Electrical – GFCI/AFCI Trips With No Load And New Wire

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I moved into a house last year that has some 2-wire receptacles, and some 3-wire receptacles. I have been adding GFCIs and AFCIs where required. I recently removed the conductors and old receptacles from a circuit and replaced them with a 12 gauge two wire with ground. The first receptacle from the breaker panel is a GFCI/AFCI. I have one receptacle wired from the load side of the GFCI/AFCI receptacle, and then one wired from the 2nd receptacle. I have been noticing that the GFCI/AFCI will be tripped when I check on it. The GFCI trip light is on when it trips. I'll reset it, go to bed, and it'll be tripped the next day. There are no loads connected to this circuit.

The other day I turned on the lights in the basement (florescent) and as soon as they turned on, the GFCI trips. It only happened once and I haven't been able to repeat it.

To troubleshoot, I have tried the following:

  • Replaced GFCI/AFCI

  • Replaced all of the wire

  • Disconnected the wire on the load side of the receptacle

So, here's the summary of problem:

  • Changing receptacles 2-wire to 3-wire

  • Wiring and receptacles on this circuit are new

  • Using existing circuit breaker

  • GFCI trips on GFCI/AFCI receptacle with no loads on it

  • I have replaced the GFCI/AFCI and still have the same problem

  • Wiring and work was checked

Any ideas what could be the problem?

Pictures:

Circuit Wiring

Panel Connections

Best Answer

AFCIs and GFCIs operate on totally different principles.

You may recall the wiring rule that all wires must be grouped together. This is so magnetic fields cancel each other out, since currents are equal. Likewise if 2 wires together are wound around a relay, and currents are equal in the two wires, then they would cancel each other out and the relay would not pick up. This is essentially what a GFCI is.

Submarines detect enemy submarines using passive sonar - they listen to sea noises and use signal processing on powerful computers to pick out artificial noises. If you've ever hooked up old fashioned speakers with speaker wire, you may have heard the crunchy sound of a loose speaker wire. If you washed out the normal 60 cycle hum, that is what arcing sounds like. An AFCI has a digital signal processor listening for that sound.

If a GFCI trips with no loads attached

Then the GFCI is defective. That shouldn't be happening/possible.

If an AFCI trips with no loads attached

Then the AFCI is hearing the sound of arcing. Because of the way wires are all interconnected at the panel, it's possible the AFCI hears arcing that is occurring on a completely different circuit. Sometimes it hears arcing that is intentional or not really arcing - I could see it being caused by an old-style fluorescent light that uses a starter, since its action is intentional arcing. For that matter a fluorescent light starts by striking its arc, but a modern electronic or even old magnetic ballast will buffer that "sound".

Silencing a warning device isn't really solving a problem, so I would focus on the root cause of the arc fault, if any.

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