fact finding report on power over local area network type cables

Issued: September 25, 2015

Copyright © 2015 UL LLC of 164 Copyright © 2015 SPI: The Plastics Industry Trade Association 20150930

Fact Finding Report

on

Power over Local Area Network Type Cables (4-Pair Data / Communications Cables)

<with errata 1 revisions>

SPI: the plastics industry trade association Washington, DC

Fact-Finding Investigations are undertaken to develop facts and issue a Report for use

by the Applicant in seeking amendments in nationally recognized installation codes and

standards. The issuance of this Report does not constitute an endorsement of any

proposed amendment and in no way implies Listing, Classification or other recognition

by UL and does not authorize the use of UL Listing or Classification Marks or any other

reference to Underwriters Laboratories Inc. on, or in connection with, the product.

UL LLC, its employees, and its agents shall not be responsible to anyone for the use or

nonuse of the information contained in this Report, and shall not incur any obligation or

liability for damages, including consequential damages, arising out of or in connection

with the use of, or inability to use, the information contained in this Report.

UL LLC authorizes the above named company to reproduce this Report

provided it is reproduced in its entirety.



Contents INTRODUCTION ............................................................................................................. 3

GENERAL ................................................................................................................... 3

OBJECTIVES .............................................................................................................. 4

DISCUSSION .............................................................................................................. 4

PLAN OF INVESTIGATION ............................................................................................ 6

General ........................................................................................................................ 6

Samples ....................................................................................................................... 6

General Test Conditions .............................................................................................. 7

TEST EQUIPMENT AND SET-UP ................................................................................ 10

TEST DATA .................................................................................................................. 13

Thermal Response to Current ................................................................................... 13

Specific Conductor Ampacities for Cables in a Bundle .............................................. 15

Configurations where only ½ of the Conductors are Powered ................................... 23

Effects of Current ....................................................................................................... 27

Different Installation Methods .................................................................................... 28

Enclosing Cables ....................................................................................................... 30

Installation Orientation ............................................................................................... 32

Firestop ...................................................................................................................... 34

Cable Comparisons ................................................................................................... 38

Cable Configurations ................................................................................................. 40

LP Cables .................................................................................................................. 41

LP CABLE REQUIREMENTS .................................................................................... 42

SUMMARY .................................................................................................................... 43

APPENDIX A - CABLE DETAILS .................................................................................. 44

APPENDIX B - TEMPERATURE TEST DATA .............................................................. 92

APPENDIX C - DATA for NEC TABLES ..................................................................... 146

APPENDIX D - CABLE HEATING TEST ..................................................................... 163



INTRODUCTION

GENERAL

The following is a report on the heating effects of dc current on 4-pair local area network (LAN) cabling when configured in various bundle sizes and simulated installation conditions. Typically these cables are 4-pair “Category” type cables originally designed and intended for the transmission of data and communications. However, changes in technologies and equipment design have resulted in these cables increasingly being used to provide low voltage (<60 Vdc), limited power along with the data and communications signals. Power levels have been steadily increasing and are expected to continue to do so. In addition, these cables are often installed in bundles where cumulative heating effect of the numerous cables in the bundle combined with limited heat dissipation for the cables buried inside of the bundle raise concerns about exceeding the temperature ratings of the cable. The current (2014) version of the National Electrical Code (NEC), NFPA 70, covers data

and communications circuits in Articles 725 and Chapter 8 respectively. Article 725

references Table 11(B), Class 2 and Class 3 Direct-Current Power Source Limitations,

for power and current limitations on these circuits. Chapter 8 contains no specific

requirements or references on power or current limitations on these circuits. Existing

data from a number of sources has suggested that the present current limits in the NEC,

where they exist, are too high for these cabling systems and the way they are deployed.

As part of the revision cycle for the 2017 National Electrical Code (NEC), public inputs

were received related to remote powering over local area networking cable. The public

inputs suggested that the existing Class 2 limits in Table 11B of the NEC permitted

maximum currents that could result in the overheating of cables and recommended

adding ampacity limitations for these applications based on wire size (AWG) and bundle

size. In addition, the public inputs suggested that special cable designs could be

developed and that might be used as alternatives to more traditional cables and AWG

size alone with less restrictions on cable designs and the installations.

These public inputs resulted in proposed first revisions for the NEC that include

requirements for limiting the power and conductor ampacities of powering over

communications cable systems based on wire gauges and bundle sizes. In addition, a

provision was included for special cables (“LP” cables) that could be used as



alternatives to more traditional cables that would allow for innovative cable designs and

less restrictions on the installations.

At the time of the development of the proposed first revisions, there was very little hard

data to support the inclusion of comprehensive ampacity tables. As a result, the

proposed ampacity table only included single cables and multi-cable bundles. In

addition, although “LP” cables were included as alternatives to traditional cables, there

were no listing requirements for “LP” cables or listed “LP” cables. To support the

development of more comprehensive ampacity tables and the development of listing

criteria for “LP” cables, the industry commissioned UL to conduct a fact-finding

investigation to develop data to support these objectives.

OBJECTIVES

1) Develop data to support changes to the National Electrical Code (NEC),

NFPA70, (Articles 840 and 725)

2) Development of requirements for the listing of LP cable

3) Determine what parameters affect a cable’s ability to handle current in a bundle.

a. What effect does Wire Gauge Have on Cable Heating?

b. What effect does Cable Construction Have on Cable Heating?

c. What effects do Cable Construction Materials Have on Cable Heating?

4) Determine the effects of different installations (i.e. bundle size, routing,

enclosing) on cable heating.

a. What effect does the installation have on cable heating

b. Assess the worst case installation scenarios and what conditions have the

most heat rise.

5) Investigate the combined effects of higher levels of power applied over

communications cables under typical installation practices permitted by the NEC

DISCUSSION

Powering over LAN Cable systems provide both data and power in one cable, usually

connected through an RJ45 style 8-pin connector. It encompasses any one of a number

of standardized and proprietary systems that provide data and power to low power

demand devices such as IP telephones, wireless access points, or IP cameras.

Low power systems are usually configured in a 2-pair powering configuration while

“higher” power systems (still power limited) may require a 4-pair powering scheme.



On systems where data utilizes only 2-pairs, a 2-pair powering scheme may be carried

on the unused cable pairs or on the same conductors as the data.

