How do I troubleshoot a tripping GFI?
I installed a new spa on the outside rear deck about a year ago. The cabling was laid (buried) about 10 yrs ago by a licensed electrician. The GFI device has intermittently tripped over the last few days. I can disconnect the spa at the spa (220V) no problem since I connected it. My question is as follows: what equipment do I need to check whether the problem is in the spa or the supply cable. I have a standard multimeter. Will just measuring the resistance between each line and ground tell me?
Expert
Maestro
Because the GFI device is tripping intermittently, it would suggest that you are barely getting enough of the ground fault trip to device. That would mean that only a few milliamps are leaking to ground. As a percentage of the total amperage flowing, the ground fault is negligible (less than a 10th of 1%). Therefore, a standard multimeter would show the resistance between ground and the hot wires as infinite, which of course is of no use to you. In addition, disconnecting the cable from the spa may conceal the problem, which is very often a ground fault at the connection. You might try disconnecting the spa and reconnecting another 220V device in place of the spa. If the breaker continues to trip, you have ruled out the spa. You have now narrowed the problem down to the cable, or the connection, or a defective GFI. Next, I would try a different cable to the new 220 volt device and/or the spa. Through the process of elimination you should be able to figure out the source of the problem.
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