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Topic Title: Water Bonding Query
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Created On: 27 November 2012 10:54 PM
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 27 November 2012 10:54 PM
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alpelec

Posts: 89
Joined: 04 November 2008

Wondering what to do about the water bonding on a house where the 10mm is at the consumer unit and heads towards the kitchen where the stop tap is but is not bonded. It has had a new kitchen a few years ago. The main water pipe is plastic to the stop tap then about 4" copper, followed by a speed fit bend feeding kitchen sink, plastic tee then off in the corner to boiler or bathroom. I can see the stop tap through the back of unit panel but after cutting a new hole cannot see any connection. Consumer is in Gargage, boiler in landing cupboard and all bedrooms around are laminate floor. How or do I need to bond? The earthing is TN-C-S. Or do I check all pipe work for insulation readings from main earth with the main earth disconnected at consumer - hopefully above 0.23Meg, and then bonding not required if I'm correct on that one. Thanks for any help.
 27 November 2012 11:06 PM
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daveparry1

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If the incoming water main is plastic theres no need to bond it, also check the gas though,

Dave.
 27 November 2012 11:07 PM
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AJJewsbury

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Is the incomer is plastic, it might well not need bonding (depending on whether any metallic pipework might be able to pick up a potential from elsewhere - e.g. buried in a solid floor or going back underground again - perhaps to an outbuilding). If you're testing you'd be looking for > 23kOhms (or 22k if you prefer) - enough to limit shock currents to less than 10mA - 0.023 Meg that is. You might well find that the test is defeated by local connections to the pipework though (e.g. exposed-conductive-parts - immersion heaters, boilers, pumps etc, or bridges to other earthed services (e.g. gas))
- Andy.
 27 November 2012 11:19 PM
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aargeitakis

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hi alpelec
did you do a continuity test for the water bond cable? perhaps is not bonded withing 600mm from stop valve.
Turn the power off and disconnect the bonding from ccu.Do a continuity test for the water bonding. Put one lead on the water bond by ccu and with a long lead or a piece of cable, touch the 4'' copper pipe to see if there is any continuity.
The other test you can do is to test between main earth and water bonding. Disconnect main earth and bondings aby ccu and do a continuity test between main earth and water bond.
Because the main pipe is plastic i will expect a high value. Dont forget to reconnect the earthing and the bondings.

Regards
Paul
 27 November 2012 11:20 PM
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alpelec

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Hi Dave - Gas as always much easier, in the garage below the consumer.
 27 November 2012 11:28 PM
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alpelec

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Thanks Andy. I did mean 0.023Meg based on the 10ma rule. If water is plastic then would I still need to do the insulation tests? I have done continuity testing initallly at all pipe work visible under the sink but nothing...Also I think all downstairs is concrete floored and no outbuildings only attached garage.
 28 November 2012 05:06 PM
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UKPN

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-----22k ? 10mA ? I dont see those in my manual, "the rule"
is that incoming services even if plastic b/f stop-cock/isolator
need to be bonded for a PME connection.

whatever next? PME for electric car chargers?

Regards.
 28 November 2012 05:10 PM
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AJJewsbury

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"the rule"
is that incoming services even if plastic b/f stop-cock/isolator
need to be bonded for a PME connection.

Ah, that'll be why we find people trying to clamp onto speedfit plastic pipe then
- Andy.
 28 November 2012 05:18 PM
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OMS

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Originally posted by: UKPN

-----22k ? 10mA ? I dont see those in my manual, "the rule"

is that incoming services even if plastic b/f stop-cock/isolator

need to be bonded for a PME connection.

whatever next? PME for electric car chargers?

Regards.


Didn't someone ever tell you anything about "Rules" ?

It goes along the lines of:

Rules - for the obediance of fools and the guidance of wise men.

Have a guess in which camp those who insist on bonding plastic services sit ? - regardless of what UKPN's "manual" says.

regards

OMS

-------------------------
Failure is always an option
 28 November 2012 05:29 PM
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UKPN

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these "rules" are actually opinions of guide book writers,
they would have a bit of credibility if the were actually in
the regs.

by the way what is the min IR these days, .5? 1? I lose
track of the times regs change.

