Trying to electrocute myself

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Do you really need to cross-bond a shaver socket given that the only exposed metalwork is the fixing screws?
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*If all is not lost, where the hell is it?

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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On Wed, 28 Jan 2004 13:36:41 +0000 (GMT), Dave Plowman

According to the regs, yes. I did a bit of sub-contacting to a firm a few years back, before earth bonding became daft. Being useless in every other aspect, (the firm, not me), I was surprised when I went on a 2nd fix of a bathroom extension to find a 4mm earth connected to anything in the room, the shower and exposed metalwork as normal but also to the light fitting, fan, shaver light, and anything else with a screew on it, whether it could be touched or not. Everything in the room was double insulated, bar the shower.
SJW A.C.S. Ltd.
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On Wed, 28 Jan 2004 13:36:41 +0000 (GMT), Dave Plowman

Which, if they are like normal socket outlets, are earthed anyway...
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On Wed, 28 Jan 2004 16:36:53 +0000, John Laird

But you have to bond them 'even more'. The iee requires that it is bonded. Even with the earth in the supply cable it is deemed to be of too high a resistance. Also as has been pointed out in some of the above threads the earth in the circuit feeding the shaver socket is not neccesarily connected to the exposed metalwork in the bathroom by means of other equipotential and supplementary bonding.
SJW A.C.S. Ltd.
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On Wed, 28 Jan 2004 17:12:05 GMT, snipped-for-privacy@telling.you (Lurch) wrote:

Interesting. I would love to see a proper estimate of the number of people who come to grief(*) through situations involving the lack of kilometres of 4mm2 bonding cable, and how those situations arose, but then I am deeply cynical by nature.
(*) Compared with, for example, the number of people who trip over their own feet and fall down flights of stairs.
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Extra credit: Define the universe and give three examples.

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No-one said the regs made sense, or that they solved all common causes of accidents in the home. Some of it is excessive, some is required. It is possible that in some instances such an excessive amount of earthing would be completely OTT, but a blanket rule has to be applied with the 'worst case scenario' being catered for. Not all electricians seem to be able to do things safely when being told what to do as it is, diy'ers would have trouble working out what was wanted and what wasn't. Lazy people just wouldn't bother applying any safety rules at all. Hang on, that's what happens now, none of this is compulsary, it's just a guide. If you buy a car with airbags you may not need them from a safety point of view but they are fitted in most instances 'just in case'. A similar rule is applied to safety measures in electrical installations, they are there 'just in case' an accident occurs and to minimise damage in the event that one does happen.
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wrote:

Not sure if you're agreeing or disagreeing with me, I'm sure it'll come clear in a minute. Meanwhile:- That's what I said. Connecting the metalwork in the bathroom together is half the job, connecting all the other bits of metal in the building together and also to a reliable earth point would be the other half.
SJW A.C.S. Ltd.
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If it was just a tingle, for a second or so, then it could just have been static building up on your clothes (nylon underwear) and being drawn away to earth through the socket cover.
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to
and in particular brown nylon y-fronts. If this is what you're wearing then go back and lick the cooker wires and get out of the gene pool.
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Much safer wearing green ones with yellow stripes....
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Bob Eager
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Unlikely to be static because:-

I have not yet come across 50Hz static.
I would be tempted to check that both sockets are properly earthed, both the one you touched and the adjacent one. Checking that they are both at the same potential with an ohm meter would be a good start. Try it on ac volts first of all. It is not unheard of for earth wire to become disconnected elsewhere in the circuit and this would not at first be apparent as it would not stop appliances from working. Best of luck and take care.

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-- Bill

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But you don't get a tingle from static - it's a sharp shock which then stops. A 'leak' of any sort from the mains carries on.
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*Why doesn't glue stick to the inside of the bottle?

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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No chance. Static builds up to si high a voltage that even with several megaohms in the path to earth, it discharges damn quickly, and won't give any kind of "sustained 50Hz tingle" like wot our original poster got. (And if there was that kind of resistance in the path to earth, the socket's earth connection's not exactly in order!).
From the details given, there's a (possibly intermittent) fault which needs sorting out. It's not clear from what we've heard whether the socket was the source of the 'tingle', with mains current passing through the OP's body on its way to earth, or its 'sink' - for example, if there's a floorboard nail which is just about contact with a live (only), and the OP stands on it, the surrounding floorboards won't give a decent path to earth so our man won't feel anything; but touching a well-earthed point - the socket cover if all the wiring's in order - creates a path to earth which our man can feel. (In such a case the strength of the 'tingle' is much dependant on how effective a contact he has with the source: do a trick like this in bare feet and you might not wake up at all :-(
Other uglies can happen with TV/video/sat etc. kit: some of these have two-pin mains connectors, and then internal circuitry which makes the aerial outer float to halfway between the live and neutral voltages. The resistance is high enough not to make the amount of current which flows dangerous to life, but you still feel a real and unpleasant tingle if you become the earth path for this voltage.
I'd definitely want to know what caused the 'tingle': what's an unpleasant weirdness on one occasion can become something much more dangerous next time.
Stefek
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snipped-for-privacy@hp.com wrote:

My DVD player does this. If you touch the metal casing you get a very faint tingle. The metal mag-mount aerial I used to have on a mobile phone used to do it too if the phone was plugged into the charger, even if the phone itself was off.
I assume that the casing/0v DC side of these things isn't really 0v. A normal 4-diode rectifier won't give a flat 0v DC but more of a ---- which means if the 0v isn't really 0v relative to your own body's potential you'll feel the pulsing.
Interestingly, since I put a TV card in the computer (in another room) and connected the aerial lead into that (earthed chassis) the DVD player which is hooked up to the TV which is hooked up to the same aerial arrangement no longer gives me that tingle. If I remove the aerial lead from the PC the effect comes back!
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Yes - you're then passing a small leakage current from your DVD player to the house earth through the aerial lead and the chassis of your PeeCee. (And if the DVD is on an RCD socket, that leakage is bringing the RCD a little closer to its tripping threshold; though the current is likely to be under a milliamp, so on its own it's a long way from causing an RCD trip.
I'd be surprised if the circuitry responsible for the leakage was as far 'inside' as a bridge rectifier on the low-voltage side, though: more likely suppression components on the live side of a switch-mode PSU. But I'm a software type by profession, not an EE, so this is hobbyist-level guesswork rather than certified circuit designer's opinion ;-)
Stefek
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