This article was posted 12/29/2006 and is most likely outdated.

Article 250 Grounding and Bonding 250.8
 

 
Subject - Article 250 Grounding and Bonding 250.8

January 12, 2006  

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Grounding and Bonding

250.8 Termination of Grounding and Bonding Conductors

Revised text clarifies that terminals for grounding conductors or bonding jumpers must be attached to enclosures in a suitable method to ensure an effective ground-fault path.

The termination of equipment grounding and bonding conductors must be by exothermic welding, listed pressure connectors of the set screw or compression type, listed clamps, or other listed fittings. Sheet-metal screws cannot be used to connect grounding (or bonding) conductors or connection devices to enclosures. Figure 250-6

Author’s Comment: The rule still doesn’t prohibit drywall screws or wood screws for being used for this purpose, just “sheet-metal” screws!



Figure 250-6
(Click on image to enlarge)

       
 

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Comments
  • You better not use drywall screws. I have not seen any green ones to date.

    Steve Moncur
    Reply to this comment

  • Try this put in drill & tap.that the way to do it.

    Chris Lepore
    Reply to this comment

  • While i am aware that it does not prohibit drywall screws or wood screws, a electrician would understand that drywall screws and wood screws are not to be used. A electrician would take the time to use a proper machine type screw with a nut should he not have the supplied manufacturs screw.

    James
    Reply to this comment

  • This concerns the comment about using a wood screw or a drywall screw for equipment ground.

    I have never seen a listing for either, and since neither is a "listed fitting", they are not allowed in our jurisdiction.

    mike tooke
    Reply to this comment

  • If you cannot use sheet metal I am sure inspectors would have a problem with wood screws. Let use nails, carpet tacks, or liquid solder for that matter.

    Robert Stevens
    Reply to this comment

  • I believe the \"intent\" is for machined threads, not coarse threads as are wood, sheet metal, drywall screws, etc. Nor do I believe these type items are \"listed\" for the use you are wanting to attach the grounds.

    C. Thomas
    Reply to this comment

  • I would also add a 1/4 20 machine bolt is a violation.

    min threads/inch for grounding if I remember correctly 28

    electorman
    Reply to this comment

  • Mike, As you are aware, for the 2008 Code cycle, CMP 5 has extensively revised the text to 250.8, and exactly defined the types of screws that may be used. Perhaps it is time to do away with your comment about drywall screws and wood screws? This seems to steer some readers into actually believing that these screws would be OK to use.

    Ron Alley, CMP 5
    Reply to this comment

  • I don't see, for the life of me, what the difference between a "sheet metal screw" and a regular drywall screw would have on the integrety of a bonding system. I personally don't like either because of the metal stripping out. I do like a standard threaded 10-32 in a metal of adequate thickness much better, tho.

    RC Brown
    Reply to this comment

  • Keep going Mike, I know of no better way to remind and educate than a little at a time as you are doing. Small bites of the large elephant.

    Thank you for doing this great job.

    David W. Smith Ph.D

    David W. Smith
    Reply to this comment

  • what is the reason, the sheet metal or self taping screw are not to be used. As we all know the screws hold building steel togeather, and when we bond to the structureal steel the building is considered bonded togeather.

    Tom Cekovich
    Reply to this comment

  • Hello, I have a question about the ground wires in the time clock. It is my understanding that the clock itself needs to be grounded. In the picture being that it does not bolt in and just clips in. So what i'm asking doesn't the two grounds need to be made together, not separate like they are?

    Boyd
    Reply to this comment

  • The rule is to prohibit 'self threading' screws, not the specific type of 'self threading' "sheet metal" screw . You cannot guarantee the integrity of threads cut by these screws in a sheet metal box, therefore the screw and nut method, or the formed thread in sheet metal method is preferred (or the rule).

    Bob
    Reply to this comment


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