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Can a circuit breaker be operated at a voltage less than the voltage marked on the breaker?

Is it OK to apply a circuit breaker on a voltage system rated lower than the rating of the breaker?

Product Line:
MCB and MCCB circuit breakers

Circuit breakers are typically marked only with a few standard voltages, while other voltage systems exist.

Yes. According to 2011 NEC article  240.83(E), a circuit breaker may be used at voltages equal to or less than its voltage rating. 
When applied on a system of lower voltage than marked, he interrupting rating is equal to the next highest marked interrupting rating. 
The only exceptions to application at less than rated voltage are:
1. QO and HOM -GFI, -EPD, -AFI, -CAFI, and DF circuit breakers must be applied on 120/240 Vac systems only (they need over 100 Vac to power the electronic modules)
2. EHB-EPD and EDB-EPD type breakers which must be applied on 480Y/277 systems only

NOTE:  Circuit breakers marked with DC ratings only are not suitable for application on AC systems, and circuit breakers marked with AC ratings only are not suitable for application on DC systems.
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