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NBSIR 79-1913

NAT'L INST. OF STAND & TECH R.I.C.

AlllDS 0ME7m

Temperature Measurement on

Operating Recessed Lighting

Fixtures

P. Michael Fulcomer

Product Safety Technology Division

Center for Consumer Product Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D C. 20234

September 1979

Sponsored by:

Consumer Product Safety Commission

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*NBSIR 79-1913 G?CltOO # A TEMPERATURE MEASUREMENT ON *1'^

OPERATING RECESSED LIGHTING

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FIXTURES

P. Michael Fulcomer

Product Safety Technology Division

Center for Consumer Product Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D C. 20234

September 1979

Sponsored by:

Consumer Product Safety Commission

5401 Westbard Avenue

Bethesda, Maryland 20016

U S. department of COMMERCE, Juanita M. Kreps, Secretary

Luther H. Hodges, Jr., Under Secretary

Jordan J. Baruch. Assistant Secretary for Science and Tachnology

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director
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TEMPERATURE MEASUREMENT ON OPERATING

RECESSED LIGHTING FIXTURES

P. Michael Fulcaner

ABSTRACT

Potentially hazardous temperatures may result from adding thermal

insulation in the attic above recessed incandescent lighting fixtures. The

National Electric Code for 1978 specifies that . .thermal insulation

shall not be installed within three inches of a recessed fixture enclosure,

wiring compartment or ballast and shall not be so installed above the

fixture as to entrap heat and prevent the free circulation of air. . .”

The purpose of this investigation was to determine the effectiveness of

various protective barriers in maintaining the requisite three-inch spacing

and in preventing over-temperature conditions when loose-fill insulation is

installed around recessed lighting fixtures.

For the devices tested, the results indicate that properly installed

open-top barriers are sufficient to allow the fixture and associated branch

circuit wiring to operate within specified ratings. However, a barrier

closed at the top by any method, can cause branch circuit wiring, the

external surface of the barrier and/or parts of the fixture to operate at

temperatures above those designated as ’’safe".

Key Words: Recessed incandescent lighting fixture; thermal insulation;

hazardous temperatures; protective barrier; branch circuit

wiring; electrical junction box; load current; thermocouple.
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TEMPERATURE MEASUREMENT ON OPERATING

RECESSED LIGHTING FIXTURES

Introduction

Rising utility rates and the decreasing supply of available energy

have resulted in efforts to make both new and existing homes more energy

efficient. For many older homes, one of the most cost effective ways to

reduce energy consumption is to increase the depth of thermal insulation in

the attic. When energy was cheap and plentiful, the extra cost of

increased insulation was greater than the cost of energy saved over a considerable period of time, but this is no longer true. Accordingly,

insulation is now an attractive means of saving energy economically.

Unfortunately, the addition of thermal insulation over the electrical

wiring and lighting fixtures of older homes may cause problems related to

the safety of the household electrical system.

The Consumer Product Safety Commission (CPSC) is currently

investigating various aspects of this household electrical system safety

problem. This report is based upon work funded by CPSC to address one

facet of the problem. Potentially hazardous temperatures may result from

adding thermal insulation in the attic above recessed incandescent lighting

fixtures. The National Electrical Code (NEC) for 1978 specifies that

. .thermal insulation shall not be installed within three inches of a recessed fixture enclosure, wiring compartment or ballast and shall not be

so installed above the fixture as to entrap heat and prevent the free

circulation of air. . .” This study was concerned with the effectiveness

of various protective barriers in maintaining the requisite three-inch

spacing and in preventing over-temperature conditions when cellulose loosefill insulation is installed around recessed incandescent lighting

fixtures. A companion report, entitled Temperature Measurement on Operating Surface Mounted Lighting Fixtures, NBSIR79-1912, concerns

potentially hazardous temperatures which may result from adding thermal

insulation in the attic above surface mounted incandescent lighting

fixtures.

Test results presented herein indicate that properly installed opentop barriers are sufficient to allow recessed fixtures and associated

branch circuit wiring to operate within specified ratings. However, a barrier closed at the top by any method, can cause branch circuit wiring,

the external surface of the barrier and/or parts of the fixture to operate

above their rated ’’safe" temperatures.

General Method

To determine representative temperatures that occur in barrierprotected recessed lighting fixtures, three such fixtures were individually

installed in a controlled environment mock-up of a ceiling complete with an overlying attic section. Cellulose loose-fill insulation was placed in the

attic portion, but kept at least three inches away from hot surfaces of the
- 2 -

lighting fixture by one of three different barrier devices. Each lighting

fixture was tested with each of the three barrier devices. Temperatures

were recorded at various points on the barrier device, the fixture, the

fixture mounting hardware and on the fixture and supply wires.

The pertinent steady state temperatures obtained for each fixture are included in chart form with this report, along with dimensional diagrams

showing the relationship of each fixture to the barriers that were used

around it.

Test Assembly Description

The test assembly consists of a 4 foot by 4 foot section of 1/2 inch

sheet rock ceiling nailed to 2 X 6 inch wood joists spaced 16 inches on center. The lighting fixture was placed equidistant between joists in the

center of the test assembly using standard hardware. To reduce convective

heat loss due to higher than normal air flow in the laboratory, the test

assembly includes sides which extend 16 inches above the ceiling and 24

inches below the ceiling.

Supply wiring to the fixture is non-metallic sheath cable with two #14

copper conductors and a separate ground (type MM, 14-2 copper with ground).

