on the Use of Aluminum

Conductors with Wiring Devices in Electrical Wiring

Systems was organized by UL in order to allow for the

exchange of information about actions that had been or should be taken to ensure proper and safe use of aluminum

conductors and wiring devices. Members of the committee

came from all areas of technical interest in aluminum

conductors and wiring devices.

• September 1972, UL issued its revised test specifications

for the listing of aluminum wire and approved the first

wire to meet these specifications. (14)

• March 1973, final recommendation of the Ad Hoc Committee

on the Use of Aluminum Conductors was released by UL to

the technical press and to various groups associated with

the installation of receptacles and snap switches in

residential occupancies.

• April 1973, UL proposed that wiring devices not listed

for use with aluminum wire be provided with a precautionary

notice.

• Effective January 15, 1974, UL required wiring devices

not marked CO/ALR be marked either "Notice-Use only

copper or copper-clad wire with this device", or "NoticeConnect only copper or copper- clad wire to this device",

or "Notice -Use only devices marked CO/ALR with aluminum

wire."

In brief, therefore, these events support the view that the use of

aluminum conductors in U.S. residences has resulted in problems. The

primary purpose of this report is to present the results of an examination

of available field data. It was hoped that data might exist which could

be used to estimate the nature, extent, and magnitude of these problems.

3. Data Requirements and Data Characteristics

Section 2 of this report outlines events which have sometimes ex- plicitly and sometimes implicitly led to inferences that aluminum electrical wiring could present an unreasonable risk to consumers (i.e., occupants

of houses, apartments, mobile homes, etc., which have been wired with

aluminum). The primary purpose of this report, however, is to present

the results of an examination of currently available field data about the

use and performance of aluminum wiring in the field. In order to place

this critical evaluation of existing data in perspective, it is necessary

to state the criteria which were used in the evaluation.

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Section 3 outlines the data required, and describes the characteristics and attributes required of data to be used to determine (a)

the nature and extent o£ use o£ aluminum wiring in U.S. residences,

and (b) the risk to consumers associated with its use.

3.1 Data Requirements

In order to state the general data requirements, it is necessary

first to cite some relevant facts about the use of aluminum wiring and

wiring practices in residences:

• As stated in Section 2, aluminum wiring was rarely

installed in residences in this country prior to 1960,

and not until 1966 was there substantial use of

aluminum in this application.

• Many different alloys of aluminum have been produced

in house wiring sizes. The performance of these

different alloys varies according to differences in

their mechanical and metallurgical properties.

• The type of wiring device used with aluminum conductors

may significantly influence the performance of an aluminum-wired electrical system.

• There are four specific common uses of aluminum (and

other) conductors within a residential unit: general

purpose branch circuit conductors, service entrance cable,

permanently connected appliance circuit conductors, and

service busbar conductors. The performance demanded and

that received from a conductor in each of these specific

applications varies.

• Any one residential unit might contain no aluminum

electrical wiring, might have aluminum in all electrical

wiring, or might have any one or any combination of the

specific aluminum wiring applications mentioned above.

• Electrical jurisdictions vary in the requirements inposed

on electrical workers who install house wiring.

• The NEC is a voluntary model code, but it has been widely

adopted, in whole or in part, by local jurisdictions. The

NEC allows insulated aluminum conductors in residences

where copper is allowed on the basis that for the same size

conductor, the current carrying capacity of aluminum is 84%

of that of copper. (18) Some localities have enacted additional requirements for the installation of aluminum wiring,

some follow the NEC, and some few probably have no codes at

all.

-7-
The preceding facts are listed in order to make the point that "use

of aluminum electrical wiring in residences" is a rather ambiguous concept. Data showing the presence or absence of (any) aluminum wiring in

residences would not provide sufficient information to determine the

nature and extent of use of aluminum wiring in the U.S. Similarly, analytical treatment of reports of failures attributed to aluminum wiring becomes

useful only when data concerning the presence or absence of failures are qualified by other relevant data. Sections 3.1. land 3.1.2 describe the

data required to determine the nature and extent of use of aluminum wiring

in U.S. residences and the risk to consumers associated with its use.

3.1.1 Data Required to Determine Nature and Extent of Use of

Aluminum Wiring

The requirements for data needed to make this determination include:

• A representative set of all types of U.S. housing (single

: and duplex houses, apartments, mobile homes);

• A representative (See Section 3.2) set of geographical

areas;

• Categorization according to specific electrical application (branch circuit conductors, service entrance cable,

appliance circuit conductors, service busbar conductors,

;^ and any combination of these;

• Categorization according to relevant installation date

(e.g., pre and post UL listing of CO/ALR devices). It

would be highly desirable for the data to be categorized

by type of connector (AL-CU, copper pigtail, CO/ALR,

"push" device, etc.)

The level of detail just described is based on the following hypothesis: If aluminum electrical wiring were established to present an unreasonable risk to consumers, that determination would necessarily be

qualified with respect to some combination of the categories just listed.

It is likely that varying levels of risk will be associated with certain

sets of conditions including specific use of the conductor, type of

wiring device, installation practice, and installation date.

There are several conceptual matters that merit thorough consideration

because they relate to the utilization of empirical data in support of

policy decisions. The development of these matters into a framework

for data collection and analysis will be one of the initial tasks of any

further data acquisition effort. Although they will ultimately require

more lengthy exposition, some of these conceptual matters are outlined

here. It is important to distinguish the level of risk to the individual

consumer from the total number of consumers at risk, and it is more

inportant to recognize that a threshold between reasonable and unreasonable risk can be defined (by policy decision) in the context of individual

-8-
risk as well as the context of national hazard. In the former case,

data on the extent of use of aluminum wiring would not be required.

In a practical sense, however, a judgment of unreasonable risk may be

inseparable from the extent of risk in two respects. First, any rulemaking activity of the CPSC iiiplies a judgment that the motivating

conditions are a matter of national (3.s well as individual) interest.

Second, the "unreasonableness" of a risk may be inextricably related

to the ease or difficulty of reducing or eliminating the hazard; in the

present context this implies such considerations as the relative availability (as well as cost) of aluminum and copper, and the impact on the

affected metal, wire, device and construction industries. Clearly, the ease of reducing a hazard may be different for existing installations

and for future installations. Finally, there is no legal requirement

that policy decisions meet a specified level of statistical defensibility.

To the extent that the CPSC sees a need to undertake actions based on best judgment, the data requirements are relaxed.

3.1.2 Data Required to Determine Level of Risk to Consumers

In addition to data regarding the nature and extent of the use of

aluminum wiring (just discussed) there are other data required in order

to determine a level of risk to consumers. But it is important to

recognize that it is, or may be, possible to determine a level of risk

associated with the use of aluminum wiring in residences, and even to

identify ways of reducing that risk, without determining the exact

mechanism of failure. As an extreme example, banning the use of aluminum

wiring would eliminate any future problem, and rewiring existing residences

would eliminate any existing problem. Neither of these solutions would

require an understanding of the causes of the hazard.

Determination of the risk to consumers is a two part problem: (a)

determining the numbers of aluminum wiring failures that occur relative

to the numbers of possible failures; and (b) determining what proportion

of those failures result in bodily injury or death (or the threat thereof)

to the occupants. To this two part problem must be added the CPSC counterpart problem: (c) determining \^^ether the level of risk is reasonable.

Data required to approach the first two determinations are

• Data to establish the population of possible failures

of aluminum wiring in a specified area. These data

must be categorized by the other relevant factors

including specific conductor application within residence,

data of installation, etc.

• Data to establish numbers of failures in the same specified area (by specific application, by installation

date) . These data must also be categorized by type of

failure: termination failure, wire failure, incipient

failure, etc.

-9-
• Data to establish the consequences o£ each failure in terms

of occupant safety (by specific application, by installation

date, etc.): fire or necessary conditions for fire, shock or necessary conditions for shock, etc. The data are specified

in this way because actual injuries or deaths related to

aluminum wire failures may be relatively rare events.

The data required for the determination of whether the risk is

reasonable or not depends on decision criteria to be established by the

CPSC. Possible data needs include data to conpare the level of risk of

aluminum wiring with other products, data concerning ways CPSC can affect

codes or installation practices, and/or data to compare the cost of one decision outcome with others. Possible needs include

• Conparable data for copper wiring as specified in the

three items above.

• Data concerning existing code requirements for electrical

wiring in residences and the enforcement practices followed

with respect to those codes. Identification of mechanisms

and usual time intervals required to change these codes

and/or procedures.

• Data concerning the training and/or licensing required of

electrical workers and electrical contractors, in order

to identify expected workmanship and ways of influencing

' workmanship.

• Data outlining the costs associated with any aluminum

wiring hazard, and, in a conparable form, costs associated

with proposed ways of reducing the hazard. These costs

would need to be identified separately for solutions

applying to new housing starts. In addition, it would

be essential to be able to assign the costs, e.g., to

the consumer, the manufacturer, the builder, the government, society, etc.

3.1.3 Data Required to Describe the Performance of Aluminum Wiring

in Residences

The desirability of performing technical field investigations is

underscored by limitations inherent in laboratory efforts. Rather strong

incentives to minimize the number of variables under laboratory investigation tend to restrict the scope of such investigation to the examination of

only a few of the relevant conditions and, therefore, possible interactions

of the various characteristics. It is believed that carefully executed

study of the interaction of these conditions is necessary, and therefore

there exists a requirement for field investigations. The information

thus obtained would provide the basis for the definition of the necessarily

limited scope of the laboratory studies.

-10-
Detailed description of the performance characteristics of aluminum

wiring in situ (as installed in residences) would require carefully

designed data collection. The performance characteristics of aluminum

as a conductor have been used to identify many variables which may (either

singly or in combination) affect the performance of aluminum conductors

as installed in residences. The goal of such a data collection would be

to describe the conditions underlying a specified level of aluminum wire

performance. As in Sections 3.1.1 and 3.1.2, these variables will be

discussed generally here. The need for operational definitions must,

however, be acknowledged.

The data which are outlined below would be collected for each

aluminum wire junction in a defined sample of such junctions. Sets of

data would be required both from residences which are known to have ex- perienced failures and from residences which are known to have ex- perienced no failures; (i.e., both "good" and "bad" connections would

be sought.)

The following data are required for each junction:

• Environment of the Connection

- Ambient tenperature , exposure to heat

- Relative humidity, exposure to humidity

- Exposure to vibration, mechanical shock or movement

- Exposure to air pollution

- Distance from salt water

• Nature of the Conductor

- Size (gauge)

- Type of insulation

- Alloy

- Specific application

• Nature of Wiring Device

- Type (twist connector, receptacle, snap switch,

other-specify)

- Connection techniques (binding screw, push-wire)

- Specification (AL-CU, CO/ALR, other- specify)

- What feeding (use)

- Current capacity

- /^plied voltage

- Oxidation inhibitor

-11-
• State of the Connection

- Resistance (load 5 nonload)

- Corrosion

- Evidence of Creep

- Torque measurements

- Metal or insulation discoloration

- Thermally or mechanically distorted contacts

• Nature of Installation

- Age (date of installation)

- Identification of installer (homeowner, electrician, etc.)

