grounding bushing

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chuckp

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Is a grounding bushing needed on a 480 volt motor with the ground pulled in the sealtite from disconnect and had to use reducing washers.
 

tom baker

First Chief Moderator
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Re: grounding bushing

Per chuck, this is a 40A branch circuit, 480V, not sure what the overloads are, 3/4" LTFC.
Circuits over 250 v to ground require assured bonding, see 250.97, reducing washers are not listed for grounding.
See section 250.118(6) and (7) for the restrictions on LTFC. If its more than 6 feet long you will need an internal equipment grounding conductor. If the LTFC is installed for flexibility then a equipment grounding conductor is needed.
My personal practice is to install an equipment bonding conductor in every raceway, raceways with 480/277 circuits are bonded at one end. 480/277 circuits have 5 times the heating power on a fault, and won't burn clear as 120 will. If its a 480 delta then its much worse.

[ November 17, 2003, 08:33 PM: Message edited by: tom baker ]
 
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