For example: 400 (watt lights) / 110 or 120 (voltage) = 3.63 or 3.3 AMPS


That's how many AMPS one 400W Light would eat up.. Add up all the electrical devices you have hooked up to one fuse BUT do not exceed 15AMP, as rated.

15 AMPS would be 15 X 110 = 1650 Watts
..which would be perfect for a one 1000W bulb set-up with all the gadgets.

I remember this vaguely so anyone with a more descriptive instruction please enlighten.