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  1. #1
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    GFCI Downstream from Gnd~Neut Short in AFCI protected circuit

    A neighbor in a single story home recently had a new roof put on. After the job was finished she discovered that turning on (wall switch) her bedroom lights that the AFCI would trip.

    The roofing company claimed to not understand how their work could have caused this, but agreed to pay for 1 service call from an independent electrician to investigate before deciding if they would accept responsibility.

    The electrician discovered a ground-to-neutral short along an exterior wall of the bedroom between the final two outlets in the run. By unplugging a table lamp from the farthest downstream outlet (downstream of the fault) the AFCI would no longer trip. The electrician checked along the wall (both inside & outside) for the possibility of a stray nail, but found nothing.

    Faced with the prospect & expense of having to tear out a portion of the bedroom wall, the roofing co. foreman asked the electrician if there was another option. The electrician said he could either disconnect the two outlets along that wall or he could put a GFCI duplex outlet ahead of the fault and leave the grounds open and taped-off then put a label on the GFCI outlet cover and the 1 outlet cover downstream to indicate "no ground". He said since it was a bedroom that it was unlikely anything other than a 2-wire cord (lamp, clock radio, etc.) would ever be used in either outlet location. He went on to say that the workaround "wasn't code" but would still be safe. His work ticket shows that he charged only for the service call, but did not charge time or material for the illegal fix.

    I would be interested in hearing others' thoughts on this.
    Thanks!!

  2. #2
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    A "no ground" GFCI installation is acceptable under the code.
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  3. #3
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    Quote Originally Posted by timebuilder View Post
    A "no ground" GFCI installation is acceptable under the code.
    True, but the code also prohibits grounding connections on the load side of the service disconnect. Wouldn't there still be a neutral-ground short, even if the ground wasn't connected to the downstream recepts?

  4. #4
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    After the ground leads were disconnected & isolated & taped back, there would no longer be any ground reference at either the GFCI outlet nor the downstream receptacle. All that remained would only be a conductor fault between the neutral lead and a now unused lead. We had a fairly spirited discussion about it over beers afterwards, but in the end all could agree that the two outlets were both working and safe. The only unanswered question was whether or not an arc fault occurring at the GFCI outlet or downstream from it would still trip the AFCI breaker at the panel. I said it would and was ready to put a C Note on it but AFCI being such a black art we had no way to prove it.

    What will be interesting is to see if the residence passes inspection the next time the property changes hands. If the inspector eyeballs the very unusual location of the GFCI outlet in the bedroom and/or spots the "no ground" labels then he/she may red tag it.

  5. #5
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    Maybe I haven't visualized this accurately. Are you saying the ground to neutral short remains in place? I thought it was between the receptacles....
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  6. #6
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    The fault has been isolated and rendered non-affecting by the disconnection of the ground leads on opposing sides of the fault. The location of the fault is inside the wall somewhere within a 10-ft span between two duplex receptacles on that same wall. The homeowner did not want her bedroom wall torn apart, nor was the roofing contractor willing to accept financial responsibility for what could become a several hundred dollar project to fix something he could not possibly have caused.

    Electrical service was restored by replacing the upstream outlet with a GFCI receptacle, with upstream (unfaulted) ground connected but with downstream (faulted) ground lead removed and taped back. then removing the ground lead and taping it back at the downstream outlet as well (last outlet on the circuit). Thus the circuit now consists of only the hot and neutral downstream of the GFCI. The faulted conductors are still in use, but the ground wire having been isolated at both sides of the fault eliminates the problem with the AFCI tripping. The GFCI protects the homeowner/occupants from injury and the "no ground" label would seem to be in compliance with NEC.

    Unarguably the right way to fix it would be to open the wall and replace the (Romex?) between the two outlets or else disconnect them both, rendering them unusable. The GFCI receptacle was the 3rd option, and while certainly not kosher, restored service to both outlets safely, albeit sans ground.
    Last edited by Cap'n Preshoot; 04-14-2013 at 09:26 PM. Reason: Addt'l info

  7. #7
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    Except that arc fault is required in the bedroom. Not GFCI.

    Quote Originally Posted by Cap'n Preshoot View Post
    The fault has been isolated and rendered non-affecting by the disconnection of the ground leads on opposing sides of the fault. The location of the fault is inside the wall somewhere within a 10-ft span between two duplex receptacles on that same wall. The homeowner did not want her bedroom wall torn apart, nor was the roofing contractor willing to accept financial responsibility for what could become a several hundred dollar project to fix something he could not possibly have caused.