- Applicable code regulations

- Evidence of code violation

'# Nature of Electrical System

- Capacity of service box

- Size of service entrance cable

- Line voltages

If faulty components or junctions are detected: • Nature of Failure

- Creep of conductor

- Corrosion of conductor and/or wiring device

- Mechanical tension in conductor

- Mechanical failure of wiring device

- Inadequate torque on clanping device

- Excessive oxidation of conductor

• Alerting Condition

- Flicker in lights

- Odor, smoke

- Erratic operation of appliances

- Electrical shock

- Noise on radio

- Fire

- Circuit opened by overload protection means.

-12-
3.2 Characteristics Required o£ the Data and

Data Collection Procedures

The enumeration of required data in Section 3.1 presupposes that those

data be valid and reliable, and represent some defined population. This

section of the report, therefore, briefly outlines some of the general

indices of validity, reliability, and representativeness that were used

in evaluating the existing field data. These qualities can usually be

assumed to be present to some degree, so the evaluation consisted of

determining the degree to which they were exhibited in the data or the

data collection process rather than determining their presence or absence.

The discussion below is not intended as an exhaustive listing of

the criteria used. It cites the more important considerations in the

evaluation process.

3.2.1 Definition of Objectives

Each source of data was examined to determine whether the data had

been collected with clear and identifiable objectives. Lack of definitive

objectives was often a precursor to more severe deficiencies in the data.

Presence of those objectives allowed a more certain framework for the data

evaluation. Indications of clear objectives were:

f Definition, prior to data collection, of the

population the data were to represent, (e.g., the performance of aluminum wire in a defined set of aluminum

wired residences ; the opinions of a defined set of

electrical inspectors concerning aluminum wire; etc.)

• Enumeration, prior to data collection, of decisions

which were to be made based on the data, (e.g. , a decision to allow or to ban the use of certain types

of connectors with aluminum wire; a decision to begin

or not begin laboratory investigation of the performance

of aluminum wire; etc.)

• Specification, prior to data collection, of the variables

that would be used to answer the primary questions

(decisions) toward which the data collection effort was

directed, (e.g., relative numbers of failures of

certain wiring devices would be used to decide whether

certain devices should be banned; numbers of failures

of aluminum wire relative to copper wire would be used

to decide whether laboratory research would be required;

etc.)

-13-
3.2.2 Sanpling Procedures, I£ Any

In cases in which the data collection involved sampling there were

two inportant criteria in addition to assessment o£ the definition of

the population:

• Sanpling process: An attenpt was made to determine

whether the sampling procedure was systematic or haphazard and whether the sampling process matched the

stated objectives.

• Estimation process: An attenpt was made to determine

whether the sample had been designed to meet statistically

describable levels of confidence.

3.2.3 Potential Sources of Observation Bias

There are certain potential sources of bias to any data collection

effort which are not directly related to sanpling or the definition of

objectives. Those most relevant to the present evaluation are discussed

below.

3.2.3.1 Nonobservation

It is often the case in field data collection efforts that it is

not possible to observe (collect data for) every relevant event. Nonobservation could have relatively little impact on the data if enough

is known to assume that the nonobserved events are few in number or

are relatively insignificant to the variables in question. There are,

however, forms of nonobservation which must be carefully considered:

• Noncoverage: This form of nonobservation can only be

assessed in terms of the data requirements. In some cases,

systematic noncoverage is desirable, and is, in fact,

specified in the definition of the population. Noncoverage

which occurs in an uncontrolled manner because of lack of

knowledge about the population or because of faulty

selection techniques, however, can be a source of severe error unless it is recognized and accounted for. If

noncoverage is not discovered before data collection

begins, either the definition of the population must be

changed, or an attempt must be made to complete the

coverage. An exanple of accidental or haphazard non- coverage would be a data collection effort concerning

wiring failures in which the population had been defined

as all aluminum-wired residences in a specified area, but

in which the only data collected were those failures which

came to the attention of the electrical inspector. In

this exanple, the failures (data) that came to the attention

of home owners and/or electrical contractors but not electrical

inspectors would not be "covered".

-14-
• Nonresponse: Nonresponse occurs when data cannot be

obtained from some portion of the defined sample or population; it occurs not because of lack of knowledge

of its existence but because of a refusal to supply

data or difficulty in obtaining the data, etc. The most

important point to be made about nonresponse is the fact

that data not collected (nonresponse) cannot be assumed

to be similar to the collected data. In cases of high

nonresponse, it is essential that an effort be made

(outside of the primary data collection effort) to

determine how the unobtained data might differ from

the collected data.

Nonresponse could be a very inportant factor in a data collection effort concerning the presence or absence

of a phenomenon such as aluminum wiring failures, because

reporting the presence of the phenomenon might be perceived

as being very inportant while reporting its absence might

be perceived as not at all important.

3.2.3.2 Observing and Recording Data

In addition to defining a population and specifying variables to meet

decision criteria, there are other specific factors concerning observation

and data recording which must be considered.

# Operational Definition of Variables: Section 3.2.1

described the need for specifying the variables which

would answer the questions toward v^ich the data collection

effort was directed. This is a necessary but not sufficient

requirement. In addition, operational definitions must be

supplied for the variables; the variables must be defined

such that there is no room for error during data collection

because of differences in interpretation of the meanings

of terms. Collection of data about the performance of

aluminum wiring in the field presents three striking

examples of the need for operational definition for

variables: "use of aluminum wire", "failure", and

"fire". In almost no case were any of these terms given

operational definitions. The individuals observing the

events were required to impose their own definitions. In some cases, the lack of definition resulted, for exanple,

in combining data in which "fire" meant only those events

for which the fire department was called, with data in which

"fire" included incidents in which the insulation on a wire,

inside a metal box, had melted.

-15-
- • Observer Limitations : Sometimes it is necessary to

select and train individuals to observe and record data.

In other cases, (particularly in surveys) it is more

appropriate and/or convenient to ask individuals who

already have knowledge of the relevant variables

and are already observing the relevant events to make

specific observations and record data. It is necessary

to be aware of the limitations of such "borrowed" observers.

/ First, such an observer does not necessarily have the same interest in the variables as the organizer of the data

collection effort and therefore, the data collection must

~ be made as relevant as possible to the observer. Second,

an individual who can provide data about one sort of event

may not be able to provide data about other related events.

For example, a fire inspector may be able to observe and

' , record fire-related events associated with aluminum wiring,

but he may have no way of observing failure- related events

associated with aluminum wiring. Third, it is necessary to

operationally define the relevant variables even when

dealing with knowledgeable observers, for the reasons cited earlier.

• Documentation: It is sometimes necessary to attenpt to

collect data about events that are assumed to have occurred

' in the past. In those cases, an attempt is made either to reuse data collected for some other purpose or to rely on

. the memories of individuals who might have observed the

events in the past. When collecting data after the event, an attenpt must be made to distinguish between those data

based wholly on memory and those based on some sort of

still existing documentation. Recollections must be used

with caution because they are so easily influenced by

intervening events. It is very useful in situations in

which no documentation (made at the time of the event)

exists , to ask the respondent to indicate how certain he

is of his response.

3.3 Summary

This section has identified the data required to make determinations

about the nature and extent of any hazard associated with the use of

aluminum wiring in U.S. residences. This includes (a) data to determine

the nature and extent of the use of aluminum wiring in U.S. residences,

(b) data to determine the level of risk to consumers associated with

the use of aluminum wiring, and (c) data to describe the performance

(causes of any hazard) in residential applications. Also described were

the characteristics required of the data, i.e., those characteristics

which might be used to judge the adequacy of available information and

data.

-16-
Section 4 applies these data requirements as criteria for an evaluation

of the information that the study team was able to locate and obtain. Section

5 discusses a general approach to a supplemental data collection effort

based on these data requirements.

4. Field Data and Data Sources Examined

4 . 1 Approach

An attenpt was made to identify any data that already existed con- cerning the performance of aluminum wiring installed in the field (as

opposed to laboratory data) . Data which were identified and obtained

were evaluated in terms of the data requirements and data characteristics

cited in Section 3 in order to determine (a) the possible uses which could

be made of existing data, and (b) the limitations of the existing data

and the data sources.

This information search involved attenpts to contact all types of

organizations and officials which were directly or indirectly concerned

with the use of aluminum electrical wiring. The first to be contacted

were those already known or suspected to have experience in this area. Subsequent contacts were based on referrals from earlier contacts or

citations in documents. This process was continued until virtually all

of the new referrals were to sources already contacted. Many of the

contacts were fruitless. Those that showed some promise were probed more

thoroughly to check the validity of the data and evaluate their usefulness.

The findings are detailed in section 4.3.

The organizations and officials contacted are listed below in six

groups. The list includes four additional contacts in the Washington, D.C.,

area that were made by the CPSC but that did not warrant additional followup.

Research Organizations (Other than NBS and CPSC)

Battelle Memorial Institute

Johns Hopkins University Applied Physics Laboratory

National Fire Protection Association

Underwriters' Laboratories, Inc.

Insurance Organizations

American Insurance Association (formerly National Board of Fire

Underwriters)

American Plan Corporation (insurers)

General Adjustment Bureau (insurance investigators)

Insurance Services Office

National Association of Mutual Insurance Companies

Value Engineering Laboratories (insurance investigators)

-17-
Fire Officials

Fire Inspector (Electrical) , Huntington Beach, California

Fire Inspector (Electrical), Washington, D. C.

Fire Marshals:

Fairfax Co. , Virginia

Montgomery Co. , Maryland

Maryland (state)

Orange Co., California

Prince William Co. , Virginia*

International Association of Fire Chiefs

International Association of Fire Fighters

Electrical Inspectors

Chief Electrical Inspectors

Baltimore Co. , Maryland

Fairfax Co., Virginia

Frederick Co. , Maryland

Idaho (state)

Montgomery Co. , Maryland

North Dakota (State Electrical Board)

Prince George's Co., Maryland

Prince William Co. , Virginia*

Providence, Rhode Island

Washington, D. C.

International Association of Electrical Inspectors

Middle Department Inspection Agency (contract organization in

the mid-Atlantic states that serves as electrical inspector

for jurisdictions not directly employing their

own inspectors)

Electrical Manufacturers

Alcoa Conductor Products

Aluminum Association

Copper Development Association

General Electric Company, Wire and Cable Division

Contacted by CPSC

-18-
Builders and Electrical Contractors

B and H Electric (contractor in Virginia)

Continental Corporation (contractor in Virginia)*

General Services Administration (U. S. Government)

International Brotherhood of Electrical Workers

Kettler Brothers (builder in Maryland)*

Marriott Corporation (hotel and restaurant chain)

Master Electricians' Association of the National Capital Area

Minchew Corporation (builder in Virginia)

National Association of Home Builders

National Constructors Association

National Electrical Contractors Association

4.2 Summary of Data Sources Examined and Their Limitations

4.2.1 Systematic Documentation

The primary obstacle to deriving information from these sources with

respect to the hazards associated with aluminum wire is the fact that

there has been relatively little interest in the field in documenting the

extent of the hazard, once its existence was accepted. Most organizations

and officials, if they felt a hazard existed, focused their attention on eliminating or reducing the hazard. It was generally thought by these sources to be unnecessary to undertake extensive documentation, since the

perceived existence of a threat to public safety was sufficient to justify

corrective action. NBS has found a generally uncritical acceptance of the

judgment that a serious hazard exists, and it is impossible to determine

to what extent this judgment has been based on anecdotal reports, opinions

and restrictive actions of others, rather than on direct experience. There

are a few exceptions to the general lack of interest in documenting the

extent of the hazard, and the information that may be derived from them

is included in section 4.3.

