Ground Clips?

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I think Pierre's asking when you consider the pitch of the 10-32 screw, and the thickness of the metal, how many full threads are engaging. I did the math in a post a while back for an Austin enclosure, I think. It was impossible to get two full threads engaged in anything other than the factory swaged hole.
 
mdshunk said:
I think Pierre's asking when you consider the pitch of the 10-32 screw, and the thickness of the metal, how many full threads are engaging. I did the math in a post a while back for an Austin enclosure, I think. It was impossible to get two full threads engaged in anything other than the factory swaged hole.
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I have heard the term for the factory provided hole as - 'peaned'. regardless of what it is called, field tapping a box is most likely not going to provide enough threads, and will be inadequate as part of the effective ground fault current path.
Why not just drill a hole and bolt/nut a small lug or other effective means?
 
You've got your brain stuck in new work mode.

Simply put, you can sometimes tap a box compliantly, and sometimes not. When you can't, compliantly, getting a nut on the back side is often a real treat. In those cases, I've been tapping the box twice and using two screws in a ground bar and call it good.
 
Pierre C Belarge said:
I have heard the term for the factory provided hole as - 'peaned'. regardless of what it is called, field tapping a box is most likely not going to provide enough threads, and will be inadequate as part of the effective ground fault current path.
Why not just drill a hole and bolt/nut a small lug or other effective means?
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Is that the code - 2 threds? A man that used to work for me said a tek screw was legal if it was colored green. Lots of mythinformation out there. I would like to do torque test on a tek vs. a ground screw. A steelworker said a button head teck is as good as a 1/4" weld.
 
two is correct

two is correct

Power Tech said:
Is that the code - 2 threds? A man that used to work for me said a tek screw was legal if it was colored green. Lots of mythinformation out there. I would like to do torque test on a tek vs. a ground screw. A steelworker said a button head teck is as good as a 1/4" weld.
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Hi Power Tech,

[250.8] in grounding and bonding methods defines mechanical termination types more distinctly in the 2008 NEC. Note that self-tapping machine screws in [250.8(A)(6)] are permitted providing the sheet metal is thick enough to allow the two tapped threads. As mdshunk mentions, a swagged hole is acceptable. This involves using a press-fit insert to increase the thread depth in the parent metal material. rbj
 
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