Found this at a thrift store I frequent, in a small box of junk outside. After parting with a dime and leaving with this, I post it here to ask What brand it may be, and what sort of breaker panel it would go in. One side of the breaker appears to be stiff cardboard.
Well, I guess I can start here, and hopefully others can add a lot to this.
Square D and Cutler Hammer produced millions of these "XO" style circuit breakers many years ago. I'm guessing that this was among the first efforts to market a single interchangeable breaker (as opposed to the "multi-breaker design"). The panel in which these breakers were installed was rated for 120/240 volt service, and had two bus bars mounted on an insulated base which extended nearly the entire interior length of the box (along with a neutral buss, of course). The XO breaker simply clipped onto the bus bars. On single pole breakers, the brighter-colored clip, shown in the second photo, tapped the current from the bus bar, while the other clip was merely a dummy. It had no internal connection, and only served to help hold the breaker in place inside the panel. The load on the panel was balanced by installing breakers with the current tap alternating between left and right busses. A double pole breaker was manufactured as a one-piece unit with two clips arranged to tap both bus bars.
In my part of the world where I live, there are many of these breakers and panels still in service. These breakers are routinely listed for sale on eBay (though I'm not so sure how good an idea it is to purchase a used circuit breaker from any source - at least with the intent of re-use).
Cliff, That "stiff card-board" wouldn't happen to be mica would it? Or something mica-based?. It's used in toasters to hold the nichrome elements in place and makes a pretty good insulator that can withstand quite a bit of heat (handy in a toaster). I have some mis-givings about CB's that merely clip onto busbars, as in I feel that the connection can never be as good as a solid screwed connection or the like. Has there ever been a problem with the joint between clip and busbar ever overheating when a lot of current is drawn through the breaker?. Just inquisitive.
Last edited by Trumpy; 04/21/0706:20 PM. Reason: Missing a set of brackets
Mike: I have seen a number of these panels over the years, both in service and removed from service (with a few in my collection). The only damage I can ever recall was to the load screw terminal of one 20 amp. circuit breaker, the result of some clown's poor attempt to lug three wires to it. The busses and breaker clips were just about as shiny as new - no evidence of arcing, pitting, burning, etc. Seems the clips used to fit pretty tightly around the busses.
The breaker pictured is a bit rare, if you look at the one in the rear, it takes 3 pole spaces, the one in front uses only 2 spaces.The one in the rear is a 20 or 30 A breaker and is a lot more common.