Was going to start to build my first pc tonight and was obviously keen to ensure I was grounded/earthed when I did so. Bought an anti-static mat and was advised to attach to the copper radiatror pipes to ensure a good earth.
But
My house is old and I'm not entirely sure its grounded. There is a wire running from the electrics and attached by a crocodile clip arrangement to the water pipe in the basement. I also noticed a wire running from the electrics to a small metal stake in the ground of the basement.
I'm a bit concerned because I remember the gas fitter mentioning the earthing but now realise he was probably talking about the gas pipes which I'm not sure have been done. I realise I need to do this but don't think it will affect the earthing when constructing my pc.
Attached are some pics. Can an electrician confirm everything looks ok?
Cheers
here's the wire from the electrics attached to the water pipe:

and here's the electrics attached to the small steel stake:

This type of earthing is used when it is a non PME system. (Seperate earth spike and (there should be) and RCD

You prob still need to get a sparky round to carry out a test on the earth system to check that you have good enough earth to allow the protection within the consumer unit to operate as it is supposed to.

Better the earthing system = safer the installation.

PS – im not a sparky so not up on the 17th edition – but I do work for an electricity company so do have some earthing knowledge

My guess would be, as long as the earths are connected in youe fusebox, and all through the sockets etc, there will be an ok earth present. But judging form the picture, the cable going to the earth stake in the ground looks a bit smaller than it should be, and i guess it might not provide a good enough earth to meet requirements.

oh, and the earth stake should be copper, not steel, that makes it far more likely you havent got a good earth, as its probably rusted away under ground and wouldnt conduct electricity as well anyway even if it was new

i'd get it checked out properly, it's an easy job to do for an electrician.

Yep, the earth stake is just that – a stake that is at earth potential.
The gas pipe earth is an earth bonding connection providing your house with additional earthing using the metal of the gas pipes.
I've built a few PCs & never bothered with any antistaic stuff though!

in terms of upgrading a PC, you just need to stop static between you and bits of the PC. You can do this without an earthing strap or any of that stuff, just by being careful how you touch things ie touch the case first then the PCB – any static you have will discharge on the case and not through the circuit boards. It's when you get up, walk across the room to pick up a RAM module, harddrive etc and then walk back to the PC you could pick up quite a charge from trainers on a nylon carpet, as you go to plug in the RAM, you'll discharge through it (BAD), but if you touch the case with your other hand first, you discharge through that and then you and the PC are at the same potential (GOOD).

If you have a static mat, clip it to the case of your PC and just make sure you are clipped to it, or rest your elbows on it. Being earthed to the ground outside will make no difference at all.

I think the stake looks copper now you mention it

modern RCD's have a test button on them

Earth rod is copper – The green verdigris round the top connection gives is away due to oxidation of the copper.

The RCD (if there is one) will have a test button, but if you are concerned get a sparky to test it – he will initate a trip via your system as the test button is just a test of the RCD operation, not it's ability to see a fault

Why not get a magnet and check, i must say i havent come across a steel one, but it does look rusty in the picture… As i said, call an electrician and ask them if they can come round, and test the earth… They shouldnt charge much, and if it needs upgrading, i doubt it would be an expensive job.

Just used the test button and it tripped the system

theres definitely an earth there… It doesnt mean its a very good earth though…

TBH – if you are just concerned about building the PC – attach the anti static mat to the copper work (assuming it is connected into the consumer unit) and you will be at the same earth potential as the rest of the house.

If you feel that there are further concerns please do consult and electrician. An bad earth is the fastest way to a house fire – more amps to operate the protection = more chance of an heating effect on the faulty cable and the surrounding surfaces

RCD's are sensitive though to small earth leakage so will trip before needing to carry anything heavy

morpheus, an rdc wont trip if something is arcing, because of say a bad connection. It will just heat up, and eventually in a worse case scenario, catch fire, then probably trip out but it could be too late then.

Id also suggest, if the earthing looks like that, the rest of the instalation isnt going to be excellent… Possibly with cables that have no earth on the lighting circuits, or even single cables… Not that an rcd is going to do anything then anyway…

RCD's are sensitive though to small earth leakage so will trip before needing to carry anything heavy

True –
This is why electricty company's insist that if they don't provide thier own earth then the customer must use an RCD to prevent the chance of a non trip even under fault conditions. (The new 17th ed require RCD protection for all cct's anyway – safe, safe safe!!)

