I have recently replaced approx 3m of lead water main to the house wit
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
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
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.
Where these earth points actually creating the main earth bonding for the
electrical supply? Or, were they just equipotential bonding to the gas and
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?
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.
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
Does this help anyone, BigWallop, Christian?
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
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.
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...
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.
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
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.
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.
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!)
"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
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