NBSIR 77-1380

NIST

PUBUCATIONS

at

Experimental Determinations

of Temperatures and Power

Losses at the Electrical

Connections of Some Duplex

Receptacles

G. W. Burns

M. G. Scroger

G. A. Evans

Temperature Measurement and Standards Division

National Measurement Laboratory

National Bureau of Standards

Washington, D C. 20234

and

R. W. Beausoliel

W. J. Meese

Building Thermal and Service Systems Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

April 1978

Final Report

Prepared for Office of Policy Development and Research

[00 Department of Housing and Urban Development

Washington, D.C. 20410
I
NBSIR 77-1380

EXPERIMENTAL DETERMINATIONS

OF TEMPERATURES AND POWER

LOSSES AT THE ELECTRICAL

CONNECTIONS OF SOME DUPLEX

RECEPTACLES

G. W. Burns

M. G. Scroger

G. A. Evans

Temperature Measurement and Standards Division

National Measurement Laboratory

National Bureau of Standards

Washington, D.C. 20234

and

R. W. Beausoliel

W. J. Meese

Building Thermal and Service Systems Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

April 1978

Final Report

Prepared for Office of Policy Development and Research

Department of Housing and Urban Development

Washington, D.C. 20410

/ y \

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secratary

Jordan J. Baruch. Assistant Sacretary for Scianca and Tachnology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Diractor

SI CONVERSION UNITS

In view of the present accepted practice in this country for building

technology, common U.S. units of measurement have been used throughout

this document. In recognition of the position of the United States

as a signatory to the General Conference on Weights and Measures, which

gave official status to the metric SI system of units in 1960, assistance

is given to the reader interested in making use of the coherent system of

SI units by giving conversion factors applicable to U.S. units used in

this document.

Length

1 in 0.0254* meter (m)

Temperature

tog 5/9 (top - 32)*

Torque

1 Ibf in = 0.113 newton meter (N m)

*Exactly

iii
EXPERIMENTAL DETERMINATIONS OF THE TEMPERATURES AND POWER LOSSES

AT THE ELECTRICAL CONNECTIONS OF SOME DUPLEX RECEPTACLES

G.W. Burns, M.G. Scroger, G.A. Evans,

R.W. Beausoliel and W.J. Meese

ABSTRACT

The data presented in this report compare the reliability of power loss

determinations with the reliability of temperature measurements as a means

for determining the quality and adequacy of electrical connections on

wiring devices used in branch circuit wiring. The basic premise for

the tests presented here is that in the laboratory the determination

of power loss is easier, quicker and not nearly as dependent on environmental factors as temperature. This research indicates that, if power

loss at a specific current level does not exceed some set value(s),

temperatures will not be excessive.

This investigation also illustrates the overheating problems associated

with copper-wire electrical connections. No. 14 copper wire connections

frequently showed significant rises in temperatures and significantly

increased power losses when tightened to a torque of only 2 Ibf'in, as compared to nominally tight connections (6 Ibf-in or more).

Key words: Branch circuits; duplex receptacles; electrical connections;

power loss; temperatures; thermocouples; wire.
TABLE OF CONTENTS

PAGE

ABSTRACT iv

1. INTRODUCTION 1

1 .1 Background 1 1.2 Objective 1

1 . 3 Scope 1

2. ELECTRICAL RECEPTACLES USED IN TESTS 2

3. TEST PROCEDURES 4

3.1 Mounting of Receptacles 4

3.2 Electrical Connections to Receptacles 4

3.3 Measurement of Connection Power Losses 6

3.4 Measurement of Connection Temperatures 8

3.5 Tests Performed 10

3.6 Acquisition of Test Data 13

3.7 Reduction of Test Data 13

4. RESULTS OF TESTS WITH CONVENTIONAL RECEPTACLES 15

4.1 Group Receptacle Tests 15

4.2 Individual Receptacle Tests 17

5. RESULTS OF TESTS WITH SPLIT-BEAM RECEPTACLES 18

6. SOME HIGHLIGHTS OF RESULTS 19

7. CONCLUSIONS 20

8. RECOMMENDATIONS 21

9. REFERENCES 21

1 . INTRODUCTION

Considerable difficulty was experienced in the evaluation of innovative

electrical connections submitted as a part of the housing service systems

in Operation BREAKTHROUGH. This was due to a lack of performance criteria

for their acceptance. Subsequently, the U.S. Department of Housing and

Urban Development sponsored a long-term research project on the evaluation

of innovative electrical connections proposed for use in residential branch

circuit wiring at the National Bureau of Standards (NBS). The first three

publications of this project were reports on "Analysis of Current Technology

on Electrical Connections in Residential Branch Circuit Wiring" [1], "A

Preliminary Approach to Performance Criteria for Electrical Connections

in Residential Branch Circuit Wiring" [2], and "Explanatory Study of Glowing

Electrical Connections" [3] . This report involving temperature measurements

and power loss determinations at the electrical connections of some duplex

receptacles is the fourth in this project.

The investigation presented in this report was carried out by the Temperature

Section, Heat Division, NBS, for the Building Services Section, Center for

Building Technology, NBS.

1.1 BACKGROUND

A safety requirement for residential branch circuit electrical connections

and wiring devices is that temperatures measured near connections must not

be excessive. These measured temperatures, however, are only an indirect

measure of the quality of the connection. Temperatures near connections

also involve other factors such as ambient conditions, heat generated

by the wire and other conducting components, heat transfer parameters,

air movement in the vicinity of the device or connection, geometry of

the device and connections, materials, and locations where temperatures

are measured. Determination of the power loss in connections or devices

appeared to be a more basic and direct means of detecting the potential

for obtaining excessive temperatures.

1.2 OBJECTIVE

The primary objective of the work presented in this report was to assess

the reliability of power loss data as a means for determining the quality

and adequacy of electrical connections used in residential branch circuit

wiring.

1.3 SCOPE

Power loss and temperature data were obtained for the wire terminations

of a number of wire binding screw duplex receptacle terminations; the screws were tightened to various torques ranging from 2 to 16 Ibf-in.*

*lbf-in = 0.1129848 N«m.

1
Power loss and temperature data were also obtained on an innovative type

of electrical receptacle, referred to subsequently as a "split-beam"

receptacle.

The influence of environmental factors on the data, such as the spacing

between the test receptacles (representing different conditions of heat

dissipation) was determined. A current of nominally 15 amperes was passed

through the terminal connections of the devices during the tests. In order

to determine any effects of supply voltage on the data, tests were performed

using nominal 115 volt and 10 volt, 60 Hertz alternating current and

using nominal 10 volt direct current. Nonmetal lic-sheathed cable with

#14 AWG copper conductors was used in all tests.

2. ELECTRICAL RECEPTACLES USED IN TESTS

Eighteen electrical receptacles were used in the tests. All the receptacles were duplex, two-pole, three-wire grounding-type devices rated at either

15 A, 125 V or 20 A, 125 V. The receptacles were of two general types:

(1) conventional receptacles having wire-bindingscrew-terminal connections

and (2) split-beam (see reference #1) receptacles having innovative electrical connections. There were five types of conventional receptacles and one type of split-beam receptacle. Three identical devices of each type were

used. Table 1 gives some descriptive information about the receptacles

used in the tests. Table 1 also shows the laboratory identification numbers

assigned to the receptacles.

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3. TEST PROCEDURES

3.1 MOUNTING OF RECEPTACLES

The test setup is illustrated schematically in Figure 1. The receptacles

were mounted on a test stand that was clamped to the top of a laboratory

work bench. The test stand consisted of forty-five pressed-steel outlet

boxes (2x2x3 in) ganged and fastened to a 1 x 6-in pine board that was supported with wooden braces. The backs of the boxes were flush

against the 1 x 6 in board and were perpendicular to the plane of the

bench top. The mid-poiots of the boxes were located about 58 inches

above the floor.

The conventional receptacles were installed in the outlet boxes by their

mounting yokes and were oriented with their ground-pin slots positioned

at the bottom. Since the split-beam receptacles do not require a separate

box, they were fastened with wood screws along the top edge of the 1 x 6-in

pine board so that all sides of the devices were completely exposed. They were oriented with their backs perpendicular to the plane of the bench

top and with their ground-pin slots positioned at the bottom.

The 18 receptacles listed in Table 1 were divided into two groups for

the tests. The two groups of receptacles, identified as groups 1 and

2 in this report, were mounted at the same time on the test stand, but

they were tested separately. Tests with the group 1 receptacles were completed before undertaking tests with the group 2 receptacles. Group

1 consisted of receptacles No. 10, 11, 13, 14, 16, 17, 19, 20, 22, and 23;

group 2 consisted of receptacles No. 7, 8, 9, 12, 15, 18, 21, and 24.

3.2 ELECTRICAL CONNECTIONS TO RECEPTACLES

For both groups the receptacle terminals were connected in a circuit, as shown schematically in Figure 1. The connections between the terminals of

adjacent conventional receptacles were made with copper conductors. No. 14

AWG, that were taken from type NM (see Reference 4) cable. The interconnecting conductors were 9.75 +_ 0.05 in long. The ends of conductors to

be connected to wire-binding-screw terminal were carefully prepared. About

7/8 in of the insulation was stripped away, and the conductor end was formed in a plane to have a 180-degree bend with an inside diameter

of 0.21 in. The loops at the conductor ends were formed in a reproducible

fashion by bending them on a special wire- forming jig.

The electrical connections to the conventional receptacles were made at the wire-binding-screw terminals, except for receptacles No. 22, 23, and

24. These receptacles had only one screw terminal; the connections were made (both black-wire and white-wire) by using one of the push-in pressure

terminals (which were secured by a screw) and the wire-binding-screw

terminal. The looped ends of the conductors were fastened to the wirebinding-screw terminals of the devices with the direction of the wire "wrap"

4
5
corresponding to the direction of terminal-screw tightening, as illustrated

in Figure 2. The terminal screws of all receptacles were tightened initially

with a torque of 16 lbf«in to seat the looped conductors.

