By Alexandr Godonoaga, owner of Cob Services LLC. Illinois electrical contractor license #26-00032356. Over 10 years wiring homes in Naperville and the western suburbs.
Every year the calls start around the first weekend of December, and they arrive in a predictable order. First the people whose outdoor outlet died the same afternoon they plugged everything in. Then, a week or two later, the people whose display worked fine until it rained, or until the snow on the roofline melted and refroze overnight.
Those are two different problems with two different fixes, and homeowners almost always guess wrong about which one they have. The first is usually load. The second is almost never load.
Here’s how to tell them apart, and what we’d actually do about each.
The two minute calculation nobody does
Every string of lights has a tag on it with a wattage. Add up the wattage of everything you’re plugging into one outlet, divide by 120, and you have your amps.
If you have ten strings at 40 watts each, that’s 400 watts, or a little over three amps. That’s nothing. If you have eight C9 incandescent strings along a roofline, you can be in a completely different place. The gap between incandescent and LED is large enough that it changes the entire answer, which is why “I ran the same lights last year” is not a useful data point if you replaced half of them in between.
The number you’re comparing against is not what’s printed on the breaker. Holiday lighting on a timer runs for more than three hours at a stretch, which makes it a continuous load, and continuous loads are limited to 80 percent of the circuit rating. A 15-amp circuit gives you 12 amps to work with. A 20-amp circuit gives you 16.
That budget also has to cover whatever else is already on that circuit, which in most Naperville houses nobody has ever mapped. The exterior receptacle by the front door is frequently sharing a circuit with the garage, the garage door opener, the second fridge, and a workbench.
LED solved the load problem and created a connection problem
Switching to LED strings drops the current draw enough that most people stop worrying about circuit capacity, and mostly they’re right to. We wrote a whole piece on how little electricity LED lighting actually uses, and the numbers are genuinely small.
What LED changed is behavior. When each string draws almost nothing, people run four times as many of them, connect them end to end in longer runs, and cover more of the house. Every one of those end to end connections is another plug sitting outdoors in a Chicago-area winter, and that’s the failure point.
The tag on each string lists a maximum number of connected sets. It’s there because the conductors in the string carry the current for everything downstream of them, and the plug at the wall carries all of it. Exceeding that number is one of the few genuinely dangerous things a homeowner can do with holiday lights, and it’s easy to do accidentally when the strings barely draw anything individually.
When it’s the GFCI, not the breaker
This is the one people get wrong most often.
Outdoor receptacles at a dwelling require GFCI protection, and a GFCI is not looking at how much current you’re drawing. It’s watching whether the current going out matches the current coming back. When a little bit leaks somewhere it shouldn’t, the device opens. That’s the entire point of it and it is the reason nobody gets electrocuted standing in wet grass holding a light string.
So when your display dies after a rain, or after a thaw and refreeze, the load has nothing to do with it. Water got into a connection somewhere. Usually it’s a plug-to-plug junction lying in the mulch, or a female end pointing up into the weather, or a cracked housing on a string that spent eight months in a garage attic.
The tell is which device tripped. If you go to the panel and find a breaker off, that’s more likely a load or a fault issue. If the breaker is fine but the outlet is dead and there’s a GFCI somewhere with a popped button, that’s moisture, and adding more circuits will not fix it. Our post on why outdoor outlets keep tripping in Naperville homes goes deeper on the diagnostic, and if you want the general background, how GFCI outlets work and why they matter covers it.
The fix is boring and effective. Get every connection up off the ground. Point female ends down. Use a drip loop so water runs away from the plug instead of into it. Wrap junctions or use the plastic connection covers sold for this. None of that requires an electrician.
What older Naperville houses are actually working with
The houses we get called to in December fall into a few groups.
Pre-1980 homes, including a lot of the stock around downtown and the Historic District, often have exactly one exterior receptacle, sometimes none, and sometimes a two-prong ungrounded outlet that somebody swapped for a three-prong at some point without running a ground. That last one looks modern and safe and has no equipment ground behind it, which matters more than people think when you’re pushing current through wet conditions.
The 1990s subdivisions on the south and west sides usually have front and back exterior receptacles, both fed off the garage circuit, both GFCI protected from a single device in the garage. That’s code-legal and it also means one wet connection at the back of the house kills the entire front display.
Newer construction is generally better provisioned, but almost never provisioned for a display. Builders put in what code requires, not what a family who does the roofline every year is going to want.
None of those are defects. They’re just houses built for a smaller electrical life than the one people live now, and if your breaker is already tripping for other reasons, that’s a separate conversation worth having before December arrives.
Extension cords and the covers that actually matter
Two things cause the problems we see that are genuinely dangerous rather than just annoying.
The first is indoor extension cords used outside. An outdoor-rated cord has a W in its marking and insulation built for cold and moisture. An indoor cord run out a window in December will stiffen, crack, and eventually fail somewhere you can’t see. The gauge matters too: a long thin cord feeding a real load heats up along its whole length.
