at my cozin shop i checked it myself he ran a rotor, voltage was 227 and ampere was 5.6 and then he plugged the device to the socket before rotor then voltage and ampere remain same on the wire of motor but amps reduce to 4.2 on wire before device
device was getting low amps but same voltage and was giving required amps to rotor
receiving 227x4.2 =953.4w
giving 227x5.6 =1271.*w
but its efficiency varies by thing you are using, the devices having magnet like fans, pumps, Rotors, Motors, Donkey=pump
will have more efficiency as compare to TV or Computer or Bulb