I was just saying to the op that if they have any doubt about their system then get it checked by a qualified sparky – its better not to take the risk

Last time I had earth bonding carried out the cable was 6mm2 which provides mechanical strength to the stake.

Last time I had earth bonding carried out the cable was 6mm2 which provides mechanical strength to the stake.

Main Earth should be – 16mm
Earth connection to gas and water – 10mm
Supp bond – 4mm

good advice from tom and lyons

TBH – if you are just concerned about building the PC – attach the anti static mat to the copper work (assuming it is connected into the consumer unit) and you will be at the same earth potential as the rest of the house.
Tom
thats what I siad I was going to do in my original post
I think from the postings, that I need to get this checked by a sparky but building the pc should'nt be a problem as far as earthing is concerned?

I built a pc by just earthing my hands on the case before touching components as previous posts suggested.

If you are going to have a electric shower though I'd get your electrics checked as tom suggests.

Hitman

Sorry it all went abit over the top. You'll find alot of people have no earthing (due to changes in thier house/plastic water and gas etc) At least you have an earth.
I get a bit carried away talking about electricity.

Good luck with the PC build – the bonding for this should be fine.

I would recommend to anyone that has doubts about thier installation to get it checked out by someone qualified.

Tom
no need to apologise – I've learnt loads as usual just from a simple post on stw
when I start my build ( probably tomorrow now) I was going to attach the anti static mat to the copper pipes on the radiator
and attach myself to the metal part of the case. Then once I'd installed the PSU I will plug that in at the mains but leave the power off.
Sound ok to you??

If you have an earth stake then you have a TT system (Terra Terra, earth to earth in English). All houses are earthed one way or another, either by TN-C or TN-C-S provided by electricity company or TT, as is yours. 10mm earth cable has nothing to do with mechanical strength, it is to safely conduct the maximum potential earth current should there be a fault.
Copper pipes are bonded in what is called supplementary bonding, where all exposed (copper pipes) or extraneous (electric heaters, light fittings etc.) have their own path to earth should they become live through a fault.

So strap your earth band on, clamp it to the copper pipes as you'll be safe to build your PC.

Well you will be at the same potential as the house earthing so should be.
Assuming the PSU will have an earth, the you will pick up the house earth to the PSU through the earth pin on the plug – so seems ok to me.

However – I have never built a PC so good luck with the build.

Where do you live ? I could do a external earth loop impedance test for you so you can realy know if you have a good earth, you can guess all you like but untill it is tested you will never know

According to the regs you should have a value of at the most 200ohms (that would give a fault voltage of less than 50v )but there are so many variables I personally would not be happy if you had a value of more than 50 ohms cos I am a fussy shit and a neeedless to say fully qualified spark

Ask your DNO if you're PMEed and if not can they do it – can't remember if there's a charge but there probably is as they recover reasonable costs.

Ask your DNO if you're PMEed and if not can they do it – can't remember if there's a charge but there probably is as they recover reasonable costs.

If you have a PME supply there should be a sticker on the cut out stating this. The fact that there is a seperate earth rod and RCD would suggest that the supply in not PME.

If you are on and underground network then a PME supply can be provided easily. However if you are on an overhead/rural feed the DNO may need to do some extra work to provide the PME system.

Can't remember if we (DNO) used to charge for this work?

If you are on overhead power lines the telegraph pole will have a red label at about 3m above ground saying PME, if it can be converted

but there is nowt wrong with a earth spike as long as you have a good earth

If you are on overhead power lines the telegraph pole will have a red label at about 3m above ground saying PME, if it can be converted

If your lucky – they get missed off all too often!! 😳

but there is nowt wrong with a earth spike as long as you have a good earth

Too true

OK I'm not a sparky and I do very little LV (that's 230V or 400V) work, but I do know a little – bit like Tom perhaps.

The fact that there is a seperate earth rod and RCD would suggest that the supply in not PME.

Earthing is a black art and generally I'm happier with the higher voltages but as I recall you don't have to take the earth spike out if you get PMEed provided you connect it up right (though strictly that's so the RCD works) – so frequently people don't.

If it is an older house it won't have been PME originally so it will have an earth spike / earth connection to a large cast iron pipe / something similar.

And I agree that there is nothing wrong with an earth spike as long as you have a good earth – getting a good earth is not necessarily as easy as one might hope though.

If you are on overhead power lines the telegraph pole will have a red label at about 3m above ground saying PME, if it can be converted

I think that depends who your DNO is – not statutory if I remember correctly.