Electrical connections to the three split-beam receptacles (No. 7, 8, and 9) were made with No. 14 AWG, two-conductor, type NM cable. The cable was prepared with the special tool, provided by the manufacturer, that cut

the outer sheath and positioned the copper conductors for proper insertion

into the innovative terminal connectors of the receptacle assembly. After

carefully positioning the prepared cable in the receptacle assembly, the

receptacle cover was clamped into place with the special tool, thus making

the electrical connections within the device. The end of the nonmetallicsheathed cable extending from the bottom of the receptacle was cut off,

and the exposed conductors were insulated with wing-nut wire connectors,

as indicated in Figure 1. In making connections to split-beam type

receptacles, the wire is not broken and, therefore, current does not

flow through connections except when current flows through the receptacle

from an attachment plug. To test this type of receptacle, a grounding

type plug rated at 15 A, 125 V was inserted into the bottom outlet of

each of the split-beam receptacles, and type NM cable was connected to

the plugs to complete the interconnections between the receptacles, and

between the last receptacle in the test circuit and the adjustable load,

as shown in Figure 1.

3.3 MEASUREMENT OF CONNECTION POWER LOSSES

The power loss across the black-wire (ungrounded) side and across the

white-wire (grounded) side of each receptacle was obtained by determining

the voltage across input and output wiring near the connections and the

current through the connection, and by taking the product of the two

determinations. The conventional receptacles have two conductors secured

by separate terminal screws, as illustrated in Figure 2. Measurements

were of current-carrying paths which consisted of a complex combination

of components that included the looped conductor ends, the two terminal

screws, the terminal plate, the break-off tab, plus any other electrically

conductive receptacle parts between the two terminal screws. In these

experiments, the electrical connections of the conventional and split-beam

receptacles are defined in terms of the measured electrical parameters,

as discussed later in this section.

A calibrated* 0.01 ohm, ac-dc, current shunt was connected in series

with the terminal connections of the receptacles, as shown in Figure 1.

The current was determined during the tests from measurements of the

voltage across the shunt. A high-precision electrodynamometer ammeter

was also included in the test circuit, but it was used only for rough

monitoring of the current.

•^Calibration performed by the NBS Electricity Division; uncertainty in the

value of the resistance of the shunt estimated not to exceed + 2 microhms.

6
STEEL MOUNTING YOKE

BREAK-OFF TAB

FRONT

•(B)

COPPER WIRE,

NO. 14 AWG

BINDING-HEAD_

TERMINAL SCREW

~5mm

1

1

PLASTIC BODY

Figure 2. Side view of a conventional receptacle showing electrical

connections to black-wire terminal and showing locations where

thermocouple measuring junctions were attached for measuring (A)

the tab temperature and (B) the wire temperature.

7
vinyl insulated copper leads, No. 26 AWG, were attached at various points

in the test circuit to obtain the voltages across the connections of the

receptacles. The leads were attached in the same manner on both sides

(black-wire and white-wire) of the test circuit. For the conventional

receptacles, a No. 26 AWG wire was connected at the midpoint of each of

the 9.75-in-long copper conductors that were used to make the interconnections between the receptacle terminals. About 1/8 in of the insulation

was removed at the midpoints of the conductors, and the No. 26 AWG copper

leads were wrapped around the conductors for several turns and were soldered

in place with Sn-Pb solder. The solder joints were wrapped with several

layers of vinyl plastic electrical tape.

In the case of the split-beam receptacles, the copper leads were attached

in the following manner: one wire was soldered to the No. 14 AWG conductor

of the type NM cable at a distance of 4 in above the terminal contact, a second wire was attached to the metal terminal parts within the receptacle

assembly by soldering with Sn-Pb solder. The attachment was made at a point directly below the bottom outlet, on the metal part that makes

contact with the blade of the plug.

Due to the manner in which the voltage leads were located in the test

circuit, the measured voltage includes the voltage across the connection

plus the voltage across a length of the No. 14 AWG conductor. Therefore,

to obtain the voltage across the connection, a correction was applied to

the measured voltage. The correction was determined experimentally during

each test from measurements of the voltage across several 8-in-long specimens

of the No. 14 AWG conductor that were connected in series with the terminal

connections. For the conventional receptacles, a correction corresponding

to the voltage across an 8-in length of the conductor was subtracted

from the measured voltages, and for the split-beam receptacles a correction

corresponding to the voltage across a 4-in length of the conductor was subtracted from the measured voltages.

3.4 MEASUREMENT OF CONNECTION TEMPERATURES

The temperatures of the connections were determined with Type K [Ni-10% Cr versus Ni-5% (Al, Si, Mn) ] thermocouples fabricated from 0 . 01 2-in-diameter

nylon and enamel insulated wire. All thermocouples were taken from the same spool (lot) of wire. Representative thermocouples from this spool were calibrated by comparison with a platinum resistance thermometer in

the range 70 to 210 °F* and by comparison with a standard Type S thermocouple

at temperatures to 300 °F. The uncertainty in the calibration was + 0.2 °F

below 210 °F and it increased to 0.6 °F at 300 °F. The calibration data were fitted with a polynomial equation that was employed for computer

calculation of values of temperature from the measured thermocouple voltages.

The standard deviation of the fit of a three-terra function to 19 data points

was 0.11 °F.

*In this report degrees F is defined as 9/5 x °C (lPTS-68) + 32.

8
For each of the conventional receptacles, two thermocouples were installed

on the black-wire connection, and two themocouples were installed on the

white-wire connection. For a given connection, one thermocouple was located on the break-off tab and the other thermocouple was located on the No. 14 AWG copper conductor. The locations where the thermocouple

measuring junctions were attached for measuring the tab and wire temperatures are shown in Figure 2. For all connections, the thermocouple used for

measuring the wire temperature was located on the top conductor, as shown

in Figure 2. In the case of conventional receptacles No. 22, 23, and 24, the

thermocouple was located on the conductor connected to the wire-binding-screw

terminal for the black-wire connection, but for the white-wire connection

the thermocouple was located on the conductor connected to the push-in

pressure terminal.

For each of the split-beam receptacles, one thermocouple was installed

on the black-wire connection, and one thermocouple was installed on the

white-wire connection. On both connections the thermocouple measuring

junction was located on the inner terminal contact.

The procedures for fabricating and installing the thermocouples follow.

Eight -inch-long thermocouples were cut from the spool of calibrated Type K

thermocouple wire, and the measuring junctions of the thermocouples were formed by welding with a tungsten inert gas welder. The thermocouple

measuring junctions were then heli-arc welded to the breakoff tabs of

the conventional receptacles and to the contacts of the split-beam receptacles (by the NBS Instrument Shops Division.) The break-off tabs of

several devices were damaged during the process of installing the thermocouples, thus increasing the electrical resistance of the connection.

The tabs were damaged on the white-wire connection of receptacles No. 10,

11, and 16 and on the black-wire connection of receptacles No. 10 and

12. For attachment of the thermocouple measuring junctions on the No.

14 AWG copper conductors, the junctions were first flattened by squeezing

with pliers, and then they were affixed to the copper conductor with a drop of Sn-Pb solder.

Cables, made up from No. 30 AWG glass-braid-insulated Type K thermocouple

wire, were joined to the 8-inch-long thermocouples by twisting the cable

wires and the thermocouple wires together. Vinyl insulated copper leads,

No. 26 AWG, were connected to the other end of the cable wires by soldering.

The latter connections were maintained at 32 °F (0 °C) in ice baths during

the tests. The difference between the emf -temperature relationship of the

Type K thermocouple wire used in the cables and that of the calibrated

thermocouples was determined experimentally, and a small correction (equivalent to about 0.5 °F) was applied to the measured thermocouple voltages

to account for the difference.

The room temperature was also measured during each test with a thermocouple that was taken from the spool of calibrated Type K thermocouple

wire. The measuring junction of this thermocouple was positioned directly

underneath and near the middle of the test stand. The junction was about 10 in below the center line of the outlet boxes.

9
3.5 TESTS PERFORMED

Tests were conducted with the group 1 and group 2 receptacles with the

devices spaced in the outlet boxes as illustrated in the three setups in

Figure 3. In this report the experimental setups 1, 2, and 3 are denoted

as receptacle spacings 0, 1, and 2, for purposes of clarity. The spacing

numbers correspond to the number of empty outlet boxes between the

receptacles

.

For each of the receptacle spacings, tests were run with the terminal screws of the conventional receptacles tightened by application of torques

of 2, 6, 12, and 16 Ibf in. All terminal screw tightening was performed

with a variable-torque type screwdriver.

Applied test voltages of nominally 10 V(dc), 10 V(ac), and 115 V(ac) were

employed. A schematic of the test voltage circuit is given in Figure 4.

A current of nominally 15 A was used in the tests. With a few exceptions,

the current was stable during each test to within 0.01 A and was adjusted

to be within + 0.1 Aof 15 A. Since the measured values of temperature and

power loss were found, during preliminary tests, to be virtually independent

of the magnitude of the supply voltage, the applied test voltage was not

precisely determined or adjusted during the tests. It was measured with

a multi-range voltmeter having an estimated uncertainty of about 3 percent

of the voltage measured.

The tests were performed in two groups. Data for each test included the

receptacle spacing, the screw torque, and the test voltage used, as well

as the test current and the room temperature during the test. Unless

otherwise noted, the terminal screws of the receptacles were not retightened

between subsequent tests. For each combination of receptacle spacing, screw

torque, and test voltage, at least two independent tests were performed.

After completing the tests with the first group of receptacles, each of the

conventional receptacles in that group was tested separately.

There were a number of tests conducted without energizing the test circuit.

These tests were performed primarily to check for loose connections in

the thermocouple circuits. However, they also provided useful information

about the temperature gradients along the group of receptacles. Such tests were usually performed after changing the receptacle spacing and after

changing the terminal screw torque.

The polarity of the applied 10 V(dc) test voltage was reversed for some tests. Tests with both polarities were essential in order to eliminate

unwanted voltage components included in the measured voltages; namely,

the IR drops across the thermocouple measuring junctions and the thermal

emf ' s in the test circuit. The measured voltages determined during a test with forward polarity were combined (by averaging) with those determined during a test with reversed polarity. It should be pointed out

that for tests in which alternating current was used, these unwanted voltage

components were also present, but they were not read by the measuring

instrument

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3.6 ACQUISITION OF TEST DATA

An automatic digital data acquisition system was used for collecting the

test data. It included a 72-channel scanner (rotary selector switch), a precision digital voltmeter (PDVM), a minicomputer, and a printer. The PDVM

was of commercial design, with 5 full digits plus 60% overranging, and it had

0.1 yV resolution for dc voltage measurements and 10 \xV resolution for ac voltage measurements. Its common-mode noise rejection was listed as greater than

160 dB for dc and greater than 140 dB for ac (60 Hz), and its normal-mode

noise rejection at 60 Hz was listed as 80 dB, based on maximum filtering.

