Outdoor Christmas lights tripping the GFCI when it rains? Here's how I find the problem

Do your outdoor Christmas lights go dark every single time it rains? The problem is almost always water sitting in a plug connection, usually one lying on the ground. A GFCI outlet is built to cut the power when roughly 4 to 6 milliamps of current leaks somewhere it shouldn’t, and one wet plug can leak that much. Today I’m sharing how to find which connection it is so you can lift it off the ground and cover it. (And please, never get rid of the GFCI!)

I’ll be honest, the first year we did lights on our house in Florida I spent half of December walking out to the garage to push the reset button. It would rain, the porch would go dark, and the next morning everything worked again. Below is everything I finally learned, in the order I’d check it.

Step 1. Know what the GFCI is telling you

A GFCI is the outlet with the little “test” and “reset” buttons. It watches the current going out on one wire and coming back on the other, and those two numbers should match. If they’re off by about 5 milliamps, it assumes the missing current is going somewhere dangerous, like through water or a person. Then it shuts off in a fraction of a second.

So when it trips in the rain, it’s not broken and it’s not being dramatic. It’s telling you water has made a tiny path to ground somewhere in your setup. That’s exactly what you want it to catch outdoors, around wet grass and metal gutters!

Two things make it worse:

• Connections on the ground. The gap between a male plug and a female plug is the perfect little cup for rainwater. A plug sitting in wet mulch or grass is basically soaking.
• Lots of connections on one outlet. Every strand and every plug-to-plug joint can leak a tiny bit when wet. One alone might be fine, but eight of them on the same GFCI can add up to enough to trip it.

Step 2. Find the bad section

This is the part that saved my sanity! It takes about 20 minutes. Do it while things are still damp, because once everything dries out the problem is hard to find.

1. Unplug everything from the outlet, including any timer or power stake.
2. Press reset with nothing plugged in. If it won’t reset, or it trips again by itself with nothing connected, stop here. That’s the outlet or the wiring, not your lights, and you need to call a licensed electrician.
3. Plug in your first run (say, the roofline) by itself and wait a few minutes. Wet leaks don’t always trip right away.
4. Add the next run, then the next. When the outlet trips, the last run you added is your suspect.
5. Test the suspect run by itself. If it trips alone, walk that run and unplug it in pieces. Start at the outlet end with just the first strand, then add the next connection, and the next. The joint that trips it is your wet one.
6. If no single run trips it but all of them together do, it’s the adding-up problem from Step 1. You need fewer connections on that outlet, or drier ones. You don’t need to hunt for one bad strand.

Nine times out of ten, my bad joint was the one sitting in the flower bed by the front steps. Every single time!

While you’re out there, look at every plug and cord you touch. Anything with cracked insulation, a melted or discolored plug, or exposed copper gets thrown away. Don’t tape it up.

Step 3. Get every connection off the ground

This one fix solved most of my problem. Nothing that plugs into anything should be lying on the ground, in mulch, in a gutter, or anywhere water collects.

• Tie connections up a few inches on a railing, a shrub branch, or a garden stake with a zip tie.
• On the roofline, make sure the joints between strands aren’t sitting in the bottom of the gutter.
• For the joints you can’t get off the ground, use a connection box. It’s a little plastic clamshell with a gasket that closes around the plug-to-plug joint so rain can’t pool in the gap.

Step 4. Add a drip loop at every cord

A drip loop is a little U-shaped dip in the cord right before it reaches a plug or the outlet. Rain runs down the cord, hits the bottom of the U, and drips off there instead of running straight into the connection.

It’s free and it takes two seconds! I do it at the outlet, at every connection, and anywhere a cord comes down off the roof. If you see a cord running in a straight line downhill into a plug, that’s where the water is going.

Step 5. Cover the outlet the right way

Take a look at the cover on your outdoor outlet. If it’s a flat flip-up lid that can’t close once something is plugged in, it isn’t keeping rain out while your lights are on. Outlets in wet locations are supposed to have an “in-use” cover. That’s the deep bubble-style one that closes over the plugs and lets the cords come out the bottom.

If yours is the flat kind, it’s a cheap part and an electrician can swap it quickly. (If you’re comfortable doing small electrical work yourself, turn off the breaker first. If you’re not sure, don’t do it.)

I also like to get the actual plug-ins off the outlet face. I plug an outdoor power stake timer into the outlet and plug the lights into that. It has six weatherproof outlets and a dusk-to-dawn timer, so I’m also not standing in wet grass at 11pm!

Step 6. Put fewer strands on each outlet

If Step 2 showed you it’s the adding-up problem, split your display across two GFCI-protected circuits. For example, the roofline goes on the garage outlet and the bushes go on the front porch outlet.

While you’re at it, check the tag on each light set. It’ll say how many sets can be connected end to end, and that number is the maximum. LED sets usually allow a lot more than old incandescent ones, but the tag is the rule for your specific lights.

Two more cord rules that matter here:

• Use cords and lights marked for outdoor use. I used an indoor cord my first year (please don’t!). An outdoor-rated extension cord has a heavier jacket made to handle moisture and being stepped on.
• Don’t plug extension cords into other extension cords to reach farther. Get one cord that’s long enough.

If you’re going to be re-hanging things anyway, I walk through clips for gutters, siding, and brick in how to hang Christmas lights without nails. The battery candles on a timer in my front porch done in one afternoon also mean a few less cords out there to begin with.

Step 7. Never bypass the GFCI

I know it’s tempting at 9pm when the yard is dark again. But please don’t run a cord through a window to an indoor outlet, don’t swap the outlet for a regular one, and don’t buy anything that promises to “stop GFCI nuisance tripping.” The GFCI is what stands between a wet cord and someone’s hand.

Call a licensed electrician if:

• The GFCI trips with nothing plugged into it.
• It won’t reset at all.
• It’s tripping in dry weather and you’ve ruled out your lights.
• You smell burning, see scorch marks on the outlet, or the outlet or a plug feels warm.
• You want an outdoor outlet added where you don’t have one (so much better than running a cord across the driveway).

Once I lifted every connection, added drip loops, and split the display across two outlets, our lights made it through every rainy night the next December!

Have your outdoor lights been tripping the outlet this year? I hope this helped you track down that wet connection! When your lights are finally staying on, be sure to post on Instagram and tag me @sugardesignco because I love seeing the beautiful decor y’all create!

-Ciera

Made something with this? Tag me @sugardesignco — I love seeing them.