What caused this exciting bad event? What do I do about it?
October 22, 2021 3:42 PM   Subscribe

There was a bad event with an extension cord today.

My outdoor outlet was installed by someone who was referred as a licensed electrician, @ 10 years ago. The outlet is on the deck, only reachable through the house. There was a short outdoor extension cord with a 3 unit end, then 2 long outdoor heavy-duty cords to the driveway for electric lawnmower, snowblower, etc. Used it last winter with no problems.
Tried electric trimmers, hmm, no action. Trimmers got left outdoors, could be dead.
Tried another tool, nope.
Reset the gfci button.
Loud noise and electric plasma/flame shot from the extension cord with the 3 unit end for @ 10 seconds. No, I had not swept, yes, the leaves caught fire, I stomped it out, got water. (moved cord, though I was confident it was dead) Extension cord with a 3 unit end was warm, end melty, next cord now permanently stuck. Disposed of.
Poured more water on deck.
Reset breaker at breaker box.

Did water get into the 3 way end on extension cord and cause this? Did the borked electric trimmer do something? Or some other thing?
Should the GFCI have reset faster? Didn't time it, adrenaline affects time sense. But it seems that an outdoor GFCI outlet should respond faster to an overload.

Finding an electrician right now is non-trivial.
posted by Mom to Home & Garden (8 answers total) 3 users marked this as a favorite
Best answer: Probably you had something contaminate the cord that caused a relatively low amperage short between hot and neutral. Something like a spider web or a wet twig jammed into both slot openings.

If the short drew less than 15A (nominally, most breakers will handle significantly more at least for short periods) and didn't drain any current to ground then both the GFCI (which guards against current leakage to ground) and a regular breaker behaved correctly. A breaker of the Arc Fault variety might have detected the short (or might not depending on circumstances). But Arc Fault may not be be required on this receptacle depending on age and location.

Test the GFCI using the built in test button. If it tests ok unless you see burn marks at the receptacle I'd just toss any other cords involved and the 3-way and not worry about it.
posted by Mitheral at 4:00 PM on October 22, 2021 [7 favorites]

I would replace the outlet the cord was plugged into. They're only a dollar - unless it was the GFCI? Sounds like it wasn't but hard to understand what connected to what in your story.
posted by flimflam at 4:03 PM on October 22, 2021

It's hard to know what caused something like this, but outdoor outlets and cords suffer a lot of wear and tear due to weather conditions. I'd replace the outlet as well as all of the extension cords. Replacing an outlet isn't hard and there are lots of good DIY videos on the internet if you need a refresher. If you're not already storing the cords inside when they're not in use, I'd do that with the new cords.
posted by quince at 4:13 PM on October 22, 2021 [3 favorites]

Best answer: Consider adding some sort of a hook so the replacement outdoor socket end hangs "downward" facing, so dirt and debris would have a hard time getting in, esp. if the outdoor socket also has dust covers. Hanging it also makes the whole thing more resistant to moisture, and rain, and not subject to puddles, if any.
posted by kschang at 5:37 PM on October 22, 2021 [3 favorites]

Best answer: Sounds like there was something wrong with your extension cords or just an unfortunate short. I agree with Mitheral that if the GFCI outlet looks fine and the test button works, there's no particular reason to replace it. Usually, when a GFCI is going bad, it trips more easily, not less. There's no reason to suspect this is related to the trimmer or any other tool.
posted by ssg at 5:45 PM on October 22, 2021 [4 favorites]

Best answer: To touch on the "replace the outlet" idea --

Using outlets that only cost a dollar is a bad idea. The cheap ones do indeed cost less than a dollar, but are very susceptible to breakage in a variety of ways. When you have an outlet that is in a location that is going to see rough duty, such as an outdoor outlet, it is worth remembering that at some point, someone is going to plug in a long extension cord, and give it a hell of a pull, and of course it will be in a suboptimal direction such as laterally. People are often bending over to plug things in and there should be a cover on the outlet, so it is common to be unable to fully see the outlet as you're plugging it in. The materials that cheap outlets are made of are somewhat brittle to begin with, so cold, physical stresses, etc., all add up to things that can damage an outlet.

You can buy high quality commercial or industrial grade outlets that will survive much greater abuse for something between five and ten dollars. Everyday Home Repairs had an interesting bit on this a year or so ago. Of course, for outside applications, outlets should be downline from a GFCI.

This misadventure doesn't sound related to that, however.

The cause of any given electrical misadventure can be hard to determine. US wiring is largely designed to avoid causing fires inside walls or killing people, but very little is done to protect cable and gear. The British, by comparison, have fused plugs and safer designs. Water is insidious, as is the fact that lots of stuff made in Asia may be built as cheaply as possible. The GFCI would only trip in certain circumstances, and mild defects can easily turn into major issues over time and with the availability of an enabler such as water. Big Clive just posted on something similar a day or so ago.
posted by jgreco at 3:00 AM on October 23, 2021 [5 favorites]

Best answer: GFCIs don't respond to overload, they respond to current on the ground. That said, they do wear out over time and have a lifespan of less than ten years.

Were you leaving your extension cords constantly plugged in? If so, don't do that.
posted by drezdn at 5:42 AM on October 23, 2021 [2 favorites]

Using outlets that only cost a dollar is a bad idea.

Here in the UK, you will find outdoor outlets which look like this and are IP 66 rated. If you have a $1 outlet and it's lasted 10 years outside, well that's about 9 more than I would have predicted!
posted by Lanark at 8:31 AM on October 23, 2021 [1 favorite]

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