I'm hooking up a new GFCI in a remodeled bathroom, replacing an older one. There are two outlets following on the circuit. The GFCI works fine, but as soon as I would plug a light into the next outlet, it would trip. Another thread suggested checking between Ground/Common/Hot wires to make sure there wasn't a short, and sure enough, I'm showing continuity between the ground and common wires. My question is, does this mean I have to run new wires, put in a new box, or is there a simpler solution?

  • Aren't ground and common supposed to be connected? At the panel? – DJohnM Feb 24 '14 at 8:06
  • @User58220 The grounding and grounded conductors should be connected at the main service panel, and only at the main service panel. If they are connected anywhere else it's a ground-fault, as it provides an alternative path for current to flow. Though you have made a good point, in that if you have not isolated this portion of this circuit, you will detect the connection at the panel. – Tester101 Feb 24 '14 at 10:58
  • have you tried using a plug in circuit tester to absolutely confirm the wiring is connected properly? Have you tried plugging something different into the outlet with same tripping result? – shirlock homes Feb 24 '14 at 11:18
  • @shirlockhomes Those plug in circuit testers won't detect a ground/neutral short (since they're connected at the panel), but a GFCI will trip if you have one. – BMitch Feb 24 '14 at 13:48
  • @BMitch, Good point, the plug in testers don't indicate neutral to ground short at the device, only an open ground or neutral. GFI's detect a difference in current between neutral and hot, not neutral and ground. It is assuming current is going to ground through a path other than the neutral or ground conductor, thus it trips. Since ground and neutral should read 0 ohms, a dead short, I'm not sure that would trip a GFI. I'm Really not sure, since I've never really tried that intentionally or seen it in the field. I could be wrong. – shirlock homes Feb 25 '14 at 0:18

The best thing to do is replace the defective wiring. Disconnect the load side of the GFCI and at all downstream junctions. Then check for neutral/ground continuity on each segment of the wiring. Once you locate the segment that shows continuity, search for a short location inside the junction box, and failing that, replace that part of the circuit.

Short of that, depending on your situation, you may not need to wire the following outlets to the GFCI load (e.g. if they are not in the bathroom). You could pigtail the load connection to the line side of the GFCI so that the downstream devices are not protected. If they need protection, they can each have their own GFCI installed, again, only wiring to the line side of the GFCI.

  • Wait... Are you saying the ground-fault is only a problem, if the GFCI device is detecting it? The way to solve a ground-fault, is to simply not detect it? – Tester101 Feb 24 '14 at 10:56
  • Nope, I'm saying replace/repair the wiring. But if you're going to ignore a ground/neutral short, there are options that will keep a GFCI from tripping. I'll leave the question of whether that's up to code for someone with more knowledge. – BMitch Feb 24 '14 at 13:46

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