What can you do if your newly-installed GFCI keeps tripping unless you detach all the other outlets in the room but all outlets are wired correctly?

Answer 1

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Answer for USA, Canada and countries running a 60 Hz supply service.It is possible (if this new GFCI receptacle was replacing a regular receptacle) that the GFCI receptacle has been added into a three-wire circuit where the neutral is "shared" (before it splits to 2 two-wire circuits). A simple GFCI receptacle will only work on two-wire circuits: one "Hot" and one "Neutral".

Also there may or may not be a "Ground" wire. If there is one, it is a protective wire and is not counted as a circuit wire.

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If you know that the GFCI is good, then a heater or other appliance that you are plugging in has a ground fault condition. This means that the bottom (ground) prong on the plug is carrying current, instead of the neutral. A GFCI measures the current coming in from the hot and compares it to the current going out on the neutral. If they differ from each other, the GFCI will trip. In your case the heater may have a fault to its frame and some of the current is going to the ground wire. Either find the fault by taking the heater apart, or buy a new one and toss the faulty one before it causes a serious problem.

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Assuming you have pressed the 'RESET' button but the GFCI always trips again immediately, there are several possible things that will have to be checked very carefully.

The newly installed GFCI could be tripping because of a neutral-to-ground short circuit, called a "neutral-to-ground fault", somewhere in the circuit it is monitoring. Here are some possible reasons for such a fault:

1) There is something plugged in to one of the outlets, such as an electric kettle, that has a neutral-to-ground fault. Any plugged-in appliance which has a neutral-to-ground fault will always cause the GFCI to trip even though the appliance's own "on-board" on-off switch may be off. So remove all appliances from the outlets and try to reset the GFCI. If all is well, plug in each appliance in turn until you find the one with the neutral-to-ground fault. (Old metal-bodied electric kettles are the worst offenders!)

2) Even if you have replaced the socket outlets there could be a neutral wire touching a ground wire because there is a nick in the insulation. *** (See Note below.) This sometimes happens when the cover is screwed down because the wires are pressed hard against each other to get them into the wall box. The PVC insulation around the wires is very soft so you have to be careful this does not happen. If there was no GFCI protecting the circuit - as in the old days when GFCIs did not exist - it did not matter if a neutral wire touched a ground wire or the metal box itself. But when you have a GFCI protecting a circuit which has that type of fault - probably left over from the days before the house had any GFCIs put in - it will always trip immediately you put power onto the circuit! The reason for that type of neutral-to-ground fault with GFCI-protected circuits is not known to everyone, especially if they have not had to find and fix one before.

Speaking from hard experience, neutral-to-ground faults in the supply wiring to the socket outlets can be a real pain to find!

*** Note: Neutral wires are colored White in USA, Canada and other countries which use similar 60 Hz mains supplies. In Europe and other countries which use 50 Hz mains supplies, Neutral wires are colored Blue for all new work. (Older wiring circuits may still have Black wires for neutral wires.)

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There are other things that can trip the GFCI:

1. Foreign matter in an outlet box (I found dead roaches in one case)

2. A noise suppressor power strip or power line filter

3. A guitar amp with a ground reverse switch

4. A water leak in the wall dripping on wiring

5. Older electronic devices made before GFCI became common

6. Some older computers

7. Devices that make sudden power surges

8. Old tube type radios and entertainment electronics

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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.