The ac voltage calibration of the PDVM was checked by the Electrical Instruments

Section of the NBS Electricity Division. The dc voltage calibration of the

PDVM was checked in our laboratory by comparing the PDVM with a precision six-dial

potentiometer. The PDVM was operated with a floating input to reduce errors

due to common-mode currents. Nevertheless, some noise pickup was evident during

the tests, particularly in the case of the ac voltage measurements. Under the

conditions of test, the uncertainties in the values of voltage determined with

the PDVM are estimated to be not more than + (0.003% of the voltage measured

+ 1 uV) for dc voltages of less than 10 mV; + (0.003% of the voltage measured

+ 10 yV) for dc voltages of greater than 10 mV; and + (0.03% of the voltage

measured + 150 yV) for ac voltages of less than 1 V. The thermal emf's in the scanner and in the No. 26 AWG copper leads connected to the scanner were less

than 1 yV.

The test data were collected by the acquisition system at a rather slow rate

to allow sufficient time for the thermal emf's generated at the switch

contacts of the scanner to decay. Typically, it took about 6 to 7 minutes

to record the voltages on all 72 channels. The system computed the

connection temperatures and power losses from the measured voltages and

printed a hard copy of the test data after each test. The test data were also recorded on magnetic tape and were eventually transferred into

the Univac 1108 computer for reduction and analysis.

3.7 REDUCTION OF TEST DATA

Final data reduction was performed on the Univac 1108 computer. A preliminary examination of the test data sorted out those tests where obvious

problems occurred, and excluded the zero power test runs. Then, for each

of the remaining tests, the power loss values were normalized for a current

of exactly 15 A. This normalization, which requires a small correction,

15 2 was done by multiplying the power loss by where 1^^^

, the measured test m

current, was within a few hundredths of an ampere of 15 A for the majority

of the tests. The temperature rise of the tab (and of the wire) was calculated

by taking the difference between the measured tab (wire) temperature and the

measured room temperature. The ratio of the temperature rise to the power

loss was then calculated for all the tests.

13
The data were then grouped for analyses in the following manner. For

consecutive tests (with the same test parameters of screw torque, receptacle

spacing, and test voltage) where the power was on continuously, the

values of the power loss, the temperature rise, and the ratio obtained

in those tests were treated as a data set, and the average of the

values and the standard deviation were computed.

For each of the three test voltages, if there was more than one data

set having identical test parameters of screw torque and receptacle

spacing, then the average of the average values of those data sets

was obtained, the pooled standard deviation of a single measurement

was computed, and the maximum and minimum values in the sets were retained. Lastly, for each of the twelve combinations of screw

torque and receptacle spacing, a grand average of the data sets was obtained, again retaining the maximvnn and minimum values.

14
4. RESULTS OF TESTS WITH CONVENTIONAL RECEPTACLES

4.1 GROUP RECEPTACLE TESTS

The experimental imprecision in determining the values of connection power

loss and temperature rise was calculated for each of the test parameter

combinations employed in the group 1 and group 2 receptacle tests. When

the terminal screws of the receptacles were tightened with a torque of

6 Ibf'in or more, the experimental imprecision (one standard deviation)

in measured values of the power loss and temperature rise typically ranged

from 0.2 to 1 mW and from 0.2 to 0.5 °F, respectively, regardless of

the test parameter combination. Comparable imprecision was also obtained

in measured values for the split-beam receptacles. However, when the

terminal screws of conventional receptacles were tightened at 2 lbf«in,

greater variability in measured values occurred for some connections,

particularly those of receptacles 10, 11, and 22, as shown later in

this section.

The principal results obtained with the conventional receptacles during

the group receptacle tests are presented in Figures 5 through 37. Figures 5 through 16 show the average power loss, temperature rise, and ratio for all

possible combinations of screw torque and receptacle spacing. For zero receptacle spacing, each data point represents an average result containing

data obtained with all three test voltages. Within the precision of these

plots (about ^-5 *F for the temperature rise and +7.5 mW for the power

loss), there was no observable difference in the power loss, the temperature

rise, or the ratio with test voltage for terminal screw torques greater

than 2 lbf«in (see Figs. 5, 8, and 11). At 2 Ibf.in (Fig. 14), the large

variation shown in some data points reflects the variability in the contact

resistance of the connection observed at this torque, as will be discussed

later. At the receptacle spacings of 1 and 2, tests were not performed

using a test voltage of 10 V(dc), but both 10 V(ac) and 115 V(ac) were

used at those spacings.

For terminal screw torques of 6, 12, and 16 lbf»in, the connections of the

receptacles that had the damaged break-off tabs clearly exhibited power

losses higher than those of the same type receptacles having undamaged

tabs (see Figures 5 through 13). The tab temperature rises were not greatly

different for the damaged connections, however. The black-wire and whitewire connections of receptacle No. 22 exhibited power losses higher than

those observed for the connections of the other two receptacles of the same type, as shown in Figures 5 through 16. The connections for this

receptacle were made using one of the push-in pressure terminals, but there

is no certain explanation for its behavior. The other two receptacles of

the same type showed no such variability. With these exceptions. Figures

5 through 16 show that there is no appreciable difference in the power

loss, the temperature rise, or the ratio between the black-wire connections

and the white-wire connections for a given type of receptacle. In addition,

at high terminal screw torques, there is surprisingly little difference

between the measured parameters for the various receptacle types, considering

the differences in their design and in the materials used for their terminals.

15
All the data for zero receptacle spacing (given in Figures 5, 8, 11, and

14) are displayed in Figures 17 through 26 as a function of the terminal screw torque. Each figure displays the power loss, the temperature rise,

and the ratio for the three receptacles of the same type, and the black-wire

and white-wire connections are given separately. With the exception of

the black-wire connection of receptacle No. 22, it can be seen that there

is little difference between the values of power loss, temperature rise,

and ratio for torques of 6, 12, and 16 lbf»in. At 2 lbf»in nearly all

connections show an increase in the power loss and the temperature rise.

The increase was especially large for the white-wire connections of receptacles No. 10, 11, and 22 and for the black-wire connection of receptacle

No. 22 (see Figs. 18, 25 and 26). Values as large as 3400 mW and 110 °F were observed for the power loss and the tab temperature rise, respectively

(see Figure 18).

The power loss, the tab temperature rise, and the ratio are plotted as a function of receptacle spacing in Figures 27 through 31. The data are

for one terminal screw torque, 12 lbf»in, and only data obtained in tests

using 10 V(ac) are used, in order to have the same bias at each spacing.

The receptacles of the same type are grouped together, with data for

the black-wire and white-wire connections exhibited. As expected, there

is very little change in the power loss with different spacing. However,

changes of 10 to 15 °F in the tab temperature rise were observed, with

most of the change occurring between the spacings of 0 and 1.

Up to Figure 31, only the tab temperature rise has been displayed. When

the terminal screws were tightened with a torque of 6 Ibf • in or more,

very little difference was observed between values of temperature determined by the tab thermocouple and by the wire thermocouple. Differences

between the tab temperature and the wire temperature for the black-wire

and white-wire connections of each of the conventional receptacles are shown in Figure 32. The results are for a terminal screw torque of 12

Ibfoin and a receptacle spacing of 1, and are from tests that employed

a test voltage of 10 V(ac). As can be seen, the tab temperature is about

8 °F higher than the wire temperature for the white-wire connection of

receptacle No. 16. This difference most likely occurred because of the

damaged break-off tab that existed for that connection. The tab temperature

was also slightly higher than the wire temperature for each of the other

connections that had damaged tabs; namely, the white-wire connections

of receptacles No. 10 and 11, and the black-wire connections of receptacles

No. 10 and 12. When the terminal screws of the receptacles were tightened

with a torque of 2 Ibf 'in, larger differences between the tab temperature

and the wire temperature were observed, as shown in Figure 33.

The effect of loosening the terminal screws and tightening them again with

a torque of 2 Ibf 'in can be seen in Figures 34 and 35. These figures show

the change in the power loss, the tab temperature rise, and the ratio after

the second torque. Figure 34 gives the results of loosening the screws,

then tightening them again without changing the receptacle spacing. Also,

after performing many tests at higher torques, the terminal screws of

the receptacles were loosened and again tightened with a torque of 2 lbf»in,

16
and the receptacles were then moved from a spacing of 2 to a spacing

of 0. Figure 35 gives the difference between the data obtained in the

subsequent tests and those obtained in earlier tests at the same spacing.

As can be seen, some rather large differences in the power loss, the

temperature rise, and the ratio occurred for the connections of receptacles

No. 10, 11, and 22.

The connections of receptacles No. 10, 11, and 22 exhibited considerable

variability in results, when their terminal screws were tightened with

a torque of 2 Ibf'in (see Figures 14 through 16). Merely cycling the

electrical power on and off to these receptacles produced changes in the

values of power loss and temperature rise, as shown in Figure 36. This

figure gives data obtained in tests using a test voltage of 115 V(ac )

.

The receptacles were mounted in adjacent outlet boxes and were not moved

or disturbed in any way between the on-off cycles of the test current.

As can be seen, substantial changes are apparent in the power loss and

the temperature rise for both connections of receptacle No. 22 and for

the white-wire connections of receptacles No. 10 and 11. No consistent

pattern with on-off cycling is apparent, although the change in the temperature rise and the change in power loss tended to be in the same direction. The small changes shown in Figure 36 for the black-wire connections

of receptacle No. 10 and 11 are typical of the changes observed for the

connections of the other receptacles.

There were two series of tests specially performed with the group 1 receptacles to determine the time required to establish thermal equilibrium

of the connections after energizing the test circuit. Typical data are given in Figure 37. As can be seen, the time required to establish

thermal equilibrium is about 75 minutes when the receptacles are mounted

in adjacent outlet boxes. The small increase in the power loss during

the first 75 minutes is expected, since the electrical resistance of

the connection is temperature dependent. Preliminary tests showed that

the time required to establish thermal equilibrium was slightly less than

75 minutes when the receptacles were spaced one or two outlet boxes apart.

4.2 INDIVIDUAL RECEPTACLE TESTS

The results obtained in the individual receptacle tests are compared in

Figures 38 and 39 with the results obtained in the group receptacle tests

that were conducted with the receptacles spaced two outlet boxes apart.

