Christmas Lights Keep Tripping the GFCI? Causes and Fixes

Outdoor Christmas lights usually trip a GFCI because of moisture in the plug connections, damaged cords or an outlet cover that does not protect a plugged-in cord. Raise the connections off the ground, cover them, inspect for damage and add one string at a time to find the bad one. Never bypass the GFCI.

A GFCI trips when current leaks to ground, and wet lights leak. That is the device working properly, so the fix is to find and remove the leak.

Common causes

• Moisture at plug connections. Plug-to-plug joints lying on the ground or a ledge, where water pools, are a leading cause.
• Damaged lights or cords. Cracked insulation, nicked jackets, crushed plugs and loose socket caps let water in.
• Wrong outlet cover. An outdoor outlet needs a cover that is weatherproof even when a cord is plugged in, often called a bubble or in-use cover, and a weather-resistant (WR) receptacle.
• Too many lights on one circuit. The load adds up as you string more together.
• Leakage from cords and timers. One forum reply points out that more cords and timers add more leakage, and that the GFCI is likely just doing its job.
• Long run times. One source says the longer lights are on, the more likely they are to trip.

How to find the problem

1. Unplug everything and reset the GFCI.
2. Plug in one string at a time. Wait a few minutes after each.
3. Note when it trips. Only in wet weather means moisture. In dry weather means a bad string or cord.
4. Inspect the culprit for nicks, crushed plugs and loose sockets. Replace it.

How to fix it

• Lift connections off the ground and point them downward so water drips off.
• Cover the joints with a weatherproof connector cover or a sealed box made for the purpose.
• Use an in-use cover on the outlet and a WR GFCI.
• Use outdoor-rated lights and cords, and fewer extension cords.
• Spread the load across more than one outlet or circuit.
• Check timers and use outdoor-rated ones.

The same logic applies to other damp locations. See why a GFCI trips on a garage fridge and a sump pump on a GFCI.

When to call a professional

• The GFCI trips with nothing plugged in.
• It trips in dry weather with every string removed.
• The outlet is wet, scorched or warm.
• You want a weatherproof outdoor outlet installed.

If a trip leaves the whole house dark, see steps to take when the whole house loses power.

What not to do

• Do not leave connections lying in puddles or snow.
• Do not use indoor lights outdoors.
• Do not keep resetting a GFCI that trips at once.
• Do not run cords through water.

Bottom line

Find the wet or damaged part by adding one string at a time, lift and cover the connections, and use a proper outdoor outlet cover. Keep the GFCI in place, because it is protecting you.