Earth provision after replacing water main with MDPE

I have recently replaced approx 3m of lead water main to the house wit
25mm MDPE.
At the weekend I made the final coonection inside the house, an removed the lead tail and stopcock that previously served the house When doing so I noticed an electrical wire attached to the lead pipe and assume this has something to do with the earth for the electric meter cupboard.
Do I need to provide anothe connection to earth. Should I extend th (now severed) wire back to the water board's supply, which is still i lead?
I think my gas has been sleeved in the last 18 months, so has tha removed that earth component also?
As you can see, I'm quite confused about this whole earthing thing Many thanks in anticipation.
Kevin, Oxfor
-- Kevin Brady
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Where these earth points actually creating the main earth bonding for the electrical supply? Or, were they just equipotential bonding to the gas and water mains?
You'll know if you look at the electricity supply head end. Is there a big thick earth wire provided from it, or close by it?
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If you have copper pipework in the house, move the earth connection to the where this takes over from the MDPE. Note that this isn't (at least shouldn't!) be your main earth. It is just ensuring that the pipework has the same earth potential as the rest of your house. The main earth is either supplied by the electricity suppler via the cable sheath (TN-S) or via the neutral (TN-C-S), or you will have an earth rod (TT) and every circuit will be RCD protected.
If you have a older house, it is possible that you have an old system that did rely on the water pipe to provide earthing and that now your house is very dangerous. As you don't seem to know enough about electrical installations to determine the type of earthing in use, I'd advise you post a picture of your meter cupboard and consumer unit so you could get further advice, as it should be obvious what type of earthing you have from the supplier's installation. If this determines a TT system, you'll need to find out if you have a good earth rod. Alternatively, just call out an electrician who will test that the earthing is safe.

Unfortunately, it is a requirement that the cable is unbroken and unjointed. If it not long enough to reach the copper part of your house plumbing, you are up sh*t creek and will need to lay a fresh cable from the earthing terminal, which might be not a nice job.
Christian.
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Okay
I've just checked out my meter cupboard:
On the board with the meter (spinning wheel) is a junction block with three yellow/green wires connected to it:
1 to the incoming mains cable, with a metal tag saying DO NOT REMOVE. 1 to the main fuseboard (not fuses but rcds - push button type) 1 to a seperate fuse box which supplies my soon-to-be-ripped-out electric shower.
Does this help anyone, BigWallop, Christian?
Cheers
Kevin, Oxford

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On Mon, 10 Jan 2005 21:50:26 GMT, "Kevin Brady"
Nope, I'd get someone in if I were you. You had all the info you needed in the previous posts really.
--

SJW
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strung together this:

I'm with Lurch on this one as well Kevin. From what you describe, it is still not clear where the main earth is coming from.
Contact your Leccy Supplier to check it for you.
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I thought this confirmed that the earth is routed to earth via the mains sheathing, but I'll contact Southern Electric in the morning - thanks for taking the time to respond.
strung together this:

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Kevin Brady wrote:

Well that's what I thought too. You said

which seems fairly clear evidence for a TN-S earth to the service cable. You just need to move the original water bonding connection onto your copper pipework as near as practicable to the stop-cock and you're done.
Oh, and also

them's MCBs not RCDs.
--
Andy

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It doesn't really prove a TN-S supply Andy. The tag around the supply cable might also be just an equipotential bonding of the steel wire armour. So I'd still say stick with contacting the Leccy Supplier, because they to might have been using the pipework as their main earth.
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Andy Wade wrote:

That's how it read to me too - not that it'll hurt the OP to *try* phoning their supplier and asking what their records show as the earthing type they've provided... but the chance of getting a sensible answer out of the mess of supply-cos, meter-readers, and bill-issuers is not my idea of a fun time. And of course the OP'll be safest if they call out a sparks, but it's not that likely they have anything other than an earth supplied by the incoming supply sheath. For the call-out charge they'd be better off getting a periodic inspection report done, which would include a look at the earthing...
Stefek
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Christian McArdle wrote:

