Please help identify this breaker

Merry Christmas

Alexis

Member
Location
Los Angeles
Hello,

It seems to be square d, but I can't find anything similar in any searches.. legs look like QO, but I don't think that modern ones would fit..

Thank you!
 

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infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Obsolete Square D type MO-4.
MO4_3115__67147.1601037545.jpg

 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
I thought the MO4 family was originally from the 1930s but the earliest panelboard I could find was from the late 40s.
 
Last edited:

rszimm

Member
Location
Tucson, AZ
I’d be hesitant to swap in a refurbished breaker. I wouldn’t think a manufacturer would discontinue a line unless there were some inherent safety issue (looking at the breaker, probably the clips tended to wear out and then arc).
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
I don’t know about that style, but Square D has retrofit kits for other obsolete breakers that allow a QO to be used. It has bussing that you install to the old buss to adapt. Might pay off to check with your local Square D distributor.
 
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