Regards.
 28 November 2012 05:33 PM
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Parsley

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Originally posted by: UKPN

-----22k ? 10mA ? I dont see those in my manual, "the rule"

is that incoming services even if plastic b/f stop-cock/isolator

need to be bonded for a PME connection.



whatever next? PME for electric car chargers?

I think the manual says betwen the MET and metal structures and metal pipes and other extraneous parts. refer to BS7671 54.8.

Note; This is the responsibility of the consumer
.

Regards.
 28 November 2012 06:26 PM
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OMS

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Originally posted by: UKPN

these "rules" are actually opinions of guide book writers,

they would have a bit of credibility if the were actually in

the regs.

They are in the regs - the requirements for bonding are quite clear - -they use the definition of "extraneous-conductive-part" - note the hyphemns to ensure all 3 words are used in the definition of what requires bonding.

So - not the opinion of guide book writers - based on IEC documents in fact.

Equally the derivation of a simple test to determine what is actually extraneous- again based on IEC touch voltage curves.


by the way what is the min IR these days, .5? 1? I lose

track of the times regs change.

Really - well the min IR values have been the same for a bloody long time - and are the same values used by the Electricity Council in thier directives to area boards - so been around for quite a while -

Regards.


regards

OMS

-------------------------
Failure is always an option
 29 November 2012 06:27 AM
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ebee

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What I do with main bonding, unless I can view the entire length, is to disconnect each end and do a continuity test.

Then do a continuity test from one end to existing pipework.

If this second test shows continuity then you know that either there is an additional connection somewhere to the pipework or that the pipework itself is being used as the bond.

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 29 November 2012 01:43 PM
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leckie

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Has something changed in the last few years?

I know that if you have plastic pipes internally and a plastic incomer there may be no need to bond, but the advice I have always been given is that if there is a substantial amount of copper then that will still require bonding.

For exampe if you had mainly plastic but in the airing cupboard there was a lot of copper pipe to pump, valves, cylinder, etc, that that would require bonding. This was certainly the viewpoint of the ECA, NICEIC, etc about 5 years ago because I remember the debates. If you had a gas boiler the boiler connections and pipework would almost certainly connect the water pipes to the earth terminal via the circuit cpc and the bonded gas pipe.
 29 November 2012 01:50 PM
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OMS

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Originally posted by: leckie

Has something changed in the last few years?

Not really

I know that if you have plastic pipes internally and a plastic incomer there may be no need to bond, but the advice I have always been given is that if there is a substantial amount of copper then that will still require bonding.

It doesn't matter what "quantity" of copper you have, only if it's an extraneous-conductive-part. A mass of copper pipe in the airing cupboards won't require bonding if it's not extraneous.

For exampe if you had mainly plastic but in the airing cupboard there was a lot of copper pipe to pump, valves, cylinder, etc, that that would require bonding.

Not unless it was extraneous it wouldn't.

This was certainly the viewpoint of the ECA, NICEIC, etc about 5 years ago because I remember the debates.

Mmmm - I suspect the advice was based on making things simple for "installers"

If you had a gas boiler the boiler connections and pipework would almost certainly connect the water pipes to the earth terminal via the circuit cpc and the bonded gas pipe.

Would those connections introduce a potential that wasn't already there ?

If they don't, then they don't need bonding do they ?




Regards

OMS

-------------------------
Failure is always an option
 29 November 2012 02:18 PM
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leckie

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But the connections would reduce the value between the pipework and the MET below 23K wouldn't they? So then wouln't they require bonding, not just connecting via a cpc?

Just had a look on Voltimum and in the Q&A bit the ECA have said that the pipework does require bonding. Would they put that in writing if there was no requirement?

Also, plastic incoming pipes have been installed for the last forty years that I recall, and I have never heard of no bonding to water until the relatively recent installation of plastic pipes.

.......and, the Gas Board wont connect a new boiler until the gas and water are bonded - or at least they didn't where I live 3 years ago In fact they made me upgrade to 10sq.mm And I have a plastic incoming supply
 29 November 2012 02:38 PM
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leckie

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Just had another look through the Voltimum answers.

ECA say bond

NICEIC say dont bond, you are introducing a hazard

Select say.......it depends!
 29 November 2012 02:41 PM
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OMS

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Originally posted by: leckie

But the connections would reduce the value between the pipework and the MET below 23K wouldn't they? So then wouln't they require bonding, not just connecting via a cpc?

