You have one of those HD 100' extension cords. One end is plugged into a live outlet. The other end is left out in the rain.

I'm careful about not doing this, but what would happen if I did?

Sue

Your next door neighbor would trip over because it's hard to see in the rain and then sue you for every penny you have. Just kidding.

Off the top my head, probably nothing would happen. Fresh water, particularly rain water, doesn't conduct electricity that well, so unless something physically got stuck into the little slots of your extension cord, I think it's unlikely that the electrical circuit could be closed just by sitting out in the rain. I don't know if it's the building code, but my garage outlets also have GFI protection, like you see in bathroom outlets, so any short circuit would quickly be shut down.

Actually, if it was a hot, sticky night, I'd sneak over to your house and hook up my window AC to it so I could sleep at night, then unplug it again in the morning.

Most likely nothing bad will happen. Although if you left it in the rain, and the live end happens to be in a puddle....well, if anything did happen you'll probably just trip the circuit breaker that the cord is plugged into. But if someone happened to be walking into the puddle...while barefoot...and decides to pick it up...

So while the probability is that nothing bad will happen, it's almost a complete certainty that nothing good could possibly result from it either. I have left many regular extension cords out in the rain with no accidents. I try and be careful, but sometimes an unexpected shower happens and I'm not at home to put everything away. So while I don't recommend it, it's not something i would worry a whole lot about.

Most modern extension cord socket ends are deep enough and narrow enough that the surface tension of water won't break past the opening or aperture. Contaminants in the water can mitigate the surface tension a bit (surfactant runoff from stuff like anitfreeze, pesticides and herbicides etc). The chance that dirty water can get to the actual electrical contact is minimal, but it is possible. If the cord is plugged into a gfdc, then it will likely trip out and open the circuit before anyone gets hurt. If no gfdc, then the contacts could short out through the water and trip the breaker. There's also a very remote chance that the water is not conductive enough for a true short, for whatever reason, and the current stays live. Usually, though, once the current has found a flow path in the liquid, it will usually compel a circuit flow to a true short or open the circuit again.

It takes a serious case of dumb butt to leave a cord thus.

The breaker will trip, at worst.... well, worst would be getting zapped when plugging something in, but even then you're looking at a wake-up call at worst (depending on circumstances).

I tell all my contractors (correct that - DEMAND from all my contractors) that they use GFI protected extension cords where exposed to the elements. Ordinary breakers may not trip fast enough to protect you from the shock. I've seen plenty of cords with hacked off ground plugs, non-water tight ends and frayed sheathing. There is no point to getting zapped over a few extra dollars of cost. If I had an electric lawnmower, you can bet your life that I would have it connected to a GFI extension cord.

BTW, you can die from as little as 47 volts.

Okay, thanks a lot! I was just kind of curious.

But not curious enough to stick the outer end in the dog's swimming pool....

Sue

Undoubetdly, GFI's are the way to go wherever water is possible. They keep the dogs safe too (if someone accidently put one end in their pool)

I got zapped (twice) by 110v tonight at "work," doing a hot wiring job. It ain't that big a deal...

GFI's are great, but be aware that they don't make you absolutely safe. In the right conditions, you could be killed by a leakage current that is too low to trip the GFI.