Figure 38 compares the results from tests using a test voltage of 10 V(ac),

and Figure 39 compares the results from tests using 115 V(ac). Both figures

show the differences between the average values of power loss and tab temperature rise obtained in the individual tests and those obtained in the group

receptacle tests for each of the four terminal screw torques. As can be

seen, for the screw torques of 6, 12, and 16 lbf»in the differences in the

values of power loss and tab temperature rise are less than 50 mW and

3 °F, respectively. For the screw torque of 2 Ibf'in, larger differences

in the values occurred. Inasmuch as the terminal screws of the devices

17
were loosened and tightened many times during the individual and group

receptacle tests, the differences shown in Figures 38 and 39 provide

a good indication of the reproducibility of the test method.

5. RESULTS OF TESTS WITH SPLIT-BEAM RECEPTACLES

Average values of the power loss, the temperature rise, and the ratio

obtained for the black-wire and white-wire connections of split-beam receptacles No. 7, 8, and 9 are plotted as a function of the time that the test

circuit was energized in Figures 40, 41, and 42, respectively. As can

be seen, some unexpected variations in the values of power loss occurred.

The largest variations were observed for the white-wire connection of

receptacle No. 9 and for the black-wire connection of receptacle No . 8 . By

comparison, the black-wire connections of receptacles No. 7 and 9 exhibited

very little variation in power loss throughout the tests. Some flexing

of the Type NM cable undoubtedly occurred when the receptacle spacing was changed. It is suspected that this flexing produced small changes in the

contact resistance, thus giving rise to the variations in the values of power

loss

.

It can be seen in Figures 40 and 41 that during the first 40 hours the values

of power loss for the white-wire connection are approximately the same as those for the black-wire connection. However, the values of temperature

rise for the white-wire connection are slightly higher than those for the

black-wire connection. The explanation for this inconsistency in the results

was found during post-test examinations of the receptacles. It was discovered

that the thermocouple measuring junction on the black-wire connection of each

receptacle was improperly located on the inner terminal contact; the junction

had been attached to the wrong side of the contact.

18
SOME HIGHLIGHTS OF RESULTS

From Figure 37, it can be seen that the approximate maximum power

dissipation can be determined immediately after energizing the circuit,

but maximum temperature required about 75 minutes to stabilize.

From Figure 37, it can also be seen that the power loss method is more sensitive than the temperature method in exposing the differences

between black-wire connections, and white-wire connections.

From Figures 5, 6, and 7, for receptacles with 16 Ibf'in screw torque

(and similar runs in Figures 8-16 at lower torques) and respectively

0, 1, 2, outlet-box receptacle spacings, it is seen that temperatures

vary by nearly 20 °F as the spacing is increased, while power loss

remains relatively constant. This demonstrates that the temperature

is affected considerably by the configuration of the test setup, while

the power loss measurement is not affected appreciably. Also, see Figures 27-31.

Figure 32 shows little difference between receptacle tab temperature

and wire temperature, while in Figure 33 tab temperature is considerably

different than wire temperature. This demonstrates that for loose

connections, the temperature of the connection is non-uniform and,

therefore, the temperature measured is dependent on the exact location

of the thermocouple measuring junction.

Figures 17 through 29 show that, for #14 copper wire connection with

a given receptacle spacing, temperatures and power losses are un-affected

if connections are tightened with screw torques of 6 lbf*in or more.

Figures 14, 15, and 16 show that #14 copper wire connections tightened

to a torque of 2 lbf»in frequently tended to overheat. Power loss

measurements gave a quicker and clearer indication of poor connection

quality than temperature measurements. Power losses were as high

as 3400 milliwatts compared to about 200 milliwatts for a number

of connections tightened with screw torques of 6 Ibf'in or greater.

Only when power loss becomes quite high, so that considerable heat

is generated, do temperature measurements definitely indicate that

there is a problem.

19
CONCLUSIONS

This research indicates that, if power loss at a specific current

level does not exceed some set value(s), temperatures will not be

excessive

.

These tests indicate that power-loss data can be reliably employed to assess the quality of electrical connections. Defective or loose

connections can be easily detected by such measurements.

Power loss determinations (and temperature measurements) of electrical

connections are virtually independent of supply voltage.

The primary performance criteria to determine the quality of electrical

connections should be a maximum power loss (at some specific current

level) rather than a maximum temperature. Power loss provides a reliable method of determining the quality of connection, and

(a) measurements can be made almost immediately without waiting

for temperature to reach or nearly reach equilibrium;

(b) environmental conditions (conditions which affect heat dissipation

in the vicinity of the connection) affect power loss determinations

much less than they affect temperature measurements;

(c) power loss measurements are less affected by placement of sensor

and leads than are temperature rise measurements

.

By drawing upon data obtained from this investigation, performance

criteria and test procedures based on the power loss concept can

be developed to evaluate the quality of electrical connections.

Copper wire terminations which are not sufficiently tight are likely

to overheat. The importance of good electrical connections was illustrated in these tests .

20
8. RECOMMENDATIONS

(1) Performance criteria to evaluate the quality and adequacy of electrical

connections should be based on the power loss measurement concept.

(2) Further tests should be conducted to evaluate the method under conditions

where the terminal connections become oxidized or corroded. Tests should

also be conducted using currents other than 15 A. Other wiring devices,

aluminum wire, and other sizes of copper wire, should be used in making

additional tests.

(3) Power losses and associated temperature rises should be determined for

wire terminations and other electrical connections installed in thermally

insulated wall sections that comply with energy conservation standards.

(4) Power loss criteria should be used to limit the losses of electrical

connections and other wiring components for energy conservation purposes,

as well as for fire safety purposes,

(5) A portable instrumentation package should be developed for field use to measure the quality of electrical connections. This instrument could

also be used to determine the power losses of other branch circuit

wiring components for energy conservation purposes .

9. REFERENCES

1. Analysis of Current Technology on Electrical Connections Used

in Residential Branch Circuit Wiring, Building Science Series 63,

National Bureau of Standards, William J. Meese and Ramon L. Cilimberg,

March 1975.

2. A Preliminary Approach to Performance Requirements and Criteria

for Electrical Connections in Residential Branch Circuit Wiring,

NBSIR 75-672, National Bureau of Standards, William J. Meese,

Ramon L. Cilimberg, and Adolfo A. Camacho, March 1975.

3. Exploratory Study of Glowing Electrical Connections, Building Science

Series 103, National Bureau of Standards, William J. Meese and

Robert W. Beausoliel, October 1977.

4. National Electrical Code, 1975 edition, NFPA #70-75, ANSI, CI 1975,

published by National Fire Protection Association.

21
SCREW TORQUE = 16 Ibf

RECEPTACLE SPACING

)f'in 1 = 0 j

I r T

8 s

9 •

I I I I I I T-T-T I r

100

1 I r I r

9

o

o

•1- • BLACK-WIRE CONNECTION

r o WHITE-WIRE CONNECTION

o 8 9

20

8

nrr I I I I I I

400

300

200

100

•

i

(10) (10) (17)

I I I 10 11 12

(10) (10) (17)

I I I

(10) (10) (17)

I L J

0

(10) (10) (17) (10) (10) (17)

' ' ' 13 14 15 16 17 18 19 20 21 22 23 24

RECEPTACLE NUMBER

Figure 5. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles during group receptacle tests: receptacles installed in adjacent outlet boxes, terminal screws tightened with a torque of 16 lbf>in The values plotted are averages of values determined in tests employing test voltages of 10 V(dc), 10 V(ac) and 115 V(ac

)

The figures in parentheses indicate the number of tests used in computing the averages. The bars give the range of the values. The symbol heights are equivalent to about 15 mW, 3 "F. and 0 015 °F/mW for the power loss, the temperature rise, and the ratio, respectively
SCREW TORQUE = 16 Ibf

RECEPTACLE SPACING =

•in 1

1 J

0.26

0.18

0.10

0.02

100

80

60

40

20

\ I I I I I I I I I I I I r^T

• o

<» o •

_J I L

8 g 9

J L»l

1 I r

400

300

200

100

o

(4) (4) (5) J—L-L

9 2

•

^ 8 « «

8

•

i—J^- L • BLACK-WIRE CONNECTION

T—mT T o WHITE-WIRE CONNECTION

8 8 o

J

• 8 »

I 1 I 8 8 i

TT-T I I I T-T

o

o

(4) (4) (5)

I I I

(4) (4) (5)

I I I

O

o

^

(4) (4) (5)

I I I

O

(4) (4) (5)

I I I

0.14

0.10

0.06

0.02

60

50

40

30

20

10

400

300

200

100

10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

22 23 24

Figure 6. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles spaced one outlet box apaii , terminal screws tightened with a torque of 16 Ibf in. The values plotted

are averages of values determined in tests employing test voltages of

10 V(ac) and 115 V(ac). The figures in parentheses indicate the numbci of tests used in computing the averages. The range of the values uas^

less than the symbol heights, which are equivalent to about 15 mW , 3 "F, and 0.015 °F/mW for the power loss, the temperature rise, and the raiio, respect ively

.
SCREW TORQUE = 16 Ibf

. RECEPTACLE SPACING

3f«in

I = 2 J

0.26

0.18

0.10

0.02

r 1 I I r I I I I i i i

r

® o • o ®

I I I

8 o •

o

J L

I I r

400

300

200

100

- ^ o

(4) (4) (5) i-J-J.

9 A

I I 1

o o

8 8

III III

• BLACK-WIRE CONNECTION

o WHITE-WIRE CONNECTION

d 9 8

I I I I 8 cm J i_

e

r 9

_L 1

m 0

J L

TT T"T-| I I I I I I

40

30

20

10

400

o

o

(4) (4) (5) -LJ,J,.

o

(4) (4) (5)

O

«

o o

s

(4) (4) (5) (4) (4) (5) J I I 10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

22 23 24

Figure 7. Values of the power loss, the tab temperature rise, and Lhe ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles spaced two outlet boxes

apart, terminal screws tightened with a torque of 16 Ibf- in. The values plotted are averages of values determined in tests employing

test voltages of 10 VCac) and 115 V(ac). The figures in parentheses

indicate the number of tests used in computing the averages. The range of the values was less than the symbol heights, which are equivalent

to about 15 mW, 3 °F, and 0.015 °F/mW for the power loss, the temperature

rise, and the ratio, respectively.
SCREW TORQUE = RECEPTACLE SPACING =

12 Ibf-in

I

ING= 0 J

0.26

I I I I I I I I I i r

0.181- • , S

• « • • 2 2

•

_ o •

0.10

0.02

J

'

I I • BLACK-WIRE CONNECTION

rn—1 III I o WHITE-WIRE CONNECTION

100

80

60

o

8

Lj I I I I I L.L..J i, .,^L,J L

rm rrn rrn— r \ r —rn—r

400

300 I- 8

° • o

8

200 |-*'^o^«» • • o

100 »-(15) (15) (8) (15) (15) (8) (15) (15) (8) (15) (15) (8) (15) (15) (8)

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

RECEPTACLE NUMBER

Figure 8. Values of the power loss, the lab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles installed in adjacent outlet boxes, terminal screws tightened with a torque of 12 Ibf.in. The values

plotted are averages of values determined in tests employing test voltages

of 10 V(dc), 10 V(ac), and 115 V(ac) . The figures in parentheses indicate

the number of tests used in computing the averages. The range of the values was less than the symbol heights, which are equivalent to about

15 mW, 3 °F, and 0.015 °F/mW for the power loss, the temperature rise, and the ratio, respectively.