There is however, a sharp distinction between the documentation

needs of fire marshals and electrical inspectors, on the one hand, and

the documentation required in this study, on the other hand, to demonstrate statistically the existence of a hazard and to develop a statistically

sound estimate of its magnitude. Due to these differing needs, it is neither

surprising nor an adverse reflection on the sources that the existing data

are insufficient for the purposes of this study. In the former case, a reasonable degree of suspicion of hazard is sufficient to warrant a response of caution in the name of public safety until the matter can be

cleared up.

*Contacted by CPSC

-19-
In the latter case it is necessary to have actual numbers of fires or failures, in order to calculate fire or failure rates with respect to

exposure. Exposure represents (a) a measured population of installations

among which failures potentially could occur, and (b) a definite period

of time, sufficiently long to average over random fluctuations.

There are at least four concepts of fire or failure that are inportant

in establishing an estimate of hazard in this study. One is sinply

failure , defined as any condition of the electrical system that prevents

it from performing as intended. Second is fire without structural damage , defined as a condition where some form of combustion is caused by a malfunction. Third is fire with structural damage , defined as destructive

burning of structural components, caused by an electrical system malfunction.

Fourth is shock hazard , which for the present discussion may remain

undefined. Of the first three, the third is clearly the most inportant

from the standpoint of hazard estimation. A structural fire is clearly

a hazard to life and limb, whereas any number of circuit failures or of

fires confined within receptacle boxes may present no hazard at all.

4.2.2 Fire Investigations

Fires have been investigated by insurance organizations, fire ^ inspectors and electrical inspectors, but the investigations have been

generally confined to cases having a particular interest, such as loss

of life, heavy financial loss, suspected arson, or lawsuit. These

investigations normally cover neither the totality of electrical fires

nor a representative cross section, A further inadequacy of the records

of these investigations, for the purpose of this study, is that they

generally contain only broad categories of cause (e.g., "electrical").

The kind of wire and the kind of device or connector are generally not

recorded, since, until recently, there was no interest in such detail.

Some insurance records identify only the class of structure and general

location, not the cause of the fire. Statistics on fires attributed to

electrical causes may also be contaminated by two other factors, according

to these sources. First, most fire departments do not have fire investigators

who are also trained or experienced in electrical matters. Reportedly,

only tivo fire departments in the U.S. have a fire investigator who is

also a master electrician, and many fire departments have no trained

investigators specifically for electrical fires. (19) Thus, it is commonly

accepted that some of the fires identified as electrical did involve

some piece of electrical equipment, but not necessarily as a cause. Second, it is reported by these sources that fires of unknown origin are sometimes called electrical and that investigation reports are sometimes

written without an on-the-scene investigation having actually taken

place.

-20-
4.2.3 Inconplete Reporting of Electrical Failures

When a homeowner experiences electrical system malfunctions, but not

fire, he is most likely either to attenpt a repair himself or to call an electrician (perhaps the contractor who installed the faulty conponent)

these cases rarely come to the attention of the fire and electrical

inspectors

4.2.4 Biases

Builders and electrical contractors being interviewed with regard

to hazardous conditions involving products installed by them have a natural

incentive to be less than candid. On the part of inspectors and others

,

perceptions of individual cases and recollections of groups of cases are necessarily preconditioned by opinions based on their own prior experiences

and on the reports of others. Thus, once an inspector has formed the

opinion that aluminum wiring is a fire hazard, the mere presence of aluminum wiring at the scene of a fire may induce him to attribute the fire to

that wiring. Furthermore, when asked to estimate numbers of fires caused

by aluminum wiring he may overestimate the number and/or include all the

incidents that he perceives to have potential fire conditions.

4.3 Summary and Evaluation of Information Found

The information conpiled from the sources identified must be presented

as an informal summary of what these people perceive and believe, since it

does not represent a formal survey. It does not establish the existence

of a hazard nor does it provide a measure of such a hazard.

4.3.1 General

Virtually all of the persons contacted by NBS were aware that there

is alleged to be a problem with the use of aluminum for electrical wiring.

Virtually all believed that in fact there is, or has been, such a problem.

All of these agreed that failures occur principally at terminations ; occa- sional failures have occurred elsewhere along the wire.

Most of the people contacted believed that the chemical and physical

phenomena relating to this problem are well understood, and felt that they

themselves understood the important phenomena. (It may be remarked here

that the laboratories engaged in studies of this problem are in some doubt

about those phenomena.) Accordingly, many of these people believe that

with present knowledge it is possible to use aluminum wiring without

creating hazards. Some of them claim that their own experience with the use of aluminum wiring has been essentially trouble-free, and they

attribute this to their precautionary measures.

-21-
An example is Fairfax County, Virginia, where some aluminum wiring

has been used but reportedly with no more trouble than with copper wiring.

The Fairfax County electrical inspector attributed their lack of problems

to stringent workmanship requirements and a more intensive inspection

schedule when aluminum wiring was used. (20) Fairfax County is a notable

example for its contrast to Prince George's County, Maryland, which is

in the same geographical area and which has reported considerable difficulty with aluminum wiring (discussed in Section 4.3.2). It should be

noted that jurisdictions using aluminum wiring without significant numbers

of problems have little or no incentive to keep fire or failure records

which separately identify aluminum installations. Therefore, it is un- likely that any widespread trouble-free use of aluminum has been documented.

A broad variety of diagnoses and recommendations were voiced by

those contacted, and few recognized this lack of agreement. Some recom- mended more than one of these measures.

In 1969 the San Mateo County (California) Chapter of the National

Electrical Contractors Association solicited information from several

cities regarding the use of nonmetal lie -sheathed cable, and some of the

replies included remarks pertinent to aluminum conductors. In 1971 both

the NBS Office of Fire Research and Safety and the Fire Inspector (Electrical) of Huntington Beach, California, queried fire officials to determine

whether there was evidence from the field that aluminum wiring had been

responsible for fires. These efforts elicited a broad variety of responses.

Since there was no attempt to design the sanpling procedure to be nationally

representative with respect to various demographic factors, and since their

objectives were dissimilar, an enumeration of the responses by type would

be misleading. Nevertheless, the following excerpts illustrate the wide

variety of perceptions and experiences with aluminum wiring that existed

at that time and that continue to exist now.

"We have found that a properly installed job of

copper or aluminum non-metallic cable is a very

safe and trouble-free wiring job."

"We have had no fires which have been attributed

to the use of aluminum wiring."

"Our records do not reflect any increase of fires

caused by aluminum wiring, over those resulting from

conventional copper wire."

"Experience is not sufficient here at this time to

determine if aluminum used in electrical wiring

is creating any problems."

"We show approximately 230 fires originating from

wiring but no designation whether it was copper

or aluminum."

-22-
"We have been aware of the possible fire hazard involved

and have expended considerable time and effort to determine

whether or not any action should be taken to curb or control

its use. There have been very few fires involving aluminum

wire. All the fires were investigated and found to be

caused by code violation or faulty workmanship."

"We cannot attribute any structural fire damage to the use of aluminum used in the wiring systems. We can report smoke

damage resulting from fire damage in switchboards."

"A survey of our fire records for approximately three years

indicates only one apparent response to a fire of this

type; this causing damage only to the outlet. However,

several calls have been received regarding the cause of

arcing, smoking or fire coming from electrical outlets some time after the occurrence."

"One serious fire occurred as the result of an electrical

short at a convenience outlet in a two story home. The

fire caused $10,000 damage. A contributing factor to the

extensive damage was the absence of a fire block at the roof

line."

"We have had problems on joints where a combination of

copper and aluminum terminated and the wrong type connector

was used. We have had fires ;^dlere aluminum cable was used on quick-wire receptacles."

"We have run into more than one condition on size six

and larger aluminum cable where it has broken down and blown

up at the point where it enters a panel. A proper connection

was used in all cases. We concluded that it was the fault of

the cable, in that it will not take any abuse or strain

where it passes through the connector."

"In recent months, we have had several dwelling fires

which involved aluminum wiring. The resultant fire

damage has varied from the cost of replacing a convenience outlet to $3,000.00. To date, there have been

ten of these fires reported to our department. We

feel certain that there have been other incidents

which have not been reported."

Probably the most significant fact to emerge from contacting these

sources is that most of these people believe not only that they understand

the problem and its solution, but also that there is a general consensus on the matter.

-23-
4.3.2 Specific Sources of Information

Several of the sources identified had particular potential as sources

of information about the performance of aluminum wiring in the field.

These sources met one or more of the following three conditions: (a)

they were frequently cited by others; (b) they were known to have made

a special effort to document fires and/or failures associated with

aluminum wiring; (c) they had taken formal action to restrict the Lise

of aluminum wiring prior to UL's announcement (July 1971) that as of

September 1, 1971, devices formerly approved for use with aluminum would

no longer be approved. These potentially inportant sources were individually contacted, and in the following paragraphs the information obtained

from each source is briefly summarized and assessed with respect to its

value as a basis for determining the extent of hazard attributable to

aluminum wiring.

. 4.3.2.1 Consumer Product Safety Commission

The CPSC has undertaken four efforts relating to such documentation:

(a) the National Electronic Injury Surveillance System (NEISS) data bank,

(b) a brief "survey" of data available fromt jurisdictions in the

Washington, D. C. , area, (c) a follow-up of some respondents to the

1972 UL survey, and (d) a continuation of the NBS data collection

described in this chapter.

The NEISS data bank has a product class (0605) representing electrical outlets, built-in wiring devices and distribution systems. The file

contains in-depth investigatory reports for 65 accidents in this class,

the earliest occurring in December 1965 and the latest in December 1973.

In 44 of the 65 cases, the type of conductor (aluminum or copper) was clearly irrelevant; exanples of attributed causes are "inserted bobby pin

in outlet" and "grasped electrically charged wires." In the other 21 cases it is inpossible to determine whether the type of conductor was

relevant, and the type of metal used is not stated; examples of attributed

causes in this group are fuse box "exploded," short in receptacle, and

faulty wiring.

The CPSC staff forwarded to NBS a report of another accident in which

there was a fire resulting in a death (although the report indicated some doubt that the death was a necessary consequence) . In this case the fire

department at the scene attributed the fire to a failure of aluminum wire.