2-pair (4-wire) Powering Configurations:

On higher data capacity systems, where all 4 pairs are needed for data transmission

speed, power is carried on the same -pairs as the data in either a 2-pair or 4-pair

powering scheme.

2-Pair (4-wire) and 4-Pair (8-wire) Powering Configurations

As can be seen from these circuit diagrams, the present state of implementation is to

utilize two pairs of conductors for each power circuit. This is true whether the system

applies the power to the unused conductors of a cable or applies a common-mode

voltage to the data pairs. This means that for a given circuit, the current in the circuit is

carried by two conductors and therefore the current for the circuit is halved for each

individual conductor.

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCPfg9fH_2scCFUMSkgodl1gLSg&url=http://www.edaboard.com/thread284927.html&psig=AFQjCNElVXe2iMzJ6rVNGEo1XtE5iIDEFQ&ust=1441374288309655

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCO79rYGA28cCFcsWkgod1QgCZg&url=http://www.edaboard.com/thread284927.html&psig=AFQjCNElVXe2iMzJ6rVNGEo1XtE5iIDEFQ&ust=1441374288309655



PLAN OF INVESTIGATION

General

Several possible investigation plans were considered. The first involved selecting a number of installation configurations considered to be representative of both typical installations and worst-case heating. This would be based on data already circulating on this subject. Different cable types would be tested in the various configurations. The second approach would concentrate on installation configurations, testing a wider variety of configurations using a single cable type. The results of these tests could then be used to determine a much narrower set of useful test configurations that could be used to test other cable types. Since this second approach would yield hard data that not only better supports the final test configurations but would also provide valuable data to support the NEC proposals related to powering over LAN cable, this is the approach that was chosen.

Samples

There were six distinct types of LAN cables tested as part of this investigation. Sample No. Description

1 CAT 5E 24AWG UTP (YELLOW)

2 CAT 5E 26AWG STRANDED FTP SHIELDED

PATCH (LT Grey)

3 CAT 6 23AWG UTP RISER CMR (Blue)

4 CAT 6 23AWG UTP PLENUM CMP (White, Pink)

5 CAT 6 22AWG UTP PLENUM CMP (Blue)

6 CAT 6A 23AWG SHIELDED PLENUM (Dark Grey)

These cables were selected to:

Include the lightest and heaviest wire gauges

Include different diameters which will affect the thermal characteristics Refer to Appendix A for detailed cable descriptions.



General Test Conditions

Thermocouples

Thermocouples would be placed on the cable jacket at various positions along the cable bundle length and at various depths in the tray or bundle. For example (from CENELEC TR 50174-99-1):

In addition, a TC would be placed on an individual insulated conductor inside of the center cable. This arrangement shall provide us with the following:

Hard data showing where the greatest heating takes place

A thermal profile along the length of the cable showing where the “end effect” becomes a concern (i.e. how close to the end shall the added radiating surface area significantly affect the results?).

Data showing if the individual wire insulation is subjected to higher temperatures than the overall cable jacket.

Current

The present implementations of powering over LAN cable utilize two 2-pair wires for each powering circuit.

As a result, test conditions are often reported as having some amperes per pair. However, in the power world, power is often considered to be delivered over a single “pair” of wires; the “+” conductor and the “-” conductor.



This has led to some confusion of whether the specified current for a test is on two pairs of conductors with each conductor carrying ½ the current or on a single pair of conductors with each conductor carrying the specified current. The NEC proposals deal with power per circuit and amperes per conductor. Amperage designations would utilize amperes per conductor to avoid any confusion. This can easily be converted to any implementation later as needed. Since the original PoE specification used 175 mA/conductor, testing would be conducted starting at this current just as a benchmark. The next implementation of PoE is expected to be in the range of 60 watts which translates to 0.3 amperes per conductor so this would be another desirable data point. After that steps of 0.5 amperes per conductor and 1.0 amperes per conductor were discussed. To accommodate future technologies, the NEC is proposing Class 2 limits that would permit up to 1.6 amperes per conductor at 60 volts. However, since the NEC Class 2 current limits are based on a power limit of 100 watts and the current limits are defined as 100/V for voltages between 20-60 Vdc, the maximum permissible current changes based on the circuit voltage. Although it is expected that higher voltages would be more desirable from a loss standpoint, there could be reasons why lower voltages might be considered. For example, there is a lot of available equipment and components available for 48Vdc because of its usage in telecommunications. With these systems, the minimum operating voltage would be 40V. As a result of the above, the plan was to test each configuration over a range of 0.5 amperes to 2.5 amperes at .25 ampere increments with the addition of the original 175 mA as a reference point that might be useful for comparing results with testing already performed by others. The same test sample would be used and the current increased after temperature stabilization without shutting the test down. This is to avoid going back down to ambient temperature for every amperage setting tested, per this example.



Test Configurations

Bundle sizes were selected based on the hexagonal densest packing structure. This

has been shown to yield the hottest temperatures due to cable density and the fact that

with this structure each new layer completely encloses the previous layer trapping heat.

This structure is characterized by the following number of cables in a bundle:

Where:

N is the total number of cables in the hexagonally densest packing structure;

n is the number of layers, surrounding the center cable. This results in N= 1, 7, 19, 37, 61, 91, 127, ....

At the high end, a bundle size of 192 was selected. This was based on 8 bundles of 24

cables that is typical of cabling coming off a server frame and considered a reasonable

worse-case bundle size.

In addition to open bundles, additional configurations were considered:

Bundles in conduit with and without fire stop

Cables in an open wire mesh rack

Cables in a closed cable tray with and without fire stop

Closed Cable tray with fire stop. The Category 5e, 24 AWG would be used for the installation configuration testing after which the other types of cables would be tested.



TEST EQUIPMENT AND SET-UP

Test Fixtures

Test fixtures used to mount the cable bundles were constructed out of 2” schedule 40 PVC pipe.

Parachute cord was used to support the cable bundles to minimize any heat-sinking effects.

Data Acquisition

Temperature and current were measured using Agilent data acquisition / switch units and a laptop PC with suitable data acquisition software. This photo shows the typical test set-up with a laptop, Agilent data acquisition unit, precision shunt resistor and power supply. The handheld meter is just used for continuity checks.