    Electrical service was restored by replacing the upstream outlet with a GFCI receptacle, with upstream (unfaulted) ground connected but with downstream (faulted) ground lead removed and taped back. then removing the ground lead and taping it back at the downstream outlet as well (last outlet on the circuit). Thus the circuit now consists of only the hot and neutral downstream of the GFCI. The faulted conductors are still in use, but the ground wire having been isolated at both sides of the fault eliminates the problem with the AFCI tripping. The GFCI protects the homeowner/occupants from injury and the "no ground" label would seem to be in compliance with NEC.

  8. #8
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    Quote Originally Posted by lytning View Post
    Except that arc fault is required in the bedroom. Not GFCI.
    My point exactly, which is why I started this thread. The AFCI is still upstream of the entire circuit in the panel and it was my contention (OK, beer-stained thought) that the AFCI would still trip in the event of an ARC Fault event occurring on either side of the GFCI except there was no way to prove it. (Bearing in mind that most all "bedroom appliances" would likely be of a two-wire variety, even if it was a heating pad or electric blanket, the presence of or absence of a ground thereby a non-issue)

  9. #9
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    Ok so all the Arc Faults would work as designed because they are 1st in the bedroom circuit. The last on the circuit is the GFCI and that is still on the Arc Fault circuit, due to the Arc Fault breaker. Therefore the GFCI is protected by the Arc Fault breaker. That would cover the NEC as I see it. Still I am not the AHJ.

    Quote Originally Posted by Cap'n Preshoot View Post
    My point exactly, which is why I started this thread. The AFCI is still upstream of the entire circuit in the panel and it was my contention (OK, beer-stained thought) that the AFCI would still trip in the event of an ARC Fault event occurring on either side of the GFCI except there was no way to prove it. (Bearing in mind that most all "bedroom appliances" would likely be of a two-wire variety, even if it was a heating pad or electric blanket, the presence of or absence of a ground thereby a non-issue)

  10. #10
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    Indeed - - and thanks. As I said earlier, the proof of the pudding will be seen when the property next changes hands and the potential buyer hires an inspector. Most mechanical home inspectors rarely check for electrical issues beyond testing the GFCI in the baths and kitchen. I've never heard of one walking around to verify every single outlet unless they were instructed to spare no effort in finding a way to fail a home to allow the buyer to back out without penalty. As example, my son just sold his 1970-vintage home with aluminum wire throughout and no pigtails. The dime store variety home inspector never looked.

  11. #11
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    I think a lot of them do use the 3 prong plug testers.
    Quote Originally Posted by Cap'n Preshoot View Post
    Indeed - - and thanks. As I said earlier, the proof of the pudding will be seen when the property next changes hands and the potential buyer hires an inspector. Most mechanical home inspectors rarely check for electrical issues beyond testing the GFCI in the baths and kitchen. I've never heard of one walking around to verify every single outlet unless they were instructed to spare no effort in finding a way to fail a home to allow the buyer to back out without penalty. As example, my son just sold his 1970-vintage home with aluminum wire throughout and no pigtails. The dime store variety home inspector never looked.

  12. #12
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    Quote Originally Posted by lytning View Post
    I think a lot of them do use the 3 prong plug testers.
    That's what they use here. It's a lot cheaper than the handheld Amprobe INSP-3.
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  13. #13
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    Quote Originally Posted by timebuilder View Post
    A "no ground" GFCI installation is acceptable under the code.
    While your statement in itself is correct, its application to the OP's situation is not applicable.

    (c) A non-grounding-type receptacle(s) shall be permitted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault circuit interrupter. Grounding-type receptacles supplied through the ground-fault circuit interrupter shall be marked “GFCI Protected” and “No Equipment Ground.” An equipment grounding conductor shall not be connected between the grounding-type receptacles.

    (1) Grounding-Type Receptacles. Where a grounding means exists in the receptacle enclosure or an equipment grounding conductor is installed in accordance with 250.130(C), grounding-type receptacles shall be used and shall be connected to the equipment grounding conductor in accordance with 406.4(C) or 250.130(C).

    The bedroom is required to be AFCI. The only solution would be to correct the wiring to be safe and legal.

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