Originally Posted by
will smith
If everything is supposed to be 120, and at a point you're seeing 240 (again assuming wiring is standard US), I'd check all the neutrals-make sure they are dedicated from stem to stern, and not possibly tied into other hots somehow, and make sure all neutral connections are tight-also from point of equipment back to the breaker panel. I've run across problems on only a few occasions, where a loose neutral caused a 120v circuit to feed 240v to the equipment-the first time I saw it I was going crazy trying to figure out where the other side of the 240 was coming from. An electrician friend of mine told me to check for loose neutrals-and I found an iffy neutral connection in a connection box (8 neutrals wire taped together). I had my doubts, but when I squared away the connection point, I was good to go. Another time I remember I just had a loose neutral at the breaker panel-that one was intermittent, and caused popped fuses that also drove more than one tech nuts...literally just a loose screw.
Might not be the ultimate answer to what you're up against now-but I don't mind sharing my "well, I've never seen that before" moments-it's worth a check anyway.
Best of luck-