Using grounding bar inside 3-gang metal outlet box

Discussion in 'Electrical Forum discussion & Blog' started by gramson, Mar 14, 2014.

  1. gramson

    gramson New Member

    Messages:
    2
    Location:
    MI
    I was thinking on installing a short grounding bar inside the metal junction or outlets/switches box.
    Since the distance inside the box between GND holes matches with the bar mounting holes, it can be easily installed. That would make much simpler, cleaner wiring inside the box. I have 5 NMB cables coming, it is already 5 GND wires, plus 3 GND wires from three switches planned to be installed in that metal box (same idea would be used for square 4†box wiring two receptacles). The short GND bar cut to 8-position length would allow making simple GND wires termination.
    The GND bar is low profile, does not take so much space in a vertical direction.
    No pigtail wire to GND screw inside the box would be used, since the bar is sitting inside metal box fastened with two screws.
    Please advice, would that be acceptable?
  2. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,799
    Location:
    Long Island, NY
    Improvising installations even with good ideas and listed components that are not intended to be used together in ways not approved by code are typically not allowed.
  3. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    If you make up the grounds neatly then it takes less room than the terminal bar and will not expose the other conductor to abrasion from the projecting screws and sharp ends of the protruding conductors.
    Although I would have pushed my grounds back before I made up the hot conductor this box shows How the grounds should be made. It was the intent of the installer to sort out the hot and terminate it first and everything left would be switch legs or travelers.

    Notice that when pulled straight out the EGC will extend out of the box the required three inches, see 300.14 and the tails left for the switches are also able to extend out of the box the required three inches.
    After doing a few thousand you will learn to gather them up, trim them to length, strip them and either install a wire nut or bend them and install them on a device without ever turning a single one of them lose with you hand until done.
    [​IMG]

    This box has a three way for one light and a single pole for the other light. The single pole is powered from the hot-in and hot-out and the three way is powered at the other three way with the neutral being fed through.

    It also shows the proper method if installing the neutrals and preventing a parallel path one on the switch and the other around the room on the receptacles. Tying all the neutrals together would work but will cause problems with Arc Fault overcurrent devices and would not be code compliant.
    Last edited: Mar 14, 2014
  4. gramson

    gramson New Member

    Messages:
    2
    Location:
    MI
    jwelectric, thanks for showing so nice and need example of high experienced professional solution.
    Well, I am removing my GND bar and learning/practicing how to make it compact and right.
    Thanks for an advise.
  5. Stuff

    Stuff Member

    Messages:
    53
    Location:
    Pennsylvania
    You will still need a wire nut or crimp. Just twisting the grounding wires together is not enough.

    Also - with a metal box you don't need to ground switches as long as you are using standard metal screws. Some say you need to remove the insulator, though.
    Last edited: Mar 15, 2014
  6. ankhseeker

    ankhseeker Member

    Messages:
    80
    Location:
    California
    This box has a three way for one light and a single pole for the other light. The single pole is powered from the hot-in and hot-out and the three way is powered at the other three way with the neutral being fed through.

    It also shows the proper method if installing the neutrals and preventing a parallel path one on the switch and the other around the room on the receptacles. Tying all the neutrals together would work but will cause problems with Arc Fault overcurrent devices and would not be code compliant.[/QUOTE]

    Is that because they are on separate circuits?

    Curious minds want to know...
  7. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    No there is only one circuit feeding the entire room. The neutrals are all joined at the other switch which is also feed in from the receptacles and out to the other receptacles in the room. If all the neutrals were under one nut in the pictured box then the neutral conductor for the three way switch would be paralleled with the neutral supplying the receptacles. This would be a code violation as in order to parallel conductors they are required to adhere to being the same length and also size 1/0 or larger. Arc Fault breakers will also see this as an arc due to the splitting of the current on the neutrals and will nuisance trip.
  8. ankhseeker

    ankhseeker Member

    Messages:
    80
    Location:
    California
    Ahhh, I get it now. Thanks!
  9. ankhseeker

    ankhseeker Member

    Messages:
    80
    Location:
    California
    Ahhh, I get it now. Thanks!
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