To quickly calculate the number of amps of electricity a given light will require use this simple* formula:
Watts / 100 = Amps
So for a 1K spotlight:
1000 Watts / 100 = 10 Amps
Assuming a typical 20 Amp household circuit we would be able to run only a single 1K spotlight (since we never want to use up all the available Amperage on any one circuit).
We could however add a smaller spotlight to this same circuit. For a 650 Watt spotlight:
650 Watts / 100 = 6.5 Amps
So the total for both would be:
10 Amps + 6.5 Amps = 16.5 Amps on a 20 Amp circuit.
Remember – NEVER push the limits on the amount of Amps you use from any one circuit. If you do, you’ll find yourself in the dark at some point.
*The actual formula would divide Watts by the line voltage (usually somewhere around 110 to 120 Volts) but dividing by 100 is easier to do in your head and results in a built-in safety factor.