Grounding A Metal (outlet) Gang Box Question

[Robert11]

Hi,

Over the years, whenever I installed and wired in a metal gang outlet or switch box in my house, I always just twisted the green wire grounds together, and then securely grounded them to the metal box itself by simply twisting around a pan-head screw (with a flat washer) thru the metal box right into the wooden stud.

Have now seen some articles and posts where this is not the right way to do it, but they never say why not, or what is the right code approved, way.

Would appreciate any comments and thoughts on.

Thanks, B.

[Takoma Park Volunteer Fire Dep]

The code is very specific on how Equipment Grounding Conductors (EGCs) are to be terminated. You have to use a machine screw that is threaded into a tapped hole in the box itself. A wood screw that is threaded into the wood behind the box will not keep predictably constant pressure on the EGC do to the expansion and shrinkage of the wood with changes in it's moisture content. The code also requires that a suitable connector must be used to splice the EGCs. just twisting them around each other is no enough.

-- Tom H

[Jag Man]

Tom,

Is the Ideal In-Sure push-in connector suitable? These are shown at:

TIA

Ed

[Tekkie]

Jag Man posted for all of us....

They are UL CSA listed so they should be.

[The Real Tom]

Only summerized as a responser to your post, please read the code for more accurate information:

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2002 NEC 250.148(A) "Metal Boxes" one or more equipment grounding conductors shall be bonded to the metal box via a grounding screw, and that screw shall be used for not other purposes.

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So imho, you cannot use a screw that also works as a means of anchoring the box to the wood stud.

hth,

tom @

[Bud]

Also can use (NEC) "a listed grounding device" such as a ground clip.

Bud--

[The Real Tom]

I've had this discussion before and still left confused, where does the NEC say a grounding clip is a "ground screw"? Or what article/section says that it is the same, or overrides the ground screw requirement?

Been hearing much about inspectors failing rough-in because it specificly says, "Ground screw"

Thank you for your insight,

tom @