Grounding switch/outlet boxes

[racerdave3]

I was just reading another post and I thought about this question. When everyone is wiring up boxes for switches and receptacles, what means are you using to ground the box? Now the code states that a grounding screw is to be a 10-32 and be green in color. Does anyone use one of the 10-32 screws that are in the box after removing the cable clamp? If so, do you leave it as an unpainted screw or dab it with green paint, and would such an installation with the green paint even be legal? I have come across jobs where this has been done (not that the head was painted green) and was just wondering what eveyone's take was on it. I always install the ground with the grounding screw, but I guess others like shortcuts.

 

[raider1]

Now the code states that a grounding screw is to be a 10-32 and be green in color.

You dont need a green screw for a ground screw in the metal box. The only requirement for a green screw is for wiring devices. (See 250.126)

The requirement for attachment of equipment grounding conductors to boxes is section 250.148.

250.148 (C) requires a connection between one or more equipment grounding conductors and a metal box be done by means of a grounding screw that shall be used for no other purpose or a listed grounding device.

Chris

 

[cowboyjwc]

I can't understand why some guys just can't follow the rules, but it's always been that way.

Sometimes I'll take something over nothing, but I don't allow them to use the mounting screws to ground to and I don't allow things like drywall screws where the boxes are mounted on plywood back boards. We used to use stove bolts sometimes when we didn't have ground screws, but that was very rare and it wasn't required to be green way back then.

I don't think I've seen the clamp screw used to often.

 

[ceknight]

....Does anyone use one of the 10-32 screws that are in the box after removing the cable clamp?

Yep, frequently.

If the customer wants 'em painted, s/he can hire a painter.

 

[goldstar]

I won't go as far as to insinuate that many of us have never done this before but IMHO, the screw that is used to clamp down an AC or RX cable is intended for use for that purpose irrespective of whether you paint it green or not. In addition, if you have a metal box in a 3 1/2" studded wall, that screw is probably going to extend too far out the back of the box and penetrate into the sheetrock if you use it this way. If you happen to be one of those electricians that uses deep metal boxes for AC cables (but are, in fact, using RX cable) and you break off the rings that prevent the AC cable from entering the box too far, then that particular screw is much too long to be used for grounding purposes and will probably penetrate the sheetrock and may even poke through the other side. There are # 10/32 threaded holes in the backs of 1-gang metal gem boxes and 4" square boxes that are intended for use with the 3/8" green ground screws. Technically speaking, we should be using the green ground screws intended for that use.

 

[celtic]

There are # 10/32 threaded holes in the backs of 1-gang metal gem boxes and 4" square boxes that are intended for use with the 3/8" green ground screws. Technically speaking, we should be using the green ground screws intended for that use.

3/8" ground screw in a 1900 box?
Wow...what else ya gonna put in that box ...a million gigawatts?

 

[LarryFine]

3/8" ground screw in a 1900 box?
Wow...what else ya gonna put in that box ...a million gigawatts?

LOL!

I have a feeling he was referring to the hex-head size.

But that was funny!

 

[goldstar]

10/32 x 3/8". What did I miss ? Did I say this incorrectly ? Tell me what the joke is cause I want to laugh too.

 

[LarryFine]

10/32 x 3/8". What did I miss ? Did I say this incorrectly ? Tell me what the joke is cause I want to laugh too.

Around these parts, hardware is sized by the shank, not the head.

 

[ceknight]

....... but IMHO, the screw that is used to clamp down an AC or RX cable is intended for use for that purpose irrespective of whether you paint it green or not........................ Technically speaking, we should be using the green ground screws intended for that use.

If I'm understanding your post correctly, a manufacturer's intent is, technically speaking, the proper determinant for hardware choice? That seems to put a lot more faith in a fastener's marketing than in its design, or at least it seems that way to me.

I suppose I should replace all my sheet metal screws with pan-head wood screws now, too? I do surprisingly little sheet metal work, but I sure seem to use a lot of those buggers...

 

[celtic]

10/32 x 3/8". What did I miss ? Did I say this incorrectly ? Tell me what the joke is cause I want to laugh too.

"Normally", the green grounding screws are 10/32 x 5/16" hexhead....a perfect fit for the Klien 10-in-1 screw driver. Now, the length may be 3/8" ...I never measured it.

3/8" ?...that's a bolt diameter.

Sorry to have backed that bus over you...LOL.

 

[goldstar]

5/16 - 3/8 What's 1/16" among friends !!! I never measured them either but I'm sure one of us is right.

You didn't run the bus over me I just didn't get the humor

 

[russ]

3/8" sounds like a good length to me, although they may be 1/2", I never measured one either.
10/32 a good thread.
5/16 a common hex head.
I think their all proper sizes.

 

[celtic]

Then it's settled....
10/32 with a 5/16" hexhead and a length of 3/8" - 1/2"

...but...

...wait...

What's this:

No hexhead?
Blasphemy!