How Many Lights Can I Put on a 15 Amp Circuit?

When carrying out residential electrical work, how many lights can I put on a 15 Amp circuit?

How Many Lights Can I Put on a 15 Amp Circuit

Suppose you're carrying out some home renovations or thinking about putting up a light display for the holiday season. In that case, you're probably thinking about how many lights you can safely add to your standard 15 Amp circuit.


As electrical systems come with many safety issues, this is a very sensible attitude. However, the answer is unfortunately not straightforward. Every light fitting and bulb has its own power requirement, so you need to consider and work it out accordingly.


So, how do you calculate how many lights I can add to a 15 Amp circuit?

First, you must consider that you need a safety factor on the circuit. You should not run the circuit at more than 80% of capacity, so this leaves you with 12 Amps. Then you need to calculate how many Amps your light will draw. The formula for this is simple:


Amps = Watts/Volts
As the standard voltage in the US is 120V, this means for a 60W bulb:
Amps = 60/120
Amps = 0.5A

If all of your bulbs are 60W, this means that you can have 24 60W bulbs on your lighting circuit.


Of course, if your supply is at a different voltage, you should amend this calculation to suit.


So you've probably realized that using LED bulbs will therefore give you room for many more lights.


For example, if using 10W LED bulbs, you can, in theory, have 150 lights.


However, you should be cautious; should you or someone else later change the bulb for an incandescent one, you might then be overloading the circuit.


What about the wiring?

The gauge of wire you should use in domestic typically varies according to the current rating of the circuit.

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For example, 20 Amp breakers for outlets will use 12 or 10 gauge wire. Lighting circuits at 15 Amps will need a slightly thinner 14 gauge.


Using thinner wire than recommended will cause the wiring to heat up and is a potential fire risk.


While the guidelines given above will allow you to select the best number of lights for your circuit, you should always be cautious when carrying out electrical work in the home.


Use certified electrical installers like Deluxe Plumbing & Heating for maximum safety in your residential electrical work so that your home remains within code.