Peter

Mexico south of the border.

Actually, for me, that's literally true at the moment.

Stewie

[QUOTE]Originally posted by CHnJ
I'm going to disagree here. The power supply is the only mains voltage component in the machine (the big silver cube screwed onto the back inside.) If it's got a dangerous wiring fault, the whole case would be live whether the covers were on or not.

I don't like to be picky here but anyone who works on any mains equipment with the power connected and removes the covers is asking for a shock.
I'm not talking about a PC with a mains fault here!
Sure the power supply is the only mains supplied component within the computer case. The power comes from the input socket on the back of the computer to the power supply. If any of the connections from this socket to the power supply are not insulated correctly and you touch them by accident you will get a shock. Those "bare" connections may not be in contact with the frame. Therefore the mains fuse will not blow.

Don't wish to preach here but I did my electrical apprenticeship in 1969 and have been in the industry since then. I've had plenty of shocks during that time, mainly because to fault find you need the power on. Anyone cleaning inside a PC should always disconnect the mains power. You have been warned:lecture:

Sorry lecture over.....must chill out

CHnJ

When it comes to electrical safety, please feel free to lecture away!

I've been mulling over my posting since I placed it, as I really don't want Pollyanna or anyone else getting zapped on my say-so, but I still maintain that with the lead switched off at the wall you'd have to have a fault in the socket or plug that meant the supply was always live AND that the fuse has never been given a chance to blow by the faulty connection AND you have to have got into the power supply box (unless I misunderstand you).

If you are working on lots of machines and equipment then that combination may well happen, but I think it's unlikely to occur to someone who has switched off a PC at the wall, is just opening the case, and removing some dust on one occasion. I'll define "unlikely" as being within the realms of what I'd do myself comfortably.

You are completely right to make your point though. By removing the covers and leaving the machine plugged with the lead in the wall, you remove the last two layers of protection preventing you from getting an electric shock.

However, I would liken that risk to having your child sitting in the back seat of a car without a car seat. Everyone used to do it, but it's illegal now because everyone agrees that kids should be protected in a crash. For one journey it should be alright. If that journey was the one crash in 10,000 journeys though - the consequences would be unimaginable.

I prefer people to be given enough information to make decisions for themselves, rather than being told "don't touch because it is deadly."

If we were discussing TVs for example, I know that the capacitors inside it could give you a fatal shock even with ithe TV unplugged: You can weld a screwdriver to its terminals just by touching it across a charged one. If anyone asked me for advice on the internal gubbins in a TV I'd have to tell them that I didn't know enough about it, so go speak to an expert.

If we all followed all the advice on all disclaimers we would never be able to live in the society we do. I know that I should use a harness to clean my badly designed windows, but I don't because I should be OK. I also know that Rod Hull of Emu fame fell to his death while fixing his TV aerial. It's all about "acceptable" risk.

You've definitely made Pollyanna aware of the possible outcome of the risk she runs - and I didn't - but I hope I've helped her put a value on the size of the risk. If you think I'm wrong, please tell me! You may well be saving my life too!

Sharpy67

Easiest solution!

Remove mains power lead. Make up a lead that has a wire connected to the earth pin of a separate plug. Attach this to your PC case and plug in connector to wall. No Live, no neutral, only earth!

Still, putting the thread back on track, touching PC boards without some sort of earthing IS liable to damage them, especially if they have an ESD label on them (triangle with a hand crossed out).

Its a FACT! and I don't who says any different! They're lying.

Nick

Megalania

Fancy! What ever happened to #14 fencing wire or wet binder twine?

Pollyana

OK, thanks for all the advice; I appreciate all the input, as you all know more than I do!
I shall keep my socks on, and will probably be wearing rubber-soled trainers anyway..... I don't entirely trust the electrics in this unit so will pull the plug out of the mains, its a UK fused plug, but some of the connections here worry me a little.The dusting attempt will be carried out during the well-scheduled Expat-Forum-Downtime and if I don't get electrocuted I'll see you on the other side. All dust removal to be done without the aid of vicious vacuum cleaners.........!

CHnJ

... or plug your metal toaster into the wall and hug it while you work : )

Sharpy67

Whilst sitting in the bath of course!

Stewie

Your right in one sense that with the wall socket turned OFF there should be no power to the PC.

Most electricians would remove the plug from the wall socket to make absolutely sure. We've had too many bad experiences to take any chances with 240v AC.

I knew an old electrician who used to test mains by licking his finger and touching the live to see if there was power there!



Keep Safe.....

lynnxa

Hang on a minute - I just found this.....................

you have internet in Queensland????

my brother in Brisbane reckons you're still using jungle drums there!!!!!!!!!!!!!!!!!!


little liar!!!!!!!!!!!!!!!


wait till I get hold of him!!!!!!!!!!!!!!

Peter

Yep, my Dad told me that Queenslanders only just got around to using knives and forks at the table, a week before the telephone lines were laid down.

This is all a couple of years ago now.