60

50

40

30

20

10

400

300

200

100
SCREW TORQUE = 12 Ibf-in

RECEPTACLE SPACING = 1

0.26

0.18

0.10

0.02

100

80

60

40

20

I I r I I r I I r T—r-T I I r

a»o* oo<» 8®*

I I I III I • BLACK-WIRE CONNECTION

I I r I I I —r o WHITE-WIRE CONNECTION

• 8 8

' '

' 9 g <»I I I

O

• 8 • 1-J.

8 • t

J—J L

8

0.14

0.10

0.06

0.02

60

50

40

30

20

10

I I r I I I T I r I I r

400

300

200

100

i

o

o

(5) (5) (6)

I I I

2 8

8

(5) (5) (6)

I I I

•o 8

(5) (5) (6)

I I I

(5) (5) (6)

I I I 10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

S

o

(5) (5) (6)

I I I

400

300

200

100

22 23 24

Figure 9. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles spaced one outlet box apart, terminal screws tightened with a torque of 12 lbf>in. The values plotted

are averages of values determined in tests employing test voltages of

10 V(ac) and 115 V(ac). The figures in parentheses indicate the number

of tests used in computing the averages. The range of the values wjs

less than the symbol heights, which are equivalent to about 15 mW, 3 °F, and 0.015 °F/mW for the power loss, the temperature rise, and the ratio, respec tively

.
SCREW TORQUE

. RECEPTACLE SPACING

12 Ibf-in 1 NG= 2 J

0.26 -

0.18

I r 1 I r T I I I I r 1 I r

0.10|-<» o *

0.02

8 • • • 9 § 9

o o 8 8

I I 1 I I BLACK-WIRE CONNECTION

III I I I I o WHITE-WIRE CONNECTION

100

80

60

40

20

8 o •

• o 8 i

CO §

I 8 8 <•

I I I

8

I in r rnrT

400

300

200

100

S

o

(5) (5) (6)

' ' '

(5) (5) (6)

I I I

0

(5) (5) (6)

I 1^ L

o S §

(5) 15) (6)

I I L

(5) (5) (6)

I I L

0.14

0.10

0.06

0.02

60

50

40

30

20

10

400

300

200

100

10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

22 23 24

Figure 10. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles spaced two outlet boxes

apart, terminal screws tightened with a torque of 12 Ibf'in. The values

plotted are averages of values determined in tests employing test voltages

of 10 V(ac) and 115 V(ac). The figures in parentheses indicate the number of tests used in computing the averages. The range of the values

was less than the symbol heights, which are equivalent to about 15 mW

,

3 "F, and 0.015 "F/mW for the power loss, the temperature rise, and the ratio, respectively.
f SCREW TORQUE = 6 Ibf-in

RECEPTACLE SPACING = 0

1 I r

o

o •

I r I I I I r

§ 9 • •

S 8

5

o 8

III III • BLACK-WIRE CONNECTION

I I I I I I I o WHITE-WIRE CONNECTION

100

80

60

40

20

9 • ® o •

« i

I L

O

I I I

8 -

,

L

o

\ I r rnrT

400

300

200

100

I I 1

o

T—FT T~Tn"

i [806]

8

o

9 o

(7) (7) (8) 1-LJ.

9 § i

(7) (7) (8)

I I I

O

(7) (7) (8)

I J I.

(7) (7) (8)

I I1 10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

(7) (7) (8) J_L«L

0.14

0.10

0.06

0.02

60

50

40

30

20

10

400

300

200

100

22 23 24

Figure 11. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections ot the conventional receptacles

during group receptacle tests; receptacles installed in adjacent outlet boxes, terminal screws tightened wih a torque of b Ibf-in. the values plotted are averages of values determined in tests employing

test voltages of 10 V{dc) , 10 V(ac), and 115 V(ac). The figures in parentheses indicate the number of tests used in computing the averages.

The range of the values was less than the symbol heights, which are equivalent to about 15 mW, 3°F, and 0.015 °F/mW for the power loss, the temperature rise, and the ratio, respectively.
SCREW TORQUE = 6 Ibf- in

RECEPTACLE SPACING = 1

0.26

0.18

0.10

0.02

100

80

60

40

20

T—I—

r

T—I—

r

T-T T

\—

r

Qt O

I I

8 8

o

I I I

! ! r

1. • BLACK-WIRE CONNECTION

T o WHITE-WIRE CONNECTION

0.14

0.10

0.06

0.02

60

50

® 8 •

_i I L_ J L

8 8 »

400

300

200

100

TT-T I I I

o

(6) (6) (6) _X_L_J_

(6) (6) (6)

I I L

(6) (6) (6)

I 1 i_

o O

g

(6) (6) (6) J I I 10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

(6) (6) (6)- 100

' ' 1 -1

22 23 24

Figure 12. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles spaced one outlet box apart, terminal screws tightened with a torque of 6 lbf»in. The values plotted

are averages of values determined in tests employing test voltages of

10 V(ac) and 115 V(ac). The figures in parentheses indicate the number

of tests used in computing the averages. The range of the values was

less than the symbol heights, which are equivalent to about 15 mW , 3 °F, and 0.015 °F/mW for the power loss, the temperature rise, and the ratio,

respectively

.
SCREW TORQUE = 6 ll)f-in

RECEPTACLE SPACIN6 = 2

f-T-r

# 0

8 g

S

o

I J

O 0 ^

-L • BLACK-WIRE CONNECTION

i •

0.14

oo

rr-T r <^ WHITE-WIRE CONNECTION

CO

0.10 E

0.06 S

0.02 g

CO

CO

o

oCL.

100

CO

UJ

ea

60

40

20

« 8 8

I I 1_

8 0 t

I I I

2

a

e

•

1 I I

I I r TT-r 1 I r I" "I I

E

»> CO

oo.

400

300

200

100

I I I

"

o

(6) (6) (6)

• 8

«

(6) (6) (6) (6) (6) (6)

I \ \

(6) (8) (6)

I I t

• e

o

(6) (6) (6) _1__J L

60

50

40

30

20

10

400

300

200

100

o

CO

QC

<

CO

<

E

•\ CO

CO

o

_J

QC

1X1 o

10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

22 23 24

Figure 13. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles spaced two outlet boxes apart, terminal screws tightened with a torque of 6 Ibf.in. The values plotted

are averages of values determined in tests employing test voltages of

10 V(ac) and 115 V(ac). The figures in parentheses indicate the number

of tests used in computing the averages. The bars give the range of

the values. The symbol heights are equivalent to about 15 mW , 3 °F, and 0.015 °F/mW for the power loss, the temperature rise, and the ratio' respectively.
SCREW TORQUE = 2 Ibf

RECEPTACLE SPACING =

•in 1 0 J

0.26

0.18

0.10

0.02

100

80

60

40

20

I I r

i 8

** 0

I I I

1200

800

400

0

5 8

J L

T—I—

T

1 I r

° o fi • • •

o o

1 I r I V

• BLACK-WIRE CONNECTION

o WHITE-WIRE CONNECTION

' '

'

8

Ml o»

I I L I I I I I L

0.14

0.10

0.06

0.02

60

50

40

30

20

10

T 1 r

• • 8

(21) (21) (8) 1

(21) (21) (8)

I I I

o

(21) (21) (8)

I I J_

O 9

(21) (21) 1^1

(8) (21) (21) (8)

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

RECEPTACLE NUMBER

Figure 14. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles during group receptacle tests: receptacles installed in adjacent outlet boxes, terminal screws tightened with a torque of 2 Ibf. in. the values plotted are averages of values determined in tests employing test voltages

of 10 V(dc), 10 V(ac), and 115 V(ac). The figures in parentheses indicate the number of tests used in computing the averages. The bars give the range of the values. The symbol heights are equivalent to about 60 mW

,

3 F, and 0.015 °F/mW for the power loss, the temperature rise, and the' ratio, respectively.
' SCREW TORQUE = 2 Ibf-in 1

. RECEPTACLE SPACING = 1

I r "~l II III I I r I I r

o

o o

J 1

o o §

o o

I I I BLACK-WIRE CONNECTION

100

80

60

40

20

I r I I I r o WHITE-WIRE CONNECTION

o

% % 9

A I J

O O

J L

O

° s

J L

8

I

o

8

J L

0.14

0.10

0.06

0.02

60

50

40

30

20

10

1200 o

1 1 1

1 1'

1

o

—r—P-P- 1 1 1

1200

800 800

400

•

- • m

8 <» •

•

• •

•

o S 8

o• • _ 400

0 "(12) (12) (6) -^..L,

, i

(12) (12)

1 1

(6)

1

(12) (12) (6)

1 1 1

(12) (12) (6)

1 1 1

(12) (12) (6) -

1 _L 1

0

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

RECEPTACLE NUMBER

Figure 15. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss obtained for the black-wire and white-wire connections of the conventional receptacles

during group receptacle tests: receptacles spaced one outlet box apart, terminal screws tightened with a torque of 2 Ibf-in. The values plotted

are averages of values determined in tests employing test voltages of

10 V(ac) and 115 V(ac). The figures in parentheses indicate the number

of tests used in computing the averages. The bars give the range of the values. The symbol heights are equivalent to about 60 mW , 3 °F, and 0.015 °F/mW for the power loss, the temperature rise, and the ratio,

respectively

.
SCREW TORQUE = 2 Ibf

RECEPTACLE SPACING =

•in 1 2 J i—T—

r

9 •

1 r I I I

o a» i »

o o

o •

1 I I

100

80

60

40

20

i I I

• BLACK-WIRE CONNECTION

o WHITE-WIRE CONNECTION

e

I I 1

8 . <» 8

J L I

o o

J L

0 •

O

1 I

1200

800

400 - •

I I r

2eB6l'fl§§]

o

TT 1 r

(8) (8) (6) (8) (8) (6) _l I l_

o o

(8) (8) (6)

I I I

(8) (8) (6)

I I I 10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

}

o

8

I I I

0.14

0.10

0.06

0.02

60

50

40

30

20

10

- 1200

800

(8) (8) (6) J I L_

400

0

22 23 24

figure 16. Values of the powei loss, the tab Lenipt la t ure lise, and the ratio of the tab temperature rise to the power loss obtained for tht- black-wire and white-wire Conner tiona of the conventional reieplaclea

during group receptacle tests: receptacles spaced two outlet boxes

apart, terminal screws tightened with a torque of 2 Ibt'In. The values plotted are averages of values determined in tests employing test volt- ages of 10 V(ac) and 115 V(ac). The figures in parentheses indicate

the number of tests used in computing the averages. The bars give the range of the values. The symbol heights are equivalent to about 60 raW,

J F, and 0.015 F/mW for the power loss, the temperature rise, and

the ratio, respectively.