Agilent



Model # 34972A LXI Data Acquisition / Switch Unit

Agilent Model # 34970A Data Acquisition / Switch Unit

Power sources

Constant Current power supplies: VOLTEQ Model # HY30005EX Maximum DC voltage of 300V and 5A, and maximum DC power of 1500W

BK Precision Model # 1685 B 1-60V, 5A Switching DC Power Supply

Measuring Current

Current measurements were made via measuring the voltage across a calibrated precision shunt resistor with the Agilent data acquisition units.



Wiring Diagram Examples

For larger bundles where the total dc resistance of the cables exceeded the power source’s ability to drive the necessary current, multiple power sources were used. The cables in the bundle were electrically divided such that the dc resistance of each set of layers would not exceed the power source’s ability to deliver the necessary current through the conductors.



TEST DATA

Thermal Response to Current

The data shows that as the current per conductor increases, the measured temperature

on the cable increases. This is an example of the measured temperature data.

Refer to Appendix B for the complete set of temperature data.

Here is some information on how to interpret the data.



The data shows that increases in the number of cables in a bundle resulted in increases

in measured temperatures. This chart shows and example of how the temperatures

increase with increasing bundle size for a Cat 5e, 24 AWG cable.



Specific Conductor Ampacities for Cables in a Bundle

The data shows that overheating does not occur at 175 mA per conductor (35 watts)

regardless of the cable type, bundle size or installation method. This represents existing

implementations of powering, such as PoE and PoE+. This is clearly shown in the

accompanying chart that shows the temperature rise for a wide variety of scenarios

tested at 175mA. Overheating does not occur even if the data is corrected for a 30oC

ambient or a 45oC ambient.

The data also shows that overheating does not generally occur at 0.3 amperes per

conductor (60 watts) which represents some of the newer higher power systems. This is

clearly shown in the accompanying chart that shows the temperature rise for a wide

variety of scenarios tested at 0.3 amperes per conductor. Overheating does not occur

even if the data is corrected for a 30oC ambient or a 45oC ambient.

Even under extreme installation conditions using 576 cables very tightly packed into an

open wire cable tray it can be calculated that a 30 degrees C rise would not occur until

the current reached 0.303 amperes.

y = 321.64x2 + 3.1692x - 0.4149; For y = 30 (oC), x = 0.303 Amperes



However, once the power goes up to the 100 watt powering range, or about 0.5

amperes per conductor, the data shows that under many installation conditions,

overheating occurs. Only a combination of smaller bundle sizes, larger wire gauges and

specialty constructions do not overheat when ambient conditions of 30oC or 45oC are

considered. This is shown in the accompanying chart that shows the temperature rise

for a wide variety of scenarios tested at 0.5 amperes per conductor. Overheating occurs

even if the data is not corrected for a 30oC ambient or a 45oC ambient.

There are systems available and more under consideration that are providing 4-pair

powering of up to 200 watts or about 1 ampere per conductor. The data shows that for a

significant number of installation conditions and cable types, cables will overheat at 1

ampere per conductor. This is shown in the accompanying chart that shows the

temperature rise for a wide variety of scenarios tested at 1 ampere per conductor.

Overheating occurs even if the data is not corrected for a 30oC ambient or a 45oC

ambient.



In order to gather data for the development of a more detailed ampacity table for the

proposed Table 840.160(C) in the NEC first revision, testing was conducted using

cables with various AWG wire sizes configured in different size bundles. Bundle sizes

were selected based on the hexagonal densest packing structure previously described.

The bundles were enclosed in conduit representing a worst-case installation condition.

Temperatures were recorded at various current levels. In all but a few cases1 at least 4

data points were recorded for each wire gauge and bundle size and used to establish

best-fit polynomial trendline curves such as these examples.

The curves permit the identification of the current that would yield a particular

temperature. A complete set of these data graphs is provided in Appendix C.

For accuracy, rather than visually use the graphs to determine the current value, the

formula for the best-fit polynomial trendline is used with an iterative methodology to

solve for “x” at a temperature “y” of 30oC, 45oC and 60oC, representing 60, 75 and 90oC

cables. An example of the resulting table is shown below.

In this example, the “Best-fit Formula (Enclosed)”row contains the actual “y” values

generated by the formula for the curves using the “Amperes” as the “x” value. The

objective is to get as close as reasonably possible to the target temperatures. For the

19 cable bundle the best fit formula is y = 39.857x2 + 4.1207x + 0.3159. By adjusting the

1 In a few cases then cable failed (insulation melted) before accurate stabilized data could be obtained for

a particular AWG/bundle configuration. These are noted in the graphs associated with these cases.



current “x” to 0.813 amperes, we get very close to the target temperature of 30oC

(30.0103) indicating that based on the data and the resulting curve, a current of 0.813

amperes would result in a temperature rise of 30oC for the cable.

The notation “R2” on the plots is a statistical measure of how close the data are to the

fitted trendline. When you have a scatterplot of data, and try to fit a line/curve to the

data, the "measure of goodness" for the fit is reflected in the R2 value. An R2 value of 1

is a perfect fit.

All of the data, trendline curves, formulas and tables can be found in Appendix C.

The following is a summary of the data, arranged in a style that could be used to

populate more comprehensive tables for the NEC.

30°C Temperature Rise (60°C Cable Rating @30°C Ambient)

Conductor Size

(AWG)

Number of 4-Pair Cables in a Bundle

1 2-7 8 -19 20 - 37 38 - 61 62-91 92 - 192

26 1.98 1.001 0.707 0.549 0.460 0.449 NA

24 2.209 1.187 0.813 0.634 0.546 0.455 0.398

23 1.242 0.893 0.674 0.582 0.590 0.452

22 1.499 1.04 0.765 0.663 0.622 0.527


Conductor Size

(AWG)


1 2-7 8 -19 20 - 37 38 - 61 62-91 92 - 192

26 2.424 1.227 0.874 0.677 0.572 0.554 NA

24 2.732 1.461 1.009 0.782 0.674 0.561 0.478

23 1.531 1.105 0.834 0.718 0.718 0.549

22 3 1.857 1.284 0.952 0.822 0.769 0.631

Revised: September 29, 2015




Conductor Size

(AWG)


1 2-7 8 -19 20 - 37 38 - 61 62-91 92 - 192

26 2.796 1.417 1.015 0.784 0.665 0.642 NA

24 3.172 1.692 1.174 0.907 0.781 0.651 0.549

23 1.775 1.284 0.968 0.831 0.823 0.628

22 2.158 1.489 1.11 0.955 0.893 0.717

Configurations where only ½ of the Conductors are Powered

INTRODUCTION

Some implementations of remote powering over LAN cable utilize 2-pair powering

schemes as shown in the following diagrams. These powering methods are still widely

used.

