Since there are no legal requirements on truth in labeling, it is legal to take an appliance that draws 20amps and place a 15amp plug on it.
My lawnmotor has a 15amp plug and draws 13amps, more than what is allowed on a 15ap circuit. My bandsaw is rated at 1.5hp with the corresponding current draw and a 15amp plug. In reality it is 2hp. Both should have 20amp plugs.
In addition, since a duplex 15amp recept can have 2 15 amp devices (30amps total) plugged in ...
I expect that 20amp recepts on 15amp circuits are not only harmless, but the same effect is common.
But again it is a violation of the NEC unless you hire an engineer and have nhim approve it,
#96135 - 11/08/0507:54 PMRe: 20A receptacles on a 15A circuit.
An engineer's approval of a violation does not make the violation go away. It is still a violation. The NEC (310.15(C))does allow an engineer to certify the maximum ampacity of a conductor using the formula printed there. Nowhere, that I can find, does the NEC allow an engineer to certify the use of 20 amp receptacles on a 15 amp circuit.
#96136 - 11/08/0508:09 PMRe: 20A receptacles on a 15A circuit.