Review Of How Many Watts Is A String Of Christmas Lights References. Dividing that number by 120 volts results in the amount of current, or amps, needed for the lights. However, a single circuit could only take 11 strings of large, incandescent bulbs that use 125 watts (1440÷125=11.5).

The led strand is 2.4 watts or 0.048 watts per light. Based on these calculations, the 100 ft section of the c9 light line would draw 6.09 amps. The exact number depends on the size and model of your christmas lights.