pipe,
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earthing
I recently did a similar task - replacing the incoming lead pipe with plastic, though being an elderly property there was no grounding wire. Now the earth for the house is at the back of the property and water-pipe-in is at the front and as far from the earth pin as it could be. Am I really required to bond the piping at the house entry point which will be seriously difficult to get to, a considerable length and is totally at one extreme of the piping system, or can I take the bonding wire to say the cold water tank which is central, is a relatively short run and is easy access.
Rob
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As I understand it, you really are supposed to run the main equipotential bonding to the entry point of the services, or to the point at which they start being metallic. I'm guessing - and it's only that - the thinking is this is the point least likely to be monkeyed about with, whereas bonding to something like your main tank is more likely to get disconnected either temporarily or permanently if maintainance work is done on the tank or whatever other "less permananent" bit of the water installation you might choose. And, pragmatically, that's where an Inspecting Sparks doing a periodic inspection/house-sale-inspection will look for the main bonding.
That said, the truly important thing for safety is that your pipework is bonded. If it's more convenient "for now" to run a bond to the tank, or a part of the rising main or other "bound-to-be-in-good-contact-with-all-the-pipework" point, I couldn't blame you for bonding there "for now", while promising yourself to run the conventional, Regs-compliant bond to the water entry point when some round tuits accumulate. But don't rely on this random set of bytes in a Usenet posting, apparently from someone you've never met, in case someone visiting your place gets electrocuted and you're held negligent for non-conformant bonding!
You do know, don't you, that the bonding needs to run unbroken (though it can "visit" multiple bonding points on the way, just don't cut it) back to the main earthing terminal next to your CU, not to the earth rod you appear to have (the "earth pin")? Does that make it easier to reach? I.e., the main bonding conductors to your other metallic services run to an earthing bar by your CU, and the conductor to your earth rod then runs from there. Also, that there's nothing stopping you running a thick-enough (10mmsq, from memory) bonding conductor round the outside of your house, and back in to the water riser? (Thickness needed here because it's not mechanically protected, most of all - if you ran it in conduit a thinner one *might* be acceptable on the TT setup you seem to have, but I'd defer to someone who knows properly rather than trust to this random collection of bytes etc etc!)
HTH - Stefek
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Stefek Zaba wrote:

I'd say it's more a case of equalising any potential difference (PD) between the incoming service, which will be in contact with the local ground, and the TN 'mains earth' provide by the supplier, which might not be at local ground potential if there's a fault on the supply network. Bonding other than at the point of entry runs the risk of an unbonded locally-grounded section of metalwork being left in place if a section of the plumbing (etc.) between the entry point and the bonding point is replaced in plastic.
The aim of bonding is not "to earth all your plumbing" and it does not matter if there are plastic bits after the main bond at the point of entry. In the high-risk areas supplementary bonding is there to prevent any localised PDs appearing.

Absolument Monsieur.

That's one of those 'requirements' that people like to make up - it's not in BS 7671. There's no objection to joints in bonding conductors; the normal rules for connections (and their accessibility) apply.

If not buried the smallest size would be 6mm^2 for the main bonding and 4mm^2 for an unprotected TT earthing conductor. The latter, if a buried insulated wire (6491X), increases to 16mm^2. I tend to use and recommend 16mm^2 for any main earthing & bonding - as you say you don't want anything too feeble.
--
Andy

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Just to hijack this thread a moment.
If you have the type of oil fired boiler which is built into the external wall such that the oil supply pipe never actually enters the dwelling, is it still necessary to cross bond to it?
(Hint - i'm hoping for an answer in the negative!)
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I don't think you should have bulk storage of flammable liquids anywhere near the main dwelling. I always thought they had to be a certain distance from the house.
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1.8 metres from a "hole" into the dwelling such as a door, window, large vent, soffit vents etc unless protected from heat radiation (fire)
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Thanks John, I knew I read something like that somewhere.
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"Zikki Malambo" wrote | Just to hijack this thread a moment. | If you have the type of oil fired boiler which is built into the | external wall such that the oil supply pipe never actually enters | the dwelling, is it still necessary to cross bond to it? | (Hint - i'm hoping for an answer in the negative!)
It might not be necessary to bond to the oil supply pipe, but my thoughts would be that in such circumstances, the boiler flow/return and other pipes would be 'services' which would have to be bonded where they enter the dwelling.
Owain
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Re bonding the flow & return....
Well, such is the design of the boiler, that they are inside the house.
Perhaps i'll crossbond them when I get a few more round tuits.
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