Please help identify this breaker

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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
PE (Retired) - Power Systems
I thought the MO4 family was originally from the 1930s but the earliest panelboard I could find was from the late 40s.
 
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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).
 

retirede

Senior Member
Location
Illinois
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).

Most redesigns are for cost reduction.
 

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
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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