ECN Forum Forums Code Related Discussion NEC & other Code issues Need opinion

JFYI, I used an Appleton 4" sq. box on Fri. that had "GR" by the tapped hole, and also 3 1/2" deep sw boxes.

Mannnnnn..... The neverending thread... kinda like the ground pin up/down issue. Just put the screw in,and paint it green

[This message has been edited by txsparky (edited 05-23-2004).]

UL does not list individual screws for any purpose. UL does list assemblies.

So, based on the code panel negative comments, the only choices for a UL Listed "conductor directly to box" grounding connection would be either a push-on ground clip or a factory built "pig tail and screw" adapter installed in a factory threaded hole.

But instead, of connecting the conductor directly, choose a mechanical lug or a crimp lug/terminal (i.e. Stakons). These can then be installed using any method (including any hole) approved by the manufacturer of the connector.

Originally posted by CharlieE:
Thanks for the beers Charlie. I had a wonderful time.

Bob,Don, Ryan,
It looks like you guys were correct regarding the use of the clamp screw or any other screw besides than a sheet metal screw as prohibited in 250.8. Art. 250.8 speaks to the general requirements of grounding and bonding conductors, which are required, unless modified by another article. So, unless another article modifies the requirements for the connection method "shall be connected by exothermic welding, ..., or other listed means." , then that is what is prescribed by the code.

However, when one reads 250.148, which was mentioned above but not considered at the length 250.8 was, one finds "(A) Metal Boxes. A connection shall be made between the one or more equipment grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose or a listed grounding device."

Unless I have missed another article, or something, this is the specific modification of 250.8 that pertains to metal boxes used for specific purposes. (IMHO, 250.8 and 250.148 are two ends of the same sausage, just separated by a lot of intervening stuff.) Specifically, absent an NEC definition of the term "grounding screw", one uses normal English rules to determine the meaning. I.e., the screw is the noun, and grounding is the adjective that describes the function of the screw. No where in Art. 100 are "screw" or "grounding - adj." defined specific to the NEC. I do not see in 250.148 the use of the term "Listed" or "Green" describing the screw, only the prescriptive restriction that it shall be use for no other purpose. Furthermore, "a listed grounding device" (ground clip) can also be used. The article does not prohibit drilling and using any old hole for the connection, within the restrictions on boxes and enclosures elswhere on substantially reducing the strength, or positioning of fasteners, and with the restriction that conductive paths other than AWG size conductors shall be properly sized. (That is, you can't use a 2-56 screw for a 15 amp circuit lug.)

I don't have the references as we don't own them, but "been there, done that, got the T-shirt" on this one with a supplier.
Jim

Just came across an excellent article pertaining to this subject in the March, 03 Electrical Contractor Magazine, page 134.

I dont have anything to add to this discussion so I wont.