bonding of main water plastic incoming

[D Skelton]

You miss the point mate,existing bonding has nothing to do with it. If a gas pipe (for example) is extraneous,it will be at earth potential or thereabouts whether it is bonded or not.There is likely to be some electrical continuity to the water system via mechanical connection between pipework at a boiler even with all bonds/earth disconnected. Thats why the IR test to establish whether bonding is required is nearly always misleading.....(IMO!)

No, I'm not missing the point, instead I am agreeing lol.

Misleading readings possible but no harm done if bonded anyway

 

[Deleted member 9648]

A local firm in my area have just had the nic crawling all over them because they didn't run a main bond to the water main. Incoming pipe was plastic covered copper, rest of houses in plastic (scheme).
I would still run a bond and connect it on to the stop valve, this would satisfy the sheets, regs, and any electrician who looks at it.

If the incomer is copper it's almost certainly extraneous and needs bonding regardless of the rest of the install being plastic.

 

[KAS1]

The more I read these threads regarding bonding, I can fully understand why, when the 15th was around nearly everything was bonded (within reason, may I add, some people went way over the top) if in doubt bond, a few tenby earth clamps and a bit 10mm doesn't cost at lot in the average house. Seems now people are just getting more and more confused and doubtful as to bond or not to bond. lol

 

[Deleted member 9648]

The more I read these threads regarding bonding, I can fully understand why, when the 15th was around nearly everything was bonded (within reason, may I add, some people went way over the top) if in doubt bond, a few tenby earth clamps and a bit 10mm doesn't cost at lot in the average house. Seems now people are just getting more and more confused and doubtful as to bond or not to bond. lol

Agree.
99% of the confusion results from a failure to understand the meaning of the terms 'extraneous conductive parts' and 'conductive parts' and that bondings only function is to prevent the possibility of a PD between the two. It doesnt help that bonding is always discussed/described in conjunction with the term 'earthing' when the purposes of bonding and earthing are entirely separate. It's a simple concept,and it never ceases to amaze me how many electricians still dont get it.

 

[Thefailsafe2012]

As this is new emerging technology and there is no common person know to it. But after it has happen, the conditions could be so different. Yet there is a little success but not enough to experiment publicaly.

Touche sir, a good point well put for the discussion at hand.....

 

[Engineer54]

As this is new emerging technology and there is no common person know to it. But after it has happen, the conditions could be so different. Yet there is a little success but not enough to experiment publicaly.

Sorry but i haven't a clue what your on about here??

 

[telectrix]

is this better?

由於這是新興技術，有沒有共同的人知道它。但畢竟它已經發生的條件是如此不同。然而，有一個小的成功，但沒有足夠的實驗

 

[Thefailsafe2012]

Sorry but i haven't a clue what your on about here??

Check out his other 3 posts, almost as daft!

 

[Geordie Spark]

As this is new emerging technology and there is no common person know to it. But after it has happen, the conditions could be so different. Yet there is a little success but not enough to experiment publicaly.

An excellent point and very well made. (for an Australian)

Now go and play with your didgeridoo and leave us in peace to contemplate our navels.

 

[Knobhead]

Nearlly as bad as Americans telling us how to do things.

 

[kevyn]

I have recently heard of a local company not running a bond to the water main as he thought it was plastic incoming and plastic through the house. Turns out that it was plastic covered copper incoming. This happened on a big estate of new builds. Nic were involved with this major faux pa.

 

[Knobhead]

Ooopps

 

[ackbarthestar]

I started reading the first three pages then went off to find this article.....

 

[jibjob]

Yes there are. You are likely to get parallel paths from other extraneous services such as gas/oil which are mechanically connected to the same system as the water via boilers etc and not practical to remove.Disconnecting main earths and bonds still does not eliminate misleading readings.

Sorry to drag this up 2 months on but this is the first time I've seen someone mention parallel paths in respect of properties that have both water & gas/oil etc, one fed by copper and the other (usually the water) in plastic up to the stop tap then off round the property in copper. This issue arose for me the other day re mechanical connections at boiler etc thus meaning there would be continuity through the pipe work from the gas meter to the water intake. With the gas bond connected i'm getting 0.02/0.03 at the water intake (MET to pipework), this reading would rise to approx 0.2 with gas bond disconnected. Clearly the entire copper pipework system is extraneous but was unsure whether to bond incoming water. ELECSA told me that so long as I was getting a reading below 0.05 at the water intake with gas bond connected that the water needn't be bonded, hmmm.
This situation must be present in millions of properties where the water comes in in plastic & the gas in copper but only the gas is bonded. I've attended a few & have always gone for bonding the water (as a result of carrying out EICRs or small works) but am now in two minds.
I guess if you did an IR from MET to stop tap & you got above 22k then that would indicate that parts of the pipework were in plastic & that at least some of it would not be extraneous, effectively isolating the gas service from the water service.
Sorry to bang on :6:

 

[Deleted member 9648]

Sorry to drag this up 2 months on but this is the first time I've seen someone mention parallel paths in respect of properties that have both water & gas/oil etc, one fed by copper and the other (usually the water) in plastic up to the stop tap then off round the property in copper. This issue arose for me the other day re mechanical connections at boiler etc thus meaning there would be continuity through the pipe work from the gas meter to the water intake. With the gas bond connected i'm getting 0.02/0.03 at the water intake (MET to pipework), this reading would rise to approx 0.2 with gas bond disconnected. Clearly the entire copper pipework system is extraneous but was unsure whether to bond incoming water. ELECSA told me that so long as I was getting a reading below 0.05 at the water intake with gas bond connected that the water needn't be bonded, hmmm.
This situation must be present in millions of properties where the water comes in in plastic & the gas in copper but only the gas is bonded. I've attended a few & have always gone for bonding the water (as a result of carrying out EICRs or small works) but am now in two minds.
I guess if you did an IR from MET to stop tap & you got above 22k then that would indicate that parts of the pipework were in plastic & that at least some of it would not be extraneous, effectively isolating the gas service from the water service.
Sorry to bang on :6:

Remember though that the 'extraneous potential'- if I can refer to it as that -comes from outside of the property....generally from being in electrical contact with the general mass of earth. If there is mechanical continuity between a gas pipe and water system within the property that does not make the water system extraneous,it just means there is continuity between the services.You need to establish which of the services,water or gas,is in electrical contact with the general mass of earth outside of the property,and introducing it into the property.And thats where the 22k IR test is misleading IMO.

 

[oldtimer]

Yep I see where you are coming from I served my time as a 14th edition spark ie all connections should be Electrically and Mechanically sound so cables run in conduit / trunking with no earth wire as the containment was the earth. And on the water side because everything was run in copper with metal sinks so everything was earthed through the continuity great then came plastic pipes and the 15th edition that said earth everything that moves so Kitchen , Bathroom and Central heating pipework had to be supplimentry earth bonded. Giving spark the biggest Gad damn headache ie you earth both the gas and water then a year later the DNO changes it to plastic or 3 months later a plumber comes in to fit an outside tap doing it all in plastic and breaking the good mechanical connection to the rest of the prop.erty

I seen this in a property where the 6mm earth was bonding a 300mm piece of pipe at the stop tap where the incomer was plastic and somebody broke into the consumer side with plastic

 

[jibjob]

Remember though that the 'extraneous potential'- if I can refer to it as that -comes from outside of the property....generally from being in electrical contact with the general mass of earth. If there is mechanical continuity between a gas pipe and water system within the property that does not make the water system extraneous,it just means there is continuity between the services.You need to establish which of the services,water or gas,is in electrical contact with the general mass of earth outside of the property,and introducing it into the property.And thats where the 22k IR test is misleading IMO.

So where you have water coming in on plastic and copper throughout and with the gas intake as copper the 22k IR test is going to be meaningless unless you can isolate one from the other. In your opinon what's the best way to proceed where this scenario exists, bond both services regardless or just the gas assuming you're getting under 0.05 at the stop tap?

 

[D Skelton]

Quite simple really, you bond what is extraneous, you leave what isn't.

It is worth bearing in mind that just because a service enters the building in plastic it doesn't neccessarily mean to say that it is not extraneous.

 

[jibjob]

Quite simple really, you bond what is extraneous, you leave what isn't.

It is worth bearing in mind that just because a service enters the building in plastic it doesn't neccessarily mean to say that it is not extraneous.

The point I'm trying to make is how do you prove it's not extraneous without breaking the mechanical continuity of the copper pipe work which goes back to the metallic gas intake. As Wirepuller (rightly IMO) points out and I quote.....
"If there is mechanical continuity between a gas pipe and water system within the property that does not make the water system extraneous,it just means there is continuity between the services.You need to establish which of the services,water or gas,is in electrical contact with the general mass of earth outside of the property,and introducing it into the property"
It's less likely that a plastic pipe will be extraneous but while the two services are mechanically connected you can't be 100% sure. It's obviously not practical (and probably a waste of time anyway) to dismantle the central heating in order to carry out the IR test successfully so how would you proceed? Bond or not bond the water? This is the question.

 

[D Skelton]

I'd find which service was extraeous by breaking the bond between them and bond that. If both were extraneous then I'd bond both. If there was no way to break the link (internal parts of boiler for example) and categorically determine which of the two services was extraneous then I'd bond both.