The amp rating for an extension cord /fuse/ or breaker is the Maximum amount of current it can draw without overheating the wires. If you plug in anything that draws less you are fine.
Electrical components just draw what they need........Unless they are malfunctioning or shorting (and thats what the fuses are for)
Electrical components just draw what they need........Unless they are malfunctioning or shorting (and thats what the fuses are for)