Saw a house yesterday where Christmas light installers ran an extension cord above the gutter - see the picture below. Is that safe? I ask since I keep imagining a gutter filling with snow and, generally speaking, seems like water and electricity don't mix.
It is not terribly safe, though weaving it over/under supports as they did at least helps to make sure it won't go flying around.
Temporary installations like holiday lights are always a bit of a problem. A few things to help mitigate potential problems:
- GFCI - This is probably the most important thing. GFCI is now required for outdoor receptacles but many older houses don't have GFCI in all now-required locations (aka "grandfathered").
- Grounding - It should be a 3-wire cord, plugged into a functioning 3-wire receptacle (though if the receptacle does not have a functioning ground pin but is GFCI protected then that will cover most scenarios where grounding would otherwise make a difference.) Except, as pointed out by Ed Beal, if the lights are all 2-wire (no ground) then ground wire on the extension cord is absolutely useless. But I would discourage 2-wire extension cords anyway because they tend to be thin junk.
- Make sure the extension cord is secured well.
- Make sure the extension cord is properly rated. It should be designed for outdoor use (some are, many are not). It should be able to handle the necessary current (Amps). Any standard extension cord, by definition, can be plugged into a 15A receptacle and therefore carry up to 15A without tripping a breaker. But many (generally not designed for outdoor use, and often not grounded) are actually not appropriate for 15A usage. On the other hand, with modern LED lights, a whole house of holiday lights will typically use only a few Amps (often less than 1 Amp).
- Every year before installation check for breaks in the cord. If you find small breaks but the inner insulation looks good then tape it up well with electrical tape (not duct tape). If you find large breaks or the inner insulation is damaged, replace it.
So long as the insulation on the extension cord is in good shape, this is no more or less dangerous than attaching it to the wall would have been.
Notice at the bottom of the picture where the cord comes out of the gutter? It's exposed to rain right there, too. While it may not be soaking in water, it will still get wet there. Either the insulation will protect the wiring or it won't.
Most cords are rated SJ at a minimum the junior hard service cord of which there are 17 variations all rated for damp locations and 1/2 include wet locations. So as long as the cord is in good shape and the end is not in the water I would not be concerned. Additional safety ? A home less than ~20 years old maybe 30 the outside circuits will be GFCI protected so even less of a problem.
Not to discount that electricity and water can be dangerous but pure water won’t conduct electricity. So in reality it’s not a big deal have you ever noticed those Christmas lights with water running over them on a metal gutter , doesn't trip the breaker or GFCI, same issue here, you will find similar wiring at my house around the holidays, the receptacles are GFCI protected
I had to prove this to a son in law . I told him to get me a bucket of water he got it out of the pool that was green at this time of year and I took a cord end and tossed it in the bucket of water ( never bet an electrician on electrical issues he had to go get beer). When he got back I pulled the cord out of the water shook it off and plugged the lights back in and they lit up.
As long as the ends aren't in the gutter and you are on a GFCI - you are just as safe/unsafe as using any extension cord outside.
My issue here is that if someone yanks that cord hard your gutters may be unsafe. I can tell you have seen similar things happen. If you feel this is completely zero chance, you are all good.