ground electrical boxes

Discussion in 'Electrical Forum discussion & Blog' started by samlin7, Jan 25, 2008.

  1. samlin7

    samlin7 New Member

    Messages:
    43
    hi

    I have 12/2 romex cable coming into a metal electrical box, I was wondering if I need to ground the metal box?

    If so, should i use 12 gauge to ground the box (or any gauge wire) and do they sell the screws to attach to the metal box so I can ground it? Or can I use any screws I see in the metal box?
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    If the ground wire will not reach to the threads where the ground screw goes then pig tail with yellow wire nut and a peice of #12 bare wire to it.
    Ground screws are avaliable at hardware stores and big box stores. They are green in color. As far as I know any screw with that thread is OK to use as long as it is green.
  3. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    988
    Location:
    NY State, USA
    The screw does not need to be green, but it does have to be a machine thread. Sheet metal and drywall type screws are NOT allowed.

    And yes, the box MUST be grounded first and foremost.
  4. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,712
    Location:
    Central Florida
    The Equipment Grounding Conductor, the box, and any device attached to the box must all be bonded together. In addition to the guidance Speedy Petey gave you, the screw used for gounding/bonding can be used "for no other purpose", so you can't use a Romex cable-clamp screw (but if you aren't using the clamp, throw it away and you can then use the screw for grounding). Somewhere else on this forum there's a nice cutaway picture showing a neat way to accomplish that: the ECG is wrapped around the screw in the box, and carries on to the screw on the device; neat, clean, with no wirenut cluttering up the works.
    Last edited: Jan 27, 2008
  5. iminaquagmire

    iminaquagmire DIY Senior Member

    Messages:
    207
    Get some panel screws. They are easy to wrap around the wire around and continue it over to the ground terminal.
  6. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    988
    Location:
    NY State, USA
    This isn't the best advice.
    There are about 10 different types of panel screws, and very few have actual machine threads.
    If you are going to go get anything, get real ground screws. I'd bet they are also ten times cheaper than panel screws as well.
  7. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,712
    Location:
    Central Florida
    Took the words right out of my fingers...
  8. BrianJohn

    BrianJohn DIY Senior Member

    Messages:
    151
    Location:
    VA
    Is this 12-2 with a ground or are you in an older house and want to run an equipment grounding conductor to each box?
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