Power load calculator
Check whether your fixtures fit the power you have. Enter the line voltage, the breaker rating and up to three groups of fixtures; the calculator gives the total power and current, how heavily the circuit is loaded, the continuous limit of the circuit and the smallest generator that carries the load with headroom.
It is a quick check for location power, house circuits and small generator setups.
How to use it
- Line voltage: 230 V for most of the world, 120 V in North America, 100 V in Japan.
- Circuit breaker: the rating of the circuit you plug into.
- Fixtures: the number of fixtures and the watts of each, in up to three groups.
Example
Four 600 W fixtures on 230 V draw 2400 W, about 10.4 A. On a 16 A circuit that is a 65 % load, inside the continuous limit of about 2944 W. A generator should be at least about 3.4 kVA.
Good to know
Current = watts ÷ volts for single-phase power. Continuous loads should stay at or below 80 % of the breaker rating. The generator size assumes a power factor of 0.9 and loading to 80 %. Local electrical rules and the gaffer's judgment come first.