DrewE wrote:An explanation that I heard was if you put a 50 amp outlet on a 30 amp circuit, somebody might come along later and somewhat logically swap the breaker to a 50 amp breaker, clueless that the wires are rated for only 30 amps. I've got a 15 amp breaker on a 50 amp circuit because the load (a pump) is cleanly under 15 amps and I want the breaker to trip if the pump starts drawing too much. It is, however, 50 amp wiring to the 50 amp outlet.
Presumably the idea is to prevent excessive tripping of breakers or running the undersized circuit at the very edge of its capacity all the time or something similar (and maybe also to encourage the makers of equipment to provide appropriately sized power cords and plugs, rather than oversizing them for "convenience" or other reasons).
