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I've only witnessed a small popcorn fart, and some really smelly magic smoke...

I remember a near miss in a meeting, when we had been brainstorming on a whiteboard, and to clarify part of the design someone pulled the overhead projector screen down to project a diagram. After a few minutes of increasingly-excited discussion one of the engineers leaped to his feet and grabbed a pen, only to have half the meeting scream "STOP!!!" a second before he started annotating the diagram - on the projector screen. He looked quite stunned for a moment.

Only peripherally an IT issue but in one job the kettle lead had gone missing as we only discovered later. That particular kettle didn't have the bit that stopped you using standard cable instead of a hot condition one so someone had found a spare computer lead and used that. Inevitably a few weeks later the lead caught fire, fortunately whilst I was in the kitchen (didn't even need a fire extinguisher, I just turned the socket off). No damage done but could have been a lot worse.

This - it's an IEC 13 cable OR it's a kettle cable - if you think they're the same it's your turn to chuck out the molten remains.

Where is that a thing? I'm not sure they have that in most of the places I have been living. (Honest curiosity)

Once witnessed a junior tech tasked with recovering data off a harddrive blow it up. I'd never realised that a floppy power cable could plug in to the jumper (master/slave) pins. The client was told the harddrive had died with the PC :)

Many years ago was interviewing for an IT Support job. Part of the interview was "here's a PC, we've broken various things in it, make it work". Was things like one of the cards was loose. But I always first checked the voltage switch. It's just common sense. And after I got the job, I joked with my manager that I'd love to set it up for an interviewee with the voltage set to 110 and see if they spot it. Although I sometimes set that part of the interview, I never did that.

3 years later, I've moved on and I get an E-Mail from my former boss saying "Ha Ha Ha" and nothing else. He wouldn't reply to me. So I contacted one of my former colleagues. Seems whoever set the machine for my replacement's interview HAD changed the voltage switch - my boss assumed it was me! Unfortunately they didn't check and blew up the power supply when they tried it...

Oh well!

I had a graduate (a graduate in Electrical Engineering) working for me on some power-measurement tasks. He wired the three-phase instrument voltage-transformer incorrectly, leaving the protection-fuses the 'wrong' side. I never knew a solid, cast-resin transformer could spread so far. If you know where to look, the traces are still there, 8 years on.

I should have checked. I should have checked. I should have checked.

I took the blame, because I should have checked.

Chatting to an engineer who was busy doing a warranty repair on a PC at the college where I work, the subject of switchable power supplies came up. He once had to visit a school and replace about 20 power supplies in PCs in the library, it turns out that one of the students had spotted the voltage switch on the PSU and flicked it to see what happened... Apparently he was quite enamoured with the sound, light and smoke effect, so proceeded to flick more voltage switches, until one of the staff caught him!!

On a similar vein, several years ago I was auditing a company that trained and certified electrical techs to work offshore. Part of the qualification process was a practical and they had a workshop with a wide range of kit they could encounter on site. One of the specific checks was on trainees checking isolation - all the kits LV but had a few flash-bangs hidden away and, if anyone didn't confirm the circuit they were working on was isolated, they'd experience an UUC* moment.

The significance of checking circuits was brought home one day when I got an urgent phone call saying one of our offshore contractors had divers trapped subsea in a bell without power. The divers had bail-out bottles to provide breathing gas for quite a while, and torches to provide some light, but their hot water suits would soon be getting cool. Power was restored fairly quickly but there was an investigation. We found they'd decided to connect emergency jumper cables from the dive-spread across to the rig supply - to save time should the dive supply fail (a separate generator). Unfortunately, the rig supply tripped during the dive (the potential of such being the reason the dive spread has its own supply); having pre-installed the emergency cables, the dive spread generator now found itself being asked to power the whole rig... and immediately shut off. Once the cause was identified, the cables were disconnected and the generator put back on-line (fortunately the breakers did their job).

*Urgent Underwear Change.

South Korea and the majority of the planet.

The thing that causes as much damage is also the AC frequency. The world generally runs on 50hz or 1 cycle every 0.02 seconds. Some weird places run on 60hz or 1 cycle every 0.01666666666R secomds. If you ever hear a good low buzz with some iffy piece of electrical equipment, that is a mains hum. Theirs is a worryingly higher note...

A few years ago the village where I live was having some major work done on the electricity infrastructure, so a massive generator was brought in to run everything. Power quality was really good, no brown outs or anything, but I did notice that clocks on things like the VCR (yes, this was a few years ago) the cooker, etc. were running fast. That was when I learned that (a) some digital clocks synch to mains power cycle, (b) some generators run faster than 50Hz

Many years ago I did some work in Taiwan, where they had 110v and 220v in the same building. We had a 220v server, which was carefully plugged into a 220v socket. Problem was that no-one had noticed that the extension lead in the middle was only rated for 110v. It worked for a while....

I took on a project recently which served to show me how much I don't know about electrics. Out of curiosity, what's the failure mode of a cable like that?

I'd have thought that a higher voltage would mean less current, and therefore less heat created in the cable. Do you just get breakdown of the cable insulation under the higher voltage?

To be grateful for the onward march of time and inevitable improvements that it can bring - namely, the 110v ~ 240v issue. Modern stuff having internal switching to prevent this kind of conflagration... That said I was always tempted to play with that setting disc on the back of my 70`s amp to see what happened when changed between the various voltages it supported (240, 220 & 110 volts). Being in the UK it was always set to 240 so I guess not much being the result.

(also I still don't get what advantages 110v has other than it being a lower number so looks more safe..)

Having moved house I needed to rebuild my small office. Nearly everything to be wired through a 'cooker switch'. I did lots of custom wiring to be clever and have eg. a dimmer control for my foot warmer in easy reach. One merry morning I switch on at the master and there's an almighty bang and a flash. Whoops! All off again and see which PSU has gone. I can smell 'electrical'. Sniff-sniff PC1. Possibly. Sniff-sniff PC2. More likely. It turns out that there isn't a trace of smoke on any PC PSU. After gingerly powering up the naked PCs they work fine. Suspicion turns to my custom wiring, but nothing there. Both screens are still working. Umm. Life returns to nervous normal when, a few days later, there's a repeat. Definitely a flash. Definitely electrical. PCs fine. Aha! Screens. I thought I could smell electrical so started a long job of dismembering a screen. Nothing to see and after the fuse was replaced all was working again. The oomph of the bang convinced me it must be a PC PSU so I ordered a replacement and held my breath each time I switched on. After a take everything apart, put it back together in the light of a couple of week's experience, I was tinkering with something else, connected to a different circuit via a 4-way. BANG! Hey! How did that happen? Then I saw it. A fine spray of soot and copper across the worktop. From a white cable. With a tiny black hole torn in it. This cable wasn't overloaded, twisted, bent, squashed, nailed, folded or otherwise maltreated; it had just decided after 20 years of use to short internally. Moral of the story: Bangs DO leave smoke stains but it's easy to fool your nose into smelling it when it isn't there. Odd.

Not always smoke stains. How about the ca 12V-rated electrolytic capacitor on a bench top power supply that can go up to 30 V ? Fortunately (a) it was only about 100 uF and (b) I was outside the room where that happened. Walked in to find a nice shower of confetti cascading down and a gibbering experimenter.