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

Read 250.8 2002 handbook. Also explains, Listed clamps or other Listed means. Shows pic of 4" square box with Listed ground screw. cable clamp box screw is Not a Gr, screw.Page 178 2002 NFPA code handbook.Now if thread correct you could use threaded hole to intall a Proper gr screw.

The handbook is not code and there is no code requirement to use a green screw. What do you do for a 250kcmil, connect the lug to the bus using a green 10-32 grounding screw???????? The only code restriction on the type of screw used for a grounding connection is that it must not be a sheet metal screw. The only other restriction is that the screw cannot serve any other purpose.
Don

Morning Don
Ist the NEC code HANDbook is put out by the NFPA same folks whom bring us the code book. Its interpreations are accepted by most electrical inspectors, Two. Now you know a 250kmcm won;t fit under a 10/32 you:d be Required to use a LISTED and LABELED lug approved for that purpose.
Also in your area if its APPROVED by the AHJ (look up def of approved) You I suppose could do it. I just think Code says no and if you:ve ever put a ground screw under a cable clamp you:d know it tends to slip out as tightened because the head is so small. Ground screw have much larger heads.
Hope I started your day in a good mood. )

Yoopersup,
My point is that if you say that the screw that is used for the termination of the EGC must be a listed "green grounding screrw" there is no way to terminate the listed and labled lug used on a large conductor to the enclosure or grounding bus.
The interpreations in the code handbook are not the offical position of the NFPA and are no more valid than yours or mine.
The code does not intend that the only screw that can be used to terminate an EGC is the green 10-32 screw. Can you provide the UL listing category for a "grounding screw"? I haven't been able to find it.
Don

Have you ever attached a lug for a 3/0 to the building steel by using a 10/32? Of course not, you use a 1/4x20. Thats because it just doesn't matter. A screw is a screw, as long as it is not a sheet metal screw.

I thought the Subject was Metal boxes ?? When did we get off on lugs to steel ect.If you feel a cable clamp screw well do the Job by all means Go for it BUT like I said try it some time you:ll see what I mean. As Far as the NEC Code handbook I feel its interpretations as as good as any you:ll find.Several of people who had a hand in the handbook are on the code panels. No hard feelings been fun sparing with you time to move on.

Boy you guy sure get testy when someone challenges you. Wish I had not brought it up. After seeing the comments and the counter comments I have concluded that if you are using NM cable and it contains a gouunding conductor ir can be bonded to the box by a screw of any discription and if it is a a ground screw that purchased at the supply house it probably will be green. Nothing in the code book requires it to be listed. So we are talking about a judgment call as to whether it is effectively bonded. So now let's talk about the fact that there are no requirements for anything to be UL listed. Or, lets talk about whether the jumper to the box for our NM cable installation is a bonding conductor or a grounding conductor. By the way, I miss spoke the situation, the screw is a 10/32 not an 8/32

Your right, the topic is metal boxes. Lets say we've got a 24"X24" J-box with 350's in it. How are you going to terminate the equipment ground to the box?

Ryan- assume NMRC and a metal box, I'd use a piece of #4 (identified with green tape) and a lug Listed for the conductor material and a bolt and nut. More than likely the bolt, nut and lug won't be green. But that has nothing to do with the oringinal question :-/

O.K. guys, I am going to pick your brains for a second or two.
Back in 93 or 96 code cycle, Elect. contractor Mag. put out a booklet of code changes,(which they still do), about the ground screw and bonding screw in panel boards had to be green and of the threaded type, and it could not be a sheet metal or tek screw.
Anyone else recall this? I cannot find My 2002 handbook to look it up cuz I moved, but my wife has seen it. Just my .02 cents!