When Christmas lights trip a breaker, the usual cause is simple math: the strings, inflatables and everything else on that circuit add up to more current than the breaker allows. If it is the GFCI outlet that trips instead, usually after rain or heavy dew, the cause is more often moisture leaking current to ground than too many lights. The fix depends on which one you have, so the first step is figuring out which device is shutting off and when.
If the numbers show your display simply needs more capacity than the outlets you have, the lasting fix is dedicated outdoor circuit installation by a licensed electrician. Before that, though, most homeowners can solve the problem with a pencil, the tags on their light strings, and a few minutes of addition.
This matters in metro Atlanta because so many Gwinnett and DeKalb homes built in the 1970s through the 1990s have only one or two exterior outlets, and those outlets often share a circuit with the garage, a porch light or even a bathroom. Add a December cold snap with wet grass and long nights of run time, and a display that worked last year can start tripping this year.
Breaker Trip or GFCI Trip: Find Out Which One First
Go to the outlet your lights are plugged into. If it is a GFCI (the outlet with Test and Reset buttons) and the Reset button has popped out while the panel breakers are all in the on position, the GFCI tripped. If the GFCI looks fine but a breaker in the panel sits in the middle or off position, the breaker tripped. Some homes have GFCI breakers in the panel instead, which have their own small test button on the breaker.
The two devices react to different things. A standard breaker trips on overcurrent: too many amps flowing for too long, or a short. A GFCI compares the current going out on one wire with the current coming back on the other, and it trips when the difference reaches about 5 milliamps, a tiny amount that usually means current is leaking somewhere it should not, such as through water in a plug connection. A GFCI trip after a rainy evening points to moisture. A breaker trip every night at the same time, right when the timer turns everything on, points to load.
Whichever one it is, reset it once after unplugging the display. If it trips again with nothing plugged in, stop there and call an electrician. Resetting a breaker or GFCI over and over is not a troubleshooting method; it pushes heat and fault current through wiring that is telling you something is wrong.
The Load Math: How Many Lights Fit on One Circuit
Watts divided by volts equals amps. Household outlets run at about 120 volts, so a 15-amp circuit can carry about 1,800 watts in total and a 20-amp circuit about 2,400 watts. But holiday lights run for hours at a time, and the electrical code treats a load that runs three hours or more as continuous. For continuous loads, the safe working limit is 80 percent of the breaker rating. That puts a 15-amp circuit at about 1,440 watts and a 20-amp circuit at about 1,920 watts. The breaker size is printed on its handle.
To find what is on the circuit, read the tag or box on each light string, inflatable and projector. The wattage is printed there. If only amps are listed, multiply by 120. Then add everything else on the same circuit, which is the step most people skip. Our guide to how many outlets can share one circuit explains why the porch outlet and the garage outlet are often the same circuit.
A worked example
Picture a 15-amp exterior circuit that also feeds a garage refrigerator. Say the refrigerator’s label shows about 150 watts while running. The display uses 20 strands of incandescent mini lights tagged at 40 watts each (800 watts), six strands of large C9 bulbs with 25 bulbs at about 7 watts each (roughly 175 watts per strand, or 1,050 watts), and an inflatable with a blower tagged at 150 watts.
Add it up: 150 plus 800 plus 1,050 plus 150 equals 2,150 watts. That is over the full 1,800-watt rating of the circuit, before even applying the 80 percent rule. The breaker is right to trip.
Now swap the mini lights and C9s for LED versions. LED mini strands are often tagged well under 10 watts, and LED C9 strands commonly run around 20 watts; use the numbers on your own boxes. Using 5 watts per mini strand and 20 per C9 strand, the lights drop to 100 plus 120, or 220 watts. Add the refrigerator and inflatable and the circuit carries about 520 watts, well under the 1,440-watt continuous limit. Same display, about a quarter of the load.
Two limits that are not the breaker
Light strings have their own connection limit. The tag usually states the maximum number of strands or watts you can plug end to end. Exceed it and the string wiring itself can overheat even when the breaker never trips. Extension cords also have ratings, and ESFI’s outdoor decoration safety tips recommend outdoor-rated cords matched to the load and never plugging two or more cords together.