Off course they would - but when you remove that CPC, the part still doesn't require bonding if it's not extraneous.

Bonding is trying to reduce touch voltage - you want anything that presents and earthy potential to be connected to the MET - so when a fault occurs the potential of everything rises and falls and the difference in potential between parts is "small".

Your CPC will do just that.

If it's not extraneous, then the massive resistance between a live exposed conductive part and a plastic water pipe will reduce the shock current to a small value.

as I said, does it introduce a potential that's not already there - clearly it doesn't - so we don't need the bond.



Just had a look on Voltimum and in the Q&A bit the ECA have said that the pipework does require bonding. Would they put that in writing if there was no requirement?

Ahhh - pardon me then, I must have got it all a**e backwards for the last few decades -

Also, plastic incoming pipes have been installed for the last forty years that I recall, and I have never heard of no bonding to water until the relatively recent installation of plastic pipes.

Really ?


.......and, the Gas Board wont connect a new boiler until the gas and water are bonded - or at least they didn't where I live 3 years ago In fact they made me upgrade to 10sq.mm And I have a plastic incoming supply

Ahhh right - so a regimentally insane pipe strangler is an authority on BS 7671 then - or is he just following a simple rule



As I said - installers like rules - it makes it easy for you to do the same thing on every job.

People tell you lies, with the best intent of course, to make it easy for you effectively. That's why you've been bonding plastic pipes for the last 40 years - it saves you having to think -

Regards

OMS

-------------------------
Failure is always an option
 29 November 2012 02:53 PM
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AJJewsbury

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But the connections would reduce the value between the pipework and the MET below 23K wouldn't they? So then wouln't they require bonding, not just connecting via a cpc?

No - additional connections will defeat the test, but don't of themselves require things to be bonded (if they did you'd have to run 10mm² to Mrs Jones's clothes iron).

The point of bonding is to try and keep metalwork at the same potential as the electrical systems earth (i.e. the MET when we're talking about the entire installation) - so we only need to consider metalwork that would naturally tend to be at some other potential (e.g. true 0V). Being connected to the MET via a c.p.c. doesn't mean it'll be pulled to some other potential.

"Floating" metalwork doesn't need bonding as it'll happily assume any potential it's exposed to - e.g. if touched by a person who is at risk of an electric shock (e.g. by also touching a faulty appliance), it'll rapidly reach the same potential as the person (hence the electrical installation). Not bonding it avoids creating path for the shock current - so saving exposing the victim the the voltage difference between the appliance and the MET - i.e. even safer!

Just had a look on Voltimum and in the Q&A bit the ECA have said that the pipework does require bonding. Would they put that in writing if there was no requirement?

Have a read of GN 8.

I guess the problem is establishing in practice whether a lump of metal is extraneous or not (as I said, the test is easily defeated) - 'if in doubt then bond' is probably the least worst approach.

- Andy.
 29 November 2012 03:30 PM
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leckie

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Edit: Sorry Andy I posted this before reading your post. Looked through GN8 and it only shows incoming water pipes being in metal, so I am seeing where your coming from. Must have been written in the 50's

Im sorry for being a moron Oms I will leave myself open to another slating. I haven't been bonding plastic pipes, but I have been bonding copper pipe installations.

Are you telling me that all the houses that have been built in the last say forty years, that will have plastic incoming water service pipes need not be bonded unless they introduce an earth potential via being buried underfloor, etc? Or do you mean that they do need bonding but only because they have, for example, cpc's that bring the resistance between pipes and the MET to less than 23k? I have seen literally thousands of new houses over this time and have never seen one not bonded. In many towns by many different contractors. Really.

Every assessment (NIC or ECA) I have ever had alway includes a check of the bond to the water, gas, etc, unless the internal pipework has been plastic.

The OP says he is going to measure for in excess of 23k. Because of the gas pipe, cpc's, he is unlikely to measure higher than 23k, in which case he will have to bond. Correct?

Sorry for being a pleb but its hard to get my brain around the idea of not bonding a copper pipe installation when i have done, and everyone I know has done for a long time. Blimey, I could have saved a fortune, anyone want to buy a job lot of 10mm and some clamps?

Edited: 29 November 2012 at 03:37 PM by leckie
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