As can be seen from the diagrams, these schemes utilize only 4 conductors in the cable

(out of 8) to carry current. As a result, there is less heat generated in each cable for the

same amount of current per conductor. This would imply that the 4 conductors could

each carry more current than each of the 8 conductors in the 4-pair power configuration

to get the same heating effect. However, ½ the number of conductors carrying current

does not translate to twice the current since the heating effect is related to the current

squared.

ASSUMPTIONS & CALCULATIONS

Cable heating is a result of power dissipation given by the formula P= I2 x R

To make things simple, the following assumptions are made:

Revised: September 29, 2015

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCPfg9fH_2scCFUMSkgodl1gLSg&url=http://www.edaboard.com/thread284927.html&psig=AFQjCNElVXe2iMzJ6rVNGEo1XtE5iIDEFQ&ust=1441374288309655

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCO79rYGA28cCFcsWkgod1QgCZg&url=http://www.edaboard.com/thread284927.html&psig=AFQjCNElVXe2iMzJ6rVNGEo1XtE5iIDEFQ&ust=1441374288309655



The power dissipation is the same for both configurations to get the same

temperature. (There might be a hotter temperature “hot-spot” on the individual

conductor since it is carrying more current but in general the temperature rise on

the cable is due to the trapped heat rather than the individual conductor

temperature.

The dc resistance would remain roughly the same for both scenarios. (It will be

slightly higher for the 4-conductor scenario since the individual conductor will be

warmer but the effect will be very small.)

Given these assumptions: P8 = P4 = Power per cable (assume same for both) I8 = Current for each conductor with 8 conductors energized I4 = Current for each conductor with 4 conductors energized R = DC Resistance of each conductor (assume same for both)

For 8 conductors energized: P8= I8

2 x R x 8 (8 conductors) For 4 conductors energized: P4= I4

2 x R x 4 (4 conductors) or I4 = SQRT (P4/(R x 4)) Since the power is assumed to be the same, the formula for 8 conductor power, P8, can be substituted for P4 to get a formula for I4:

I4 = SQRT (P8/(R x 4)) = SQRT ((I82 x R x 8)/(R x 4)) = SQRT (I8

2 x 2)

Calculating I4 for a number of different I8 currents we get the following along with a

“factor” for each.

I8 I4 Factor (Factor = I4 / I8)

3 4.2426 1.4142

2 2.8284 1.4142

1.3 1.8385 1.4142

.6 .8485 1.4142

.3 .4243 1.4142

The factors are consistent, as would be expected.



TESTING & DATA

To validate the calculations and assumptions, tests were performed on a 61 cable

bundle mounted in metal conduit and a 91 cable bundle mounted in Schedule 40 PVC

conduit with 8 conductors carrying current. The tests were repeated with no changes to

the test set-ups with 4 conductors carrying current. The results with best-fit trendline

curves are shown below.



The curves permit the identification of the current that would yield a particular

temperature.

For accuracy, rather than visually use the graphs to determine the current value, the

formulas for the best-fit polynomial trendlines developed from the data are used with an

iterative methodology to solve for “x” at various target temperatures “y”.

The following tables were generated for various target temperatures:

The “Factor” is the ratio of the current for the 4-conductor tests divided by the current for

the 8-conductor tests.

SUMMARY

The data indicates that a factor of approximately 1.4 would be valid to estimate how

much additional current could be carried by a 4-pair cable when only ½ of the

conductors are powered.



Effects of Current

The data shows that in many cases, very small increases in conductor current resulted

in large increases in measured temperatures.



Different Installation Methods

This graph shows an example of how different installation configurations affect the

measured temperatures.

Photographs of Different Installation Configurations



Enclosing Cables

The data shows that enclosing cables has a dramatic effect on the measured temperatures. These graphs show the difference between open cable and a cable enclosed in conduit. It can be seen that for the entries on the far right there is no data for the enclosed cables. This is due to the temperatures exceeding the physical limits of the insulation materials in the enclosed scenario.



The data shows that sometimes different enclosed installations only made a minor

difference in the measured temperatures.

The following comparison shows the same cable in open air, in a 4” X 4” closed cable

routing assembly and in 4” schedule 40 PVC conduit. As expected the data shows that

enclosing the cable results in considerably higher temperatures. However, there is not

much difference between the installation in the 4” X 4” enclosed cable routing assembly

and the 4” schedule 40 plastic conduit as shown by the overlapping curves and the data

plotted on the column graph. The data shows that the 4” PVC conduit resulted in slightly

higher temperatures. This is expected since the volume of the cable routing assembly is

slightly larger than the conduit allowing for some additional heat dissipation from the

cable bundle.



Installation Orientation

Since cables can be installed in any orientation, a comparison test was run on Cat 5e, 24 AWG cable in an open wire style cable tray. The test configuration consisted of 576 cables filling the tray with 18 layers of 32 cables. The cables were energized with 0.5 amperes per conductor with all conductors carrying current. The exact test set-up was used for both tests. Only the orientation was changed.



Summary

The results indicate very little difference between the horizontal and vertical

orientations, with no significant difference on the cables at the center of the tray bundle

(CH 14 through CH 16).



Firestop

When trying to compare the effects of adding firestop to cable bundles in metallic

conduit, we came across variations that did not appear to be attributable to the addition

of the firestop. For example, several of the tests showed that temperatures were lower

for the configurations with the firestop. This would not be expected since the firestop

prevents heat from escaping at the ends of the conduit. This was more pronounced for

smaller bundle configurations.



Especially for the smaller bundles or single cables, it appears that the unexpected

temperatures are the result of a heat-sinking effect where a cable contacts the conduit

and the relative position of the thermocouples to these points affects the temperature

readings. This would not be as pronounced with larger bundles which would have a

more consistent lay and where the thermocouples are buried deep within the bundle.

Because different cable bundles were used due to cable damage when the original

open-end test was run to cable destruction, the cable lay inside of the conduit was likely

different providing a different heat-sinking profile.

To check this, tests were performed on a single cable and a 7 cable bundle in metal

conduit. Each test was first run without firestop. After thermal stabilization, firestop was

carefully added without disturbing the cable. Temperatures were again allowed to

stabilize and the results recorded. The data showed essentially no difference in the

temperatures. This was consistent with the larger cable bundles where the lay / heat

sinking effects did not appear to be significant. In these cases also, the data showed

that adding firestop had little or no effect on the measured temperatures.



