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Joined: Jan 2004
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I have a Contractor who maintains that an acceptable way of bonding/grounding a metal box used in a NM cable installation, would be to wrap the bare equipment ground wire around the screw that is used with the cable clamp. Now there are no cables under the clamp and the clamp is still installed so the bare wire is under the head of the screw and between the screw head and the clamp. I maintain that the Contractor should be using the 8-32 hole provided for installing a GREEN screw and not use the cable clamp screw what-so-ever for grounding. I don't think he should even use the silver colored cable clamp screw in the hole provided for the GREEN ground screw. I need something official for a reference. Thank You in advanc.
George Little
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Joined: Mar 2003
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Joined: Mar 2003
Posts: 849
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Joined: Nov 2000
Posts: 2,148
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There is no code rule that requires the use of a "green" screw for the connection of the EGC. The use of the clamp screw with the clamp still installed would be a violation of 250.148(A), but there is no violation if the clamp is removed and the clamp screw is used to connect the EGC.
Don
Don(resqcapt19)
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Joined: Mar 2003
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250.148A says a GROUNDING screw used for NO other purpose! A box clamp screw is Not a Grounding screw. For one thing the head is usually to small and the wire tends to slip out when tightened.
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Joined: Aug 2003
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Yoopersup: I concur with Don. What is to prevent you from using a Sta-Con from satisfying your dilemna?
Ryan Jackson,
Salt Lake City
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Joined: Dec 2003
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...Now there are no cables under the clamp and the clamp is still installed so the bare wire is under the head of the screw and between the screw head and the clamp.
Why the heck would you leave an unused clamp in the box anyway? Not only would it prevent the screw from being firmly tightened on the ground wire and is a violation of 250.148(A) but it counts as a conductor in calculating box fill.
Dunno, but whenever I see unused clamps still in place it screems DIY!
-Hal
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Joined: Jun 2003
Posts: 681
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I agree with Don and Ryan. There is no definition of a ground screw in the NEC. The usual mentioning of a green hex head screw is for devices 250 126. Yoopersup has provided two good references.
Pierre
Pierre Belarge
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Joined: Nov 2000
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Yoopersup,
Please show me the NEC definition of a "grounding screw".
Don
Don(resqcapt19)
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Joined: Jul 2001
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I believe there is no UL listing for ground screws only.
The only UL Listed screw items I have ever seen are a combination of screw and wire pig tail.
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