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I had one the other week where I was replacing an outlet in the kitchen. I flipped the kitchen breaker and the lights and appliances all turned off. I skipped the important step of actually testing the outlet and stupidly assumed it no longer had power. Turns out it was on a different circuit from the rest of the kitchen. The outlet was stuck in the wall box so I reached a flathead screwdriver in to try and pry it out, and turned my screwdriver into an arc welder for a second. Fortunately I wasn't hurt and only got a melted screwdriver tip and a smoky smell out of it, but I'm definitely not going to let myself make that mistake ever again.

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I made the mistake of not testing _all_ of the wires in an outlet a couple of months ago.

I used a non contact voltmeter, and had shut off the breaker to the outlet I was working on. Little did I know that the jackass that did some previous wiring in the house had run wires from a different breaker in to this box. It was done in such a way that I didn't fully realize it could have separate live.

My palm below my thumb touched the live and neutral and gave me a pretty solid shock.

I'll definitely test every single freaking wire in a box from now on. F people who try to play electrician without knowing what they are doing!

I saw an electrician who did know what he was doing change a fuse board incorrectly. He accidentally swapped one end of two different ring mains so that they were in different breakers! Same result as yours. Always test every live wire. Those glowing voltage sniffer screwdrivers can be pretty handy.

It isn't against code to have different lines inside one box (at least at any of the places I've lived).

Easiest way is to flip the mains everytime. I wouldn't trust those pencil testers though (the non-contact ones, the light ones yes).

I discovered an outlet like this in my house. Had a lamp plugged in to the outlet (since I could see it from the breaker box) and was sequentially going through and flipping each breaker off, then on again. The light never turned off...

Look at the slotted screw heads on outlet face plate. Are they both aligned vertically/horizontally, or are they at odd angles?

If they are both aligned, the outlet was probably but not necessarily last worked on by a real electrician. If the screws are at odd angles, the outlet was probably but not necessarily last worked on by a DIYer.

Real electricians align the screws, as a sort of professionalism and a nod to any future electrician who might work on that outlet.

Where? Here electricians leave cable offcuts, stripped insulator, plaster around on the floor so consistently it’s a meme (I know because for some reason I was getting tradie reels popping up flipping through Facebook).

We have a joke at work that you know that an electrical engineer (and not a licensed electrician) did the wiring if it’s too neat (for example, a colleague of mine seriously has cable trays through his roof cavity)

I have one even better, just to show how you can't be sure...

Replacing an outlet. Shut off the 2-pole breaker for the shared-neutral circuit it was on. Outlet tester showed the outlet was off. Pull the receptacle out. Used a multimeter to test each wire contact to ground; all were 0v.

Only when I disconnected all the wires did one of them develop potential because somebody had apparently tied a neutral wire to a hot in another box, but I still don't understand the situation and had an electrician address it.

So even testing each individual wire isn't certain unless they're all hanging free, unless you make the assumption that things were wired correctly in the first place.

When I'm working with home circuits I use indicator screwdriver all the time and I'm touching everyting metal with it at every step of the way.

I'm very rarely surprised with what happens but it still happens occasionally.

For example today I was surprised when RCD tripped when I shorted ground and neutral on a circuit that was disconnected by its own breaker.

I had to think for a brief moment to understand that yeah, it's perfectly reasonable that this happened and no, I'm not in any danger.

> The outlet was stuck in the wall box so I reached a flathead screwdriver in to try and pry it out, and turned my screwdriver into an arc welder for a second.

I've got a screwdriver that incorporates a non-contact AC current sensor. Mine is a Gardner Bender SDT-354 [1] that I think I bought at Home Depot or Lowe's.

When the current sensor is turned on if you bring the tip of the screwdriver near a live AC wire an LED in the handle starts rapidly blinking and a beeper starts rapidly beeping.

It once may have saved me from a nasty shock. I have an outdoor light over the garage that is controlled by a light sensor, and the light sensor was going bad. It would turn the light on when it got dark but not turn it off in the morning. So I'd flip the breaker for that light off and then back on every morning.

When morning when I went to open the electrical panel in the garage I got a shock from the panel door. I went in and got the current sensing screwdriver and went back to the garage to see if I could get an idea of what the heck was going on.

As soon as I stepped into the garage the screwdriver started blinking and beeping. A little experimenting showed it would go off anywhere in the front half of the garage that was more than about a meter above the floor.

It turned out that the metal garage doors and the metal rails their rollers rolled on and the metal tracks the garage door openers pulled the doors on were all connected to live AC.

I got the fuck out of there and called an electrician.

What happened was that in the shed next to the garage that houses my well some critter had chewed through some of the insulation on some of the wiring for powering the well pump. I'm not sure how but that somehow made the cover and door of the electrical panel and all those metal parts of my garage door system electrified, but without stopping the well pump from receiving power.

[1] https://www.amazon.com/Circuit-Alert-Blade-Screw-Driver/dp/B...

Yeah I have the standalone tool and it's a must-have for electric work. While replacing some switches in my house I thought I had the right breaker (sidenote: those breaker-detector tools are like magic, much better than the "is the light still on?" method). The lights went out but when I jammed my tester in the gang box it started beeping. I ended up needing to flip off 2 breakers (took me a while to find the second one) before it finally stopped beeping. From that moment on I promised myself that no matter how "sure" I was, I would ALWAYS stick the tester in before reaching in, even if I hadn't touched the breaker box between working on a switch.

I've been bitten enough times in software alone by things I was "sure" about, I don't take any chances when it comes to electricity.

An important habit when using testers: test the tester first on a known live wire. You don't want to find out the hard way if your tester has stopped working.

Cool story! I have a brand new screwdriver set from the other end of the safety spectrum.

Every one had a warning sticker saying 'non-insulating handle' on the plastic/rubber handle.

I'm not sure where they found conductive plastic, but had I known before purchase, I'd have gone with a different set.

It's not necessarily that the handle is conductive after all (it likely isn't, but there are conductive polymers out there -- I've made some in Chemistry class), but rather that it hasn't been tested and certified for its insulating properties (e.g. the VDE 1000V classification). They're covering their ass by saying that it's not intended to be an insulating handle because they didn't design it to be.

I have one of those little screwdrivers with a small light to detect current; I always use it on everything electric before I actually touch anything.

It amazes me how often strange anomolies slip through safety procedures. I use a voltmeter to check before working on wiring, and like you, have still managed to grab a live wire more than once. Last time, it was a situation much as yours - had the breaker off for the circuit I was certain I was working. And I checked with the voltmeter. But like a damned fool, I only checked the hot to ground voltage, and not the neutral to ground, or hot to neutral. Yep, you guessed it - the outlet was on a circuit for a different room, and was miswired in a junction box, reversing neutral and hot. I got the full benefit of the 120v. Fortunately, standing on a dry wooden floor in rubber soled shoes, I was a lousy path to ground, but still a dangerous situation I have no desire to repeat.

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