SUMMARY

The data shows that the addition of firestop at the ends of a 6 ft. conduit does not

significantly affect the temperatures near the center 3 feet of the cable. Most of the heat

is trapped at the center of the conduit in either case.



Cable Comparisons

The data shows that the cable design and construction has as much effect on the

temperature rise as AWG size. These comparisons show some examples.



Cable Configurations

These tests were performed to determine the difference in measured temperatures (if

any) between a “perfect” hexagonal bundle and a more random circular bundle.



LP Cables

As a result of the public inputs and resulting proposed first revisions to the NEC, a need

was identified to develop requirements for a special-use cable that could be used as an

alternative to traditional cables. Where the ampacity tables were sufficient for existing

installations and new installations where the use of traditional cables was desirable, it

was recognized that cables could be designed specifically to handle powering over

communications cables without all of the limitations necessary for cables of unknown

heating and heat dissipating characteristics. The objective, then, was to develop

requirements that would permit a cable to be identified specifically for this type of

installation and use.

It has been well established that cable heating can be managed via:

– Increased AWG size

– Cable design

– Material selection

– Installation Practices

It was less clear how the interaction of these elements might affect a cable’s ability to

handle increasing current levels. For example, there was little data available showing

how changing a cable’s construction without changing the AWG size might affect

temperatures or how variations in the installation might affect the temperatures for the

same cable.

Obtaining data on these variations was necessary to determine how an “LP” cable might

be evaluated. The following tests were identified as being critical in this endeavor:

Different Installations. Testing the same cable in various installation

configurations to gain a better understanding of how bundle size and routing

(open air, conduit, cable trays, cable routing assemblies, etc.) affects

temperature

Orientation. Determine the effects of horizontal vs. vertical orientation on cable

temperature in a bundle.

Cable Comparison. Test different cable types and constructions under the same

installation and use conditions to obtain comparison data to better understand

the effects of cable design on temperature.

Test Variations. Study what test variations have on temperature rise and under

what conditions. For example, how does current increase affect temperatures or

the effects of different size conduits.



LP CABLE REQUIREMENTS

As part of the fact-finding investigation, UL LLC has undertaken the development of a

method for determining the ability of a cable to carry current under reasonable worse-

case installation conditions including bundling of large numbers of cables, enclosing the

cables in raceways, cable routing assemblies or conduit and elevated ambient

temperatures. This effort has resulted in the test procedure described in APPENDIX D,

“Cable Heating Test”.



SUMMARY

In consideration of the fact-finding character of the investigation, the foregoing Report is

to be construed as information only and should not be regarded as conveying any

conclusion or recommendations on the part of Underwriters Laboratories Inc. regarding

the acceptability of the construction or performance of the product for recognition by any

code or standard or for any other purpose.

The investigation resulted in the development of data in support of comments /

proposals related to including more extensive ampacity tables in the NEC to better

manage powering over LAN cable systems.

The investigation has identified that for certain powering over LAN cable installations

with power levels exceeding 60 watts, overheating of the cables will occur.

Cable heating can be managed via:

Increased AWG size

Cable design

Material selection

Installation Practices

The investigation produced data leading to the development of testing

requirements for “-LP” cables.

Randy Ivans Program/Project Manager Wire and Cable Commercial & Industrial UL LLC.

Anthony Tassone PE Principal Engineer (PDE) Wire & Cable Commercial & Industrial UL LLC.



APPENDIX A - CABLE DETAILS



Number of pages in this package ____ [including additional pages __-__] (Fill in when using printed copy as record)

TESTS TO BE CONDUCTED:

Test No.

Done3 Test Name

[ ] Comments/Parameters [x] Tests Conducted by2 [ ] Link to separate data files4

1 X DETAILED EXAMINATION: 5E 24AWG

Tim Falvey 2015-09-01

2 X DETAILED EXAMINATION: 5E 26AWG

Michael Askin 2015-09-02

3 X DETAILED EXAMINATION: 6 R 23AWG


4 X DETAILED EXAMINATION: 6 P 23AWG


5 X DETAILED EXAMINATION: 6 P 22AWG


6 X DETAILED EXAMINATION: 6A 23AWG


[X] Safety Certification - Unless specified otherwise in the individual Methods, the tests shall be conducted under the following ambient conditions. Confirmation of these conditions shall be recorded at the time the test is conducted.

Ambient Temperature, C 23 ± 5

Relative Humidity, % 50 ± 20

Barometric Pressure, mBar NA


TEST LOCATION: (To be completed by Staff Conducting the Testing)

[x]UL or Affiliate []WTDP

[]CTDP []TPTDP []TCP []PPP

[]WMT []TMP []SMT

Company Name: UL LLC

Address: 1285 Walt Whitman Rd. Melville, NY

TEST EQUIPMENT INFORMATION

[x] UL test equipment information is recorded on Meter Use in UL’s Laboratory Project Management (LPM) database. TEST SAMPLE IDENTIFICATION:

The table below is provided to establish correlation of sample numbers to specific product related information. Refer to this table when a test identifies a test sample by "Sample No." only.

Sample Card No.

Date Received

[] Test No.+

Sample No. Manufacturer, Product Identification and Ratings

XXXX 1 1 CAT5E 24AWG UTP (YELLOW)

2 2 CAT5E 26AWG FTP SHIELDED PATCH (LT GREY)

3 3 CAT6 23AWG UTP RISER CMR (BLUE)

4 4 CAT6 23AWG UTP PLENUM CMP (WHITE)

5 5 CAT6 22AWG UTP PLENUM CMP (BLUE)

6 6 CAT6A 23AWG SHIELDED PLENUM (DARK GREY)

+ - If Test Number is used, the Test Number or Numbers the sample was used in must be identified on the data sheet pages or on the Data Sheet Package cover page.


