What Do Those Letters Mean?

When buying Square D breakers or any other brand, you are asked to select the poles, amps, volts and type. The listing of types is long and starts with simple single letter designations all the way to combinations of three or more. This grouping of letters indicates the type of case the Square D circuit breakers or any other brand are made of. The frame or case determines the actual size of the circuit breaker, plus the maximum voltage and current it can safely handle. If you are selecting replacement Square D circuit breakers, it's a simple thing to choose a case type identical to the one you are currently using, but if you need to purchase brand new circuit breakers for a new sub panel or upgraded breaker box, consult a customer service rep if you need assistance selecting the proper breakers and case types.