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buck

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I know there have been other threads regarding concentric and eccentric knockouts listed for grounding. There seems to be no definitive answer and the Soares Grounding Book says panels, gutters and wireways with concentric and/or eccentric knockoutshave not been tested or listed for grounding. Does anyone know of a link (UL, ETL, etc) where I can get a hard copy printout of what is a definitive answer?
Thanks in advance
 
Re: Listings

Concentric or eccentric KO's need to be listed for bonding at over 250 volts. I've seen cases of Steel City boxes with a note on the label stating that they are listed for bonding over 250 volts. I'm assuming that this is a UL listing and you would probably have to check the manufacturer's individual box(s) to see if it's listed for bonding over 250 volts if the information is not present on the materials shipped with the box. You might want to start by looking here:

http://www.ul.com/info/uldirs.htm

[ July 20, 2005, 09:57 PM: Message edited by: infinity ]
 
Re: Listings

There are three types of knockouts available on the market, concentric, eccentric, and tangentle. Most makers of heavy duty switches now use tangentle knockouts which are listed for bonding in a system over 250 volts to ground. Almost all manufacturers of 4 square boxes with combination KO's have their product listed for bonding and will say so on the case. Read the fine print on the equipment, some switches will come with two type of prepunched KO's.

Fred
 
Re: Listings

Originally posted by derf48:
There are three types of knockouts available on the market, concentric, eccentric, and tangentle.
Click to expand...
ummm, WTH does a "tangentle" look like? :D )
 
Re: Listings

Tangential KOs are those with additional points where the KO is connected to the body of the cabinet where they are being removed. In other words, it has four points to carry current instead of one or two. Tangential is from the root of tangent.

By the way, this is a guess, I have never heard the term either but it looks like tangent. :D
 
Re: Listings

ahhh...I know exactly what you mean ...PITA KO's ...LOL.

...but are we talking about the same animal?
 
Re: Listings

Tangential knockouts are used so that box sets are not needed for different size conduits when entering a disconnect switch, etc. The back edge of the KO is part of each size opening. These are common on Square D disconnects.
 
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infinity,
Tangential knockouts are used so that box sets are not needed for different size conduits when entering a disconnect switch
Click to expand...
I thought that was "eccentric".
Don
 
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