DETAILED EXAMINATION: UL 444, Clause 5

Sample No. 1

Ambient Temp.: 24C Humidity: 61% RH

Note: All units are expressed in terms of: [x] Inches [ ] mm

[x] Identification

Print Type: None Ink Indent Tape Other:

Print Content:

0394 FEET CAT-5E GENERAL CABLE J 2001345 CMR C(ETL)US 4PR 24AWG 75C GENSPEED 5000 IWC---VERIFIED BY UND LAB INC ONLY TO ANSI/TIA-568C.2 CAT-5E--- TESTED TO 350MHZ 03-14 302136F2 PAT 5767441 CAT-5E

Print Interval: 24.25 inches

No. of Insulated Conductors 8 No. Of Bare Conductors 0

Brief Assembly Description: Jacket, 4 pairs of solid-insulated conductors, rip cord


DETAILED EXAMINATION (Sample #1): (CONT’D) UL 444, Clause 5


Note: If additional space is required please continue under “attached Component” section

[x] Jacket Overall Jacket

Inner Jacket 1

Inner Jacket 2

Inner Jacket 3

Color Yellow n/a n/a n/a

Overall cable diameter, in. .190 n/a n/a n/a

Core diameter under jacket, in. .156 n/a n/a n/a

Major axis, in. n/a n/a n/a n/a

Minor axis, in. n/a n/a n/a n/a

Average thickness, in. .016 n/a n/a n/a

Min. thickness at any point, in. .015 n/a n/a n/a

Minimum thickness after rip, in. n/a n/a n/a n/a

Average web thickness, in. n/a n/a n/a n/a

Average web width, in. n/a n/a n/a n/a

[ ] Note: If ave. or min. point jacket thickness exceeds / is less than the

following requirement contact engineer before proceeding:

Min Ave. , in. Min Point , in.




Sample No.

[ ] Armor [x] Assembly

Type of Armor n/a Lay of conductors, in. .5

Convolutions per inch / mm n/a Lay of conductor pairs, in. 5.7

Diameter over armor, in. n/a Lay of members, in. n/a

Diameter under armor, in. n/a

Strip width, in. n/a

Average thickness, in. n/a

Min. thickness at any point, in. n/a

[ ] Braid Parameters Braid 1 Braid 2 Braid 3

Type of braid n/a n/a n/a

Strand diameter, in. n/a n/a n/a

No. ends n/a n/a n/a

No. carriers n/a n/a n/a

Picks per inch / mm n/a n/a n/a

Core Dia. under braid inch/mm n/a n/a n/a

Calculated % coverage n/a n/a n/a



Ambient Temp.: C Humidity: % RH

[ ] Tapes, binders, rods, rip cords, and fillers

Type n/a n/a n/a n/a n/a

Thickness, in. n/a n/a n/a n/a n/a

Width, in. n/a n/a n/a n/a n/a

Lap, in. n/a n/a n/a n/a n/a

Overall diameter, in. n/a n/a n/a n/a n/a

Helical/longitudinal n/a n/a n/a n/a n/a

Calculated % coverage n/a n/a n/a n/a n/a

Count n/a n/a n/a n/a n/a

Major/minor axis, in. n/a n/a n/a n/a n/a

Ripcord present? n/a n/a n/a n/a n/a

Sample No.

[x] Insulation Conductor Conductor Conductor Conductor

Color ORANGE n/a n/a n/a

Separator tape present? no n/a n/a n/a

Average thickness, in. .0075 n/a n/a n/a

Minimum thickness at any point, in. .006 n/a n/a n/a

Minimum thickness after rip, in. n/a n/a n/a n/a

Average web thickness, in. n/a n/a n/a n/a

Average web width, in. n/a n/a n/a n/a

[ ] Insulation Covering

Color n/a n/a n/a n/a

Average thickness, in. n/a n/a n/a n/a

Minimum thickness at any point, in. n/a n/a n/a n/a

[ ] Note: If ave. or min. point insulation thickness exceeds/is less than

the following requirement contact engineer before proceeding:



DETAILED EXAMINATION: (CONT’D) UL 444, Clause 5


[x] Conductor Conductor Conductor Conductor Conductor

1 2 3 4

Type (i.e. Al, Cu, etc.) cu n/a n/a n/a

Coating present? no n/a n/a n/a

Diameter of solid conductor, in. .01975 n/a n/a n/a

Diameter over insulation, in. .0346 n/a n/a n/a

Number of strands n/a n/a n/a n/a

Strand diameter, in. n/a n/a n/a n/a

Lay of strands, in. n/a n/a n/a n/a

Circular Mil Area (CMA) n/a n/a n/a n/a

AWG size 24 n/a n/a n/a


METHOD: UL 444, Clause 4.1 – 4.11

Solid Conductor:

Specimen: #1

Min. #1 Diameter, in. .0197

Max. #1 Diameter, in. .0198





Average Conductor Diameter, in. .01975

Conductor AWG Size 24


DETAILED EXAMINATION (Sample #1): (CONT’D) UL 444, Clause 5 DETAILED EXAMINATION, CONDUCTOR:


Sample No.______

[x] Conductor DC Resistance

Length of specimen (ft/meter) 1

Conductor resistance (measurement 1), ohms/kft 26.85




Minimum of 4 measurements, ohms/kft 26.85

Temperature of conductor, C 24

Multiplying factor for adjustment to resistance at

____C *

Conductor resistance adjusted to ____C, Ohms/1000 (ft/meter) *

*Resistomat calculated at 20c


DETAILED EXAMINATION (Sample #1): (CONT’D) UL 444, Clause 5 DETAILED EXAMINATION, INSULATION:



Insulation:

Specimen: #1

Thickness: Min #1, in. .006

Max #1, in. .009

Average Thickness, in. .0075

Outside diameter: Min #1, in. .035

Max #1, in. .035

Min #2, in. .034

Max #2, in. .035

Min #3, in. .034

Max #3, in. .035

Average Outside Diameter, in. .0346


DETAILED EXAMINATION (Sample #1): (CONT’D) UL 444, Clause 5 DETAILED EXAMINATION, JACKET:



Jacket:

Specimen: #1


Max #1, in. .017



Max #1, in. .185

Min #2, in. .189

Max #2, in. .201

Min #3, in. .175

Max #3, in. .205


Core diameter: Min #1, in. .149

Max #1, in. .151

Min #2, in. .154

Max #2, in. .169

Min #3, in. .140

Max #3, in. .171

Average Core Diameter, in. .156



Sample No. 2


Note: All units are expressed in terms of: [X] Inches [ ] mm

[X] Identification


Print Content: YFC FTP CAT.5E 350MHZ PATCH ISO/IEC 11801 7 EN 50288 3P

CONFORMS TO GIGABIT ETHERNET 26AWGX4 TYPE CMX(UL) C(UL) CMH E164469-F5

Print Interval: 48.5 Inches


Brief Assembly Description: JKT, POLY AL WRAP, DRAIN WIRE, CLEAR POLY WRAP,

8 INSULATED STRANDED CONDUCTORS





[X] Jacket Overall Jacket

Inner Jacket 1

Inner Jacket 2

Inner Jacket 3

Color GREY

Overall cable diameter, in. .230

Core diameter under jacket, in.

