How Many Holiday Lights Are Too Many?

It’s the week before Christmas, and all through the house,
Not a lamp or plug’s working, not even your mouse.
The family’s all gathered, their eyes fixed in stares,
In hope the electrician soon will be there.

Not exactly how you were planning to spend a holiday evening? You might be surprised to learn that a little simple math can avoid the power outages that are common when holiday lighting causes breakers to trip, fuses to blow, and circuits to overheat.

Check Your Circuit Panel

Most household circuits are rated to carry either 15 or 20 amps of current, so the first thing to check is your panel. Breakers and fuses are marked with their ratings, so it’s easy to determine the load they will take. A properly installed panel will be clearly marked with what that breaker or fuse controls.

Do the Math for Correct Amp Usage

Let’s look at a 15-amp circuit (the principle’s the same for a 20-amp circuit—the math’s just different).

First, know that you should keep the load to no more than 80% of the circuit’s rating for safety’s sake and to avoid knocking it out if there’s a surge, such as when you turn on an appliance or string of lights. 15 x 80% (0.8) = 12, so keep the load to 12 amps or less.

Next, add up the draw of all the things you plan to put on that circuit. Be aware that one circuit may serve more than one room and that all outlets and fixtures in a room may not be on the same circuit. This is especially true in kitchens.

Check the Draw of Your Lights

Then look at the draw of the lights you plan to add. They should have a tag listing either the amps or watts they will draw. That information is probably on the box they came in, too. If you need to convert watts to amps, it’s simple: Amps = watts/volts. So using the standard U.S. residential voltage of 120, 60 watts/120 volts = 0.5 amps. Take away the TV, ceiling lights and table lamps from the 12-amp capacity, and that’s what you have left to work with.

Going Big

The good news is you’ll probably have room for plenty of lights for the tree. But what if you want to go Full-Griswold with your outdoor lighting? That can become trickier, because you probably have a fairly limited amount of capacity at your outdoor outlets, especially if they’re on a shared circuit with indoor service, and you probably will want a fair number of light strands to wrap around trees or decorate the house. Here’s an example.

Your 25-foot string of incandescent lights says it pulls 185 watts of power. You need 12 strands to cover all the things you want to light up. Well, 12 x 185 = 2,220 watts / 120 volts = 18.5 amps. That’s way over 15 amps and even past the 16-amp safety limit of a 20-amp circuit. You’ll need at least two circuits, depending on how much reserve power they have left.

Switch to LED Bulbs for More Draw

Or you could say “out with the old and in with the new” and switch to LED lights, both indoors and out. That same 25 feet of lighting using LED bulbs will only draw about 3.6 watts of power or less than 40 watts for all 12 strands. Yes. LED lights cost more, but when you consider they’ll use over $50 less electricity every season in our example, and can last up to 40 times longer, it seems like a pretty smart investment.

LED lighting is the future, both for holiday lighting and everyday use. And with adaptability growing and prices coming down every month, there’s little reason to put off switching.

Learn more about the differences among incandescent, compact fluorescent and LED lighting here.

Whatever direction you choose to go, the pros at Allstar Electrical Services are ready to help with your home’s electrical needs. Besides seasonal lighting needs, short days and cold nights can add stress to a weakened or inadequate electrical system.

For more information about holiday lighting issues, read:

All of us at Allstar Electrical Services wish you a happy holiday season and a healthy, prosperous year to come!

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