Wiring is such that the cable carrying branch circuit current passes

through the junction box into which the light fixture is connected. The

method by which each fixture was connected into the branch circuit is

discussed in the following section.

Lighting Fixtures Description

Dimensional diagrams of the three lighting fixtures tested are shown

in figure 1. Fixture A is rated for a 150 watt lamp, fixture B for a 75

watt lamp and fixture C for a 100 watt lamp.

Fixtures A and C are prewired units which means that branch circuit

supply wire rated for 60°C can be (and was) connected directly into the

electrical box supplied as part of the fixture. Higher temperature fixture

wire connects this box to the lamp socket. Fixture B requires a separate

junction box (not supplied with the fixture) for connection to the branch

circuit supply wire.

For fixture A, the frame, electrical box, B (see figure 1), and lamp

socket assembly, S, form a permanently connected unit. The box is mounted

on the fixture frame with the floating socket assembly connected to the box

by a flexible metal cable through which the fixture wire runs. The frame

assembly contains a hole into which a separate reflector, R, is to be

inserted. This frame assembly is mounted above the ceiling over a hole

which matches the one in the frame. The socket assembly is then pushed

down through the hole and mounted on the reflector in either the high or

low position, and the reflector then pushed up into position above the

ceiling. A trim assembly (the glass bezel, louver or other enclosure

visible from below the ceiling) is then added below the reflector. The
- 3 -

reflector can be removed from the frame and interchanged with other

reflectors and trim assemblies designed to achieve a distinctive lighting

effect.

The maximum wattage lamp to be used in this fixture is specified

according to socket assembly position for certain reflector-trim

combinations. Access to the electric box is gained from below with the

reflector removed.

Preliminary tests were run on this fixture to determine the

combination of parts vrfiich produced the highest temperatures. This is

discussed further in the Results Section of this report. At this point it

suffices to say that the highest temperatures under rated conditions were

obtained with the socket mounted in its high position and a "pin-hole” trim

assembly attached into the reflector from the ceiling side. This trim

assembly has a blackened interior shield (not visible from below)

surrounding a two-inch diameter central hole through which the light is

emitted

The spacing between electric box and reflector in this fixture (see

figure 1) is insufficient to allow a barrier which is three-inches from the

reflector to pass between the box and the reflector. Thus, the electric

box must be located inside the barrier.

Fixture B is of a type generally known as a "high hat.JJ The box, B,

on top of this fixture is not intended for connection of 60°C rated

household supply wiring and such connection was not made for our tests.

However, if 60°C rated wire were connected into the box, B, contrary to the

installation instructions which accompany the fixture, this could result in

badly overheated supply wiring. (See the Results Section.)

Supply connections for fixture B were made in a separate junction box

located 18 inches from the fixture. Wire rated for 150°C was connected

from this box through a flexible metal conduit to a connection with lamp

socket fixture wire in the box, B, located above the reflector. Six feet

of the 150°C rated wire was supplied with the fixture, but the flexible

metal conduit was not. A piece of BX cable from which the original wires

had been removed was used. In order to replace the fixture, access to box

B is gained by releasing three retaining clips and pulling the fixture down

through the ceiling.

Fixture C is a prewired unit with connection between box B and lamp

socket S achieved with high temperature wire protected by a 3/8 inch

diameter rigid metal tube. The reflector R is removable for access to the

electrical box B from below. The lamp in this unit is mounted

horizontally.

The spacing from box to reflector for this fixture permits a barrier

three inches from the reflector to pass between the box and reflector.
- 4 -

Barrier Description

The three barriers tested, X, Y and Z, are commercially produced items

sold expressly for the purpose of keeping insulation at least three inches

away from recessed lighting fixtures.

Barrier X consists of four asbestos panels, 12 X 16 X 1/8 inches

thick, assembled with eight metal clips to form an open ended box. Either

the 12 inch or the 16 inch dimension can be placed vertically depending on how the box is put together, but the clips are so designed that 12 inch

vertical panels cannot be mixed with 16 inch vertical panels in the same

box. The clips will, however, permit shorter box dimensions than the panel

width (12 or 16 inches) by extending sides beyond the corners. (See

diagram B-X of figure 1.) This barrier is heavy enough to remain in place

without staples or tape.

Barrier Y is cut to size from a 14 inch wide by 24 foot long roll of

30 gauge aluminum which is a yellow color on the exterior side. Bending

locations are provided every two inches along the roll. Since two inches

of the overall height are designed as fold-out tabs for stapling or taping

the barrier in place, the finished height of the barrier is only 12 inches.

Six metal clips are supplied in a separate plastic bag, two of which are used to clip the cut ends together to form the barrier. Cutting can be

done with tin snips or a large pair of shears. The resulting edges are

sharp. This barrier has very little weight and must be taped or stapled in

place.

Barrier Z is a 26 gauge galvanized sheet metal box which comes in two

sizes. The smaller is 11 inches high and 14 1/2 inches square, while the

other is a rectangle 11 inches high, 14 1/2 inches wide and 20 inches long.

Barrier Z is made to fit over and completely enclose the recessed light

fixture. The box is heavy enough so that it need not be held in place by

staples or tape.

Barrier Installation

Although barrier Y was the easiest to customize to a particular

fixture, installation problems were encountered with each of the barriers.

Instructions which accompanied each barrier are reproduced in Appendix A.

