GFCI Voodoo - Page 2
RSS | Subscribe | Contact Us | Advertise | About Us
Page 2 of 2 FirstFirst 12
Results 26 to 38 of 38

Thread: GFCI Voodoo

  1. #26
    Join Date
    Jul 2008
    Posts
    1,672

    Re: GFCI Voodoo

    Thanks, Willie.

    The three conductors between house and shop are heavy copper, insulated, and they run through metal conduit (or at least they do at the shop end of things, not sure about the house end).

    Could it be that the metal conduit between the house panel and the shop subpanel serves as the ground connection?

    The guys at the electrical supply house suggested I add an additonal buss bar inside the subpanel which would be insulated/isolated from the metal of the subpanel, with all the neutrals bonded to that bar, and leave all the grounds hooked to the existing bar, which is bonded with the metal case of the subpanel (and conduit). That way, the neutrals and grounds would be separate all the way back to the main panel.

    Would that work?

  2. #27
    Join Date
    Feb 2012
    Location
    Hell I see Sparks
    Posts
    3,634

    Re: GFCI Voodoo

    The problem with bonded ground and neutral is; the return path for electricity can travel thru the ground instead of neutral. This is known as open neutral and can cause 240volts to reach your 120 equipment. Member Brocolli linked a good post explaining better than I can.

  3. #28
    Join Date
    Feb 2012
    Location
    Hell I see Sparks
    Posts
    3,634

    Re: GFCI Voodoo

    Here's A video explaining open neutral


  4. #29
    Join Date
    Oct 2015
    Posts
    75

    Re: GFCI Voodoo

    Just to add something to the conversation, a GFCI does not require a ground to work properly. All it senses is an imbalance between the potential and neutral. The neutral and earth ground should only bonded together at the main panel.

  5. #30
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    4,744

    Re: GFCI Voodoo

    If the conduit is continuous, connected tight at all joints, and lock nuts tight, and not in concentric knockouts, it can serve as the ground. I would load test it to confirm if you don't have access to all joints to confirm they are good.

    Most panels come with a neutral buss insulated from the box. A bonding screw, or strap connects them to the box. Remove the bond, and add an equipment ground buss. Land equipment grounds on it. I use Square D PK27GTA, or smaller, (PK12GTA). If you don't have Square D panel, drill .147 holes, and use the self threading screws provided. I clean away paint around the screw hole, and use a bit of NOALOX on back of box, threads, and under the head of the screws. It will never corrode, or surface oxidize.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  6. #31
    Join Date
    Jul 2008
    Posts
    1,672

    Re: GFCI Voodoo

    Quote Originally Posted by Willie B View Post
    If the conduit is continuous, connected tight at all joints, and lock nuts tight, and not in concentric knockouts, it can serve as the ground. I would load test it to confirm if you don't have access to all joints to confirm they are good.

    Most panels come with a neutral buss insulated from the box. A bonding screw, or strap connects them to the box. Remove the bond, and add an equipment ground buss. Land equipment grounds on it. I use Square D PK27GTA, or smaller, (PK12GTA). If you don't have Square D panel, drill .147 holes, and use the self threading screws provided. I clean away paint around the screw hole, and use a bit of NOALOX on back of box, threads, and under the head of the screws. It will never corrode, or surface oxidize.
    Thank you sir!

  7. #32
    Join Date
    Jul 2008
    Posts
    1,672

    Re: GFCI Voodoo

    FWIW, the whole problem with the HF tripping the GFCI receptacle seems to be associated with some old dead/dying fluorescent light fixtures. I unplugged and removed several fluorescent fixtures, replaced the GFCI receptacle, and now my problems with HF Start tripping the GFCI seem to be gone. A welder friend of mine suggested that maybe the HF was going into the ballasts or other electronics in the fluorescent fixtures, and creating some kind of noise on the AC lines (a few bad fixtures were downstream of the GFCI receptacle) that caused the GFCI to trip.

    On another note, I bought some LED shop lights that seem to work real nice. They're bright, they have no ballasts, they use less power than the fluorescents, and they supposedly work fine when it's cold.

  8. #33
    Join Date
    Sep 2012
    Location
    West of Minnesnowta, USA
    Posts
    402

    Re: GFCI Voodoo

    Quote Originally Posted by Kelvin View Post
    FWIW, the whole problem with the HF tripping the GFCI receptacle seems to be associated with some old dead/dying fluorescent light fixtures....
    Kelvin,

    Glad you are getting a handle on this. When I posted a few days ago about not having the neutral isolated from the ground in the sub panel possibly being a cause was incorrect. The ground and neutral need to be isolated, otherwise the ground will be carrying part of the neutral current. The ground is only there to carry fault current and provide protection. However, the more I thought of this, I could not see how that could cause the GFCI to trip, at least in theory.

    I do have a GFI that occasionally trips for no reason that I can see. It is in a room with a fluorescent fixture that is in need of a tune up. Thanks for providing the 'round tuit.'
    Tim

  9. #34
    Join Date
    Feb 2012
    Location
    Hell I see Sparks
    Posts
    3,634

    Re: GFCI Voodoo

    I have a dying flourescent tube close to my GFI. Now Im wondering if my intermittent GFI trips when the lights are on.

    Nice fix Kelvin.

  10. #35
    Join Date
    Jul 2008
    Posts
    1,672

    Re: GFCI Voodoo

    Quote Originally Posted by Insaneride View Post
    I have a dying flourescent tube close to my GFI. Now Im wondering if my intermittent GFI trips when the lights are on.

    Nice fix Kelvin.
    The funny thing about it is, before the GFCI started tripping, sometimes when I hit HF Start, it would cause half-dead, half-lit fluorescent tubes to LIGHT UP, even without actual arc initiation.
    Last edited by Kelvin; 08-15-2018 at 03:10 PM.
    Syncrowave 250DX
    Miller 330 A/BP
    Miller Big Blue 251D

  11. #36
    Join Date
    Feb 2012
    Location
    Hell I see Sparks
    Posts
    3,634

    Re: GFCI Voodoo

    Quote Originally Posted by Kelvin View Post
    The funny thing about it is, before the GFCI started tripping, sometimes when I hit HF Start, it would cause half-dead, half-lit fluorescent tubes to LIGHT UP, even without actual arc initiation.
    Now I wonder if the HiFreq messed up my bad lights.

    A static shock to the tubes will cause them to flouresce for a moment so its not surprising your MILLER's HF lit them up. Now I need to try welding with lights on and see if thats my problem. I dont need the GFI anyway.

  12. #37
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    4,744

    Re: GFCI Voodoo

    If you follow the instructions in the Miller manual you will minimize the HF RFI problem. My TIG machine is 14 feet away from my living room TV. I get no complaints about interference. I've had three different Miller TIG welders, never a complaint about TV, or radio interference.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  13. #38
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    4,744

    Re: GFCI Voodoo

    I happened to pick up a bit of something packaged with a pool light transformer. It talks of collapsing magnetic field creating enough induced coil voltage to trip a ground fault. Newer electronic fluorescent ballasts have far less of this phenomenon, but old magnetic ballasts certainly could. Hayward offers a snubber, a capacitor placed parallel with the transformer primary.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
RSS | Home | Penton Media | Contact Us | Subscribe | For Advertisers | Terms of Use | Privacy Statement