.

183

Major axis, in. -

Minor axis, in. -

Average thickness, in. .023

Min. thickness at any point, in. .022

Minimum thickness after rip, in. -

Average web thickness, in. -

Average web width, in. -







Sample No.

[ ] Armor [X] Assembly

Type of Armor Lay of conductors, in. .375

Convolutions per inch / mm Lay of conductor pairs, in. 4.0

Diameter over armor, in. Lay of members, in. -

Diameter under armor, in.

Strip width, in.

Average thickness, in.

Min. thickness at any point, in.




[X] Tapes, binders, rods, rip cords, and fillers

Type POLY AL

WRAP CLEAR POLY

Thickness, in. .0009 .0006

Width, in. .750 .813

Lap, in. .188 .250

Overall diameter, in.

Helical/longitudinal HELI HELI

Calculated % coverage TBD TBD

Count 1 1

Major/minor axis, in. - -

Ripcord present? - -

Sample No.

[X] Insulation Conductor Conductor Conductor Conductor

Color BLUE

Separator tape present? NO


Minimum thickness at any point, in. .008





Color


Minimum thickness at any point, in.







[X] Conductor Conductor Conducto

r Conductor Conductor

1 2 3 4

Type (i.e. Al, Cu, etc.) Cu

Coating present? NO

Diameter of solid conductor, in. .018

Diameter over insulation, in. .036

Number of strands 7

Strand diameter, in. .0060

Lay of strands, in. .438

Circular Mil Area (CMA) 252

AWG size 26



DETAILED EXAMINATION (Sample #2): (CONT’D) UL 444, Clause 5 DETAILED EXAMINATION, ROUND CONDUCTOR: (CONT’D)



Stranded Conductor:

Specimen: #1

Number of Strands 7

Strand 1 – Min. Diameter, in. .00605

Max. Diameter, in. .0061













Average Strand Diameter, in. .0060

Total conductor area, in2 / mm2 252



DETAILED EXAMINATION (Sample #2): (CONT’D) UL 444, Clause 5 DETAILED EXAMINATION, insulation:



Insulation:

Specimen: #1


Max #1, in. .010



Max #1, in. .03585

Min #2, in. .03601

Max #2, in. .03601

Min #3, in. .03641

Max #3, in. .03643






Jacket:

Specimen: #1


Max #1, in. .024



Max #1, in. .227

Min #2, in. .228

Max #2, in. .228

Min #3, in. .229

Max #3, in. .242



Max #1, in. .182

Min #2, in. .183

Max #2, in. .183

Min #3, in. .183

Max #3, in. .184




Sample No. 3



[X] Identification


Print Content: CAT-6 GENERAL CABLE J 2001345 CMR C(ETL)US CMG 4PR 23AWG

GENSPEED 6 IWC VERIFIED BY UND LAB INC ONLY TO ANSI/TIA-568C.2 CAT-6

Print Interval: 24 inches


Brief Assembly Description: JKT, RIP CORD, FLAT FILLER, 8 INS CON






Inner Jacket 1

Inner Jacket 2

Inner Jacket 3

Color BLUE


Core diameter under jacket, in. .191

Major axis, in. -

Minor axis, in. -












Sample No.






Strip width, in.







Type FLAT

FILLER

Thickness, in. .0012

Width, in. .171

Lap, in. -

Overall diameter, in. -

Helical/longitudinal HELI

Calculated % coverage -

Count 1

Major/minor axis, in. -

Ripcord present? -

Sample No.


Color BLUE








Color











1 2 3 4


Coating present? NO



Number of strands -

Strand diameter, in. -

Lay of strands, in. -

Circular Mil Area (CMA) -

AWG size 23



Solid Conductor:

Specimen: #1













Insulation:

Specimen: #1


Max #1, in. .009



Max #1, in. .03825

Min #2, in. .03828

Max #2, in. .03837

Min #3, in. .03839

Max #3, in. .03882






Jacket:

Specimen: #1


Max #1, in. .020



Max #1, in. .226

Min #2, in. .228

Max #2, in. .229

Min #3, in. .229

Max #3, in. .231



Max #1, in. .190

Min #2, in. .190

Max #2, in. .192

Min #3, in. .193

Max #3, in. .194




Sample No. 4



[X] Identification


Print Content: CAT-6 GENERAL CABLE J CMP 90C C(UL)US 4PR 23AWG GENSPEED

6 PLENUM VERFIED (UL) ANSI/TIA-568C.2 CAT6



Brief Assembly Description: JKT, RIP CORD, FLAT FILLER, 8 INS CON






Inner Jacket 1

Inner Jacket 2

Inner Jacket 3

Color WHITE



Major axis, in. -

Minor axis, in. -












Sample No.

[ ] Armor [x] Assembly





Strip width, in.




Type of braid

Strand diameter, in.

No. ends

No. carriers

Picks per inch / mm

Core Dia. under braid inch/mm

Calculated % coverage





Type FLAT

Thickness, in. .012

Width, in. .173

Lap, in. -



Calculated % coverage -

Count 1


Ripcord present? -

Sample No.


Color BLUE








Color











1 2 3 4


Coating present? NO



Number of strands -




AWG size 23



Solid Conductor:

Specimen: #1










DETAILED EXAMINATION (Sample #4): (CONT’D) UL 444, Clause 5 DETAILED EXAMINATION, insulation:



Insulation:

Specimen: #1


Max #1, in. .010



Max #1, in. .03894

Min #2, in. .03902

Max #2, in. .03907

Min #3, in. .03916

Max #3, in. .03980






Jacket:

Specimen: #1


Max #1, in. .016



Max #1, in. .208

Min #2, in. .208

Max #2, in. .209

Min #3, in. .212

Max #3, in. .216



Max #1, in. .177

Min #2, in. .177

Max #2, in. .178

Min #3, in. .181

Max #3, in. .186




Sample No. 5



[X] Identification


Print Content: GenSPEED EfficienC MAX CAT 6 ENHANCED POE++ E105765-L CMP

(UL) C(UL) 4PR 22AWG 90C VERIFIED (UL) ANSI/TIA-568C.2 CAT6



Brief Assembly Description: JKT, RIP CORD, FLAT FILLE, 8 INS CON






Inner Jacket 1

Inner Jacket 2

Inner Jacket 3

Color BLUE



Major axis, in. -

Minor axis, in. -












Sample No.

