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Thread: testing heat trace cable-help

  1. #1

    Question testing heat trace cable-help

    How can I perform a simple test on a heat trace cable in the summer to know if the run is working? Will an IR Thermometer be effective for this? Thanks gang !!

  2. #2
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    Take an amp draw and compare it with the data tag on the cold lead.

  3. #3
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    Primative and simple...put an ice cube on the sensor to see if the actuator works.

    If your concerned about the run being kinked, and shorting for any reason, megger the run section only.
    Don't let fear be your guide!

  4. #4

    Red face Forgot to mention....

    There is no actuator, it is simply switched on or off. IR thermometer to read temp. difference maybe?

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    Quote Originally Posted by pridelion
    There is no actuator, it is simply switched on or off. IR thermometer to read temp. difference maybe?

    Where is this cable located? The IR thermometer is not a bad idea.
    Instructor, Industry Advocate

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    usually about 6 watts per foot

    Figure out the total footage. the cable should be stamped how many watts per foot it is. If it is say 100ft at 6 watts per foot . Next find the voltage and do some simple math 600 watts /120volts =5 amps. Then turn it on and see if it draws 5 amps simple. Just like Marc said.
    By the way I think meggering a heat trace cable is a bad Idea it is not an insulated cable it is a semiconductive material and will read a bad resistance every time. It is pointless
    Last edited by quogueelectric; 07-29-07 at 01:59 PM.
    The tail does NOT wag the dog.

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    Quote Originally Posted by quogueelectric
    By the way I think meggering a heat trace cable is a bad Idea it is not an insulated cable it is a semiconductive material and will read a bad resistance every time. It is pointless
    That was my knee jerk reaction, based on the old ceiling radiant heat Chromalox and other companies used to make. Then, I remembered that the newer stuff has a braided shield which is grounded (such as "Warm Tiles"), which would benefit from a megger test. With older heat trace cable, there's no ground to reference to megger it.

  8. #8
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    A current measurement may not tell you much. A lot of the heat trace is self limiting and draws a lot less current as the temperature goes up. On a hot summer day it may draw almost no current if it is freeze protection trace.
    Don
    Don, Illinois
    "It is the first responsibility of every citizen to question authority." B Franklin

  9. #9
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    Meggering heat trace is the preferred method for testing on new installs (or was a couple of years back) Oilfield gear is wrapped to beat the band to keep moisture out of the pipes in processing areas.

    Per instruction from the manufacturers rep standing beside me, started at 500 VDC and bumped through the settings to 2500 VDC. When installed properly, all parts in the run should meg. Better to "blow up" your stuff than to have to come back later.

    Would read whatever the manufacturers directions are, and follow that. Would think any reasonable install would stand up to 1000VDC meg test...but would call the brand name, of said gear, before testing!

    Chromalox, or Raychem, would be my preferred brands, for dependability and harsh weather conditions.
    Don't let fear be your guide!

  10. #10
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    IEEE and Tyco-Raychem recommend meggering. Don't stop at 1000V, per the test procedures, many problems will not show up @ 1000V. You need to take it to 2500V. I have seen it pass at lower voltage and fail at higher. Twist the bus wires together, and check to braid. Then check from braid to pipe or something that is bonded to ground. Remember to get a hotwork permit if you are in a hazardous area, not just for the megger end, but the whole tracer.


    Back to the OP, when the cable is warm, even though it is not energized, high ambient temps or high pipe temps will not give you the inrush current on self-regulating cables that you will get when everthing is cold.

    Most plants do their heat trace PM's in October to get ready for winter. That way you have cold mornings, cooler pipes.


    If you have to test in summer, can you put cold process in the pipes and turn on the trace to watch in-rush and to verify your GFEP does not trip?

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