PC in unearthed socket

[Peter Twydell]

I shall be taking my old PC to the Netherlands, to use in the MIL's house when we're there on holiday. It's got a standard UK PSU with earth connection. Trouble is, sockets in NL don't have earth connections, except in places like the kitchen and garage. I'll be using the PC in an upstairs bedroom.

I don't want to rewire the room, so do I (a) just plug it in as it is (different plug, of course) and have no earth connection, or (b) go to the local components shop and fit a local PSU?

I asked this question in a PC ng and got replies like "Does 'earth' mean 'ground'?" and 'Fit an adapter' and such, falling into the chocolate teapot range of usefulness. Not a single answer relating to the question though.

Here's hoping for some sense here!

[Chip]

On Sat, 17 Sep 2005 16:39:48 GMT,it is alleged that Peter Twydell spake thusly in uk.d-i-y:

PCs MUST be earthed, a 'local' psu is likely to be identical to the "UK' model (if it's CE marked, it's legal to use anywhere in europe).

Even in the great (previously) Unearthed States of America, PCs have three prong plugs, (causing much consternation when confronted with old 2 prong outlets, but that's OT).

The fact of the matter is they WILL work with no earth but will become hazardous to your health and sanity. Not only do they become unstable, but the filters will cause leakage to the unearthed case. This tends to float the case at around 100-125 volts to ground(earth) causing you to go 'hmm what's this vibration feeling here...owwww'.

Guess what happened to me a few months ago (broken earth pin on the inlet socket).

A temporary expedient would be to do the 'adapter' thing, with a flying lead for the earth and clamp it to the earthed pipework somewhere.

All modern outlets in .nl should be earthed. I would seriously suggest that 'rewiring the bedroom' might actually be a very healthy idea.

[Frank Erskine]

It would certainly help to use some form of RCD adaptor, just to give you a bit of protection. Perhaps fit an RCD plug to the PC, then make an adaptor consisting of a trailing 13A socket connected to a NL-type (Schuko?) plug.

[Harry Bloomfield]

It happens that Chip formulated :

I concur with the above.

The lack of an earth can cause instability due to the lack of filtering and it can cause the PC to generate more radio interference. The 'tingle' you feel might also be quite substantial were you to also be in contact with earthed metalwork at the time.

[Andrew Gabriel]

Holland often doesn't provide earthed outlets in earth-free areas of the home. You can't get an electric shock from the PC because there is no earthed metalwork nearby for the current to pass through you. Contrary to what you might imagine from some of the responses, the dutch are not rapidly dying of electrocution as a result. This is a scheme which is recognised in our wiring regs, but not permitted in the UK except in special circumstances which I can't remember (and I don't have the regs on me to look it up).

You'll find dutch PC's have exactly the same PSU's as UK PC's. You just plug it in. There shouldn't be any earthed metalwork in the room, but you might like to just cast your eye around and keep the PC away from any that you notice.

Well, this is really an international wiring query rather than anything specifically relating to PC's.

[Lurch]

On 17 Sep 2005 18:15:24 GMT, [e-mail] (Andrew Gabriel) scrawled:

Er........ Tell you what, just to prove that theory do me a favour, go and stick your fingers on a live phase cable in the back of a socket, but don't touch anything metallic. Does it hurt, are you dead?

More through luck I think.

Recognised as what, bad practice?

[Hamie]

If you're not a valid path to earth, it won't hurt a bit. Same reason birds don't die when they land on the bare wires. An electric shock is caused by your body being an easier path than the wires the electricity would normally pass though. A body in isolation provides no such path.

(Same reason an isolating transformer works).

H

[Lurch]

On Sun, 18 Sep 2005 17:44:29 +0100, Hamie scrawled:

Well, wrong again. The reason birds don't die after landing on power lines is that they are not touching the erth, therefore not forming a path to earth, which is correct. What isn't vorrect is the fact that you will not get a shock by not touching metal. You provide a path to earth by being stood on earth, or on a floor in a house, or in loads of places really.