The local CPSC survey found no records relating to aluminum wiring

failures other than those found in the NBS investigation, summarized

below in section 4.3.2.6.

In March 1974, the Los Angeles field office of the CPSC attenpted to

contact six jurisdictions in California that had reported aluminum-wirerelated fires in the 1972 UL survey. The field office was successful in

obtaining written records from three jurisdictions. The records are reports of individual incidents and do not represent conplete coverage

-24-
of a statistically definable sanple. For that reason and because these

reports are not based on consistent definitions of "fire" and other

iirportant terms, they provide only anecdotal information rather than

statistical data.

Since the NBS data collection and evaluation (project phase I)

was completed (June 1974), the CPSC has continued to collect reports

of incidents that have come to their attention.

4.3.2.2 Underwriters ' Laboratories , Inc . Field Surveys

In 1969, subsequent to receiving reports of problems in the field

with aluminum wiring, UL and the National Electrical Manufacturers

Association (NEMA) conducted a survey to attenpt to explore the

performance of aluminum wiring in the field. In 1972, UL conducted

another survey to evaluate the field performance of aluminum conductors

in branch circuits. In 1974, UL administered follow-up questionnaires

to a number of the respondents to the 1972 survey. This section dis- cusses the data and data collection procedures of these three efforts.

1969 UL/NEMA Survey

In 1969, UL and NEMA conducted a survey as part of a "Fact-Finding

Study, Terminations for Aluminum Conductors in Electrical Distribution

Equipment". A statement from a report of its results --" ... there is

statistically a failure rate of approximately 7 to 1 of aluminum over

copper." (21) -- has apparently become the source for a number of publicly

available pronouncements:

"Underwriters' Laboratories found in conparison,

homes constructed with aluminum wiring were seven times

more likely to have a fire." (22)

"One estimate has placed the present failure rate of

aluminum terminations as at least 7 to 10 times the

rate for copper in applications below 100 to 200

anperes." (23)

If the presumed relationship between the UL report and these statements

exists -- and there appears to be no alternative source for these

statements -- this early UL/NEMA survey takes on great significance.

The following evaluation shows that the survey provides no acceptable

basis for the original statement (and, therefore, the re-reported statements) and will, it is hoped, prevent its data from being used as evidence

of the numbers of aluminum failures relative to copper failures.

-25-
According to the UL/NEMA. report, approximately 12,500 questionnaires

were distributed by mail: 1,000 were sent to (unspecified) industrial

users of electrical equipment, and about 11,500 were sent to electrical

inspectors and electrical contractors identified simply "... through

connections with the National Electrical Contractors Association and

the international Association of Electrical Inspectors." (24) The

survey had an extremely low response rate (See 3.2.3.1). Only 13.5%

of the 11,500 electrical inspectors/electrical contractors returned

questionnaires and about 171 of the industrial users returned questionnaires. The UL/NEMA report does not discuss the implications of the

response rate, nor does it cite any efforts to determine why it occurred

or whether nonrespondents might differ from respondents in terms of the

relevant variables -- rates of failures associated with aluminum and

copper wiring. The low rate of response, since there was no determination

of its possible effect on the data, is sufficient in itself to render any

analytical treatment of the data useless. The most that could be reported

from these data would be "those who responded said ..."; certainly it is

not possible to make any assunptions that these data are representative

of any populations.

Beyond the matter of representativeness, there would still be major

questions concerning the validity of these data. The survey questions

were, in some cases, ambiguous. Concern for internal validity can perhaps best be summarized by the report's author:

"In looking at the answers received as a whole, it

is apparent, because of the differences in percentages

involved in questions which seem to supply in general the same information, that either the persons to whom the

questions were directed did not understand what was being

asked, or there was not sufficient care taken in making

the replies." (25)

The data collected from this survey should be used only as a collection

of anecdotal accounts from the field. As such it demonstrates some thinking by individuals experienced with aluminum wiring. It is most un- fortunate that these data were analyzed and the resulting observations

reported as they were.

1972 UL Survey

In December of 1972, UL mailed questionnaires to approximately

1,100 chief electrical inspectors, members of the International Association of Electrical Inspectors (lAEI). The questionnaire was designed to

get field information about the use and performance of aluminum wire

terminations at snap switches and receptacles between 1962 and 1972.

The questions were specifically concerned with terminations of aluminum

conductors at wire binding screws and to copper pigtails. (26, 27) The

evaluation below will show that although the data from this survey provide

useful descriptions of the perceptions of some electrical inspectors

concerning the performance of aluminum wire, these data cannot be pro-

-26-
jected to estimate the level of risk to the consumer associated with the use of aluminum wire.

The reports of this survey and the 466 returned questionnaires were

carefully examined because this survey was regarded as the most promising

source of data to perform the estimation of hazard. Unfortunately,

these data have deficiencies which preclude their use for this purpose.

The most important of these are discussed below.

• Population: It is known that not all individuals

with local responsibility for electrical inspection are members of the lAEI. Although a vice president of the

lAEI estimates that approximately 80% of the chief electrical

inspectors in the U. S. are members of the lAEI, (28) no other source was even willing to guess at the total number

of independent electrical inspection jurisdictions that

exist in this country. Therefore, the population for

this survey must be defined specifically as all chief

electrical inspectors who are members of the lAEI, not

all electrical inspection jurisdictions in the U. S.

(It should be noted that a few of the respondents to

this survey were from Canada and the Virgin Islands,

etc. , and these responses were not separated from

U. S. responses in the tabular reports.)

• Response Rate: 466 of the 1,100 chief electrical

inspectors returned questionnaires, for a response

rate of about 42%. (29) The UL project leader stated

that 10 of the nonrespondents had been contacted by

telephone and that their lack of response was reported

to be caused by "... lack of interest, which was ex- plained as little or no experience with aluminum con- ductors." (30) A small telephone validation survey was conducted by NBS .Twenty- five of the nonrespondents were

selected randomly and were contacted with the following

results: (a) All 25 jurisdictions had allowed aluminum

wiring to be used during some part of the 10 year interval,

in 23 of the 25 jurisdictions at least some homes or apartments had been wired with aluminum during that period, and

4 of the 25 said that "thousands" of aluminum wired homes

or apartments had been built during that period, (b) Of

the 23 jurisdictions which reported aluminum wired residences built in that time interval, 19 said that at least

some of the residences had aluminum branch circuits. (Although they were not questioned specifically about aluminum

wiring problems, some respondents did volunteer that they

had had problems, that they did not like aluminum wiring,

or that they had had no problems.)

-27-
The MBS validation survey shows that it is not possible to

support the assuinption that nonrespondents had "little or no experience with aluminum conductors", but this brief

survey is not sufficient in itself to show exactly how

the data from the UL survey might have been affected

by the low response rate.

Consistency: Lack of consistency in wording some of

the major questions in the questionnaire prevents

comparison even of responses supplied by a single

respondent. The following three questions are the

primary occurrence of this lack of consistency

(enphasis ours):

"1. Have building or electrical codes in your

jurisdiction allowed the use of aluminum

wiring at any time in the last 10 years?"

"4. Has direct termination of aluminum wire to

binding head screws of snap switches and

receptacles been allowed in your jurisdiction

at any time during the last 10 years?"

"13. Have copper pigtails been used in your jurisdiction at any time during the last 10 years

as a means for terminating aluminum branch

circuit conductors in switch boxes and receptacle outlets?"

It is not possible to compare Questions 1 and 4 directly

with Question 13, because in the first two questions the

word "allowed" is used while in the last question the

word "used" appears. Comments written on returned

questionnaires and statements made during the NBS non- respondent survey indicated that many more respondents

said aluminum was allowed than said it was used.

Interpretation: No definitions were supplied for "failure",

"fire", or "occupancy", etc. (See Section 3.2) There is no way to determine what definitions were used by the

respondent and how the numbers reported were determined.

The lack of operational definitions throughout the

questionnaire demands that caution be used even in making

statement such as "There were at least... reported fires."

Reliability: Although the questionnaire and covering

letter for the survey both clearly stated that information

was required for terminations of aluminum conductors at

snap switches and receptacles, (which implies branch circuit

wiring) , some respondents explicitly indicated that their

answers incorporated information on service entrance

-28-
cable and/or appliance circuits as well. Inclusion of

these responses contaminates the stated meaning of the

data; it also creates uncertainties concerning the

possibility of their inplicit inclusion by other

respondents

• Accuracy: The numerical values supplied by respondents

were usually their best estimates. The variability in

accuracy cannot be ascertained, although it is known

that the numbers of failures and fires supplied ranged

from approximate percentages of numbers of aluminum

wired homes (e.g., 10% of total); to a linear extrapolation of 18 months of data to an estimate for ten years

to actual numbers observed.* UL follow-up contacts with

some of the respondents indicated that almost all of the answers were based on inpressions and memory rather than

systematically-kept historical records. (31)

Thus, although it would probably be possible to overcome the limitations inposed on the results by nonresponse, the other deficiencies of

the data resulting from the many limitations of the survey instrument

do not recommend such an effort. Under these circumstances, the survey

data must be confined, as with the earlier 1969 UL survey, to use only

as a fertile source for anecdotal information of varying quality and

utility.

1974 UL Survey

In January 1974, UL mailed a follow-up questionnaire to each of the

53 jurisdictions that had reported at least one aluminum associated fire

in response to the 1972 questionnaire. Despite intensive follow-up

by UL, only 30 questionnaires were returned. Due to the deficiencies

of the 1972 survey on which this survey was predicated, only anecdotal

information can be validly derived from this survey. Notes included

by the respondents to this survey indicated that "the answers to the

original questionnaires were incorrect in a great many cases, and that

reported fires at receptacles were caused by other factors than poor

aluminum wiring terminations." (32)

4.3.2.3 American Plan Corporation

The Wall Street Journal reported in September, 1972, that American

Plan Corporation, an insurer of automobiles and mobile homes, intended to

stop writing coverage on mobile homes equipped with a aluminum wiring,

because a study revealed a "suspiciously large number" of fires in such

homes. (33) A company official (34) indicated the conpany "no longer

felt that conclusions drawn at that time were sufficiently significant

The most extreme response, a report of 100 fires in Prince George's County,

Maryland, is given explicit attention below (4.3.2.6).

-29-
to require a distinction between aluminum and copper wiring." Thus,

contrary to the iirpression given by the article, this is not a source

of data on aluminum wiring failures.