Because of flexibility limitations with barrier X, the required three

inch spacing between the barrier and the light fixture enclosure could not

be achieved for either fixture A or C (see diagrams A-X and C-X of figure

1). This barrier will not fit between joists with its 16 inch dimension

horizontal and the barrier cannot be assembled with its sides of different

heights. The 1/8 inch thick asbestos panels are difficult, if not

dangerous, to cut, so that the barrier could be installed only with the 12

inch dimension horizontal. This dimension was not sufficient to provide

the required spacing except for fixture B.
- 5 -

Since barrier Y is relatively lightweight, it had to be stapled or

taped in placed to insure that barrier to fixture spacing would renain

constant. This was sometimes awkward, and always time consuming.

Barrier Z was sometimes difficult to install in between the joists

particularly where a supply wire happened to pass through a hole in the

joist in an area to be occupied by the barrier. In such instances, the

sides had to be bent inward to provide space for the supply wire.

Installation of any of the barriers requires the cutting of notches

for the supply wiring to pass through. Barrier Y is the easiest to cut,

but modification (notching) of all three models requires tools that

insulation installers may not normally carry. Barrier Y can be cut with

shears, but heavy duty tin snips are required to cut barrier Z. Small

sections of barrier X can be broken out with pliers or similar tools. If it

is not notched, barrier Z is the most likely to damage non-armored supply

wire because of the barrier weight and relatively sharp lower edge.

The location of the electrical junction box relative to the barrier is

not addressed in any of the installation instruction furnished with the

barriers. This is perhaps due to the fact that the National Electric Code

is rather ambiguous on this point. Section 370-19 of the 78 code states

that "junction, pull and outlet boxes shall be so installed that the wiring

contained in them can be rendered accessible without r^oving any part of

the building. . ." This probably does not preclude having to gain access

to the attic and then dig through whatever insulation is installed in order

to gain access to the fixture supply wire connectors. Some local

jurisdictions may have other requirements, of course. In any event,

placing the electrical junction box outside the barrier, as was necessary

when barrier X was used with fixture C, can present significant problems

should changing of the fixture subsequently become necessary or desirable.

Electrical connections are not available from below unless the barrier is

removed; once removed, the barrier would be extremely difficult (if not

impossible) to replace in its original location and yet have all the loose

fill insulation outside the barrier.

Once a barrier is installed, there is the practical problem of

introducing loose fill attic insulation without allowing the insulation to

fall inside the barrier or to completely bury it. In Northern latitudes

vrtiere insulation depths of up to 16 inches are recommended, the problem

could be particularly acute: the heights of barriers Y and Z are only 12

and 11 inches, respectively.

Insulation can be kept outside the barrier during insulation

installation by blocking the barrier top, but this blockage must be removed

when the job is finished. Access to the barriers will be difficult if the

joists, walking planks, etc. are buried under 8 to 10 inches or more of

loose fill insulation. One solution is to remove the lighting fixture

reflector and push the blocking cover off from below, but this requires

that non-electricians dismantle parts of the electrical lighting fixture.

This procedure will not succeed in removing insulation which gathers on top

of barrier Z.
- 6 -

Testing Procedures

Rated lamps were installed in each fixture. Lamp current and voltage

and branch circuit load current (if any) were monitored by means of

transducers connected into the test set-up. Supply voltage was initially

adjusted so that the particular lamp installed would dissipate the power

for which it was labeled. This adjusted voltage was then held constant by

an ac voltage regulator.

Each lighting fixture was tested with each of the three barrier

devices. In addition, the two pre-wired fixtures, A and C were tested both

with and without an external 15 ampere load on the branch circuit wiring.

This was done to determine what effect the added current might have on the

tCTiperature of branch circuit wiring which enters the fixture junction box.

Fixture 3 was not tested with an external load because the branch circuit

wiring was connected into a junction box located over 18 inches away from

the fixture and separated from it by thermal insulation.

Cellulose insulation meeting Federal Specification #HH-I-515C , Type 1,

Class 25, was installed in the attic to a depth of between 11 and 16 inches

depending on the height of the barrier device being used. Testing was done

with the barrier uncovered at the top and for one or two covered

conditions. Barriers X and Y were tested with cardboard over the top and

again with fiberglass batts equivalent to R22* over the top. The cardboard

used was 3/32 inch thick. Barrier Z was tested in two conditions: with no insulation covering its top metal surface and with 4 inches of cellulose

loose fill covering this surface. Both size configurations of barrier Z

were checked with fixture C to determine what effect box size has on the

various temperatures measured.

’/^en light fixtures and/or barrier devices had to be changed,

sufficient insulation was r^ioved with a large shop vacuum to allow the

exchange to take place. After the exchange was completed, the removed

insulation was replaced into the attic around the barrier.

Temperatures were recorded at various points on (1) the barrier

device, (2) the fixture, (3) the fixture mounting hardware, (4) the supply

wire and (5) the fixture wire by means of 30-gauge chromel-alumel

thermocouples connected to a programmable data logging device. The

thermocouples were held in place by teflon tape, .003 inches thick,

installed so that the thermocouple bead was in contact with the subject

surface and no more than partially covered by the tape.

The data logging device contained 40 input channels, 20 for each of

two simultaneous tests. Of the 20 channels, two were assigned to monitor

lamp voltage and current, one to record branch circuit load current in

excess of the lamp current, and the remaining 17 to monitor temperatures.