2 6 12 16

SCREW TORQUE, Ibf-in

Figure 18. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function

of the terminal screw torque for the white-wire connections of conventional receptacles No. 10, 11, and 12. The receptacles were installed in adjacent outlet boxes. The values plotted are averages of values determined in tests employing test voltages of 10 V(dc), 10 V(ac), and 115 V(ac). The bars give the range of the values.
E

BLACK-WIRE CONNECTIONS

RECEPTACLE SPACING = 0

CO

Q=

CD

<

CO

CO

o

O

Q0.26

0.18

0.10

0.02 • 13 1 A 14

f 15 J

RECEPTACLE NO.

E

0.14 C3

o

0.10

uuCO

QC

U.Ub Q-^

UJ

h0.02

<

1—

u. 100

oc

<

QC

LUO.

QQ

80

60

40 -

20

I -

60

50

40

30

20

10

- 500

400 -

CO

CO

o

o

6 12

SCREW TORQUE, Ibf-in

Figure 19. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function of the terminal screw torque for the black-wire connections of conventional receptacles No. 13, 14, and 15. The receptacles were installed in adjacent cutlet boxes. The values plotted are averages of values determined in tests employing test voltages of 10 V(dc) , 10 V(ac), and 115 V(ac). The bars give the range of the values.

CO

CO

o

cc

LUo

OC-3 o

CO

oc

<

QC

QQ

<

CO

CO

o

o

Q-
CO

OQ

<

CO

CO

o

o

WHITE-WIRE CONNECTIONS

RECEPTACLE SPACING = 0

T

- ^-^——8

o 13 1 4 14 [ 15 J

RECEPTACLE NO.

e

0 14 o

0.10

LUCO

cc 0.06

QLU

»— 0.02 OQ<

CO

CO

o

o

CO

cc

LU

QC

<CC

CO<

100

80

60

40

20

I

60

50

40

30

20

10

CO

CO

oI oc

iXI o

Q.

6 12

SCREW TORQUE, Ibf-in

o

CO

QC

LU

QC

<

QC

QQ<

CO

CO

o

oaFigure 20. Values of the power loss, tlie tab teiuperature rise, and

the ratio of the tab temperature rise to the power loss plotted as

a function of the terminal screw torque for the white-wire connections

of conventional receptacles No. 13, 14, and 15. The receptacles were installed in adjacent outlet boxes. The values plotted are averages

of values determined in tests employing test voltages of 10 V(dt),

10 V(ac), and 115 V(ac). The bars give the range of the values.
E

BLACK-WIRE CONNECTIONS |

RECEPTACLE SPACING = 0 J

CO

03

<

CO

CO

o

o

Occ

<cc

UJo.

00

<

0.26

0.18

0.10

0.02

100

80

60

40

20

A 1718 JRECEPTACLE NO.

E

0 14 CJ> o

•s

0.10

UJCO

cc 0.06

CI.

0.02

UJ

hCD<

1—

CO

CO

o

cc

CD

QI -

60

50

40

30

20

10

CO

CO

o

o

6 12

SCREW TORQUE, Ibf-in

o

CO

CC

<cc

CD

<

CO

CO

o

o

Figure 21. Values of the power, the tab temperature rise, and the ratio

of the tab temperature rise to the power loss plotted as a function of

the terminal screw torque for the black-wire connections of conventional receptacles No. 16, 17, and 18. The receptacles were installed in adjacent outlet boxes. The values plotted are averages of values determined

in tests employing test voltages of 10 V(dc), 10 V(ac), and 115 V(ac). The bars give the range of the values.
E^ 0.26h

WHITE-WIRE CONNECTIONS

RECEPTACLE SPACING = 0

oc

Q03

<

00

00

oI cco

O0.18 -

0.10

0.02

T

0 16 1 A 17 \ 18 J

RECEPTACLE NO.

c

0.14 C9

o

n in

UJ

C/3

0.06

LU

h0.02

<

00

ooo

oa.

u. 100 -

CO

cc

<cc

CO

<

80

60

40

20

- A40

30

20

10

1000 - - 1000

CO

CO

o

o

Q6 12

SCREW TORQUE, Ibf. in

oo

CO

oc

<

QC

CO<

CO

ooo

o

Figure 22. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function of the terminal screw torque for the white-wire connections of conventional receptacles No. 16, 17, and 18. The receptacles were installed in adjacent outlet boxes. The values plotted are averages of values determined in tests employing test voltages of 10 V(dc), 10 V(ac), and 115 V(ac). The bars give the range of the values.
E

0.26h

' BLACK-WIRE CONNECTIONS 1 RECEPTACLE SPACING = 0 J

<

CO

CO

o

QC

O

Occ

<

GC

<

E

•> CO

CO

o

oex.

0.18

0.10

0.02|-_L

100

80

60

40

20

• 19.1

4 20 }

2lJ

RECEPTACLE NO.

E

0.14 0

0 10

UJCO

O.Oo

Q_

1 1 1 1—

0.02 CQ<

CO

CO

o

oex.

I L I I -

500

400

300

200

100

I r I I r

60

50

40

30

20

10

500

400

300

200

100

ooLU

CC

<

QC

QQ<

E

CO

CO

o

oa6 12

SCREW TORQUE, Ibf-in

16

Figure 23. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function of the terminal screw torque for the black-wire connections of conventional receptacles No. 19, 20, and 21. The receptacles were installed in adjacent outlet boxes. The values plotted are averages of values determined in tests employing test voltages of 10 V(dc), 10 V(ac), and 115 V(ac). The bars give the range of the values.
E

0.26

WHITE-WIRE CONNECTIONS

RECEPTACLE SPACING = 0

QQ<

00

o

o

0.18

0.10

0.02^

T T T T

20 } 21 J

RECEPTACLE NO.

E

0.14 CJ

o

0.10

^ f

1 CO

CC 0.06

0.02

LLI hCO<

00

CO

o

_I

cco

Q.

CO

cc

<

OQ<

100

80

60-

40

20

60

50

40

30

20

10

oo

CO

cc

<cc

CQ<

E

CO

CO

o

ocoa_

E

CO

CO

o

o

6 12

SCREW TORQUE, Ibf-in

Figure 24. Values of Che power loss, the tab temperature rise, and Che ratio of the tab temperature rise to the power loss plotted as a function

of the terminal screw torque for the white-wire conneccions of conventional receptacles No. 19, 20, and 21. The receptacles were installed in adjacenC outlet boxes. The values ploCCed are averages of values deCermined in tests employing test voltages of 10 V(dc), 10 V(ac), and 115 V(ac). The bars give the range of the values.
Figure 25. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function

of the terminal screw torque for the black-wire connections of conventional receptacles No. 22, 23, and 24. The receptacles were installed in adjacent outlet boxes. The values plotted are averages of values determined in tests employing test voltages of 10 V(dc), 10 V(ac), and 115 V(ac). The bars give the range of the values.
WHITE-WIRE CONNECTIONS

RECEPTACLE SPACING = 0

1

d

0.14 ^

0.10 ^

cc H0.06 ^

<

RECEPTACLE NO

^1 aTI .

I

- 1000

6 12

SCREW TORQUE, Ibf-in

Figure 26. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function

of the terminal screw torque for the white-wire connections of conventional receptacles No. 22, 23, and 24. The receptacles were installed in adjacent

outlet boxes. The values plotted are averages of values determined in tests employing test voltages of 10 V(dc) , 10 V(ac), and 115 V(ac). The bars give the range of the values.
5

E

SCREW TORQUE

LUCO CO

CO

cc o

QC

UJ LU H- o

<

1—

0.24 -

CO

QQ<

E

CO

CO

o

o

E

o

1 A14

0

« LUCO CO

10 QC so

O06 TE

LU

CO o

< o. 02 1—

CJ) o

CO

QC

QQ<

CO

COo

_J

QC

LU

o

RECEPTACLE SPACING

Figure 27. Values of the power loss, the tab LeioperaLut e rise, and the ratio of the tab temperature rise to the power loss plotted as a tunciiu.i of the receptacle spacing for the black-wire and white-wire connections

of conventional receptacles No. 10, U, and 12. The terminal screws of the receptacles were tightened with a torque of 12 Ibf-in. The values plotted are averages of values determined in tests employing a test voltagt- of 10 V(ac). The range of the values was less than the symbol heights, which are equivalent to about 15 mW, 2 °F, and 0.012 °F/mW for the power loss, the temperature rise, and the ratio, respectively.
E

[screw torque = 12 Ibf-inj

SE CO

CO

QC o

QC

UJ LU

1—

CO o

< Q_

CO

oc

Q-

<

E

•> 00

CO

o

QC

UJo

13 14 15 RECEPTACLE NUMBER

• A BLACK-WIRE CONNECTION

O A WHITE-WIRE CONNECTION

0 14

- 0.10

0.06

0 02

RECEPTACLE SPACING

Figure 28. Values of Che power loss, (.he tab lempeiaiui e rise, and the ratio of the tab temperature rise to the power )oss plotted as a tuficii>ji> of the receptacle spacing for the black-wire and white-wire connections

of conventional receptacles No. 13, 1^, and 15. The ttrminal screws ot

the receptacles were tightened with a torque of 12 Ibf-in. The values

plotted are averages of values determined in tests employing a tesr voltage

of 10 V(ac). The range of the values was less than the symbol heights, which are equivalent to about IS mW, 2 °F, and 0.012 °F/mW for the power

loss, the temperature rise, and the ratio, respectively.
0.241-

0.18

0.12

0.06

[screw TORQUE = 12 Ibf- inj

, p—f >—

I

16 17 18 RECEPTACLE NUMBER • A BLACK-WIRE CONNECTION

O A WHITE-WIRE CONNECTION

0 14

0

^ UJCO CO n 10 uu OS

Q. 1 cc 0 06 UJ

I— UJ

CO o

<

0 02

30

- 20

uo

CO

QQ<

CO

CO

o

ccoa.