LED vs. Incandescent: What the Switch Actually Buys You
The example above is not unusual. LED holiday lights use a small fraction of the power of incandescent strings, and for many homes that one change ends the tripping without any electrical work. ENERGY STAR’s page on decorative light strings covers the efficiency difference and what to look for when buying.
There is a limit to what LEDs fix, though. If the trips are GFCI trips caused by moisture, LED strings can trip a GFCI just as easily as incandescent ones when water gets into a connection. And if the circuit is already loaded by a freezer, a space heater in the garage or a pool pump, a lower-wattage display may still push it over the edge on a cold night.
When It Is Moisture, Not Load
Georgia winters are more damp than frozen, and that is hard on outdoor connections. Rain, heavy dew and humid nights let water bridge the contacts where strings plug into each other or into a cord. Each small leak adds a little stray current, and a GFCI does not care where it came from. Signs that moisture is the culprit include trips that happen after rain or at dawn, trips that stop once the weather dries out, and trips that follow one particular string or cord.
The safe next steps are simple. Unplug the display, let connections dry, and keep plug connections off the ground and out of puddles. Replace any string or cord with cracked insulation, crushed sections or corroded plugs. Use only lights and cords marked for outdoor use. Never bypass or replace a GFCI with a standard outlet to stop the trips; the GFCI is the device protecting someone from a shock in wet grass.
If the GFCI trips with nothing plugged in, or will not reset at all, the problem is in the outlet or the wiring, not the lights. That calls for a licensed electrician. Our holiday lighting electrical safety guide covers broader decorating safety, from ladders to timers.
When a Dedicated Outdoor Circuit Is the Right Fix
Use this rule: if your math shows the display, after any LED swaps, still uses most of a circuit that also serves other things, or if you are running extension cords through windows and doors to reach indoor outlets, you have outgrown your existing outlets. A dedicated outdoor circuit is a new circuit from the panel to one or more weather-resistant, GFCI-protected outlets with in-use covers (the bubble covers that stay closed with a cord plugged in). It serves the display and nothing else, so a December load never fights the garage freezer.
This is permitted work in Georgia, done by a licensed electrician, with an inspection by the local building department. What drives the price is mostly distance and access: how far the outlet is from the panel, whether the wire can run through an open attic or crawl space or has to cross finished walls, whether the panel has room for another breaker, and how many outlets you want. If the panel is full or showing its age, our breaker and fuse replacement work may be part of the plan. If your breaker trips even when the display is off, our article on a circuit breaker that keeps tripping covers the year-round causes.
Plan the Display Around the Circuit, Then Fix the Gap
Start with the tags and the addition. Many homeowners find that switching to LEDs and moving a few strands to a second circuit solves the problem for the season. If the numbers still do not work, or the trips point to moisture you cannot keep out, it is time for a closer look at the outlets and wiring.
Kalahari Electrical Services is family-owned, licensed and insured (GA EN213186), and has served Gwinnett County since 2001. We handle electrical repair in Grayson, Lawrenceville and across metro Atlanta, including tripping outdoor circuits and new GFCI-protected outlets. For code background on circuit and GFCI rules, the NFPA 70 National Electrical Code page is the official source.
Call 678-665-2309 or schedule an electrical repair visit, ideally before the lights go up, so any new circuit can be permitted and inspected in time for the season.
Frequently Asked Questions
How many Christmas lights can I put on one 15-amp circuit?
For lights left on for hours, plan on about 1,440 watts total for a 15-amp circuit, which is 80 percent of its 1,800-watt rating. Add the wattage from every string tag plus anything else on that circuit, such as a garage refrigerator. LED strings let you fit far more lights within that limit.
Why do my Christmas lights trip the GFCI only when it rains?
Water in plug connections lets a small amount of current leak to ground, and a GFCI trips at about 5 milliamps of leakage. Keep connections dry and off the ground and replace damaged strings. If the GFCI trips with nothing plugged in, have an electrician check the outlet and wiring.
Is it safe to keep resetting the breaker for my holiday lights?
No. Reset once after unplugging the display. If it trips again, reduce the load or call a licensed electrician, because repeated resets push heat through wiring that is already overloaded or faulted.
Do I need a permit for a dedicated outdoor circuit in Georgia?
Yes, adding a new circuit is permitted work that a licensed electrician performs and the local building department inspects. The circuit should feed weather-resistant, GFCI-protected outlets with in-use covers.