Holiday Lights Tripping the GFCI? Causes and Fixes

It happens in a lot of Valley front yards every November. The lights go up Saturday, look great that night, and by Tuesday the whole display is dark, the outlet by the garage door is dead, and nobody knows which button to push.

Most of the time that is a GFCI doing exactly what it was built to do. The real job is figuring out what it is reacting to, because the fix is almost never the outlet itself.

What a GFCI Is Watching For

A GFCI compares the current going out on the hot wire with the current coming back on the neutral. If some is missing, it is leaking somewhere it should not be: through water, a damaged cord, or a person. According to the Consumer Product Safety Commission (opens in a new tab), a GFCI cuts power when that difference is as small as six thousandths of an amp.

That sensitivity is the point, and it is why holiday lights and GFCIs fight. Hundreds of feet of thin cord and dozens of plug connections sit outside overnight. Any one of them taking on a little water is enough. The National Electrical Code requires GFCI protection on outdoor receptacles at homes (section 210.8), and it has since 1973.

Tripped GFCI or Tripped Breaker?

A breaker trips on too much current. Lights plus a space heater in the garage on the same circuit is an overload, and the breaker in your panel will be in the middle or off position. Why breakers keep tripping covers that side.

A GFCI trips on leakage, not load. One bad strand drawing almost nothing can trip it, and the breakers will look normal. A breaker cares about how many amps are flowing. A GFCI cares about thousandths of an amp going the wrong way. One wrinkle: if your GFCI protection is built into a breaker in the panel, that breaker trips on either problem.

Why the Front Yard Goes Dead From the Garage

A lot of Valley homes have one GFCI outlet protecting a chain of outlets downstream of it: the front porch, the back patio, sometimes a bathroom. That GFCI might be in the garage or a bathroom, and the outdoor outlets themselves may have no buttons at all.

So the lights on the front of the house trip a GFCI behind a closed garage door. Check the garage, every bathroom and the exterior walls, and check the garage fridge after any trip, since it is often on that same GFCI. Our post on bathroom and garage outlets that stop working walks through finding it.

The Usual Causes in a Valley Yard

Sprinklers and drip lines. Spray heads hit outlets and connections near landscaping, and a drip emitter that has drifted under a plug keeps it wet for hours. If you overseeded with winter rye, your sprinklers are running more than usual right now. If it trips around the same time every night, compare that to your irrigation schedule.
Winter rain. When a winter storm comes through, every connection lying on the ground takes on water.
Plugs in low spots. Connections in a puddle, in damp gravel, or under the roof's drip edge. Get them off the ground.
Sun-damaged cords and strands. Strands stored in a hot garage, or cords left out through a Phoenix summer, get brittle and crack, and cracked insulation lets water in. Look for split jackets, cracked sockets and bare wire.
Indoor or cheap extension cords. Use cords marked for outdoor use and rated for what you plug into them.
Too much on one run. Every strand leaks a tiny amount. Stack up enough of them, add moisture, and it adds up. Also check the label for how many strands can connect end to end. The CPSC's holiday safety guidance (opens in a new tab) says never string together more than three sets of incandescent lights. LED strands usually allow more, and the label is what to follow.
Inflatables. The blower is a small motor sitting on wet grass. Water in the motor, or a cord pinched where it enters the inflatable, will trip a GFCI.
Timers. A plug-in timer not rated for outdoor use can collect water inside. Use an outdoor-rated one and keep it off the ground.

Troubleshooting Strand by Strand

Unplug everything from the dead outlets.
Find the tripped GFCI and press RESET until it clicks.
If it will not reset with nothing plugged in, or trips again right away, the problem is in the wiring or an outlet box, not your decorations. Stop here.
If it holds, plug things back in one cord and one strand at a time, waiting a minute between each.
When it trips, the last thing you added is your suspect. Set it aside and keep going, because there can be more than one.
Look the suspect over for cracked sockets, split insulation, corroded plug blades or water in a connection. A wet strand may be fine once it dries. A damaged one goes in the trash.

If it only trips at night or after the sprinklers run, test in the evening when things are damp. While you are at it, press TEST and then RESET. The CPSC recommends testing every GFCI at least once a month.

Never Bypass It

Somebody always suggests running a cord through a window to an indoor outlet, or swapping the GFCI for a regular outlet. Do not do either. The GFCI is the only thing between a wet cord and whoever touches it, often a kid grabbing an inflatable. If it is tripping, something is leaking, and removing the device just means nothing stops it.

The one real fix on the device side is replacing a GFCI that has actually failed. They do wear out, especially outdoor ones that have baked on a west wall for years. Outside, that means a GFCI replaced with a weather-resistant GFCI.

Check the Cover

Outdoor receptacles in wet locations need an in-use cover, the deep bubble style that closes over the plug while something is plugged in. The National Electrical Code (406.9(B)) requires them to be weatherproof whether or not a plug is inserted, with a hood that is listed and marked "extra-duty." A flat flip lid that only closes with nothing plugged in is wide open all season.

Summer sun is hard on these covers. One that is cracked, chalky or will not latch is not keeping water out. Swapping one is quick, and it is one of the first things we check on any outlet call.

Roofline Lights on Tile

On concrete tile roofs, cords get pinched between tiles or under clips, the insulation wears through in the wind, and that spot sits in the rain runoff. Use clips made for tile, keep plug connections off the roof surface, and never staple or nail through a cord.

LED vs. Incandescent

ENERGY STAR puts certified LED light strings at roughly 92 percent less energy than incandescent strings. That makes overload trips much less likely and lets you run more lights per circuit. It does not stop GFCI trips. A wet LED connection leaks the same as a wet incandescent one, so LEDs fix the breaker problem, not the GFCI problem.

When the Fix Is on the House Side

If you have dried everything out, tossed the bad strands and it still trips, the answer may be in the wiring:

A GFCI that will not reset, trips with nothing plugged in, or feels warm.
Outdoor outlets sharing one GFCI with the garage, a bathroom and the garage fridge, so one wet strand takes everything down.
No outlet where the display actually is, so the lights run on a chain of extension cords across the yard.
A breaker that trips whenever the lights and the garage are both in use.

A new outdoor receptacle where you need it, with GFCI protection and a proper in-use cover, or a dedicated circuit for the outdoor outlets, keeps the display from taking down the rest of the house. That is exterior electrical work we do across Mesa, Gilbert, Chandler and the rest of the Valley. When a trip does not make sense, electrical troubleshooting means finding where the current is going, not just pressing the button again.

If you would rather have somebody track it down, request an estimate and tell us what is tripping and when.