[ ] Armor [ ] Assembly





Strip width, in.




Type of braid

Strand diameter, in.

No. ends

No. carriers

Picks per inch / mm

Core Dia. under braid inch/mm

Calculated % coverage





Type FLAT

Thickness, in. .011

Width, in. .173

Lap, in. -



Calculated % coverage TBD

Count 1


Ripcord present? -

Sample No.


Color BLUE








Color











1 2 3 4


Coating present? NO



Number of strands -




AWG size 22



Solid Conductor:

Specimen: #1













Insulation:

Specimen: #1


Max #1, in. .010



Max #1, in. .04155

Min #2, in. .04218

Max #2, in. .04224

Min #3, in. .04224

Max #3, in. .04262






Jacket:

Specimen: #1


Max #1, in. .016



Max #1, in. .219

Min #2, in. .220

Max #2, in. .222

Min #3, in. .224

Max #3, in. .227



Max #1, in. .191

Min #2, in. .191

Max #2, in. .194

Min #3, in. .195

Max #3, in. .199




Sample No. 6



[X] Identification


Print Content: GENERAL CABLE L GENSPEED 10MTP CATEGORY 6A 4PR/23AWG UTP

PLENUM CABLE C(UL)US CMP 90C VERIFIED(UL) ANSI/TIA-568C.2 CAT-6A PAT 5767441,

8354590, 8183462 10MTP.US



Brief Assembly Description: JKT, POLY AL WRAP, POLYESTER WRAP, STAR FILLER,

8 INS CON






Inner Jacket 1

Inner Jacket 2

Inner Jacket 3

Color GREY



Major axis, in. -

Minor axis, in. -












Sample No.






Strip width, in.







Type

POLY AL WRAP

WOVEN POLYESTER

WRAP

Thickness, in. .0032 .0063

Width, in. 1.0 .750

Lap, in. .250 .188

Overall diameter, in. .239 .230

Helical/longitudinal HELI HELI

Calculated % coverage TBD TBD

Count 1 1

Major/minor axis, in. - -

Ripcord present? - -

Sample No.


Color BLUE








Color









[x] Conductor Conductor Conducto


1 2 3 4


Coating present? NO



Number of strands -




AWG size 23



Solid Conductor:

Specimen: #1













Insulation:

Specimen: #1


Max #1, in. .011



Max #1, in. .042

Min #2, in. .042

Max #2, in. .043

Min #3, in. .043

Max #3, in. .043






Jacket:

Specimen: #1


Max #1, in. .017



Max #1, in. .274

Min #2, in. .283

Max #2, in. .283

Min #3, in. .286

Max #3, in. .287



Max #1, in. .244

Min #2, in. .250

Max #2, in. .252

Min #3, in. .253

Max #3, in. .255



DETAILED EXAMINATION (Sample #6): (CONT’D) UL 444, Clause 5 STAR FILLER DIMENSIONS:


d Thickness at any point, mils ______41______ w Average Thickness, mils _____20_______ Minimum Thickness at any point, mils _____17_______ Maximum Thickness at any point, mils _____24_______ l Average Thickness, mils ______70______ Minimum Thickness at any point, mils _____65_______ Maximum Thickness at any point, mils _____74_______


APPENDIX B - TEMPERATURE TEST DATA


Thermocouple Placement - General

TC6 and TC7 are at the center of the cable bundle length. TC7 is inside the jacket on

the individual wire insulation. TC6 is on the outside of the cable jacket.


TEMPERATURE TEST DATA


APPENDIX C - DATA for NEC TABLES


APPENDIX D - CABLE HEATING TEST

The proposed requirements for the UL Standard(s) for Safety are to be considered as tentative and are only meant to demonstrate the form and content of such a proposal. They have not been presented to the relevant industry nor subjected to UL's standards development procedure. The requirements are shown only as examples and are based on the results given in this Report. 7.24 (NEW) Cable Heating Test

77.24.1 When tested as described in this section, the temperatures measured on the insulation and

jacket of the cables, after being corrected to an ambient of 45oC, shall not exceed the temperature

rating of the cable.

7.24.2 The cables shall be arranged in a bundle consisting of 192 cables and electrically connected in

series to a power supply capable of providing the rated current marked as part of the LP rating. The

inner 37 cables shall be arranged as shown in Figure 4. The remaining cables shall be evenly

distributed in a random fashion to form a 192 cable bundle. The bundle shall be placed in a 6 foot

long (1.83 m) commercially available non-metallic conduit (Schedule 40) with the minimum diameter

needed to install the bundle without putting pressure on the cables. Each end of the conduit shall be

filled with insulation.

7.24.3 The temperatures shall be measured on the outer jacket and conductor insulation of the center

cable at the midpoint of the cable. In addition, temperatures shall be measured on the jacket and

conductor insulation on the center cable two feet (0.6 m) on each side of center thermocouple.

7.24.4 Temperatures are to be measured by means of thermocouples consisting of iron and

constantan wires not larger than 24 AWG (0.21 mm2) and not smaller than 30 AWG (0.05 mm2).

When thermocouples are used in determining temperatures in electrical equipment, it is common

practice to employ thermocouples consisting of 30 AWG iron and constantan wires with a

potentiometer-type of indicating instrument. This equipment is to be used whenever a referee

measurement of temperature is necessary.


7.24.5 The thermocouples and related instruments are to be accurate and calibrated in accordance

with standard laboratory practice. The thermocouple wire is to conform to the requirements specified

in the Tolerances on Initial Values of EMF versus Temperature tables in the Standard Specification

and Temperature-Electromotive Force (emf) Tables for Standardized Thermocouples, ANSI/ASTM

E230/E230M.

7.24.6 A thermocouple junction and adjacent thermocouple lead wire are to be securely held in good

thermal contact with the surface of the material whose temperature is being measured. In most

cases, acceptable thermal contact results from securely taping or cementing the thermocouple in

place

Example of Cable Heating Test

fact finding report on power over local area network type cables

Documents