The second is the receptacle cover. Outdoor receptacles need an in-use cover, the bubble style that closes over the plug while something is plugged in. The old flip-up flap covers only protect an empty outlet, which is precisely when it doesn’t need protecting. If your exterior receptacle has a flat flap and a cord holding it open all December, that’s the single cheapest thing on this page to fix. We covered the details in installing weatherproof GFCI outlets outdoors.
And nothing should be running under a rug, through a doorway that closes on it, or stapled through its insulation.
Inflatables, projectors, and timers
Inflatables are the item that quietly changes your math. The lights on them draw very little. The blower is a motor, it runs the entire time the thing is up, and motors draw a startup surge well above their running current. Three or four inflatables on one outlet with a timer is a common setup and a common trip.
Timers have their own rating, printed on the timer. It’s usually well below the circuit rating, and it’s the timer that fails first when you exceed it. Read it before you daisy chain a display through one.
Roof heating cables belong in this conversation too. If you run them for ice dams, they are a real continuous load that shows up in exactly the same weeks as the lights, and they should not be sharing an outlet with a display. We laid out the case for and against roof heating cables in Naperville separately.
Is it my house, or is it Naperville Electric?
Worth knowing, because Naperville is not ComEd territory. The city runs its own municipal electric utility, and roughly 95 percent of the distribution cable here is underground, which is a large part of why local reliability is as good as it is.
The practical version: if your neighbors’ lights are on and yours are not, it’s your house. If the whole street is dark, that’s the utility, and outages get reported to Naperville’s Customer Care Center at (630) 420-6060, which is staffed around the clock. The city’s electrical safety pages list the utility contacts and the clearance rules around their equipment.
If it’s your house and the smell of something hot is involved, stop reading and call somebody. That’s an emergency call, not a December inconvenience.
What we’d actually install, and when
For a house that does a real display every year, the answer is usually one dedicated exterior circuit with its own breaker, GFCI protection, in-use covers, and receptacles placed where the display actually goes rather than where the builder put them. Front elevation, back yard, and a soffit outlet on a switch if there’s a roofline involved, so nobody is on a ladder in January unplugging things.
The soffit outlet is the one people are happiest about afterward. It’s a small job on most houses and it eliminates the cord running up the side of the house entirely. If you want that integrated with the rest of your exterior lighting, our custom lighting work covers landscape and soffit circuits at the same time.
Do it in October. We can trench, drill, and work outside comfortably in October. In late December we’re doing the same job in frozen ground with the display already hung, and it costs you more in schedule than it does in money.
If you have other work you’ve been putting off, bundle it. As a licensed electrical contractor serving Naperville and the western suburbs, we can put in an exterior circuit on the same visit as the outlet you’ve been meaning to replace or the panel that’s been full for two years.
Please stop resetting it
If a breaker or GFCI trips once after a storm, reset it and move on. If it trips again immediately, or trips repeatedly over a few days, something is wrong and repeatedly re-energizing it is how a nuisance becomes a fire. That’s true of a display and it’s true of anything else. Circuit overloads and how they actually start walks through the mechanism.
Unplug everything, reset the device, and add loads back one at a time. If it holds with nothing plugged in and trips as soon as a specific run goes back on, you’ve found your bad string. If it won’t hold with nothing plugged in at all, the problem is in the wiring and it needs somebody with a meter.
Questions we get in December
Why does my outdoor outlet only trip when it rains? Because it’s a GFCI doing its job. Water is getting into a connection and current is leaking. It’s not a capacity problem and adding a circuit won’t fix it. Find the wet junction, get it off the ground, and use connection covers.
How many strings of lights can I plug into one outlet? Two limits apply and you have to respect both. The tag on the string tells you the maximum number of sets you can connect end to end. Separately, the total wattage on that circuit should stay under 80 percent of the breaker rating, since a timed display counts as a continuous load. On a 15-amp circuit that’s 12 amps.
Can I add an outdoor outlet myself? Naperville requires a permit for electrical work inside city limits, and the work has to be done by a state-licensed electrical contractor registered with the city. Homeowners doing work on their own primary residence have their own process through the city. Either way it is not a no-permit job.
My whole street is dark. Do I call you? No, call Naperville Electric at (630) 420-6060. If it’s just your house, then call us.
Is it worth putting in a dedicated circuit just for holiday lights? If you decorate seriously every year, yes, and it pays for itself in not having to solve this every December. If you put up a wreath and two strings, no. We’ll tell you which one you are.
Get it sorted before the ladder comes out
Cob Services LLC is a family owned electrical contractor based in Naperville. We install exterior circuits, GFCI receptacles with in-use covers, soffit outlets, and switched landscape lighting, and we pull the permit through the City of Naperville.
October and November are the right months for this. December is when we’re fixing it instead.
Cob Services LLC 2020 Calamos Ct Suite 200, Naperville, IL 60563 Phone: (630) 427-5923 Illinois electrical contractor license #26-00032356 Licensed, bonded and insured. Free estimates, no trip or dispatch fee. Office hours: Monday through Friday, 9:00 AM to 5:00 PM. Emergency line 24/7. Serving Naperville, Lisle, Aurora, Plainfield, Bolingbrook and Downers Grove.
Request service or call (630) 427-5923.