I am troubleshooting some heat tape in some eaves troughing and downspouts. The breaker keeps tripping. The tape works intermittently. It is 8W per ft 240V tape.
I can't find the fault. Anyone have experience with this stuff?

Is it the GFCI that keeps tripping, or is it the o/c keeps tripping?

There isn't a chance that the tape has been cut?.
I've seen this before with one of the wires being cut right through and only making intermittent contact.
Sounds rather dangerous actually, especially around snow!.

There is actually two systems I'm dealing with. One is GFCI'd and the other is not. Both systems are tripping the o/c. I can't find any cuts in the cable. That is what I first suspected. Is there another way that heat tape can fail?

Is it tripping on overload or short circuit. I would measure how much current the heat tape is drawing. Somebody may have double lugged the breaker to feed another load, and now your drawing to much current.

My first guess would have been a defective GFCI. My second guess would have been a fault to ground. But those posibilities have been ruled out.

The last system I installed had a small control module (to measure temperature and presence of water in the eaves troughing). The module was to be installed under the eave, I did not think the eave would provide very much protection from the weather, and the unit would probably evetually fail as a result. The other posibility is the tape is itself shorting out (maybe a break down of the insulation is causing this).

Some self-regulating heat tapes draw more current when they are cold. I measured one at three times it's rated current. The current dropped to normal in about a minute - a long enough time to trip the breaker. Check the amps when you first reset the breaker.

[This message has been edited by twh (edited 03-12-2004).]

well i think i found the problems. one set of tapes had 120 and 240 tapes combined on the same system. the other set of tapes had water leaking into the contactor box. thank you everyone for the input.