Originally Posted by beenthere
If you read 120 volt to ground from black to ground, then it can't be shorted/read 0 ohms.
Well - let's just forget that measurement. I must have made an error in measuring the ohms - I suppose there is a possibility of another load on the circuit, but I can't imagine how as it is a 22 amp circuit on a 30 amp breaker - and the heat system in the house is off except for this testing.
I've verified the following:
1. 30 amp circuit, no GFI (home built in '68)
2. Everything I'm seeing indicates this is not like modern radiant floors - it is a single-wire radiant circuit. With one break, the circuit is completely dead. That also means I can't use a thermal imager to locate the bad spot
Seems it is most similar to the single-wire circuits they use for those dog fence transmitters... on them you use a handheld AM radio to detect a generated signal to find the break. I don't want to have to buy a dog fence just to use the transmitter to diagnose my ceilings. Those things are expensive.
3. We're getting power for sure on the black side - although I want to ask, do you recommend I also test white-to-ground by penetrating the wire's insulation?