ECN Forum Forums General Topics of the Trade General Discussion Area grounding

Joe,
Your last picture is what most in the trade would call a sheet metal screw. I agree that the code should require a machine screw or bolt, or other listed connection.
I don't see the inspector as having any choice. The code clearly only says you can't use sheet metal screws. This makes, by default, all other types of screws acceptable for grounding. This is one of the problems when the code is written to prohibit something as opposed to being written to requires something.
happy holidays
Don(resqcapt19)

Don:

This is a good reason to develop a Proposal for the 2005 NEC.



[This message has been edited by Joe Tedesco (edited 12-24-2001).]

Guys,
Lord knows I hate to get in on a good argument, but don't forget the BOCA, and standard engineering practices, would probably appreciate some mention of NOT removing the oxidation coating on a connection. A tapped hole, it is not necessary to remove the paint (or coating) to achieve a proper ground, and BOCA appreciates our not beginning a 'rust' hole because we find it convenient. Just thought I would mention that so your proposal could take that into account BEFORE we step on toes.

I need to elaborate the definition that I am trying to form, detween a self tapping screw, and a self tapping dolt. A self tapping bolt makes the same npn thread that a tap would. I would not use the screws you are showing in your pictures, because the threads are not npn. I believe the intent of the NEC was that, over time "IF" the screw was to become loose, or in need of repair than this same bolt could be refastened (torqued) or replaced, and done so without damage to the metal. Knowing my intent would you pass this version of a self tapping bolt ?
Look at the threads of the green screws suppled by the manufactures of most diconnects. there are two versions out, one is a mach bolt, that the hole supples it's threads, the other is npn threads that is tappered to go into the suppled hole that has no threads, it uses only the threads that it makes.
George Corron : (2002 NEC) "250.12"

Take one of the 8-32's out of a 4S, etc.metal box.
This is the screw that's a self-tapping.
It's OK. TEKscrews are sheet metal screws.
It's simple, don't split hairs.

After looking closer at 250.8, I can't permit any screws or bolts to be used to connect grounding conductors, except maybe the green 10-32 screws used in small enclosures. The section clearly requires the use of listed means to make the connection. I don't know of any screws or bolts, with the exception of the green 10-32 screws, that are listed for grounding connections. If I have a compression lug with a 3/8" hole on my grounding conductor, how can I connect it to the enclosure or building steel or other metallic object and be in compliance with 250.8?
Don(resqcapt19)

Guess I've been lucky in a way, I've been on heavy industrial (or similar) for a long time, Don, use Cadwelds, that's just about all I've seen in the last 10 years anyway, they're cheaper than you think, and reusable.

I believe your reading into that article more than what you should. I think the intent covers more "the Clamping of the conductor." and they didn't hit much on the way you would mount the clamp, Other than restrict the use of one kind of screw, and allow all others.

The substantiation for proposal 5-306 in the 1995 Report on Proposals that resulted in the "sheet metal" wording being placed in to the code indicated that this rule applies to both the direct connection of a grounding conductor as well as to the connection of a lug on a grounding conductor to the enclosure.
Don(resqcapt19)

Many fans, light fixtures, etc. come with a self tapping 8-32 screw to connect the ground.
Don, I think you might have gone a little bit overboard in your interpretation. (besides, you don't "permit" anyone to do anything other than your own work unless you're an AHJ)