If you're saying that every single outlet in a NL home is provided by power from its own individual isolating transformer then theoretically this works as you say above. It doesn't work if there is more than one fault on seperate circuits as it's not the earth potential, it's the relative potential across 2 fault paths that does the electrocuting. It's just that because of the way we have UK earths set up it's generally the earth that has the highest differential potential from the live conductors.

Still misleading and potentially dangerous information no matter what variation of made up we go on.

[Set Square]

So the OP will be ok as long as he can levitate?

[Andrew Gabriel]

No.

413-04 "Protection by non-conducting location". It's not permitted in the UK except in special situations, but some other countries do use it. I don't know what the dutch regs say, but the IEE regs forbid the use of earthed socket outlets in such locations.

[Andy Luckman (AJL Electronics)]

No, for the same reason that birds can sit on a live cable without harm. As you are aware, it the mils that kills. No earth, no flow, no danger.

[dave]

Just btw, it doesn't need many mils to kill and earth paths have a funny habit of being where you don't expect them to be.

[Peter Twydell]

In message , Peter Twydell writes

Thanks for all the suggestions.

I think what I'll do is replace the existing socket with an earthed one and run an earth wire. This might be clamped to the iron radiator in the room or possibly go to the earthed socket by the CH boiler the other side of the wall. The wall is probably soft anyway, so making a small hole won't be a problem. When I mentioned rewiring the room, I was thinking in terms of running a wire through the conduit, which might be tricky as I've no idea of the route. It will be possible to use narrow trunking on the surface, though.

[Lurch]

On Wed, 21 Sep 2005 13:28:29 +0100, "Andy Luckman (AJL Electronics)" scrawled:

And you've just done that have you, stuck your finger on a live cable in the back of a socket?

[<me9]

I recently started disconnecting part of an unused circuit to old external lighting. After I had removed parts, and touched the live conductor, I realised I'd reset the MCB feeding the circuit. I never felt a thing when I touched the live conductor. I was wearing rubber soled shoes, and was up a stepladder with plastic feet. I'm glad I hadn't touched the adjacent garage door (which I had never got round to earthing with edn 15 regs). Up the ladder was (at the time) an earth free environment. I'm not going to try it again though.

[Andrew Gabriel]

I've done it with a lightswitch, accidentally. Felt only very slight tingling -- probably only a milliamp flowing as it was barely on the edge of being perceptable.

I've done it deliberately when changing a CU with live tails (not something I would ever suggest anyone try, but along the lines of "do as I say, and not as I do", something I've done a few times). When I believe I have got myself well isolated, I check it by brushing the _back_ of my hand against a live conductor to make sure there's no current path through me. The danger in handling live tails is not so much directly from electrocution as it is from flash burns if you should happen to accidentally short out the meter tails. The resulting arc could generate the best part of a megawatt of heat a few inches in front of your face, with the resultant molten and vapourised metals blasted outwards from it too. Such a short circuit could be triggered by a reflex reaction to an electric shock, so being pre-prepared not to get an electric shock is just as important as well protecting yourself from possible flash burns (exposed skin covered, at least eye and preferably full face protection).

[Lurch]

On Wed, 21 Sep 2005 23:57:58 +0100, scrawled:

But the point I'm trying to make is that you can't just go round touching phase conductors willy nilly and not get shocks only whilst touching an earthed object.

I've lost interest now anyway.

[Owain]

The man who changed my eletcricity meter took great care to bend the live tail well out of the way.

I don't know why he didn't just pull the service fuse though, I do.

None of that.

And I've just realised he used red and black tape, not brown and blue.

Owain

[charlieB]

The PC probably has a Class 1 power supply and the earth provides back up in the (unlikely) event that the "basic" (as defined in EN60950) insulation in the PSU should fail.

Earth leakage due to EMC filtering Y-caps and the like will be quite low - maximum permitted under EN60950 is 3.5mA - well below the trip level of an RCD.

No piece of home/office equipment should be relying on the earth connection to make it safe under normal operating conditions.

regards Charlie

[Frank Erskine]

Just a few minutes ago I had a wander around Homebase (looking for a bell-push), and noticed that all their T+E cable is still in the old colours :-)