How Many Lights on a 15 Amp Circuit

The number of LED lights that can be installed on a 15 Amp circuit depends on the wattage of the lights and the total wattage capacity of the circuit.

On a 120V supply a 15 Amp lighting circuit has a maximum wattage capacity of 1800W, with a total combined wattage of lights to not exceed that. We look at how many LED lights can be on a 20 Amp circuit to avoid issues such as flickering, dimming or even tripping of the circuit breaker due to an overload.

The number of lights that can be installed on a single circuit requires two simple calculations.

Calculate 15 Amp Circuit Capacity

To determine the total wattage of lights that can be accommodated, use the formula:

watts (capacity of power available) = Volts (voltage of the lighting circuit) x Amps (capacity of the circuit breaker)

For example in the USA using a 15 Amp circuit,

Total capacity = 120V*15A = 1800 Watts

Calculate How Many LED Lights on a 15 Amp Circuit

Then to estimate how many LED lights can be safely installed on a single circuit, check the wattage of your bulb and use the formula:

Number of LED lights = Maximum circuit wattage / LED Watts rating

A 60W incandescent bulb equivalent in an LED bulb is often rated at 8.2W

1800W/8.2W = 219

Therefore, a 120V 15A circuit can accommodate up to 219 8.2W LED bulbs.

This formula can be applied to all light sources, including fluorescent, halogen and incandescent whose wattages will be higher resulting in a reduced number of lights compared to LED.

Derate the Capacity

However, even though it is unlikely so many bulbs would be used on such a circuit, a derating of 80% is applied as good practise to ensure the combination runs within capacity.

Therefore, the number of LED bulbs is reduced to 176.

We also look at How Many Light Can Be On a 20 amp circuit and How Many Lights can be on a Switch.

Andrew Orange, the owner of Orange Lighting qualified and worked as an interior designer in 1993 before specialising in lighting working on high profile projects based in London. Since starting Orange Lighting Ltd in 2003 he has been sharing his knowledge and unique teaching style mostly to his designer clients, offering practical real life advice born from running a busy consultancy and lighting supply business. Launching in 2020, his blog has evolved into Quick & Easy Lighting, curating some 25 years design experience into making the lighting choice and design process achievable and easy to understand for all.