Power is power.... easy as PIE..... P = I x E.
Power = (watts, VA)
I = (amps)
E = (volts)
Power = (watts, VA)
I = (amps)
E = (volts)
NEC 2008
210.6 Branch Circuit Voltage Limitations.
210.6 (A) Occupancy Limitation. In dwelling units and guest rooms or guest suites of hotels, motels, and similar occupancies, the voltage shall not exceed 120 volts, nominal, between conductors that supply the terminals of the following:
(1) Luminaires (light fixtures)
(2) Cord-and-plug connected loads 1440 volt-amperes, nominal, or less or less than 1/4 hp.