4.3.2.4 International Association of Electrical Inspectors

The International Association of Electrical Inspectors (lAEI)

makes an annual tabulation of electrical fires and accidents. This is

based on a survey of approximately 1,100 association members who are chief electrical inspectors in their respective jurisdictions. The

survey identifies various types of appliances, cables, distribution

panels, lighting fixtures, receptacles, switches, terminations and

splices, etc. For each category, the form asks for the number of

electrical accidents in three sub-categories: shock, fatality and fire

(no definitions are supplied for the categories or the subcategories)

Only in the "terminations and splices" category is a distinction made

between copper and aluminum conductors. The lAEI tabulation provides

no means of inferring an accident rate, i.e., no means of rating the

number of accidents reported to the total number of copper or aluminum

terminations (for exanple) in use. Conceivably, numbers of terminations

in use might be obtained from individual jurisdictions represented in

the survey responses. Also, the totals of accidents reported may be

useful as evidence of hazards, if a survey follow-up is undertaken to

determine the validity of the reports. In the most recent survey

(reporting accidents in 1973) 227 responses were received, making a response rate of about 20%. As discussed above in connection with the

1969 UL survey, a response rate this low precludes any valid analysis

of the results. No follow-up of the respondents nor of the nonrespondents

has been attenpted. The survey has not been used as a basis for any

analysis, and the published tabulation (35) cautions against using

the information for comparing one material with another.

4.3.2.5 National Fire Protection Association

The National Fire Protection Association (NFPA) has recently polled

over 800 fire marshals at the state and local levels. Only in the case

of mobile homes, trailers and recreational vehicles did the survey ask

for aluminum wire to be identified. This data collection effort had a

case history format rather than a tabulation format (such as the lAEI

and UL surveys) , and thus does not provide a basis for calculating

failure rates. Furthermore, only 32 responses were received.

4.3.2.6 Prince George's County, Maryland

The chief electrical inspector of Prince George's County, Maryland,

maintains a special file which documents incidents involving aluminum

wiring. This file, which was begun in July 1971 was provided to NBS

in March 1974 and was found to contain records of 17 such incidents,

four of which were fires resulting in structural damage. The local CPSC

survey identified eight fires in this file. Their reporting of four

additional fires is apparently to be explained as follows: Three were

-30-
fires that did not involve structural damage (one in a distribution panel

and two in outlets) , and one represents a call to the fire department

due to a short circuit in an outlet but where there was no damage to

the structure.

The figure of 100 fires reported for Prince George's County in the

1972 UL survey was reportedly derived as follows. (36) At the end of

1972, the file contained 11 incidents which had occurred in an 18-month

interval. All of these incidents were considered to be potential (if

not actual) fires. In addition, it was known that con^laints had been

received \^^ich were not added to the file. On this basis the chief

electrical inspector estimated a rate of ten fires per year. Since the

UL survey asked for the number of fires in ten years, an estimate of

100 fires was supplied.

4.3.2.7 Washington, DC

The Fire Inspector (Electrical for Washington, DC, has taken an active interest in problems associated with aluminum conductors for the

past several years. However, due to the nature of new construction in

Washington in recent years, aluminum conductors employed there are almost

exclusively busbars in office buildings, rather than wiring in the sizes

found in houses. There are only four or five aluminum-wired houses in

the city, and all branch- circuit wiring in large buildings is copper. (37)

Residential applications could potentially include high rise buildings

where such busbars might be used, and the explosion and toxic gas effects

observed in office buildings could pose a threat to civilians as well

as firefighters.

4.3.2.8 Huntington Beach, California

The Fire Inspector (Electrical) of Huntington Beach, California,

has also kept records relating specifically to incidents involving

aluminum wiring. In the period May 1970 through August 1971 there were

four fires attributed to aluminum wiring that caused structural damage,

one of which caused a death. (38)

4.3.2.9 Summary

If accurate estimates of the numbers of aluminum installations can

be obtained for Prince George's County, DC, Huntington Beach, and lAEI

respondents then estimates could be developed for the rates of fires

with structural damage. However, the estimates are likely to be very

rough -- perhaps useless -- because of the rarity of the phenomenon and

possibly also due to inconplete or inconsistant record-keeping.

Estimating the number of fires in an extended period - say, ten

years - on the basis of fires occurring in a shorter period involves

several assumptions or adjustments. First, it must be assumed that the

observed fire rate (e.g., fires per thousand homes per year) is the true

-31-
fire rate over the entire ten-year period. Second, the estimate must be

adjusted to correspond to the numbers o£ houses at different times within the ten-year period. Third, it should be based on the number of

actual fires that have occurred. Any estimate that may be derived

necessarily depends very much on these considerations.

This can be illustrated by using the Prince George's County data

for the 18 months ending DeceniDer 1972; among the 11 incidents there had

been seven fires, four of which resulted in structural damage. Assuming

that the aluminum-wire homes were built at a constant rate throughout the

ten-year period (and starting at the beginning of that period)* and assuming a constant fire rate (fires per thousand homes per year) , the estimated

total number of actual fires in that ten-year period would be 25, and the

estimated number of these fires with structural damage would be 14. Using

all of the data in the Prince George's County file up to the time when the

file was examined in the course of this study, there have still been only

the same seven fires, four with structural damage, during a period of

32 months (July 1971 through February 1974). This results in ten-year

estimated of 14 actual fires, 8 of which caused structural damage. It

should be clear from these examples that the necessary assuirptions and

the rarity of the phenomenon make rate estimates somewhat arbitrary

and rather unreliable.

The foregoing discussions clearly show that the field data, as they

now exist, are insufficient for establishing a rigorous statistical hazard

estimate. It is conceivable, however, that some of the extant data could

be used in conjunction with data derived from a new data collection effort

designed around the needs of this study. (See Section 5 for a discussion

of a data collection undertaking.)

Clearly, reports of problems with aluminum wiring have caused UL

and affected industries to respond (See Section 2) , and either direct

experience or reported experience has convinced some state and local

officials that there was or is a sufficient problem (or sufficient

possibility of a problem) that they should take actions to restrict the use of aluminum wiring. These actions are discussed in the following

section.

4.4 State and Local Restrictions on the Use of

Aluminum Wiring

Numerous state and local jurisdictions have placed restrictions on the use of aluminum for residential wiring. A review of these restrictions

provides some indication of the climate of opinion about aluminum wiring

problems. Of greater interest is the basis on which each action was

taken -- e.g., actual experiences of problems within the jurisdiction,

or the recommendations of other jurisdictions or UL -- as this information not only provides a clue to potential sources of data, but also

_

As reported by Mr. Kuntz. (39)

-32-
indicates the extent to which a judgment by one authority may be

reflected in the actions of others.

The restrictive actions that have come to our attention are listed

in this section. The list must be regarded as inconplete. The actions

have been identified through a miscellany of sources: the Aluminum

Association, copies of notices to contractors, newspaper articles,

personal knowledge, etc. In many cases the source information was fragmentary (and occasionally contradictory) , and to date most of the

jurisdictions involved have not been contacted for confirmation and updating of the reported information. The purpose of the list is only to

indicate the variety of restrictive actions that have taken place. A

thorough survey of restrictions would be an extensive undertaking in

itself. Section 5 discusses a plan for such a survey.

Ordinarily one might not consider as a restriction the simple re- quirement that only UL- listed components be used. However, in July 1971

UL withdrew their approval, effective September 1, of all then available

devices for use with aluminum wire and established a new approval program

for such devices, and in the preceding month UL had initiated new requirements for their approval of aluminum electrical wire. For nearly a year

in the case of devices, and for more than a year in the case of wire, no such components were approved by UL. Thus, during this period, a state or local requirement that all components used be listed by UL

amounted to a prohibition of aluminum wiring. This requirement remained

a "restriction" for some time afterward as few devices and wires gained

approval and became available. For this reason, the following list of

restrictive actions includes some overt notices by state and local

authorities, following the change in UL requirements, stating that

electrical conponents in aluminum wiring applications must be listed for

that application by UL.

The list provides scanty clues as to the bases for the restrictive

actions undertaken. In at least five cases the restriction was inposed

prior to UL's July 1971 announcement. There was, however, a series of

meetings and correspondence between UL and several other parties prior

to July 1971; at least some of these five jurisdictions were included.

Therefore, the experiences of these jurisdictions may have been part of

the basis for the UL action. Of the other 26 jurisdictions in the list,

there is evidence that at least 10 were responding to the UL action. Of

course, this does not preclude their having had independent basis for

action. In at least one case (the Texas State Building Commission)

the restriction on aluminum wiring was part of a ban motivated by a failure of a bus system in a large building rather than by failures of

branch circuit wiring.

Although it is inpossible to determine from presently available

information exactly how much independent basis there has been for restrictive actions, it is clear that some jurisdictions have had an independent

basis and that some actions were based on the ejqDeriences of others.

Even though of somewhat questionable validity, a survey of electrical

-33-
RESTRICTIONS ON BRANCH CIRCUIT and

SERVICE ENTRANCE WIRING OF ALUMINUM

This list must be regarded as in the text.

incomplete and tentative, as explained

Place Effective date

Latest date known

to be in effect

Type of

restrictions

Arizona

Tucson 12/21/71* 11/9/73 Bans Al nonmetallicsheathed wire for

branch circuits

**California

Huntington Beach 9/3/70

Los Angeles II/I/7I

** Orange County 12/70 & I/7I

(9 jurisdictions)

Sacramento 12/1/71

District of Columbia 1/7/72

present

2/1/72

present

Bans Al wire

Requires UL approval

or devices

Bans Al #6 and

smaller

Requires UL approval

of devices

Bans the old wire alloys

Bans AL-CU devices unless

body of connector is

aluminum

Florida

Macclenny 8/1U/73

Tampa 5/15/72

Georgia

DeKalb Coiinty 8/IO/7I

**Idaho ^/1/71

11/9/73

11/9/73

present

Bans Al wire

Bans Al #8 & smaller

Bans Al smaller than #8

Pigtails required

unless UL-approved

devices are used.

Kentucky

Lexington & Fayette Counties h/l/l2

Louisiana

Baton Rouge

11/9/73

Requires UL approval

of devices

Ban lifted in However, UL approval of

1973 devices is now required

Asterisk indicates the earliest date known, from present information, to be

in effect.

i Double asterisk marks restrictions known to antedate UL's July 1971

announcement

-3U-
Place

Maryland

Baltimore Co.

Effective Date

1/1/72

Montgomery Co. 5/26/72

Pr. George's Co. 3/1/72

Michigan

Dearborn

Mississippi

Jackson area

Nevada

9/6/T3

New York

**North Dak:ota

Ohio

Cincinnati

**Rhode Island

Providence

South Carolina

Myrtle Beach

Tennessee

Mirrfreesboro

,

Lebanon, Franklin

Woodbury

Texas

State Building

Commission

Arlington

Houston

(a) 2/1/72

(b) 7/1/72

1968

5/1/73

Approx. 1965

2/29/72

Jan. 1972*

Richardson

1/12/72

H/l/72

2/II+/72

Garland, Piano, 9/1/73

Farmers Branch,

Lewi svi lie,

Carroleton, Mesquite

Virginia

Arlington County 2/7/72

Latest date known

to be in effect

present

present

11/9/73

11/9/73

11/9/73

11/9/73

1970

11/9/73

present

Ban lifted

3/7/72

Ban lifted in '73

11/9/73

Type of

restrictions

Requires pigtails or UL approval of devices

Bans Al #6 and smaller

Bans Al #6 and smaller

Bans Al #10 and 12

Bans Al in FHA-insured

and HUD-financed housing

Bans Al in mobile homes,

except grounds and

lead-ins

(a) Requires pigtail

on #10

(b) Requires pigtail

on #12

Banned Al wire

Requires pigtails

Bans Al smaller than #6

Bans Al wire

Bans Al smaller than #6

Washington 9/1/71 10/i|/73

Banned Al wire

Requires UL approval

of devices

However , UL approval of

devices is now required

Requires UL approval

of devices

Ban Al branch

circuit wire

in dwellings

Bans Al wire

Requires pigtails

-35-
inspectors conducted in September 1971 by the Information Gathering Service

of Harvard Student Agencies, Inc., lends some support to the impression

that the UL announcement in July 1971 had a large influence. The survey

cited that UL announcement and asked whether the respondent intended to

require contractors using aluminum in branch circuit installations to use only wiring devices approved by UL for that use. Although only 501 of the

2,000 electrical inspectors replied to the questionnaire, 407 of the

respondents said that they intended to require UL approved devices for

aluminum and an additional 63 inspectors said that they had already prohibited or severely restricted the use of aluminum in branch circuit

installations.

