Even in the 90's Stud finders with the ability to sense cables existed and were not particularly expensive. Sounds like someone should have added the purchase of one of those into the "upgrade" cost.

Still, this is a good lesson for everyone that Electricians are absolutely the worst for a) following wiring rules, b) using common sense when installing wiring, and/or c) enjoy playing pranks with the wiring on house owners (and all subsequent house owners!). We've found wiring in our house (from 3 owners previous to us) that stretches diagonally across walls instead of only horizontally or vertically, uses random coloured wiring (not related to what the wire is actually carrying), and other parts that feel like the cables were laid down during the brief period when MC Escher thought a career as an electrician sounded like fun.

Anytime you think "Nahh, the Electrician could never be that stupid!", check, check, and triple check to make sure, because you can be absolutely certain, the one time you dont check, they will have been...

uses random coloured wiring (not related to what the wire is actually carrying)

Our estates people asked me once what a Cat 5 cable was for as it was in the way and they wanted me to move it. I said it wasn't anything to do with IT, so they went and chopped it. The next day the alarm company came asking who chopped their cables. The alarm company had just used some left over Cat 5 cable rather than their usual cable to wire up the sensors.

But did those exist in the 90s, which this must have been with Netware in use? They do a fine job of showing you where the US 110v 15A lines so they could have easily found that line for him, if modern electronic studfinders (that detect the physical stud itself rather than detecting nails and also detect electrical lines) existed at a reasonable price back then.

I remember "stud finders" back in the day used to be a plastic box with a plastic rod that spun with magnets on its ends. The rod would move when you moved it over a stud, though in my experience they were pretty terrible at doing so unless you were lucky enough to pass directly over a nail. They were so useless my dad relied on rapping his knuckles on the drywall and listening carefully as the knocking makes a more hollow sound in the cavities between studs (this would not apply to exterior walls due to the insulation, of course, so wouldn't have helped our friend since there was a window there and that method probably wouldn't work so well with plaster rather than drywall)

And I agree 100% about electricians. I've done enough DIY electrical work to realize that you should never trust that electricians followed the code that existed when the work was done, let alone what more modern code you may be familiar with. Nor should you assume that the work had been done by an electrician at all, in homes certainly you have DIY work (which I've contributed to myself in addition to the efforts of a previous owner) that may be done "differently" than expected. In an office setting you would hope that's not the case, but I wouldn't be shocked (ahem) especially back in the 90s when computers were more seen as a necessary evil than something you build you business on that a company might have a project to "turn this storage room into a machine room for our servers" and the guy in charge hires his cousin "who has worked construction so he knows how to demo/build walls and run wire".

"that stretches diagonally across walls"

Many years ago I lived in a house with ugly porous tiles in the kitchen, dining area and loo.

So I rented a Kango hammer and started removing them in the kitchen and suddenly heard an odd hiss above the noise of the hammer - some !?@#! had laid the gas pipe diagonally across the kitchen floor, embedded in the mortar used to set the floor tiles! Fortunately I got to the main gas valve before anything happened.

When I removed the tiles in the dining area I discovered they'd put a sheet of plastic on the wooden floorboards, then mortar, then the tiles. As result of which the floorboards and the joists carrying them had largely disintegrated due to dry rot :( Oh, and that floor carried the spiral stairs going to the upper floor, so had to get help from a mate, go to the workshop, cut a bit of 6" pipe, weld plates top and bottom and fit that under the spiral stairs before I could go to bet (rather late). At least when I removed the ugly tiles in the loo and hall I discovered a nice, undamaged granito floor under them.

The joys of undoing other folks' DIY! -->

Not gas, but water. I was converting a room from a small bathroom into a cupboard and was removing all the old pipe work and going to cap it off. I got my circular saw and adjusted so it was just about able to cut through the floor boards and nothing more. Cut along and then heard pssssssss and got wet. Ran and shut off the water that was now going everywhere. After I got the boards out, I looked at the pipe. It was notched into a joist OK, but they had not put a metal blanking plate over the top (as regulations said they should). so my saw blade had just nicked the copper pipe with the smallest of nicks, producing a really fine spray. A bugger to fix as it was so close to a joist that using a yorkshire joint was fun (no room for compression). I left that floorboard open for a day with an extinguisher next to it

Never assume anything about how an electrician will have installed cables. Doubly so for buried cables.

My parents were redecorating a room in their house and wanted to move some electrical sockets. They started to chip away at the plaster to discover that the cable to the existing sockets didn't run up/down or left/right, but diaganolly. But it wasn't a simple diaganol: It had kinks in it.

