Older SQ D Main Breaker

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steve66

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Location
Illinois
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Engineer
Could this breaker (and its main lugs) be listed for 2 sets of wire? It's a 600 amp breaker, so it seems like it would have to be listed for 2 sets of wire. How else would you land 600 amps of wire? A single 1250 KCM?

But the lug openings do appear to be round, not elongated. My understanding was that lugs made for 2 sets of wire are usually elongated, not round.

This is a SQ D "MLW" panel. Sorry, the pictures weren't the greatest, and I didn't get a model number off the breaker itself:



Sq D Panel.jpg
Sq D Panel line lugs.jpg Lug CLose up.jpg

(Yes, I know there are more than two conductors landed on each lug, but please disregard that.)

Also, this is the first time I've seen a panel main breaker that also has load side lugs. Is there anything that would prevent one from using the load side lugs? Yes, I know this looks like its about a #6 wire, but assuming they were properly sized tap conductors, can the load side lugs be used?

load side lugs.jpg

Thanks.
 

jim dungar

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Location
Wisconsin
Occupation
PE (Retired) - Power Systems
That appears to be an old brand labeled Westinghouse or ITE breaker. ML panelboards were obsoleted 50 years ago.
The breakers were rated for (1) conductor per hole. 3-hole lugs were available.
 
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steve66

Senior Member
Location
Illinois
Occupation
Engineer
It is a Sq D panel.

Did Westinghouse make breaker for Sq D? I should have got a label from the breaker.


I believe the panel was probably installed in the 40's or 50's, but its still going strong..


Panel Label.jpg

IMG_0146.jpg
 

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jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
It is a Sq D panel.

Did Westinghouse make breaker for Sq D? I should have got a label from the breaker.


I believe the panel was probably installed in the 40's or 50's, but its still going strong..

Yes, prior to the mid-60s most of the larger frame breakers were brand labeled.
You would have to look on the side of the breaker for any part number.
 
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