Resistance on heat trace testing

Welcome to the forum.

Nobody else responded, so I'll try.

I don't know much about that cable, but if it's self-regulating, you probably won't get meaningful resistance readings, and I'd be concerned about high-voltage damage.

Added: Are you testing line-to-line, or both-lines-to-ground/earth?
 
I agree with Larry, if this is self regulating heat tape the resistance changes with temperature. Suggest you contact mfg
 
Capsfloyd said:
Please explain the resistance using a megger on testing Raychem heat trace , 5 watt , 277 volt
20 amp .
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They specify insulation resistance testing prior to startup.
Insulation resistance testing (using a megohmmeter) should be conducted at three voltages; 500, 1000, and 2500 Vdc. Significant problems may not be detected if testing is done only at 500 and 1000 volts.
A clean, dry, properly installed circuit should measure thousands of megohms, regardless of the heating cable length or measuring voltage (0–2500 dc). The following criteria are provided to assist in determining the acceptability of an installation where optimum conditions may not apply.
All insulation resistance values should be greater than 1000 megohms. If the reading is lower, consult Section 10, Troubleshooting Guide.
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This answers my question:

5. Connect the negative (–) lead to the heating cable metallic braid.
6. Connect the positive (+) lead to all heating cable conductors simultaneously.
 
hillbilly1 said:
They are just looking for installation damage, if you don’t do it, and when (not if) it catches fire, your on the hook, not them.
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Have never seen that happen with the type of heat trace that has a full braided metal shield under the jacket and over the actual heating tape and I have installed tens thousands of feet of it on industrial projects. I have seen that on some very old heat trace prior to the use of the metal shield and on some of the home use stuff, especially the non-self-regulating types.
 
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