GFCI Problem

Discussion in 'Electrical Forum discussion & Blog' started by Papo_60, Jul 27, 2009.

  1. Papo_60

    Papo_60 New Member

    Hi, newbee to this site with my first question/problem.

    A while back I updated (ivory to white) the outlets, switches & exhaust fane in the master bath at my son's house. Nothing major. They had one GFCI outlet which I replaced with a standard 3 prong outlet.

    Both the master & common bathrooms are on the same breaker so I decided to put in a GFCI breaker rather than replace the 3 GFCI outlets that were in both baths. There are a couple of additional hallway outlets on this breaker also.

    When I installed the GFCI breaker it trips every time I switch it on. The original GFCI outlets worked fine. What is the best way to determine what might be causing the circuit breaker to trip? I rechecked all the boxes in the master bath & all grounds are connected?? Would a unconnected gnd wire somewhere in the loop cause this?? Should I replace the other two GFCI outlets with standard outslets, could this be the problem?? If not, what is the most likely problem??? I am sure there are a couple of junction boxes in the attic, which feed the different baths/halway outlets, that I have not looked at yet.
    Thanks for any help,
  2. Thatguy

    Thatguy Homeowner

    Neutral and ground connected together and/or
    bad GFCI.

    Disconnect the neutral wire from the load side of the new GFCI and check for no continuity between it and the ground wire.
    Reconnect the neutral.

    Put a 7-1/2w incand. lamp in series with the ground wire that serves the cable downstream of your GFCI.
    If the voltage across the bulb reads from 0.6 vac to up to 120vac you've found your leakage path to ground. A normal reading would be less than 15 mVac.
  3. drick

    drick In the Trades

    You should have just stuck with individual GFCIs in the bathrooms. Now if the GFCI trips you just bought yourself a walk to the load center. You are also protecting things (lights, hall outlets, etc) that don't need GFCI protection. Its going to get real dark in the bathroom if the GFCI trips at night and its protecting the light. The way the bathroom is wired also violates current NEC standards, but thats another can of worms you might not want to get into. The NEC states that ONE bathroom can be entirely on ONE 20A breaker OR outlets in the bathroom(s) can share a 20A breaker provided nothing else is connected to that circuit (ie no lights, hall outlets, etc).

    Anyway if you are going to use a GFCI breaker first get rid of the extra GFCIs. Next open up all the outlet and switch boxes on that circuit and check to be sure that the bare ground is stuffed to the back of the box and not accidentally touching a neutral screw. Since you installed a GFCI breaker the fault could be anywhere on that circuit and not just on the part you touched. Since there was no GFCI before the ground touching a neutral screw on the old outlets would not have tripped the breaker, now it will. This is a common problem.

    A disconnected ground wire would not cause a problem. In fact a GFCI will work with no ground wire at all. They operate by measuring the power exiting the hot wire against the power returning on the neutral wire. If there is an imbalance between the two wires- because of something like you being shocked - they trip. They also trip if any power is sensed returning on the ground wire if present.

    Last edited: Jul 27, 2009
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    Are you feeding the GFCI devices in the other bathrooms with the new GFCI CB? Often not a good idea. Also, if all of the bathrooms are on single breaker, it wouldn't meet code today. You need a 20A dedicated circuit to the can't go outside of the bathroom to feed other rooms (but I think you could feed multiple bathrooms - at least you could awhile ago, probably not today).

    Get a group of people using hair dryers in each room, and you'll quickly pop the breaker.
  5. Papo_60

    Papo_60 New Member


    Thanks for your responses to my GFCI problem.. This house was built back in the 60's & at that time no GFCI devices were required to protect the bathrooms or outside outlets (at least here in NY). A couple responses to your inputs:

    • The CB is only a 15 Amp & does trip now & then when hair dryers, etc. are being used in both rooms &/or the vac plugged into the hallway outlet. Not a good situation but alternative is too expensive to undergo at this time.
    • I plan to go back to the individual GFCI outlets as I did not find any boxes with gnd's touching the neutral screw on this circuit. In fact, 2 yrs ago, when they moved into the house, I replaced all outltes/switches (ivory for white) & I rapped all devices with elec. tape before replacing..
    • Thanks for the explanation of how the GFCI works & doesn't work. I didn't think a missing gnd would have caused the problem but I would not have bet on it before your input...
    • One thing I will do later this week is (after putting the GFCI CB back in) is disconnect the neutral wire from the load side of the new GFCI and check for no continuity between it and the ground wire. I will also disconnect a wire from one of the CB's above or below the GFCI CB & connect this wire to it, if the GFCI CB does not trip this should help eliminante the GFCI being bad???

    One question about lights in the shower & switch for this light (with dimmer control) being right outside the shower door. Wouldn't this set-up also require some sort of GFCI protection????

    Guys, thanks again for your help. It is very much appreciated...
  6. ActionDave

    ActionDave Electrician

    No GFCI protection needed on switches, only on recepts.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    If the neutral is shared with another circuit, that will cause the GFCI outlet or breaker to trip, when there is a load on that other circuit.
  8. ActionDave

    ActionDave Electrician

    This would make the breaker trip if there were any load.
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