This may sound like a stupid question, but if you use a fuse or breaker that was rated for 250VAC on, say a 12.5VDC power supply, would the OCPD still be effective? For example, let's say you have a fuse with a resistance of 0.1Ω. That means at 250V 20A, there is 20 times as many watts than at 12.5V 20A, and therefore less heat to blow the element. Does it matter, or is it purely based on amperage? I see regular with the 250V rating protecting the secondary side of a class 2 transformer (not the wall wart type, usually the ones for higher end use... kinda like a laptop pwer supply.) is the 250V just a MAX rating, or a WORKING VOLTAGE rating?
thanks,
Josh.