RECEPTACLE SPACING

Figure 29. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function

of the receptacle spacing for the black-wire and white-wire connections

of conventional receptacles No. 16, 17, and 18. The terminal screws

of the receptacles were tightened with a torque of 12 Ibf-in. The values plotted are averages of values determined in tests employing a test voltage

of 10 V(ac). The range of the values was less than the symbol heii;hia, which ciT6 equivalent to about 15 inW ^ 2 ° F , and 0.012 **F / mW for the powe

r

loss , the temperature rise , and the ratio , respec t ive J y

.
E

SE CO

CO

o

Q-LU UJ

hCO o

< o.

0.24h

0.18

0.12

0.06

[screw torque = 12 Ibf-inj

^—

CO

cc

QQ<

CO

CO

o

cc

LUo

Q.

T T T

E

20 21 RECEPTACLE NUMBER

A BLACK-WIRE CONNECTION

WHITE-WIRE CONNECTION

14

CO

10 cc OS

Q. cc 06 UJt—

LU

CD o

<t a. 02 1—

CJ

o

CO

QC

Q.

CQ

CO

COo

oa.

RECEPTACLE SPACING

Figure 30. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted 'as a function of the receptacle spacing for the black-wire and white-wire connections

of conventional receptacles No. 19, 20, and 21. The tenninal screws

of the receptacles were tightened with a torque of 12 Ibf- in. The values plotted are averages of values determined in tests employing a test voltage of 10 V(ac). The range of the values was less than the symbol heights which are equivalent to about 15 mW. 2 °F. and 0.012 » F/mW for the power loss, the temperature rise, and the ratio, respectively.
E

0

1^ 0.24

III CO

DC o 0.18

Q.:e

LU

cc

UJ 0.12

hCO o

< 0.06 1—

(screw torque = 12 Ibf-inj ^ )—

I

Ll- 0 50

LU

cc 40

a_UJ 30

»—

CO

< 20

400

E

CO 300

CO

o

ccLU 200

o

100

T T

122 23 24 RECEPTACLE NUMBER

• A BLACK-WIRE CONNECTION

O A WHITE-WIRE CONNECTION

— 0 14

o

•

LIJ 00 CO

0 .10 CC OS

Q. 1 cc 0 06 LU

hLU

CO o

< Q0 02 1—

30

20

10

400

300

200

100

o

cc

CQ

<

CO

COo

oa.

0

RECEPTACLE SPACING

Figure 31. Values of the power loss, the tab temperature rise, and the ratio of the tab temperature rise to the power loss plotted as a function

of the receptacle spacing for the black-wire and white-wire connections

of conventional receptacles No. 22, 23, and 24. The terminal screws of the receptacles were tightened with a torque of 12 Ibf-in. The values plotted

are averages of values determined in tests employing a test voltage of

10 V(ac). The range of the values was less than the symbol heights, which

are equivalent to about 15 mW, 2 °F, and 0.012 °F/mW for the power loss, the temperature rise, and the ratio, respectively.
SCREW TORQUE = 12 Ibf-in

.RECEPTACLE SPACING = 1 r

• BLACK-WIRE CONNECTION

I I I II I I o WHITE-WIRE CONNECTION

8 o • o

Q ® 8

' i i ' i-J-J, i___J_J L_l_i

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

RECEPTACLE NUMBER

Figure 32. The tab temperature rise and the difference between the wire temperature and the tab temperature for the black-wire and white-wire

connections of the conventional receptacles: receptacles spaced one outlet box apart, terminal screws tightened with a torque of 12'lbf in. The difference was calculated from the averages of values determined during

three consecutive tests in which the test voltage was 10 V(ac). The 99% confidence limits for the difference between the averages are less than

the symbol heights, which are equivalent to about 0.8 °F for the difference

and about 1.5 °F for the tab temperature rise.
[SCREW TORQUE = 2 Ibf- in

I RECEPTACLE SPACING = 0

03

<

20

^

10

o

=3

0

-Id

S -20

III III

i

[71.3»f]

r""!""TM'! —"'""I"-"]-TM", , , ,

o

9

•—g t© • •^ *•

•• 1

m •

0 •

o

<B •n•

o

• -

0

o

III III —L- • BLACK-WIRE CONNECTION -i—

CO

QC

<

QC

QQ<

100

80

60

40

20

I I r o

o

o

o WHITE-WIRE CONNECTION 1-31

i

I I I

o

• . 9

I I I

o a» • -

I I I 1 L L

10

5

0

-5

-10

60

50

40

30

20

10

o

CO

<

I LU

QC

LUu

UJ

QC

LU

ULL. O

LU

QC

<

QC

o

CC

QC

00

<

10 11 12 13 14 15 16 17 18 19 20 21

RECEPTACLE NUMBER

22 23 24

Figure 33. The tab temperature rise and the diifereme between the wire temperature and the tab temperature for the black-wire and white-wire

connections of the conventional receptacles. receptatles installed in adjacent outlet boxes, terminal screws tightened with a torque ot 2-lbt in. The difference was calculated from the averages of values determined duiing

three consecutive tests in which the test voltage was 10 V(ac). The 9y% confidence limits for the difference between the averages are less than

the symbol heights, which are equivalent to about 1.5 °F for the difference

and about 3 °F for the tab temperature rise.

f SCREW TORQUE = 2lbf

[RECEPTACLE SPACING

E

0.10

• in 1

T—I\—r1 I I—

r

DIFFERENCE

o

IN RATIO : ^fTM^

T—

r

• BLACK-WIRE CONNECTION

o WHITE-WIRE CONNECTION

0.05 1

o

-0.05

C_3 Z

cc

£

LU

C3

LU

CC

400

200

0

-200

-400

-600

III II II

|- DIFFERENCE IN POWER LOSS

I —1

1 —1

i -

[5851 48)

• -^-^

•

o

•

O ^[-2378] o

.-Jl«,TML 1 1. J

400

200

0

-200

-400

-600

E

LUzLU

CC

10 11 13 14 16 17 19 20

RECEPTACLE NUMBER

22 23

Fi gu re 3 3. Change in the power loss, the tab r empe r ai ure ii^e, and the ratio or Che tab temperature rise to tht power I.v^n tor the blai>k-wiit- and white-wire connections ot the ronveni lona] i tt-eptac its in Oroup 1 due to retightening the terminal screws with d torque ot 1 lbt*in. Difference equals average of values obtained in tests 20j 2(rl, 20^*, 205, and 206 minus average of values obtained in testa P. Ifa, anJ 19. The receptacles were installed in adjacent outlet boxes, and ttie test voltage was 10 V(ac) for each of the tests. The bars give the 9'>2 confidence limits for the differences bet ween the averages.
SCREW TORQUE = 2 Ibf-in

RECEPTACLE SPACING = 0

t I I I I I I I r DIFFERENCE IN WIRE TEMPERATURE RISE

T—r—

T

-

- . 1

^ ^ - - o- ^- - - -

F'""Wr ^ ^««» —I n j^j^

I

I I I I

10

0

H-10 5

I I ^"rn^ I I I I —

r

DIFFERENCE IN TAB TEMPERATURE RISE

o

zUJ

ec

(22 11 10 -<t^ RECEPTACLE NUMBER

pBB|sil[S^&S^^ IS A » BLACK WIRE CONNECTION

AO WHITE-WIRE CONNECTION

DIFFERENCE IN POWER LOSS

o

LU

QC

-10

200 ^a

--400

I I I I J L

n—I—I—I—I—I

\—

r

(2.4) (2.0) (1.2) (4.0) (2.0) (4.3) (0.5) (15)

1

f I I r

(3 2) (2.3) (2 0) (2 2)

(39.6) (0.2) (12.7) (0.2) (17.7) (0.5) (0.2) (17.1) (16.0) (0.4) (0.4) (3.1) i_J I L_l I I I I I I I I

1 10 13

ON-OFF CYCLES

Figure 36. Change in the power loss, the tab temperature rise, and the wire temperature rise for the black-wire and white-wire connections

of conventional receptacles No. 10, 11, and 22 as a function of the number of on-off cycles of the test current. The recepiacles were installed in adjacent outlet boxes and their terminal screws were tightened with a torque o£ 2 lb£-in. Ihe test voltaije was 115 VUc)

for the values plotted. Difference equals average value during indicated

cycle minus average value during first cycle. The bars give the 95% confidence limits for the difference. The figures in parentheses give

the time, in hours, that the test current was on and off during each

cycle.
(SCREW TORQUE = 12 lbf-in\

I RECEPTACLE SPACING = Oj

TIME, min

Figure 37, Power loss and tab temperature as a function of time for the black-wire and white-wire connections of the indicated conventional receptacles. The test circuit was energized at time equals 0 by applying

a test voltage of 10 V(ac); the test curent was maintained at 15 A. The values plotted were obtained in tests 161 through 172: receptacles in- stalled in adjacent outlet boxes, terminal screws tightened with a torque

of 12 Ibf'in.
40 -

E

CO00

o

oOl.