Three ac to dc transducers were used to change ac voltage and current

readings into the low voltage dc accepted by the data logger.

*Because of the limited time available for testing, two layers of available

R-11 insulation batts were used rather than waiting to obtain the specified

R-19.
Of the 17 temperature monitored points, six were located on the

barrier, four on the enclosed fixture, one in the electrical box, one at

the junction of fixture mounting hardware and the wood joists, one on the

lamp socket and three on the fixture and supply wires. One channel was

assigned to monitor ambient room temperature. Initially ambient

tonperature both above and below the test ceiling were monitored, but since

variation from room ambient was insignificant, one of the channels was

assigned elsewhere.

More precise information on thermocouple locations for each

fixture/barrier combination tested is included in the left hand column of

the data sheet for that fixture. The plan view locations of thermocouples

on each barrier are shown by small circles in the diagrams of figure 1.

Two or more thermocouples were often attached at the same horizontal

coordinates, on the barrier, but at different heights above the ceiling.

For this reason, most of the plan diagrams have only one or two places

marked on the barrier for thermocouple measuranents. Where more than one

horizontal location was used, a letter next to the circle in the plan

diagram corresponds to the same letter notation on the respective data

sheet to indicate horizontal position of the thermocouple on the barrier.

The data logging device was programmed to monitor voltage, currents,

and temperatures every 15 minutes. Each test wag continued until none of

the recorded temperatures changed by more than 1 C in 3 hours or until a reliable prediction could be made of the final steady state temperatures.

With open top barriers, tests that were started with all points at room

ambient required 2 to 3 hours before temperatures reached steady state

values. With barriers closed at the top by R22 insulation, this time

ranged from 6 to 9 hours.

A return to room ambient conditions was not always required between

tests. Tests proceeded without a cool-down cycle if temperatures in the

following test would be equal to or higher than those in the preceding

test. Examples of this are when an external 15 ampere load is added

without changing the barrier configuration, or when the barrier top is

covered following an open top test. A short cool down cycle was used when

a reduction of some temperatures might be expected under the new

conditions. An example of this is when a no load, cardboard covered

barrier test follows an uncovered test on the same barrier, but with a 15

ampere external load on the supply wiring. In this case, the decrease in

supply wire temperature when the load is ranoved may more than offset the

increase due to the cardboard over the barrier.

Results

The steady state temperatures recorded for each light fixture under

the various testing conditions are listed in tables 1, 2 and 3. Table 4 is

an extraction and compilation of this data to show temperatures at four

critical locations (one location is shown under two different conditions)

for each light fixture/barrier combination tested and for each of the
- 8 -

different barrier top conditions under the specified combination. All

listed temperatures have been corrected for an ambient of 20^C*.

Temperatures exceeding the limits specified for each location are circled

in table 4.

The four critical temperature locations noted in table 4 and the

limiting temperatures at each location are:

1. Outer surface of barrier device—90°C maximum. Section 410-65 (a)

of the 78 NEC states that "fixtures shall be so constructed or installed that adjacent combustible material will not be subjected

to temperatures in excess of 90 u."

2. Supply wire insulation—60°C maximum. Household branch circuit

wiring is normally of the type rated for 60^C. Since the

temperature of the wire increases if there is an external load on the branch circuit, both no load and load conditions were tested

and are recorded in table 4.

3. Fixture wire insulation—150 to 200°C maximum. Fixture wire is

normally rated for 150^C maximum and was so rated for fixtures B

and C. Fixture A uses wire rated for 200°C maximum.

4. Fixture enclosure—150°C maximum. According to the Underwriters’

Laboratory Standard for Safety for Electric Lighting Fixtures,

UL57, August 15, 1977, no point on the outsige of a recessed

lighting fixture enclosure should exceed 150 C in temperature.

The data contained in table 4 provides the basis for statements in the

Summary section.

Temperatures measured in the electric box mounted above the reflector

of fixture B did not exceed the rating of the fixture wire intended to be

used in this box. However, loss of, or failure to follow ^he light fixture

installation instructions could result in cgnnectiog of 60 C rated branch

circuit wiring into this box. Since the 99^ to 150^0 temperature^ recorded

in this box under various conditions of operation far exceed a 60 C wire

rating, such connection could result in very unsafe operating conditions.

Fixtures A and B, in addition to being tested under different barrier

conditions, were also tested under different fixture conditions for the

same barrier arrangement. This was part of an effort to determine a worst

case condition for each fixture. This information is included in tables 1

and 2, respectively.

Three variations were tried with fixture A. In one, the socket

assembly was placed in the "low'' position on the reflector while still

using a 150 watt lamp and pin hole trim assembly. The manufacturer's

»Room ambient temperature sometimes varied plus or minus a few degrees from

the desired 20^C. In such cases, this difference was either added (if the

ambient was less than 20^0, or subtracted (if the ambient was greater than

20®C) from the actual reading to arrive at the temperature listed in the table,
-9 -

catalog indicates that a lamp of 75 watts or less should be used under

these conditions. Temperatures on the mounting hardware and lower portions

of the open-topped barrier were about 6°C higher with the socket assemblymounted in the "low” position. Even though this configuration produced

slightly higher temperatures, it was not used in obtaining data for this

fixture because it represents an over-rated condition.

