500mcm into 350mcm Lug?

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adelle

Member
How do I legally (if even possible) fit a 500mcm wire into a 350mcm lug.

This is a UPS installation into an existing system. The old 300kva transformer is wired with 500mcm from a 400a breaker - as it should be. The new feed to the transformer from the UPS is only 250a and the feed breaker can only accept 350mcm max. The 300kva transformer is only loaded to 106kva so we aren't over loading anything.

I would rather not replace the existing 500mcm wire if possible. Can I just cut off a few strands as the wire only needs to be 350mcm?
 
H

hardworkingstiff

Senior Member
Location
Wilmington, NC
adelle said:
Can I just cut off a few strands as the wire only needs to be 350mcm?
Click to expand...

I would not.

1st thing I would do is check to see if the lugs can be changed to a larger size.

2nd thing I would do is use pin terminals (see Roger's post following this one).

3rd thing I would do is to butt splice a short piece of 350 to the 500. I know that T&B makes a butt connector that is range rated when using the proper crimp tool.

(I'm saying to myself "DUH", I use pin terminals on type W cable all the time,..... DUH).
 
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infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
hardworkingstiff said:
What's a mac adapter? Is it similar to a pin terminal?
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Same thing, different name:

Pin%20Terminals.jpg
 
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