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49528867 (banned)
join:2010-04-16
Fort Lauderdale, FL

49528867 (banned) to Jack_in_VA

Member

to Jack_in_VA

Re: The most screwed up electrical work I have ever seen.

said by Jack_in_VA:

What's with the concentric knockouts?

It was an example of how important a good path to ground is and the fact that even though a concentric knockout provides a metallic connection it is insufficient to be trusted to handle fault currents.

Now if a concentric knockout is insufficient, doped up threads are truly insufficient.

250.92 Services.

Bonding jumpers meeting the other requirements of this article shall be used around concentric or eccentric knockouts that are punched or otherwise formed so as to impair the electrical connection to ground. Standard locknuts or bushings shall not be the sole means for the bonding required by this section.

Wayne

Nick_L
Premium Member
join:2003-01-22
Pittsburgh, PA

Nick_L

Premium Member

Since we're doing Q&A, if you don't mind, would you explain eccentric knockout? Concentric I understand.

Thx
49528867 (banned)
join:2010-04-16
Fort Lauderdale, FL

49528867 (banned)

Member

said by Nick_L:

Since we're doing Q&A, if you don't mind, would you explain eccentric knockout? Concentric I understand.

Thx

Whereas a concentric knockout has a blank plug surrounded by larger and larger rings an eccentric knockout has the blank plug against the edge of cabinet surrounded by larger and larger knockouts that resemble the letter C.

While I am out today I will see if I can find one and post a shot of it.

Wayne

Nick_L
Premium Member
join:2003-01-22
Pittsburgh, PA

Nick_L

Premium Member

Thanks for the education. I've not seen those (that I'm aware of, anyway).
49528867 (banned)
join:2010-04-16
Fort Lauderdale, FL

49528867 (banned)

Member

said by Nick_L:

Thanks for the education. I've not seen those (that I'm aware of, anyway).

I didn't have a chance to locate one today but this is a catalog shot of some.




Wayne

Nick_L
Premium Member
join:2003-01-22
Pittsburgh, PA

Nick_L

Premium Member

Thanks.