A second variation involved the use of a fresnel lens trim assembly

and associated reflector. This arrangement provided a closed assembly on

the bottom, but the reflector contained two 1/4 inch wide by 1-1/2 inches

long slots designed to accept the fresnel lens^mounting hardware. With an open top barrier, all temperatures were 1 to 2°C lower with the fresnel

lens assembly installed in place of the pin hole trim assembly. With a covering of R22 over the barrier, temperatures with the fresnel lens

assembly installed were 5 to lO^C lower than with the pin hole trim

assembly under similar conditions.

The third variation was conducted with a 150 watt reflective flood

lamp in place of the normal 150 watt lamp. This lowered temperatures at

all locations from 5 to 20°C with an open top barrier.

For fixture B, substitution of a 75 watt reflective flood in place of

the regular 75 watt lamp lowered temperatures on the open topped or

cardboard covered barrier about 3^0. Temperature decreases on the fixture

surface were much more dramatic, ranging from 15 to 20^C.

Summary

These test results indicate the following:

1. Properly installed open-topped barriers are effective in

maintaining the three inch spacing between thermal insulation

and the light fixture enclosure.

2. The three inch clearance requirements of the NEC, as provided by

the open-topped barriers, are sufficient to allow these fixtures

and associated branch circuit wiring to operate within their

specified temperature rating.

3. Barriers in which the air flow is restricted by covering the top can cause branch circuit wiring, and in some cases, fixture

wiring to operate above their rated "safe" temperatures.

4. The branch circuit wiring was always the first item to exceed

its rating.

5.

When a barrier is closed on top by a layer of insulation,

temperatures on the exterior surface of the barrier can exceed the

90x limit specified by the National Electric Code, and

temperatures on various parts of the fixture itself can exceed the
- 10 -

150*^C limit required by Underwriters' Laboratory Standard for

Safety for Electric Lighting Fixtures (UL-57).

6. Fixtures rated for and operated with lower wattage lamps provide a wider margin of safety than do fixtures rated for and operated

with high wattage lamps.

7. Significantly lower maximum temperatures are observed as the

volume enclosed by a barrier increases.

Comment

If limited to lower wattage fixtures (or to higher wattage fixtures

using less than rated lamps), closed top barriers not covered with

insulation could possibly provide safe operating conditions if: (1)

connecting branch circuit wiring were of a higher temperature rating, and

(2) the total volume enclosed by the barrier were larger. Increasing

barrier height is one method of achieving the latter; this would in turn

alleviate another potentially serious problem—the burying of the barrier

under insulation.
BARRIEf^

Z

CARRIER

Y

PARRIER

X

11

Inches

high

1?

Inches

high

16

Inches

high

RXTURE

A^ HXTURE RXTURE

C

• FIXTURES ARE MOUNTED EOUIOtSTAMT 8ETWEEN 2«« JOISTS.

• JOBTS ARE SPACED 18 INCHES ON CENTBt

• BRANCH CIRCUrr WIRING IS SHOWN ENTERING AND LEAVING SOX

FOR FIXTURES A AND C.

• THSWOCOUPLE LOCATIONS ON 8ARRIBI ARE SHOWN BY A CIRCLE AND ACCOMPANYING LETTER SYMBOL. THE SYMBOL IS USED IN THE DATA TABLES TO PROVIDE LOCATION INFORMATION.

Fiqure 1

Dimensional Diagrams of Each Lighting Fixture and of

the Various Light Fixture/Barrier Configurations Tested.
' „a ’ -'1 I'l'

^Ti 1 1 inir ^ ^ kiidBt.-,,rf

.-! '< zim V "^2

‘^- '

,

»»*.' »*i( ^

f ..A

i^ihruOk »«i Mwrwflii i»**'iJli«!'Mci,«rt^‘-^ •>** rntm^ •

i': «r"'^ "" .~r

'.rn* J»

'
TABLE 1. TEMPERATURE OATA FOR FIXTURE A Fixture rated for one 150 watt lamp with adjustable socket in "high" position.

I Temperatures in °C are- listed on the data sheet. Readings have been corrected for an ambient

I of 20°C. Too reading made with 15 amp additional load on supply wiring. Bottom reading made

I with no additional load.

Lamp

Trim

Socket Position

Barri er

150W Pinhole

High

X

150W 150W 150W 150W Flood 150W

Pinhole Fresnel lens Pinhole Pinhole

j Pinhole

Low High High High j High

X X Y Y 1

i

Z

Thermocouple

Location

1 Fixture Wire.

1/4 inch from socket

135 135 155

155

191 188 134 135

187

183 136 137 158 193 111 199

198 220

Socket. 139 157 193 189 141 217

i On metal cl ip 139 157 190 138 140 186 141 160 195 133 216 235

j Supply wire

49 87 118 107 51 111

i Inside junct. box

I 33 71 97 36 31 36 34 71 103 29 95 124

i Junction box, B

41 80 112 100 45 106

; Inside top center 33 73 101 36 31 39 35 73 106 30 97 128

j Supply cable casing

43 81 115 102 48 106

i 1/2 inch from box 31 70 97 31 30 87 31 70 103 29 93 123

j Socket housing, S . 153 99 161

! Outside top center 96 95 149 97 130 167 79 160 184

1 Socket housing, S . 92 125 161 150 161 Outside side center

1 92 124 159 91 90 146 91 123 158 74 160 184

j Reflector, R, exterior. 86 102 136 127 88 148

Side, 2 inches up 36 101 134 94 77 123 38 104 138 59 147 170

Barrier: 118 111 72

top center 114 108 73 128 71 146

outside 34 73 107 99 32 (R)* (R)- 78 (R)*

j 10 inches up 33 72 105 37 33 97 33 76 114 27 77 129

• outside 36 (F) (F) 84 (F)

j 6 inches up 34 77 111 30 33 123

; outside 39 74 105 95 38 (R) (R) 87 (R)