4.5 Estimated Numbers of Homes with Aluminum Wiring

One aspect of estimating the level of hazard associated with aluminum

wiring is the number of homes (including apartments and mobile homes)

having such wiring. A home may have aluminum wiring throughout, or only

in a recent addition or recently rewired section, or only at the service

entrance. There are no records of the number of such homes in the nation.

An order- of-magnitude estimate has been made of the number of homes wired

entirely with aluminum, but there is no basis for estimating the number

of homes wired partly with aluminum. It is known that current home con- struction predominantly uses service entrance wiring of aluminum.

The order- of-magnitude estimate was derived by dividing the amount

of aluminum wire produced from 1960 through 1971 by a quantity representing

the amount of wire per home. Only a very approximate estimate can result

from this procedure, both because the wire production data are estimates

subject to error and especially because a single number used to represent

the average wire content of a home is necessarily a rough approximation.

The production data (in millions of feet of cable) were provided by

the Aluminum Association in 1972 and are based on a survey of their

members (40) They are presented here along with their equivalent in

millions of meters.

Year Millions of Feet Millions of Meters

1960-1965

1966

1967

1968

1969

1970

1971

These figures represent an aggregate of wire sizes; the Association was

not able to make estimates for individual wire sizes. These may be taken

as representative of housewiring sizes. The Association members supplying

the raw data from which these estimates were derived ordinarily reported

production quantities by weight rather than length. Consequently, it was

77

119

192

349

419

569

771

23

36

59

106

128

173

235

-36-
necessary for the Association to convert from weight to length, and this

contributed some uncertainty to the estimate since a single conversion

factor was applied to a conglomeration of wire sizes.

In 1972 a number of aluminum-wired homes was estimated at NBS,

based on the wiring required for an average three-bedroom house. The

resulting estimate was 1.5 million homes. This estimate was obtained in

such a way that 1.5 million homes is conservative and the actual number

of houses is probably higher than 1.5 million.

The Aluminum Association estimated that the 1970 wire production

was enough to wire about 450,000 homes. (41) Applying this relation to

the production data for 1960-1971, the estimated number of homes wired

with aluminum is 2.0 million.

More recently a new estimate was derived at NBS from the same production data with a somewhat different approach to the amount of wire

per home. Data compiled by the National Association of Home Builders,

(42) representing six sizes of houses, indicated an (unweighted) average

of 0.86 feet of wire per square foot of floorspace. An estimated average

of 2,000 square feet of floor space per home was derived from a postulated

mix of two apartments of 1,000 square feet (each) to two houses of 2,000

square feet (each) to one house of 4,000 square feet; that is, such a mixture of sizes was assumed to be a plausible representation of the homes

constructed with aluminum wiring. The resulting estimate of the national

total of such homes is 1.45 million. x

To make the estimates current, extrapolations were made to the end

of 1974. (No new production data were obtained.) A lower bound was extrapolated by assuming no increase in annual production beyond 1971.

Extrapolating from the estimate of 2 million gives an estimated 3.8

million homes by the end of 1974, and extrapolating from the 1.45 million

figure results in an estimate of 2.8 million homes at the end of 1974.

Higher estimates may be obtained by assuming that the 36% annual

increase in aluminum wire production from 1969 to 1971 continued unimpeded through 1974. Extrapolating from the 2 million home estimate

yields an estimate of 5.5 million homes as of the end of 1974, and

extrapolating from the 1.45 million yields an estimate of 4 million

homes by the end of 1974. These extrapolations ignore whatever effect

the imposition and lifting of bans and other restrictions may have had.

These estimation procedures have been detailed here to impress upon

the reader that this estimation is based on rather simple and arbitrary

methods, and that the resulting estimates should not be interpreted as results of any extensive research. Without considerably more satisfactory

data and considerably more refined estimation procedures (both of which

may be impossible to attain) the most that can be said is that there are probably "at least a few million" homes wired with aluminum, and undoubtedly

more than 1.5 million. Less cautious assertions are frequently hear, but

they evidently are unsupportable.

-37-
4.6 Conclusion

The search of field data has found that no available data have the

characteristics necessary in order to develop a statistically sound

estimate of the level of hazard associated with aluminum wiring. Neither

do the available data establish the relation of aluminum to copper

wiring in this regard.

But although the data do not establish statistically that there is a significant hazard, no more do they establish that there is not a hazard.

There is, of course, anple evidence to suggest that there is a substantial

hazard, but actual experience with the performance of aluminum wiring has

varied widely. Similarly, there is no consensus regarding the remedies

that are appropriate, although few of the persons contacted in this search

were aware of the lack of consensus. It follows that until this lack of

consensus is widely recognized, it is likely that any action that the

CPSC might take would be viewed as inappropriate by many persons who think

of themselves as knowledgeable in this area.

The extensive data requirements relevant to this study are entirely

foreign to the operational data requirements of most of the organizations

.and officials contacted. Although there is no unwillingness to cooperate, some of the persons contacted do not appreciate that distinction in data

requirements. Consequently it has not been sufficient to rely on verbal

- assurances that detailed documentary data are available; the extant records

must be critically examined and subjected to validity checks. There are

some collections of records that give a superficial inpression of having

the requisite characteristics. These are documentary data in the sense

that they exist in the form of written documents. It is essential, however, to consider the somewhat subtle question of what is documented. In some cases fires are documented; in some cases, opinions; in some cases,

estimates; in some cases, recollections of incidents long past. The UL

surveys are exanples of the creation of documentary information consisting

largely of estimates based on recollections, even though the respondents

themselves might not characterize their information this way. Such

documentary data must not be accepted at face value, without assessment

according to the criteria discussed previously (Section 3.2). Data obviously are not rendered valid merely by virtue of being in a signed

document; assertions are not true merely by virtue of being attributed

to documentary sources. Even the fact that a public authority has committed

itself to a course of action restricting the use of aluminum wiring does not

irply that aluminum wiring problems have been experienced within the res- pective jurisdiction.

There is no accurate estimate available on the extent to which aluminum

wiring is now in use, i.e., how many homes employ aluminum conductors in

various forms . Furthermore , the risks to the individual consumer -

- i.e.,

. his chances of experiencing problems with his electrical system, and the

possible consequences of such problems -- are inpossible to estimate

accurately with presently existing information.

-38-
In this climate of uncertainty the CPSC must make some determination of the next steps to be taken. The following section of this

report begins by identifying alternative responses available to the

Commission and concludes with a summary description of additional field

data requirements and a brief discussion of the efforts entailed by a commitment to obtain these data.

5. Satisfying the Data Requirements

Sections 2 and 4 of this report have presented some of the actions

and field data which have been used as bases for questioning the safety

of using aluminum wiring in residential applications in this country.

Section 3 outlined the data (and data characteristics) required to

determine the extent of use of aluminum electrical wiring in U. S.

residences, to determine the level of risk to consumers associated with

its use, and to describe in detail the performance of aluminum electrical

wiring as installed in residences. Section 4 also presented an evaluation

of the existing field data in terms of the Section 3 criteria.

The information thus far presented has shown that while there have

been problems in using aluminum wiring in residential applications, the

existing field data are of neither sufficient quality nor sufficient

quantity to make statistically defensible estimations of the nature and

extent of aluminum wire use or of the level of risk to consumers of such

use. The reason for this inadequacy is that a scientific determination

would require (a) an extensive, and therefore expensive, data collection

effort, (b) a sample design that represents all the inportant variables

in aluminum wire applications, and (c) a consistent set of definitions

and categories throughout the data collection. Section 4.2.1 noted that

fire marshals and electrical inspectors had no need for such a rigorous

data collection in order to carry out their duties.

Neither is the CPSC required by law to base its actions on statistically defensible findings. With regard to risks associate with aluminum

wire, the CPSC has three choices. It can

• Judge that no "unreasonable" risk exists. In this case, no further action would be required.

• Judge that available information is not sufficient to establish whether an unreasonable risk exists, but acknowledge that

the possibility of such risk exists. In this case, the CPSC

would seek further expert advice and/or laboratory and field

investigation. It must be noted that if an unreasonable risk

to the consumer should now exist, further investigations could

be at the expense of additional losses.

-39-
• Judge that aluminum electrical wiring in residential applications presents an unreasonable risk to consumers. In this

case, while further investigation would not necessarily be

excluded, the CPSC would be required to make immediate recom- mendations leading to reduction of the level of risk. Such

a judgment, then, presupposes sufficient knowledge to propose

solutions

Under the second choice, there remains a need for new field data for

two purposes. The first is to establish the existence and extent of an unreasonable risk in the use of aluminum wiring. The second purpose is to

establish the actual circumstances in which aluminum wire has been used

(see Section 3.1.3) to provide guidance in establishing the initial

conditions of laboratory experiments and in the interpretation of their

results, in order to relate the experimental work to performance to be

expected in the field.

If at any time the CPSC determines that there is an unreasonable risk,

a different kind of data will be needed for effective inplementation of

CPSC recommendations or rulings. It will be necessary to identify the

electrical inspection officials who ultimately will be involved in any

new procedures for the use of aluminum wire (including remedial action

that may be applied to existing installations) , and this identification

will not be simple since the jurisdictional organization of the electrical

inspection function in this country is complex and fragmentary. It will

be advisable to have measures of the existing inspection staffs, facilities,

workloads and practices if it is proposed to place additional burdens on

them.

The CPSC decision process need not be discussed further here. It

is presented in order to make two points: CPSC judgments will influence

the extent of future CPSC supported investigations, and CPSC decision

criteria may influence the nature of future CPSC supported field data

collection.

Section 5 presents a general outline of a field data collection

effort which would meet the data requirements outlined in Section 3. This

effort assumes a desire on the part of CPSC to establish the level of risk

associated with aluminum wiring at a moderate level of confidence, and

a desire to recommend or inclement remedial actions.

