Christmas Light Tips from an Electrician

Tis the season of fallen leaves, dropping temperatures, and the mad rush to put up Christmas lights before the snow falls.  But did you know that you have more to worry about than frostbitten fingers? According to National Fire Protection Association (NFPA), an average of 150 homes are burned, with 8 people killed and 14 people injured annually from incorrect use of holiday lights?

While you’re shaking out the strings of tangled twinkle lights, consider these Christmas lighting tips from a Master Electrician on how to safely deck your halls, roofs and trees for the holiday.

How Many Strings of Christmas Lights Can I Connect?

To understand how many Christmas lights you can safely connect end-to-end, you must first determine the number of watts you can put on a circuit.

A standard wall outlet is 120 volts and is wired to a circuit breaker or fuse, usually 15 or 20 amps. Your goal is to not overload the circuit breaker/fuse. To be safe, a good rule of thumb is never put more than 80% load on your breakers/fuses, which is 16 amps.

The good news is that the box of lights will usually list the amps, so the math is done for you! If not, the equation looks like this: If you have a 15 amp circuit with 120 volts and factor in an 80% load, you can have a total load of (120*15*0.8) = 1440 watts.

Here are the estimated watts for different Christmas lights, but best to check the package:


So if you are using C9 Stringer Sets, you could connect (1440/175) = 8.2, or 8 strings. LED lights use significantly less wattage and, unlike incandescent bulbs which have filaments in each bulb causing it to get hot, LEDs use a path of electrons and always stay cool. It’s best to use LED lights when connecting many strings together.

Also, remember that most circuits are also shared with a room in the home; so be sure to account for things like appliances when determining how many strings you can plug in. When in doubt, use the “Rule of 3” – 3 strings can be plugged in end-to-end.

Other Helpful Tips


Use the right extension cords

Be sure to use the outdoor extension cords when hanging Christmas lights outside, as indoor extension cords are not heavy duty enough. Also avoid having cords in high traffic areas, such as under the welcome mat.

Also be sure not to plug in a massive bulk of cord connectors to the outlet, as the weight may draw the plugs away from the outlet and expose the contact terminals, which is a possible fire hazard.

Inspect and test BEFORE hanging

It’s best to plug in the lights prior to hanging them up to ensure they light up.  Also, closely inspect each string for damaged or frayed wires, which could cause fires.  Throw away any strings that look worn.

Set a timer

To save on your electrical bill, and to be safe, always unplug the lights when you leave the house or turn in for the night.  An alternative is to use a timer than can be set to turn on/off during specific times.

When to Call an Electrician

If you plan on decorating your house Griswold-style, and even if your plans are more modest, we recommend running separate ground fault circuit interrupter (GFCI) outlets, which are special electrical outlets that are installed in areas where there is a risk of electricity meeting water like in outdoor outlets and in kitchens and bathrooms.

GFCI outlets have the “test” and “reset” buttons on the front, and monitor the flow of an electrical current. So when a fault happens, the GFCI breaks the electrical circuit and shuts off the flow of energy, preventing electric shock, fires and damage to things plugged in (such as appliances).

Be sure to call a licensed electrician to install the GFCI outlet to ensure it’s don't correctly. By installing separate GFCI outlets, you will have piece of mind that you aren’t exceeding the amp limits and risking a fire, and, as an added bonus, you can decide where to place to outlet for optimal convenience. This limits the number of extension cords you’ll need, which also means more safety.

Horizon Electric is dedicated to providing high quality electrical services. We look forward to helping you with your next project!