' 3 inches up 38 74 101 44 36 92 36 76 107 29 35 116

1 inside 40 77 109 98 38 R) (R) 92 (R) ! 3 inches up 39 77 104 44 37 93 37 77 109 30 90 124 j outside 40 71 101 92 36 (F) (FJ 33 (F)

1 inch up 38 72 98 44 36 38 34 75 99 29 32 113

, Mounting hardware. —35 49 69 63 32

' June, of joist 4 strap 34 51 67 40 34 60 32 49 66 28 31 104

Exposed trim. 97 77 117

1 At ceiling 114

' 73 94 77 98 55 117 129

' Ambient room 21 21 22 20 20 21

i

1 20 23 21 21 20 21 19 19 20 19 20 20

*Latters in parenthesis indicate barrier thermocouple locations on corresponding diagrams

(A-Y and A-Z) of figure 1.
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TABLE 2. TO-IPERATURE DATA FOR FIXTURE 8 Fixture rated for one 75 watt lamp

\

\

Temperatures in °C are listed on the data sheet. Readings have been corrected for an ambient

of 20^C. Readings made with no additional load on supply wiring.

Lamp

Trim

Barri er

C

o

O

Thermocouple

Locati on 2

75W Louver

X

-oo c -a

<u w

Or rfl O

4-» (9

CSJ CM

75W Ref. Flood Louver

X

-a

fOO <9 C: T3

<uCi. s-NJ 0 0 2^

75W Louver

Y

rsW

(9O

sr -o

<u ^

O. <9 O cj R22

batt

75W Louver

Z

(9as

OJ

<9 ca

<u 4^

<D O s

O

f— i.

<U = >

o

Fixture wire.

1/4. inch from socket 95 113 126 77 91 96 115 149 131 145

Socket.

On metal clip 102 116 130 79 92 102 119 153 138 151

i Fixture box, B. Inside on reflector top 99 113 127 74 86 99 116 152 137 150

j Fixture wire casing.

j 1/2" outside barrier 27 42 51 26 41 28 42 66 46 58

j Fixture box, B.

I Outside, top center 60 86 101 50 71 60 88 125 99 116

1 Fixture box, 8.

1 Outside, side canter 67 89 103 53 73 67 92 128 105 120

1 Reflector, R, exterior.

j Side, 4 inches up 93 107 122 68 31 94 111 147 131 146

1 .Reflector, R, exterior.

Side, 2 inches up 85 99 113 65 77 89 104 140 127 139

1 Barrier:

1 top center 54 83 50 58 113 54 96

i outside

i 10 inches up

1 (R)^' 31 56 74 (R)* 30 52 (R)* 30 60 101 (R)’* 53 87

outside 1

1 6 inches up

1 (F) 32 58 74 (F) 29 55 (F) 32 59 98 (F) 57 33 1 outside

i

t 3 inches up (R) 37 59 74 (R) 34 55 (R) 35 58 93 (R) 56

! inside

i

i

• 3 inches up (R) 38 50 75 (R) 34 56 (R) 35 59 95 (R) 59 81 1

I outside \

I 1 inch up (F) 33 55 69 (F) 29 57 (F) 32 53 84 (F) 55 75 !

1

j Mounting hardware

1

1

1 June, of joist S strap 29 37 44 28 38 30 41 59 53 67 !

[ Exposed trim.

j at ceiling 70 76 37 61 67 70 79 no 105 117

i

j Ambient room 19 19 20 19 20 20 20 20 20 21 i

*Latters in parenthesis indicate barrier thermocouple locations on the corresponding diagrams

{3-X, 8-Y and S-Z) of figure 1.
(: f ajiutxn jw KfK anuTAflJw ,t sjarr

I I I III ;

i)« .

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ae-; -1*1_-. ;

’ ^'*
TABLE 3. TEMPERATURE DATA FOR FIXTURE C Fixture rated for one 100 watt lamp"

Temperatures in °C are listed

20°C. Top reading made with

additional load.

on the data sheet. Readings have been corrected for an ambient

additional 15 amp load on supply wiring, bottom reading made with

3fno

Lamp

Trim

Box Location

Barrier

c-o

o

H- -O

C- Thermocouple ^

Location

.

lOOW

Flat White Glass

Outside Barrier

X

-o

<T3 4^ O ^ ^ A

<U 1. evi a. 'O <^J O O Qi

lOOW

Flat White Glass

Inside Barrier

Y

*oS. 4^

4^ o

c- *a

oj u c\j i C\4 O CJ

lOOW

Flat White Glass

Inside Barrier

Z

<13 4-» -M

1) fjy (V “ O

*

0) s- ^ CJ 2 >

cQ o

lOOW

' Flat White Glass

Outside Barrier

Z

ft3 (13

<U c/1 <U S OSo

oj i- W OJ

fO = >

ca ^ o

Fixture Wire, 76 93 115 72 92 113 ! 103 118 107 125 1/4 inch from socket 76 92 114 72 92 in