It must be noted that the procedures described below are not yet

fully developed and would, therefore, be subject to modifications based

on additional developmental work: The variables discussed will require

operational definitions (which must relate both to data collection procedures and analytical tasks) ; the data collection procedures and operational definitions must be tested in situ , and revised as necessary; and

samples must be designed to meet criteria which will be established by

conparing desired levels of statistical confidence with economic and

time constraints.

-40-
The field data collection plan described in Section 5 involves two

distinct types of data collection efforts. One, to determine the extent

of aluminum wire use and to estimate the magnitude of effort required to

correct any existing problems, is an extensive, nation-wide "macro" effort.

The other, to identify the specific nature of any hazard and to estimate

associated risks, is an intensive, localized "micro" effort. Logically,

the work would proceed in a stepwise fashion; determining the level of

risk first and then approaching the other tasks only as necessary. Time

constraints, however, might dictate concurrent efforts so that if un- reasonable risk were established, appropriate tasks could be readily

performed.

5.1 The Macro Study

The characteristics of data to be sought in the field to determine

the extent of use of aluminum electrical wiring and to determine the effort

required to reduce or eliminate any hazard associated with its use were

outlined in Section 3.1.1 and part of Section 3.1.2, and are repeated

below.

• A representative set of all types of U. S. housing (single and

duplex houses, apartments, mobile homes);

• A representative set of geographical areas

• Categorization according to specific electrical application

(branch circuit conductors, service entrance cable, appliance

circuit conductors , service busbar conductors , and any combinations of these;

• Categorization according to relevant installation date (e.g.,

pre and post UL listing of CO/ALR devices). It would be highly

desirable for the data to be categorized by type of connector

AL-CU, copper pigtail, CO/ALR, "push" device, etc.).

t Data concerning existing code requirements for electrical

wiring in residences and the enforcement practices followed

with respect to those codes. Identification of mechanisms

and usual time intervals required to change these codes and/or

procedures

• Data concerning the training and/or licensing required of

electrical workers and electrical contractors, in order to

identify expected workmanship and ways of influencing

workmanship

-41-
5.1.1 Sample for the Macro Study

These data must be collected in such a way as to represent the

national use of aluminum wire. The macro effort could best be accom- plished by collecting the necessary data from a sample of electrical

inspection jurisdictions drawn from all such jurisdictions in the

United States. Since a nationwide enumeration of these jurisdictions

is not available, the county (or county-equivalent) is probably the most

reasonable substitute sanpling unit.

A Census -derived enumeration of counties and county- equivalents

exists, and use of this sampling unit would provide another advantage -- for these sample units it is possible to obtain Census housing data.

(It may be logically assumed that those areas with larger housing in- creases would be areas with possibly greater use of aluminum electrical

wiring.) Using the list of counties, a stratified sampling plan would

be designed according to residential construction rates. It may be

possible to inprove the accuracy of projections by increasing the sanpling

rate for the strata with higher construction rates.

Although in some instances county/county- equivalent may, in fact, be

an electrical inspection jurisdiction, it is known that in some instances

there are several electrical inspection jurisdictions within one county.

In those sample counties containing multiple jurisdictions it would be

necessary to identify and contact each separate jurisdiction.

5.1.2 Data Collection for the Macro Study

Within each jurisdiction, the source of data would be the chief

electrical inspector or equivalent. In order to cover the time interval

in question, it might be necessary to contact more than one person in

each jurisdiction.

A data collection form has been partly developed to conform to the

data required and the interviewing technique employed. Face -to -face

interviews would probably be excluded because of cost constraints, so a combination of mail and telephone contacts is the recommended method.

The questions to be asked would address the following topics

• organization of the electrical inspection function

• the inspector's knowledge and attitudes about copper, aluminum

and coated aluminum (e.g., copper-coated or nickel -coated) wire

• inspection facilities , resources and workload

• inspection procedures and practices

• electrical codes and legal requirements , including specific

requirements concerning usage of aluminum

-42-
• numbers of dwelling units constructed, by type and time frame

• percentage of new units wired with aluminum

• by type of wire involved, numbers of installations of:

• service entrance or feeder cables

• appliance circuits with wired- in appliances

• appliance circuits with receptacles for plug- in appliances

• general purpose branch circuits:

devices directly connected by binding-head screws

devices installed by push- in connection

devices installed by pigtail connection

light fixtures

others connections

• use of "new aluminum alloys"

• use of CO/ALR devices

• use of nonmetallic- sheathed cable

• use of nonmetallic boxes

5 . 2 The >4icro Study

The field data required to determine the nature of any hazards

caused by aluminum electrical wiring and to estimate the associated risks

were outlined in section 3.1.3 and part of Section 3.1.2 and are repeated

here

Determination of Level of Risk:

• Data to establish the population of possible failures of aluminum

wiring in a specified area. These data must be categorized by

the other relevant factors including specific conductor application within residence, date of installation, etc.

• Data to establish numbers of failures in the same specified area

(by specific application, by installation date) . ifiese data

must also be categorized by type of failure: termination

failure, wire failure, incipient failure, etc.

-43-
• Data to establish the consequences of each failure in terms of

occupant safety (by specific application, by installation

date, etc.): five or necessary conditions for fire, shock or necessary conditions for shock, etc. The data are specified

in this way because actual injuries or deaths related to

aluminum wire failures may be relatively rare events.

The data required for the determination of whether the risk is

reasonable or not depends on decision criteria to be established by the

CPSC. Possible data needs include data to compare the level or risk of

aluminum wiring with other products, and/or data to compare the cost of

one decision outcome with others:

« Comparable data for copper wiring as specified in the three

items above.

• Data concerning the levels of risk associated with other

products installed in homes.

• Data outlining the costs associated with any aluminum wiring

hazard.

Determination of the Physical Nature of the Hazard:

• Environment of the connection, (e.g., temperature, humidity,

vibration, etc.).

• Nature of the conductor, (e.g., size, specific application,

etc.).

• Nature of the wiring device, (e.g., type, connection technique,

applied voltage, etc.).

• State of the connection, (e.g., loaded and unloaded resistance,

evidence of creep or corrosion, etc.).

9 Nature of the installation, (e.g., age, evidence of code

violation, etc.).

• Nature of electrical system, (e.g., capacity of service box,

line voltages, etc.).

• If failure, nature of the failure, (e.g., creep, corrosion,

mechanical failure, etc.).

• If failure, alerting condition, (e.g. , flicker in lights,

odor, electrical shock, etc.).

-44-
The micro study itself could be considered to have two distinct parts

because the data required for estimating level of risk are qualitatively

different from the data required to identify hazards per se . The former

data could be collected by asking people to supply information, while the

latter data would have to be collected by observing and measuring the

actual performance of electrical wiring systems on site in homes. Both

parts of the micro study as outlined here, however, would require collecting

data about the performance of aluminum wiring in a set of residences.

5.2.1 Sample for the Micro Study

For both parts of the micro study, the population would probably be

defined, for exanple, as all aluminum wire junctions in a specified area. Cluster sanpling would then be used (i.e., residential units containing

aluminum electrical wiring) , and a sanple of such clusters (residences)

would be selected. Because of the nature of the analysis, the definition

and enumeration (or estimation) of the population would be as in^Dortant

as, and could be as demanding as, the data collection itself.

The installations on which performance data would be sought would

be subdivided in some or all of the following ways, depending on the cost

entailed and the amount of detail sought in the conclusions to be developed.

The installations would be subdivided according to their components, in

order to preselect installations with"old" wire alloys and "old" (non-CO/ALR)

devices, those with "new" alloys and "old" devices, and those with "new"

alloys and CO/ALR devices. There might also be a geographic division to

include three climates: (a) wet, warm and salty (southern coastal),

(b) wet and cool (inland) , and (c) dry and cool (inland) . A division

between aluminum and copper is, of course, necessary, and a group of

installations using copper- coated aluminum would be desirable. It may

be important to subdivide the sample by (or control for) other variables

such as the quality of workmanship and the type of electrical code

requirements

Sanple size and overall sanple design and sample selection procedures

would depend on further developmental work. The samples for the two parts

of the micro study would be designed together; probably the sample for the

engineering measurements to collect data on the nature of the hazard would

be a subset of the sanple for data on the level of risk.

5.2.2 Data Collection for the Micro Study

A form would be designed to collect engineering measurement data to

identify any hazards associated with the use of aluminum wiring. This

form would be suitable for recording measurements and observations made

of the wiring system in each sample residence. It would be necessary to

obtain permission and legal waivers to gain access to each residence and

its wiring. (No measures or observations are proposed which would alter

the state of the electrical system.) In this regard, it is assumed that

data collection teams would work only in cooperation with the local

electrical inspection authority and/or government. A most likely site

for pretesting this data collection procedure would be military housing,

because of the relative ease in gaining access.

-45-
The purpose of the other part of the micro study is to estimate the

degree of risk in relation to "exposure" to aluminum wiring, i.e., in

relation to some defined quantity of aluminum wire in use. Data on the

performance of the wire would be obtained by asking residents or others

to report symptoms, not necessarily limited to fires or even to failures.

On the one hand, the reported characterizations of performance would be

related to the corresponding physical measurements, which in turn would be

related to laboratory conditions. On the other hand, the performance

characterizations would be assessed as to hazard potential: fire, predisposing conditions for fire, "primary shock hazards" (necessary conditions

for shock) , and "secondary shock hazards" (malfunctions that would tend to

induce residents to expose themselves to shock hazards while attenpting

diagnosis or repair)

There are three basic approaches to this part of the micro study -- the performance survey.* The first approach would sample dwellings

according to a Census Bureau sanpling plan. The second would sample

in localities determined beforehand to have certain inportant characteristics. The third approach would direct the survey efforts to locations

of known fires, and determine the characteristics afterward.

The first approach would utilize the dwelling sample enployed in the

Census Bureau's Quarterly Survey of Residential Alterations and Repairs.

(The Census Bureau also has a Monthly Survey of Housing Starts, Sales and

Completions, and an Annual Housing Survey, but these are not as suitable for the present purposes as the quarterly survey.) The chief

advantage of this approach is that it would provide a nationally representative sanple of housing units. Although there are repair data available from this source now, the level of detail is insufficient for the

aluminum wire study. Thus the quarterly survey provides only a basis for

*A fourth approach has sometimes been suggested. It is statistical

analysis of existing fire data for counties that are matched by demographic variables and paired by the type of conductor (aluminum and

copper). It is unlikely that any counties can be accurately characterized as predominantly aluminum-wired. Smaller units (communities)

that can be so characterized would be very difficult to satisfactorily

match with demographically similar copper-wired communities (of the same age). Defects in the quality of existing fire data, such as those mentioned in Section 4.2.2, would preclude the use of data just

for fires attributed to electrical causes , and would thus require that

gross fire data (all causes, or perhaps all except arson) be lumped

together. In order for a statistical analysis to detect among many

variables a difference in fire rates, between aluminum and copper,

would require that the difference be large in conparison with the

lower rate (which may not be the case) or that the data base be

very large (probably prohibitively large) . Even if this approach

were feasible, it would only give fire rates and would give no other

performance data and no basis for relating symptoms to engineering

measurements, since there would be no interviews and no measurements.

