Shocking Continental Electrics.

[karona]

One for the sparkies in here. I touched the metal bit of a USB cable plugged into my PC and got a shock, not just a tingle, a real belter. I was standing, with bare feet, on a steel reinforced concrete floor, recently laid onto bare earth.
I'm in the far east of Europe, so part P etc doesn't apply. The house has recently been renovated, rewired by a registered electrician, and I have the (compulsory) safety certificate for it.
My power is from an overhead supply, two wires tapped off a three phase supply. There is no earth circuit in the house, all sockets are wired with two core cable, the earth pin in the sockets is linked to the 'neutral' blue conductor in the socket itself. All pipes in the house are welded plastic, so there's no earth wires for them either.
I'm guessing the concrete slab still has a high water content, making a good earth circuit through my feet, and tiling the floor will break that circuit. I've isolated the PC from the mains via a BFO truck battery and a 500 watt inverter (it's the internet server for the whole village) so the immediate danger is removed. The question (at last!): How do I protect myself from further shocks?
I'm guessing that adding an earth circuit to the sockets and putting in an earth spike outside is actually going to earth the whole village supply, resulting in a big bang, so maybe a whole house breaker would be a better idea, but what type? Residual current? earth leakage?. Whichever I specify will have to be installed by a professional, but will have to be ordered from the UK, so I need to ask for the right one.

Thanks

[finlo]

Firstly i'd say you have reversed polarity ie the earth circuit would then be connected to the live!

[Deva Link]

General point - it's a really bad idea to handle electrical equipment while in bare feet, especially if standing on a damp concrete floor!

It sounds like the floor is live, perhaps due to some continuity with a live electical connection in a socket or some other piece of electrical equipment. I've seen that happen on newly plastered walls. Or someone could have nailed etc through a cable.

What protection method is used at the moment - just a fusebox? I'm way out of touch with this stuff, so hopefully someone else can advise, but think you'd need an RCD - Residual Current Device - although if the electrics are a bit dodgy you could have a lot of trouble with nuisance tripping which could be a pain of it drops the server out all the time. Maybe it should be powered through a UPS.

[karona]

I hadn't considered the idea that the floor might be live! I've now booked a sparky to come and have a look, it could be that the socket has been wired arse about face and the live's linked to earth.
The server's now on a 'super' UPS: a trickle-charged tractor battery feeding a 500 watt inverter, should be good for several hours, power cuts are quite common out here in the sticks. The floor's being tiled next week too.

thanks all.

[hidetheelephants]

karona said:

My power is from an overhead supply, two wires tapped off a three phase supply. There is no earth circuit in the house, all sockets are wired with two core cable, the earth pin in the sockets is linked to the 'neutral' blue conductor in the socket itself.

I'm not an electrician, just a ship's engineer, but that sounds bloody dangerous. AFAIK neutrals, despite their name, can often 'float' away from zero volts, especially if the grid/ power generation system isn't well regulated; practically speaking, touching the neutral while standing on damp concrete could easily be fatal.

The neutral SHOULD NOT be connected to earth points. The way RCDs work is to measure the difference between current on the live conductor and current on the neutral conductor; faults in appliances/wiring allow some current to go down the earth, creating a diference between live and neutral currents causing the breaker to trip. If the neutral and earth are wired together as described, an RCD may not work and you may kill yourself. If it was my gaff, I'd want it rewired to UK regs with an earth circuit onto a bloody big spike in the ground.

Edited by hidetheelephants on Saturday 3rd October 02:07

[GreenV8S]

hidetheelephants said:

I'd want it rewired to UK regs with an earth circuit onto a bloody big spike in the ground.

^^ What he said. At the very least, make sure that the electrical earths are connected to a good sound local earth and not to live or neutral. Live is easily fatal, neutral is potentially fatal (especially if it gets mixed up with live). As long as the house electrics do actually carry an earth wire along with live/neutral, you should be able to do this without much disruption and without trying to earth the whole village. Having got a good separate earth stops it being a death trap, but I'd be much happier with RCD protection at the distribution unit.

Is it likely that other houses in the area are similarly dangerous?

[karona]

The problem was an incorrectly wired socket, with live linked to earth. The 'neutral' feed to the house is earthed by the electricity supplier, so installing a seperate earth circuit and a bfo spike is possible, but would be a huge amount of work. I'm having a whole house RCD installed instead. I already have low voltage emergency lighting installed (it gets fking dark out in the sticks, and we get frequent power cuts) so it won't need to be a split load setup.
Rewiring to UK spec is not an option, the Powers That Be would not issue a safety certificate and the house would be unsaleable.