1 103 115 108 123

Socket. 83 101 121 80 99 119 j 109 124 114 130

On metal clip 33 100 120 80 99 117i 109 121 114 129

Supply wire. 63 75 90 41 70 95 79 99 86 100 Inside junct. box 32 45 59 26 52 74 62 78 55 67

Junction box, B. 52 65 31 31 60 87

! 69 89 74 39 Inside top center 33 47 61 26 53 76 63 80 53 70

Supply cable casing. * 38 65 90 74 94 81 94 j 1/2 inch from box - - - 25 51 73 61 77 53 63

[ Socket housing, S. 53 76 101 47 72 97 84 102 90 no

Outside top center 53 75 100 48 72 94 33 97 90 108

Reflector, R, exterior. 88 114 136 89 113 135 124 139 129 145 : Top center 90 113 135 90 113 133 125 136 129 145 i

Reflector, R, exterior. 66 85 107 65 84 106 97 112 101 119 1 Side, 2 inches up 66 84 106 65 85 103 97 109 102 118 i

1 Barrier; 56 101 59 94 52 97 56 104

top center - 55 100 - 58 80 52 92 56 102 !

1 outside 32 62 92 27 55 84 56 75 58 96 1 10 inches up

lUJ 31 60 39 ( R) 27 54 79 ( R) 55 70 [Q) 59 94 1

outside 38 64 89 31 56 31 55 77 61 38 i 3 inches up

1 LJ 37 63 87

(.r) 31 56 73

In)

55 73

(.b) 62 35

outside ( n \ 40 68 93 30 55 80 58 79 70 94

3 inches up 38 65 90 l R) 29 55 77 1 R) 56 74 Iw) 69 91

inside 39 68 94 ( Q\ 31 57 32 ( 0^ 61 82 { r\\ 73 97

3 inches up

I WJ 38 65 91 \ R)

31 56 79 [ R) 60 77 I j) 72 94

outside 42 66 89 { c\ 31 53 75 51 34 72 94

1 inch up

10) 38 62 85 1 r)

31 53 72 [ R) 50 80 [Ql 70 90

Mounting hardware. 32 46 62 31 48 65 56 71 64 30 June, of joist & strap 32 46 61 31 48 64 56 67 64 81

Exposed trim. 39 41 51 41 42 54 55 62 58 66 At ceiling 40 40 51 41 43 53 55 60 59 65

Ambient room. 21 20 21 20 20 20 20 20 20 20

1 20 20 21 19 19 19 18 20 19 19

'Letters in parenthesis indicate barrier thermocouple locations on the corresponding diagrams

(C-X, C-Y , C-Za and C-Zb) of figure 1.
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table 4. EXTRACTION AND COMPILATION OF CRITICAL

TEMPERATURE DATA FROM TABLES 1 , 2 AND 3

Pass/Fail judgements in the table are- made on the ability of

a barrier to prevent excessive temperatures when used with a specific light fixture.

Temperatures in *^C listed in table.

Circled readings are above the maximum specified for that

point (see text).

Fixture A 150W rating

vertical lamp

150W

Fixture B 75W rating

vertical lamp

75W

Fixture C lOOW rating

horizontal lamp

lOOW

On

Barrier

(max)

Supply

Wire

-

No

Load

Supply

Wire

-

15A

Load

Fixture

Wire

On

Mousing

(max)

On

Barrier

(max)

Supply

Wire

-

No

Load

Supply

Wire

-

15A

Load

fixture

Wire

On

Mousing

(max)

1

On

Barrier

(max)

Supply

Wire

-

No

Load

Supply

Wire

-

15A

Load

Fixture

Wire

On

Mousing

(max)

! Barrier

C (/> QJ C

3 /T3 o

Si ^ —

Top Covering

!

i Open

Pass

38 33 49 135 92

Pass

37 99* - 95 93 Pass

38 32 63 76 90

1 X

i

1

3/8 inch

cardboard 74 (0) 155 124 Pass

59 113* - 113 107 65 45(^^^92 113

R22 fiberglass

batt

Pass

74 127* - 126 122 59 114 135

1

1

;

;

1 Y

1

I

Open

Pass

36 34 51 137 97 Pass

35 99* - 96 94 Pass31 26 41 72 90

3/8 inch

cardboard 77 @(^^ 158 130 Pass

60 116* - 115 111 56 52 (^' 92 113

j

i R22 fiberglass

batt (Q@(^’i93 (@

^ Fail (l^ 152* - 149 147 79 111 133

1

i z

1

I (Electric Box

! Inside)

Bare metal

85 @^1 98 (@)

Pass

57 137* - 131 131 56 (^(^^103 125

4 inches loose

fi 1 1 over metal ^ Fail (^ 150* - 145 146 :^0)(^^115 136

Z

i (Electric Box

; Outside)

!

]

Bare metal

70 55 (^^08 129

4 inches loose

fil 1 over metal

\

i :^'(^<^^123 145

*These temperatures were measured in the box on top of this fixture. If supply wire rated for 50°C is brought into this box, an "above specification" condition will result.
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3ARRIEJ5 X: INSTRUCTIONS

SmPlE^ FAST mSTAULAHOU

StartassemblV'by’attactiingadjust^ Clip panel*^

tp panels i*2z a» Clip panel; #4)a&illustratedl abl^metal clip. of panel ConnecT iilustrateP.

112. paneK wim secondrclips Clip, top

and bottom* of panels*.

Score- and notcfr i panel to accept

wiring.