-46-
further survey work. Due to confidentiality requirements of the Census

Bureau, the initial contact with residents to be surveyed would have

to be made by Census Bureau personnel; where a waiver can be obtained,

subsequent survey contacts could be made by others. The necessity for

Census personnel involvement in providing the sample and carrying out

at least the first round of survey contacts (along with other Census

Bureau obligations) would result in considerable time and expense. A

further drawback is that very few aluminum installations would be obtained

from this sample, and therefore the resulting statistics may be of little

value in determining the performance of aluminum wire. Furthermore, this

approach depends on the resident to know what type of wire he has, and

therefore will result in a substantial proportion of nonresponses and incorrect responses.

The second approach would select communities known (primarily from

builders and contractors) to have the types of wire and devices of interest

(along with the other sample design characteristics such as climate) . This

san^ling design does not depend on the resident's knowing whether he has

aluminum or copper wiring. Because the performance data would be obtained

by asking residents about symptoms, and this in itself tends to bias the

respondent, it is essential that this survey design include a control groLqD,

i.e., a group of dwellings wired with copper, to allow valid conparisons

to be made. This approach would require careful consideration of the tradeoff between cost and statistical quality. Cost constraints might so limit

the sample size that the results could only be regarded as "typical" but not

nationally representative, with a consequent danger of being misleading

in the same way that some existing data are.

The third approach would concentrate on fires, and would obtain fire

data of the requisite detail and quality by investigating fires specifically

for the purposes of this study. For a few months, all fires occurring in

certain jurisdictions would be screened by local fire officials to identify

those of potential interest to this study. Participating fire officials

would be trained as necessary, and their departments probably would have

to be paid for the burden that the study would place on them. It is

anticipated that about ten fire departments covering appropriate geographic

areas would have the technical conpetence and willingness to participate.

Fires of potential interest would be reported by telephone to the study

staff, and in many cases a staff member would go immediately to the fire

site to investigate further. Measurements would also be made at matched

buildings where no fire occurred. When possible, residents where the fires

occurred would be interviewed. The chief drawback of this approach, aside

from the usual problems of cost and sample size, would be a sample bias

toward installations that had fires, with a less than proportionate sanpling

of non-fire performance. Further, residents where the fires occurred may

be unavailable and undoubtedly would be biased by recent experiences.

Of these three approaches to the performance survey, the first is

least likely to be feasible, due to the high expense combined with the

little likelihood of useful results. The second approach would seem

to be most promising, since its sanple design does not have the bias of

-47-
the third approach. However, the choice would eventually depend on the

joint evaluation of cost and statistical quality, which in turn would

depend on detailed sajrple design and procedure development work.

5 . 3 Summary

To develop a measure of the national hazard potential associated with

the use of aluminum wiring and a corresponding measure for copper wiring

as a baseline for comparison, two types of data not now available would

have to be collected. The first would be data on the extent of use of

aluminum wiring, obtained from an extensive, nationwide "macro" survey

of electrical inspectors. The second type of data would be risk data

obtained from an intensive, localized "micro" survey of dwellings. These

two surveys would mostly address the issue of hazard, but would also develop

some data to solve whatever problems may be identified.

The CPSC is not required to base its rulings on hazard data of the

statistical quality contenplated here, and thus would not need to undertake the surveys described here, if in its judgment an adequate alternative basis for a ruling exists. However, inplementation of regulatory

measures may require some of the data that would be developed by the

macro survey, and laboratory experiments require field data of the type

that the micro survey would develop if the experiments are to be related

to performance of aluminum wire in residential use.

The data collection plan discussed in Section 5 is necessarily

very general. Although a significant amount of development work has been

done, a significant amount still remains to be done before exact procedures

can be stated. Included in the required developmental work are two

inportant conceptual activities -- operational definition of variables

and the mathematical formulation of the analytical tasks in terms of

these variables. (It should be noted that these two processes are highly interrelated and iterative.) The design of samples and specification of exact procedures will in large measure depend on this conceptual

work. Cost estimation would depend on the sampling design and data

collection procedures.

Procedures for the macro study are more straightforward than those

for the micro study. Therefore, although these activities would be

initiated concurrently, it is assumed that the macro data collection

could be initiated more quickly than the micro activity.

-48-
REFERENCES

1. Mutual Substitutability of Aluminum and Copper , A Report of the

National Materials Advisory Board, NM/VB 286, April 1972, p. 36.

2. Ltr. from Baron Whitaker, President of Underwriters' Laboratories, Inc.

to the Honorable John E. Moss, Congressman from California.

April 7, 1972.

3. IMderwriters ' Laboratories, Inc. Bulletin of Research Number 48,

"Aluminum Building Wires and Connectors," September 1954, p. 5.

4. Inter-Office Memorandum from T. Gregory to P. Mara of The Aluminum

Association, "Estimated Shipments of Aluminum Electrical Building

Wire, 1960-1971". April 28, 1972.

5. Op. Cit., Mutual Substitutability of Aluminum and Copper , pp. 9 and 36.

6. F. Hehre and G. Harness, Electrical Circuits and Machinery . Volume I,

Direct Currents, John Wiley ^ Sons, Inc., New York, 1940, p. 96.

7. Op. Cit. , ]^4itual Substitutability of Aluminum and Copper , p. 36

8. Ibid, pp. 12-14.

9. Ltr. from Underwriters' Laboratories, Inc. to the Electrical Council

of Underwriters' Laboratories, Inc. and Manufacturers of General

Use Snap Switches and Attachment Plug Receptacles. August 18, 1966.

10. Op. Cit., UL Bulletin of Research Number 48.

11. Battelle Proposal and Past Research on Aluminum Wiring, c. 1973.

12. Op. Cit., Ltr. from Whitaker to Moss, April 7, 1972.

13. Tape transcription of presentation on aluminum wiring by Capt. Carl L. Duncan, Huntington Beach Fire Department, Huntington Beach, California,

January 20, 1971.

14. Op. cit., Ltr. from Whitaker to Moss. April 7, 1972.

15. Ltr. to Leviton Distributors. March 10, 1972.

16. Ltr. from Circle F Manufacturers to all Circle F Customers. April 6, 1972.

17. Conversations with Thomas D'Agostino of Underwriters' Laboratories, Inc.

February and March 1974.

-49-
References ^continued)

18. National Fire Codes, 1972-73 ed. , Volume 5.

19. This information was provided by Inspector Robert J. Kelly of the

Washington, D. C. Fire Department, during a seminar at MBS on January 21, 1974. The two investigators referred to are himself

and Capt. Carl L. Duncan of the Huntington Beach (California)

Fire Department.

20. Conversation with Mr. Melvin Young, Chief Electrical Inspector

of Fairfax County, Virginia, January 9, 1974.

21. Ltr. from G. E. Schall, Jr. of Underwriters' Laboratories, Inc.

to J. J. Kirk of the National Electrical Manufacturers Association.

March 31, 1970. p. 2

22. Speech by the Honorable John E. Moss, Congressman from California,

to the National Association of Homebuilders . Houston, Texas.

January 8, 1973.

23. Battelle Proposal and Past Research on Aluminum Wiring, c. 1973.

24. Op. Cit., Ltr. from Schall to Kirk. March 31, 1970. p. 7.

25. Ibid.

26. Memo from Baron Whitaker of Underwriters' Laboratories, Inc. to

Members of the Ad Hoc Committee on the Use of Aluminum Conductors

with Wiring Devices in Electrical Wiring Systmes. May 21, 1973.

27. Underwriters' Laboratories, Inc. Tabular Report, "Underwriters'

Laboratories Survey: Aluminum Wire Terminations". February, 1973.

28. Conversation with Mr. L. E. LaFehr, Executive Vice President of the

International Association of Electrical Inspectors. January 23, 1974.

29. Op. Cit., Memo from Whitaker to Ad Hoc Committee. May 21, 1973.

30. Ibid.

31. Attachment "About the Questionnaire" to letter of March 25, 1974,

from UL President Baron Whitaker to Jacob Rabinow, NBS.

32. Ibid.

33. Wall Street Journal, September 22, 1972.

34. Conversation with Richard Sumner, Assistant Vice President and

General Manager of the Underwriting Department of American Plan

Corporation, March 11, 1974.

-50-
References (continued)

35. lAEI News, September -October 1974, pp. 30-31, International Association

of Electrical Inspectors, Park Ridge, Illinois.

36. Conversations with Joseph Kuntz, Chief Electrical Inspector of

Prince George's County, Maryland, on February 25 and 28, 1974.

37. Conversation with Mr. William Meyer, Chief Electrical Inspector of

Washington, D. C. , March 13, 1974.

38. Letter from Carl L. Duncan, Deputy Fire Marshal of Huntington Beach,

California to Ollin C. Cleveland, Building Director of Huntington

Beach, June 1, 1971.

39. Conversation with Joseph Kuntz, Chief Electrical Inspector of

Prince George's County, Maryland, February 28, 1974.

40. Op. Cit. , Inter-Office Memorandum from Gregory to Mara, April 28, 1972.

41. Ltr. from Lawrence M. Kushner, Acting Director of NBS to the

Honorable John E. Moss, Congressman from California, October 20, 1972.

42. Conversation with Mr. Skinkle of the NAHB Research Foundation,

February 5, 1974.

USCOMM-NBS-DC -51-
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PURLICATION OR REPORT NO.

NBSIR 75-677

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

nAzLAKJJ Aooboof4EiN 1 Ut ALUMINUM bLcLlKiCAL WIRING IN

RESIDENTIAL USE

5. Publication Date December 1974

6. Performing Organization Code

7. AUTHOR(S)

Elaine D. Bunten, John L. Donaldson, Eugene C. McDowell

8. Performing Organ. Report No.

9. PERFOR.MING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDaI?DS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4410104

IT. Contract /Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

U. S. Consumer Product Safety Commission,

Washington, D. C. 20207

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.)

In the mid-1960s, aluminum wire began to be used in significant quantities for

residential branch- circuit wiring. Reports of problems from various localities

in the U.S. raised serious concern and controversy as to the safety of this

application. An official determination on this matter is within the

jurisdiction of the Consumer Product Safety Commission. This report reviews

the history of the use of aluminum in residential wiring and describes the

characteristics essential to data to be used to evaluate the performance of

aluminum wiring in the field. The examination of existing field data shows

that no available data have the characteristics necessary to develop a reliable estimate of the level of risk to consumers associated with

aluminum wiring. Neither can the available data be used to establish the

relative risk of aluminum compared to copper wiring. There is only a gross estimate of the extent to which aluminum wiring is now in use in

U.S. residences. Statistically sound estimates of risk would be

possible only after data collection on a large scale.

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)

Aluminum wire; consumer product safety; electrical failures; electrical fires;

electrical wiring; fire hazards

18. AVAILABILITY

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Washington. D.C. 20402. SD Cat. No. C13

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22. Price

1 ! Order From National Technical Information Service

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USCOMM-DC 29042-P74