Mike Lamb Posted October 30, 2011 Report Share Posted October 30, 2011 I have not seen this before. None of the breakers are marked as to what their overload rating is and they all sit in one housing. Any additional info on these would be appreciated. Click to Enlarge 35.48 KB Click to Enlarge 44.11 KB Click to Enlarge 74.66 KB Link to comment Share on other sites More sharing options...
John Kogel Posted October 30, 2011 Report Share Posted October 30, 2011 It is a Square D MB4 (Multi Breaker with 4 positions) and it must be from or before the early 50's. Got all that off the label. [] Link to comment Share on other sites More sharing options...
Jim Katen Posted October 30, 2011 Report Share Posted October 30, 2011 The MB and MO series breakers were very similar. I see the MO ones fairly often, the MB less so. I know that the MOs always had the amp rating printed right on the toggle handle but it would wear off in time. If you hold your flashlight at an angle to the toggle so that the light grazes the surface, you might be able to make out the numbers. Both the MO and the MB were available from 15 amps to 50 amps. The guys down at Oregon Breakers tell me that these were, possibly, the worst breakers ever made. (They're in the business of testing and reselling used breakers.) Link to comment Share on other sites More sharing options...
Jim Katen Posted October 30, 2011 Report Share Posted October 30, 2011 Found an old one for sale here: http://www.breakeroutlet.com/_e/Very_Ol ... KER_MB.htm Link to comment Share on other sites More sharing options...
Mike Lamb Posted October 30, 2011 Author Report Share Posted October 30, 2011 Thanks. Link to comment Share on other sites More sharing options...
Douglas Hansen Posted October 31, 2011 Report Share Posted October 31, 2011 My house in Palo Alto had one of these, a recessed laundry room subpanel. One of the breakers wouldn't reset, and someone had double-tapped another breaker to keep things going. After I moved in, another double-tapped breaker failed, so I replaced it with a new surface mounted box over the old one, pulling the wires into the back of my new one. The house was built in 1938. I was a bit surprised that it had breakers at that age. The main outside and the other outside circuits were fuses. Link to comment Share on other sites More sharing options...
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