Side panels ar» adjustable- to maintain- 3” code; clearance: Insulation carr be: blown around panels to required. R-Valua (up. to: 16" of material).Protect other heat sourcesrsucfr a»

furnace flues.
.«» 9« msm «» a>i «im«m) «oK) ¥» •fi^mumurti

^‘- ' .aif'utMW rMnn^

US' •'^i-'^ <od JflO <qlte»/<aw tmw 4wwaJ>
BARRIER Y INSTRUCTIONS

Installation Instructions

Measure too iignt fixture nousing. tnen cnecK taoie at ngm tor lengtti ot material neeoea. unroll, and using measuring rule, cut to lengtrr.

Witti yellow side taang you; Oend taos out to form case. form inieid to fit fixture. <eeoing unit T from light fixture an all sides."

Overiao enos and fasten

with enclosed Clio. Send overiao

at Clio to secure.

Place snield over light. Cut ooening in case tor electric caoie with surticienr clearance.

Secure Oase with 3/8* staoles. taoe. or adhesive. Caver too

of -nieid and insulate surrounding proteaed fixture. Remove covering.

Make sure "'EARNING"

sticker is Clearly Visible.

How to determine

length

for Square or Rectangular Fixtures

FIXTURE LENGTH FIXTURE LENGTH MEASUREMENTS HEEDED MEASUREMENTS HEEDED

s-xe* 50* 3'xr 56" 6*xr 52" a'xs” 58" s'xa* 54' 3'x9' 60* 6*x9" 56" 8'xlO' 6r

5'x 1(T S3' 8'x 11' 64' Txr 54' 9'x9' 52*

Rinmila (o dnennlfra the length for guard needed:

(1) Add the measurement of 2 adjoining sides

(2) Multiply this sum by 2 and add 26 inches. EXAMPLE — A box 6" X 8* requires a 54 inch guard'

(1) 6'*3* = 14-

(2) 14-x2=28'> 26' =

54-

RECOMMENOEO GUARD LENGTH FOR ROUND FIXTURES

DIAMETER

OF FIXTURE GUARD SIZE

4" 32'

5" 36'

6* 38" T 4r

8' 44'

9’ 48'

"NOTB. It the liqm is unfler a root truss, or against ttie lloor loist you may

nave to cut sections of me snieid ano oend to aiiow me ooard to gass tnrougti the snieid.
iMtIm Y^tobot woH

rt^fi»{

wan^ *ww^ i »T*(i< mfm

*rs» xrigimkim iasa*

V n»-» 1

»<?

*KV

•» Tr«-» le

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'

' ' '

fit

AMurM oMSiv m^vrniL' SMi'e timlinipv

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. -V « T >

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*1* 1 51^1*
barrier z instructions

I

j

1 side 1 side- Z

3TEF I

Send long sneets

at notches^.

STEP Z

Turn box Uprignt .

STEP 3 ATTACH side I by Pushing down

corner at point A

umii locked.

PUSH DOWN AT

POINT A.

STEP 4- TA? edge of side I into Channel from

point A to point 3. Cent i.tue tapping

to ooinfs C end 0

TAP

STEP 5 Turn box over ond

continue with side Z

os in step 3 and 4-

side Z
,. .^T—MK-l’TM- .. ..X7X1W.KIMIII J1-.4,. . »k Hi: ill *1 . ,J^

wcrfjuniiu J-TO«M»iv.r .' ' «^ ‘.v,»^. i J,

'pr

'.;' '

•'

j» »

I- • ,v
U.s. DEPT. OF COMM.

bibliographic data

SHEET

1. PUBLICATION OR REPORT NO. NBSIR79-1913

4. TITLE AND SUBTITLE

Temperature Measurement on Operating

Recessed Lighting Fixtures

5« fecijstertfj No.

5. Publication Date September 1979

7. AUTHOR(S)

p. Michael Ful comer

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS fsrreer, City, St^te, ZIP)

Consumer Product Safety Commission

5401 Westbard Avenue

Bethesda, Maryland 20016

13. Type of Report & Period Covered

15. SUPPLEMENTARY NOTES

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

16. ABSTRACT (A 200-word or leaa {actual aummary o{ moat aignificant information. If document includes a significant bibliography or

literoture survey, mention it here,)

Potentially hazardous temperatures may result from adding thermal insulation in

the attic above recessed incandescent lighting fixtures. The National Electric

Code for 1 978 specifies that ". . .thermal insulation shall not be installed within

three inches of a recessed fixture enclosure, wiring compartment or ballast and

shall not be so installed above the fixture as to entrap heat and prevent the free

circulation of air. . ." The purpose of this investigation was to determine the

effectiveness of various protective barriers in maintaining the requisite threeinch spacing and in preventing over-temperature conditions when loose-fill

insulation is installed around recessed lighting fixtures.

For the devices tested, the results indicate that properly installed open-top

barriers are sufficient to allow the fixture and associated branch circuit wiring

to operate within specified ratings. However, a barrier closed at the top by any

method, can cause branch circuit wiring, the external surface of the barrier

and/or parts of the fixture to operate at temperatures above those designated

as "safe".

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)

Recessed incandescent lighting fixture; thermal insulation; hazardous temperatures

;

protective barrier; branch circuit wiring; electrical junction box; load current;

thermocoupl e.

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16. availability Unlimited C For Official Distribution. Do Not Release to NTIS m Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003- ^ Order From National Technical Information Service (NTIS), Springfield,

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