No, Volts remain constant. House wiring is typically 120v regardless of the appliance, except for certain high-power systems (electric dryers, house a/c units). 55 18W-CFL's will use 990 kW/h.
The formula is AMPS x VOLTS = WATTS. Like the example above, the 1000W light is AMPS x 120V = 1000W...