0

-40

40

0

-40

- 40

LUO

UJ^ 0

a

-40

160 h

0

-160

WHITE-WIRE & •BLACK-WIRE CONNECTIONS

I I I r

oo e

J I L

T—

r

-• cr

1 V

• o

I I I I I T—

r

1

o —I

E = 16 Ibf.in

1 1 1 1

•

e —^ —

"

,-1.TM

8

1 1 1 1 H

E = 12 Ibf-in

1 1 1 1 J

8

1 1 1 1 1 ^

{screw torque = 6 Ibt-i

9(5)

0

-9(-5)

9(5)

0

-9(-5)

9(5) o

I I I I I T I I r

o

'^[-342] •

I I I I

uo

CO

cc

<

cc

CD<

u

UJ

cc

{screw torque = 2 Ibf-in

12 15 18 21 24 12 15 18 21 24

RECEPTACLE NUMBER

Figure 38. Difference between the values of power loss and tab temperature

rise obtained in individual receptacle tests and those obtained in group receptacle tests conducted with the receptacles spaced two outlet boxes

apart. Difference equals average of values obtained in individual receptacle

tests using a test voltage of 10 V(ac) minus average of values obtained in group receptacle tests using a test voltage of 10 V{ac). Bars give the 95% confidence limits for the difference between the averages.
o WHITE-WIRE & •BLACK-WIRE CONNECTIONS

j

T—I—I—n—^ ' n—I—I—

f

{screw torque = 16 Ibf.in}

I I

5

[1240 i20]^

r""T

|scRE^ JERQUE = 12 Ibf-in)' ' ' ^ O -I

1 r

{screw torque = 6 Ibf-in s

-

-* §

l_l L

dS. ^

I I I

' ' ' {screw TORQUE = 2 Ibf-in}

^[34.6il.3°F]

12 15 18 21 24 12 15 18 21 24

RECEPTACLE NUMBER

Figure 39. Difference between the values of power loss and tab temperature

rise obtained in individual receptacle tests and those obtained in group

receptacle tests conducted with the receptacles spaced two outlet boxes

apart. Difference equals average of values obtained in individual receptaile

tests using a test voltage of 115 V(ac) minus average of values obtained in group receptacle tests using a test voltage of 115 V(ac). Bars give the 95% confidence limits for the difference between the averages.
SPLIT-BEAM RECEPTACLE

2 U<2

E^ 0.18 h

C2 0.10

0.02 - o

I

I

1

CC

60

40

20

600

500 1-

1

1

CO^ 400

oa. 300

200

n ui LoJ [RECEPTACLE 0-hKh2H -^jsPACING

E

TT

0 i A i 9 9 i A«

! !

I I

J

0.10 "

^o.o6LJ^

oo o

0.02^

117V(ac) lOV(ac) lOV(dc) <—TEST VOLTAGE • a BLACK-WIRE CONNECTION o .\ o WHITE WIRE connection! '

' -j 40

- 30

- 20

o

QA

OA ii

i8l

OA

Aq

to

^1

AO

A*

A a o

a o

A

A •

O A

10

o

CO

OC

<

- 600

- 500 1

oo

COo

o

200

20 60 80

TIME, h

Figure 40. Values of the power loss, the temperature rise, and the ratio

of the temperature rise to the power loss for the black-wire and white-wire connections of split-beam receptacle No, 7 plotted as a function of the time

that test circuit was energized. Each of the data points represents the average of values obtained in several (2 to 4) tests. The bars give the

952 confidence limits for the averages. The symbol heights are equivalent

to about 15 idW , 3 T , and 0.015 °F/mVI for the power loss, the temperature

rise, and the ratio, respectively.
SPLIT-BEAM RECEPTACLE No. 8

E

60

40

^ 20

f A O J

600

500

COg 400

I DCO

Q.

300

200

A A o A LO Q

'a

TT

o 5o

ij oj [RECEPTACLE

^"^^^ "^SPACING

E

o ^ And '

I A d • ^ Ad

I I

117V(ac) lOV(ac) lOV(dc) <—TEST VOLTAGE • Am BLACK WIRE CONNECTION

O A WHITE WIRE CONNECTION

A O OA A o O ^

*9»

A O Q

ao

A 88

•

ADO

• A\

0.10 ^

0.06

0.02^

CO

GOO

o

40

30

20

H 10

CO

cc

<

QC

600

500

400

300

200

00

GOO

OO20 40

TIME, h

60 80

Figure 41. Values of the power loss, the temperature use, and the ratio of the temperature rise to the power loss for the bJack-wire and white-wire connections of split-beani receptacle No. 8 plotted as a function of the time that test circuit was energized. Each of the data points represents the average of values obtained in several (2 to 4) tests. The bars give the 95Z confidence limits for the averages. The symbol heights are equivalent

to about 15 mW, 3 °F. and 0.015 °F/mW for the power loss, the temperature rise, and the ratio, respectively.
SPLIT-BEAM RECEPTACLE No. 9

o

ti: 0.18 h

CO

OC ^ 0.10

I 2 0.02 hi

>

oo.

ex

<

60

40

20

600

^ 500

E

i 400 I-

$ 300

o

200

2-*- 0 1 >-«2>'^ 0-»-<1 ^<2>-»- 0-^<1»-'2 RECEPTACLE

SPACING

^

^ o 2 5

A A O [oo]

A A • A [4

5 A|

A

i I

I

117V(ac) lOV(ac) 10V(dc

A

8^1 58^

A H«

A Oi

A

I

A 0|

A#I®A n

A

A

TEST VOLTAGE

Ml BLACK WIRE CONNECTION

WHITE WIRE CONNECTION

A O

A ®

O A

AO

• ^1 A « Ml

Oi A

' O

O A

A QQl

A « «

O

A HB «

Ad

• A A^

1

600

500

400

300

200

CO

COo

o

20 40

TIME, h

60 80

Figure 42. Values of the power loss, the temperature rise, and the ratio

of the temperature rise to the power loss for the black-wire and white-wiie connections of split-beam receptacle No. 9 plotted as a function of the time that test circuit was energized. Each of the data points represents

the average of values obtained in several (2 to 4) tests. The bars give

the 95% confidence limits for the averages. The symbol heights are equivalent

to about 15 mW, 3°F, and 0.015 °F/mW for the power loss, the temperature

rise, and the ratio, respectively.
SPLIT-BEAM RECEPTACLE No. 8

E

Lji- 0.18

o

«\oo UJCO COo

0.10

oc 1 QCUJ 0.02

o

Ll. 0 60

CO

<

40

20

600 h

500

COg 400

I

OCI. 300

200

l'|i2>j^-0 0 -^h 1 4-2

^ 5

A

O

5o

I I

117V(ac) 10V(ac) lOV(dc) TEST VOLTAGE • AH BLACK WIRE CONNECTION

O A WHITE WIRE CONNECTION

^ 5

• A

O A

A •

OA A O Q

•

ADO

[RECEPTACLE

"*|SPACING

E

Ho.io ?

- O.OOlu

CO H0.02^

CO00

o

o

Qi

40

30

20

H 10

CO

cc

<cc

600

500

400

300

200

CO

COo

o

20 40

TIME, h

60 80

Figure 41. Values of the power loss, the temperature rise, and the ratiu of the temperature rise to the power loss for the bJack-wire and white-wire connections of split-beam receptacle No. 8 plotted as a function of the time that test circuit was energized. Each of the data points represents

Che average of values obtained in several (2 to 4) tests. Ilie bars give the 95Z confidence limits for the averages. The symbol heights are equivalent

to about 15 mW, 3 "F, and 0.015 °F/mW for the power loss, the temperature rise, and the ratio, respectively.
SPLIT-BEAM RECEPTACLE No. 9

u: 0.18 -

LXJ CO

a.

COi2 0 .10

00

UJ<ac

0.02

60

40

20

600 -

$ 500 1-

E

CO

"0, 400

ccS 300

oA. 200

RECEPTACLE

SPACING

5

^ A o [o o]

A A « A [«

I I

117V(ac) lOV(ac) lOV(dc)

A H BLACK WIRE CONNECTION

A WHITE WIRE CONNECTION l"Tr!3

A 0|

A

A O

OA

5!

AO O

• a1 A tt m

0|

o A

A OQ]

A H •!

O

a o

A 11 #j

O A

CO

DC

LU

ccZD

I—<or

Ad

600

500

400

300

200

CO

COoI DCO

20 40

TIME, h

60 80

Figure 42. Values of the power loss, the temperature rise, and the ratio

of the temperature rise to the power loss for the black-wire and white-wire counections of split-beam receptacle No. 9 plotted as a function of the time that test circuit was energized. Each of the data points represents

the average of values obtained in several (2 to 4) tests. The bars give

the 95% confidence limits for the averages. The symbol heights are equivalent

to about 15 mW, 3°F, and 0.015 "F/mW for the power loss, the temperature

rise, and the ratio, respectively.

NflS-1 14A (REV. 7-73)

U.S. DEPT. OF COMM. 1. PUBLICATION OR RFPORT NO. 2. Gov't Accession BIBLIOGRAPHIC DATA MocTn -in i oon No. SHEET NBSIR 77-1380

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Experimental Determinations of Temperatures and Power

Losses at the Electrical Connections of Some Duplex

Receptacles

5. Publication Date April 1978

6. Performing Organization Code 462.03 and 221.11

7. AUTHOR(S) G.W. Burns, M.G. Scroger, G.A. Evans, R.Wl' Beausoliel

and W. J. Meese

,8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work IJnii No.

11. Contract /Grant No. IAA-H-37-73 (120)

12. Sponsoring Organization Name and Cotnplete Address (Street, City, State, ZIP)

Office of Policy Development and Research

Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report & Period Covered Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

One of a series of reports in a program on the evaluation of innovative electrical

connections

,

16. ABSTRACT (A 200-word or less factual summary of most sigpificant information. If document includes a significant

bibliography or literature survey, mention it here.) The data presented in this report compare the reliability of power loss determination with the reliability of temperature measurements as a means for determining

the quality and adequacy of electrical connections on wiring devices used in

branch circuit wiring. The basic premise for the tests presented here is that

in the laboratory the determination of power loss is easier, quicker, and not

nearly as dependent on environmental factors as temperature. This research

indicates that, if power at a specific current level does not exceed some set

value(s), temperatures will not be excessive.

This investigation also illustrates the overheating problems associated with

copper-wire electrical connections. No. 14 copper wire connections frequently

showed significant rises in temperatures and significantly increased power

losses when tightened to a torque of only 2 Ibf-in, as compared to nominally

tight connections (6 Ibf-in or more).

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

)

Branch circuits; duplex receptacles; electrical connections; power loss; temperatures;

thermocouples; wire.

18. AVAILABILITY [X Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

[ For Official Distribution. Do Not Release to NTlS

UNCL ASSIFIED 65

1

1 Order From Sup. of Doc, U.S. Government Printing " Washineton. D.C. 20402. SD Cat. No. C13Office 20. SE( URITY CLASS

(THIS PAGE)

22. Price

[")( ] Order From National Technical Information Service

Springfield, Virginia 22151 (NTlS)

UN( LASSIFIED $5.25

USCOMM.DC 29042-P74