They ended up replastering the entire wall once they've chased out the existing cable runs (and replacemed them with sensible runs!)

My parents some decades ago moved into a house to which some additional sockets and lights had been retrofitted. I was somewhat taken aback when I leaned against a wall and it lit up from the sparking behind the plasterboard.

The UK rule of wiring only vertically or horizontally doesn't seem to apply here in Portugal where it's more common to see walls chased out diagonally, presumably because it saves on cable. I always thought it a bit ironic that the ring main was supposed to save on scarce postwar cable while the routing rules caused more to be used.

However, I was kind of hoping that the new power supply would originate in a different building and we'd get to find out what happened when the RS-232 cable created a ground loop for all the manufacturing machinery.

Same parents in the same house:

They couldn't work out why they kept on getting static electricity shocks when touching the mirror in the hall (This being the 70s & 80s nylon was very much in vogue so static shocks weren't unusual). They later discovered they hadn't been getting static electric shocks but mains electric shocks: The previous owners had put the nail in the wall the mirror was using straight through the live cable burried in the wall.

Lucky the drill was sufficiently insulating to prevent a truly shocking experience. This is precisely why I like these little cable detection gimmicks, even if the plans of the building are available and show where the wires should be. I have encountered enough short-cuts and assorted wiring horrors (including a yellow/green wire carrying 220 V AC) that I don't trust anything. Measure twice, drill once, one might say.

There's a reason why electrical wiring in commercial construction (in the US in recent electrical code at least) is protected by metallic conduit. Sure you CAN drill through that if you're using an appropriate drill bit, but if you encounter metal while drilling into a wall and decide to keep going whatever happens after that is your own damn fault!

"including a yellow/green wire carrying 220 V AC" (240V hereabouts)

Not too keen on the the non-contact mains A/C detectors - seen too many false negatives. I've kept my very old inherited neon indicator screwdriver. What's the NRA's unofficial motto? - I suppose if I tried testing 110KV might be more apt than I would like (certainly missing a thumb :) Double check with a cat iv meter - (on ac volts range :)

Two switches for one light appears to be the logical limit of average sparky (at least of yore.) They appear to have found more possible arrangements than logic alone would allow :(. One nasty one seen in old houses, (really nasty with ES) has the bulb off but both connections to the bulb are active - half the time.

I am not entirely sure colour (red-green) blind electricians are purely apochryphal as I have lived in two separate regions each with its own notorious representative of this urban legend. And have experienced the work of one.

It is not unusual, in the UK at least, where there is a light switch next to a doorway, for the electrician to run their cables behind the architrave on the door frame then up to the ceiling from the top of the door. The reasoning is that is saves time by not having to chase out the plaster all the way to the ceiling. Not sure if that has been banned in the current UK regulations now though.

What 'Antoine' should have done is at least take the front of the plug socket off to see which way the cables were coming from, or better still, pay to have a qualified electrician do the job.

" for the electrician to run their cables behind the architrave on the door frame then up to the ceiling from the top of the door. The reasoning is that is saves time by not having to chase out the plaster all the way to the ceiling. Not sure if that has been banned in the current UK regulations now though."

Most likely breaches the spirit of the regulations in respect of Electrical Safety Zones, but for a lazy electrician they could probably "interpret" the architrave as being within the ESZ for a light switch that's adjacent to the architrave. I've had a qualified electrician insist that because a cable is within a partition wall it qualifies as "protected" because one side of the wall is tiled and there's a couple of appliances in front of it. How that protects the back of that wall is presumably some magic of the regulations.

As with other posters, never, ever assume, always use a cable detector.

We had a great one.

We had an electrician who was doing something in the main machine room and needed to drill a hole in a partition wall through to the comms room. Only he managed to drill perfectly between two power cables running up the wall on the other side, shorting both and causing a bit of a bang and a mess. We were out for a day recovering from that.

Fun times!

We moved nearly 2 years ago, and we were not anticipating have a re-wire of the house, but when the electricians came to do a "simple 2 bathrooms and kitchen of downlighters", it soon became apparant that the old owners bodged it badly.

When I got to the outbuilding, that is a mess wiring wise - what I thought was a main is a spur, how they have run the lights is odd, but from seeing how a light socket was partly embedded into a wall, I guess at one stage it was a single room and then split.

I started to call the old owner "mr mastic" as if there was a job (so reattaching blown plaster to the walls), then mastic was used

Yup, this is where I would've said "I'm out"

Not being a licenced elechicken, I would have gotten a serious beating at work for doing that.

If the place later burned down for any reason, it would have been my fault.