Battery Equivalents and Replacements

How Many LED Lights Can You Run On a 15 Amp Circuit?

LED light bulbs are much more energy efficient than older incandescent lights. Actually, LED light bulbs produce much more light for the same amount of spent energy that many manufacturers emphasize the wattage of equivalent incandescent light bulbs more than the actual wattage of the LED light bulb.

Although the user can run more LED light bulbs on the same circuit than incandescent bulbs, it is a good idea to calculate how many LED lights a user can actually run on the same electric circuit, for example, 15 Amp circuit.

Published: August 3, 2022.

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Little Bit of Math

Electric circuits are designed with a certain safety margin - for example, 15 Amps circuits can withstand even more current, but 15 Amps electric breakers limit the actual current through such circuits.

So, to avoid tripping such electric breakers, an "80% Rule" is applied - instead of 15 Amps, we will do the calculation for 12 Amps:

15 Amps * 0.8 = 12 Amps

If the line voltage is 120 volts, that means that such a circuit can constantly provide 1440W:

P(W) = U(V) * I(A) = 120V * 12A = 1440 Watts

If we are going to connect only 100W incandescent light bulbs, that means that we can add "only" 14 of them:

1440W / 100W = 14.4

(Of course, 14.4 light bulb is rounded to 14 light bulbs.)

LED light bulb with a similar light strength (given in lumens) on average requires ~14W.

Thus, in order to calculate how many 14W LED light bulbs we can run on a 1440W line, we write:

1440W / 14W = 102.86

Thus, a 120V 15A circuit can support up to 102 14W LED light bulbs, which is more than 7x more light bulbs for the same power consumption.

Of course, running so many light bulbs at home is unnecessary, but one can see how much energy can be saved by replacing incandescent light bulbs with LED light bulbs.