If your Yorkshire or North East England give me a shout – I'm the design manager for YEDL and NEDL so one of my guys can sort out the DNO side of things if needs be. Don't do actual house wiring though and unlike the LBS I can't do mates rates.

By the way and only out of interest – Tom who'd you work for?

img

I work for Central Networks in the Birmingham area. I also do very little on the LV side anymore. I'm an SAP/Project manager on the EHV networks (upto and including 132kV) looking after maintenance and repair work (also alittle construction as required)

Im not qualified to talk about house wiring, but I am a selected person for advise on depleted earthing on distribution systems – and yes it is a black art 🙂

Blimey, this has got deep.

To the OP, the idea of earthing when handling PC componentry is that you don't zap any IC's. The important thing is that you aren't at a hugely different potential than the pc case, so the obvious thing is to earth you and the case to the same earth. Whether this is properly earthed or not is irrespective, what matters is that you are both as the same potential and since you'll be earthing both to your radiators, which is one very big metal network, that will drag everything down nicely.

You'll be fine.

For what it's worth, I've been building PC's for years and all I'll do before starting is hold the PC case and touch a radiator. I've never had boards blow on me.

According to the regs you should have a value of at the most 200ohms (that would give a fault voltage of less than 50v )but there are so many variables I personally would not be happy if you had a value of more than 50 ohms cos I am a fussy shit and a neeedless to say fully qualified spark

Really?

Voltage is a constant in this scenario – let's say 240v, because we very rarely find 230v. It's current that kills and at 200 ohms resistance 1.2 amps will pass through under fault conditions. Approx 0.05 amps is enough to f*ck with your heart.

However your RCD should be 30ma (0.03 amps sensitivity), therefore will protect you from death if it's working correctly.

We used to plug the PC in then turn off the plug – using the mains grounding.
We also used static mats and static straps connected to the chassis of the PC.
But then I worked for a well known IT company in the UK.

Tom – CE Electric UK here. I was down in Birmingham at Austin Court just last week speaking on sustainable networks.

Incidentally to the OP, if the question is just about building a PC, then provided you wipe the static off you hands, you'll be fine. Grasp the copper pipe (or other unpainted bit) going into the radiator before you pick up each circuit board and hold the boards by the edges used to be the advice.

cheers everyone
happy I managed to be earthed through radiator pipes
getting a sparky in re:something else so will ask them to check the earthing of the house

TheArtistFormerlyKnownAsSTR – Member

According to the regs you should have a value of at the most 200ohms (that would give a fault voltage of less than 50v )but there are so many variables I personally would not be happy if you had a value of more than 50 ohms cos I am a fussy shit and a neeedless to say fully qualified spark

Really?

Voltage is a constant in this scenario – let's say 240v, because we very rarely find 230v. It's current that kills and at 200 ohms resistance 1.2 amps will pass through under fault conditions. Approx 0.05 amps is enough to f*ck with your heart.

However your RCD should be 30ma (0.03 amps sensitivity), therefore will protect you from death if it's working correctly. TheArtistFormerlyKnownAsSTR – Member

According to the regs you should have a value of at the most 200ohms (that would give a fault voltage of less than 50v )but there are so many variables I personally would not be happy if you had a value of more than 50 ohms cos I am a fussy shit and a neeedless to say fully qualified spark

Really?

Voltage is a constant in this scenario – let's say 240v, because we very rarely find 230v. It's current that kills and at 200 ohms resistance 1.2 amps will pass through under fault conditions. Approx 0.05 amps is enough to f*ck with your heart.

However your RCD should be 30ma (0.03 amps sensitivity), therefore will protect you from death if it's working correctly.

You speak the truth 😳

In my defence I should of added that a TT instalation ( basically a system that need a earth spike) must be protected with a 30ma RCD to comply with the regulations so

If you have a 30ma fault current multiplied by 200ohms (ohms law is V=I x R)
you will be left with a potential fault touch voltage of 6 volts which is less than 50v fault voltage which is what I should of said

However your RCD should be 30ma (0.03 amps sensitivity), therefore will protect you from death if it's working correctly

Fallacy – A 30mA setting means that it will trip for any current over 30mA (roughly speaking) – but you can still have a far higher current flowing during the tripping time (and I know it's instantaneous but there is still a tripping time – admittedly a short one)

Nothing will guarantee you won't kill yourself – but a RCD will reduce the risk significantly. As will decent wiring, decent earthing, knowing a good electrician and using them, not buying a house from a chartered electrical engineer who doesn't realise he isn't an electrician, etc.