Originally Posted by Thunder Pig
Circuit breakers are marked in Amps because they trip on overcurrent, not excess power.
While this is true, the reason for the amps rating is because the voltage is constant in your example. The load or amount of current(amps) drawn is not. The breaker is set to open when the variable(amps) exceeds the rating. But if you want to be picky since power(watts) is voltage x current, the wattage used goes up and blows the breaker.
Nope, not an engineer just someone who fixes Uncle Sam's flying machines support equipment.
Knowledge is power, need more power, watts the matter with that?
Who said the voltage was constant?
The same breaker can be used for 120 or 240VAC.
A 15A breaker will hold at 1440W in a 120V circuit or 2880W in a 240V circuit.