Electrocution

[Steve Walker]

There used to be a toy museum in Cockermouth. In one cabinet was an early, electric, model railway. That had a controller that plugged into a light fitting, with the removed bulb plugged into the top of the controller, which had a rheostat. As soon as the train derailed, the tracks would have no load and go to 240V!

I too got one off a tape recorder - my fault, I did not expect them to use 240V directly to power the erase head!

I've had a couple from accidentally contacting something that needed to stay live, while working on something else in the same enclosure. Only the tape recorder one was a proper belt, leaving me with a painful, but numb and unresponsive arm, but only for a few minutes.

These days I've obviously improved, so none for quite a few years - except for my boiler supply/switching, which floats at about 90V when I disconnect both live and neutral at the supply end of the cable. There are no other connections to either cable and boiler, so it must be an induced voltage from parallel cabling.

Now we also have RCBOs on the non-lighting circuits and will be adding them to the lighting soon.

[Brian Gaff (Sofa]

Yes well I can believe that as well. I visited Brookman's Park back in 1961, and unlike today, the only thing between us and the high voltages and rf was a line of stands with a ribbon stretched between them, we were actively encouraged to use a small neon lamp with a coil attached and see if we could get it to light, Of course we did, I was 11 at the time. We were told to keep clear of the transmission lines that ran on about 1M stands from transmitter building to a small brick building at the base of each aerial and were allowed to go inside the building of one not in use at the moment to see the huge coil and clamp of the matching system. There are people who still live nearby to large transmitters who can hear the program on such diverse things as the chains on mirrors and their cookers, Also keeping the rf out of telephones etc is not easy at those field strengths. Brian

[Brian Gaff (Sofa]

Yes well, the bodger who fitted the kitchen was not an electrician, it turned out just a kitchen fitter trying to save time and extra money in that out of sight out of mind way some people have. The older TVs of course had the chassis at half mains voltage and the aerial socket was supposed to contain isolating capacitors, but even those can get charged up to high voltages and also you can get leaky capacitors after some time and this practice luckily has now almost stopped, in favour of the switch mode psu which is then supposedly isolated by its much smaller transformer working at the higher frequencies. Having said that I have seen cheap Chinese wall warts actually come apart when you try to pull them out of a socket leaving live ends of the mains pins bare inside. Not a good design. Brian

[The Natural Philosopher]

I got my first serious shock - we had an electric heater that always 'tingled' - from a 12v train transformer used to drive a train set. I was using it to drive an overhead live rail train I had made out of Meccano with the super big Meccano electric motor in it. It wouldn't go - it sat there buzzing so I calculated the overhead rail needed to be lifted a bit ...so I grabbed the train and lifted the overhead rail with my other hand..and broke the circuit between motor and transformer...

YEOWCH!! I hadn't even begun to study electricity and had no idea such a thing as inductance existed. I thought 12V was 'safe'

I was only about 8 or 9 I think

[Brian Gaff (Sofa]

One popular one is the ceiling rose syndrome. There is no point in turning off the light if you discover you need either a new block in the ceiling or a new bit of pendant wire as we all know there is an unswitched live up there in that rose and a screwdriver in the wrong hole while up a ladder can be a very unpleasant surprise, I always after my first encounter with this situation tripped the cut out on the circuit first.

Brian

[Brian Gaff (Sofa]

Erm well are you suggesting bridging them with a charged up hv capacitor? Not nice, and probably dangerous, at least the ladies only picked them up in one hand then very quickly dropped them and swore. Brian

[Brian Gaff (Sofa]

Yes I know about those but they are very strictly current limited. Brian

[Brian Gaff (Sofa]

I don't hink you would be working on cars in bare feet though would you? Brian

[Brian Gaff (Sofa]

Another thing which strangely seem to help is the good old tesla coil, often sold as the violet wand etc, though I'm not sure if all that ozone is good for you, it does if stroked across ones skin seem to reduce pain, but its all a bit over the top and showy, and probably could be done much easier with a more targeted approach and les in your face pomp so to speak. Brian

[Brian Gaff (Sofa]

Yes they do, but its only at the discretion of the person as its by no means pain free. Not that I've tried it, but know somebody who had it once.. Brian

[Brian Gaff (Sofa]

Well, I'd become used to them by the age of 16, after all I had a father in the tv business, and none of our tvs had a back.

Obviously, I was protected when I knew no better but following the rules then I feel you do become immune to some extent over time.

Brian

[Brian Gaff (Sofa]

I'm always wary of so called safety devices that rely on electronics. That is why I used to pull out the breaker on that circuit completely. OK some bodger might have routed a live from a different ring, but very unlikely.

Brian

[Theo]

I can manage 415v. Next door is TNCS (earth connected to neutral) but has a break in their neutral, so when they turn the cooker on the earth becomes live with phase L1.

You and your neighbour share a water pipe. Through your neighbour's earth bonding, the water pipe is now live with their phase L1. The water pipe doesn't have good conduction to earth potential (during a drought, say).

You're on a different phase L2, and so a fault on your cooker exposes live parts at L2. The sink is joined to the water pipe at potential of L1, and so there's 415v between cooker and sink. You don't have (good) earth bonding.

I could get to 586v if it was being rectified and smoothed. I doubt it was though :)

Theo

[Brian Gaff (Sofa]

I do hope the Spanish have improved their plugs and sockets as I got a belt from a bedside light in the Canary Isles in a chalet. There were two errors. The 2 pin connectors into the wall used a kind of poke in a hole and screw the pin in over the wire connection system leaving strands of wire poking out round the dodgy, and the not long enough cable from the light had been twisted together to another cable to reach the plug and wrapped in insulating tape. So I follow the wire down, first get a tingle from the wire sticking through the tape and then get to the plug and get a belt from the bits of bare wire round the not very well fitting pin of the plug. I had quite a few words with the building manager and wondered if the intention was to kill his residents off. He said guests were not supposed to touch wiring, Well, like what kind of excuse is that. I also remember a lift in an apartment building where we went to collect some photos having a broken emergency cut switch which had been wedged on with a bit of old plastic tubing and some duct tape, so goodness knows how you were supposed to stop the lift if it went wrong! Brian

[Brian Gaff (Sofa]

You might have been very well hydrated so the current went through the water!

Brian

[Owain Lastname]

I remember having an RCD plug on my electric blanket in 1989 or so.

It was quite a lot later I saw a consumer unit with even a mainswitch RCD. MK Sentry was launched in the 1980s but if anyone was getting rewired at that point I think they still went for Wylex fuses.

Owain

[charles]

we had a teacher at school whose hair was completely white. He'd been working on a circuit from which he'd removed the fuse. Someone passing saw the fuse on the side and re-inserted it. Moral - put the fuse in your pocket.

[Brian Gaff (Sofa]

There was one odd occasion during the assembly of the space station where one astronaught felt what he described as an electric shock while inserting a bolt with a powered driver, They never did find out the reason, as those gloves are multi layer and covered in a kind of silicon stuff on the outside to aid grip. I suspect static, but I never did hear of any resolution. Electricity can be very odd stuff, I mean they still do not really know what makes lightning suddenly break down the air insulation to ionise it and discharge. The current idea is the millions of cosmic rays we all are bombarded by every day from deep space events. Then there are the sprites and ball lightning to work out. The latter I have witnessed and am really no wiser at all. Brian

[Jethro_uk]

No, but the direction of current will be across the chest ....

[Brian Gaff (Sofa]

Yes I mentioned the first one earlier and there have been deaths on stage due to faulty gear and mis wired electronics.

Brian