Electrical bonding to lead water supply pipe

hatt55

I've asked this on another forum, but hoping to get some more information. I also know its very unlikely that someone can give me a definitive answer on a web forum, but hopefully this can inform any imminent discussions with an electrician/plumber.

I have had a small leak as the mains water pipe enters my house, a Victorian terrace. A lead pipe comes under the door through the dirt, then a stop tap, then it changes to copper a metre or so in via a plastic junction. Both this junction and the stop tap have sprung a leak. I'm getting this fixed via my home emergency cover. They came and had a look and plan to chop out a section of lead pipe and replace with a plastic stop tap. This would then get connected to the copper. So it would now go Lead Pipe > Plastic (with stop tap) > Copper.

What I've just realised is that there is a yellow and green wire clipped to just beyond the stopcock on the lead pipe, which I understand is some kind of bonding. The plumber didn't make any mention of what they plan to do with this is they cut away the section of lead that it is attached to. Either that means they have a plan and didn't need to tell me, or they don't have a plan. They didn't ask anything about my electrical set up (not that I could have told them anything much). 

If they chop out this section of lead pipe and replace with plastic, what should this wire be clipped to (if anything)? And if it no longer needs to be clipped to anything, should I ask that they don't just leave it sitting in the subfloor soil of the hallway - what that be unsafe or mess up anything else? Even if there is a plastic section, there will still be a stump of lead pipe coming under the front door through the soil. I don't know if the plastic 'insulates' insulates this from my system.

Years ago I attempted to have a water meter installed (didn't happen, long story) and I remember asking an electrician about something similar. I must have read something on line to prompt the question. I feel like he said something that suggested my current electrical set up - the consumer unit is quite new - meant that these wires might be redundant and it would be fine. But, I wouldn't like to guarantee that.

Because this is being done through a home emergency policy, there are a lot of hoops to jump through to speak to anyone. There is a possibility that if I ask this question when they return, they will scratch their chin and say that they need an electrician, thus delaying the repair to the pipe which I would really like to happen soon. 

Could anyone advise what questions I should be asking or if this sounds like I might be worrying over nothing?

rob7475

If they are introducing a short length of plastic between the lead and your copper pipework, as far as I understand, bonding is no longer required as there is no continuity so the risk is removed.

Keep_pedalling

Make sure this is just a bonding connection, in some older houses the lead pipe was used to provide the main earth connection. 

Rodders53

I'd suggest that the current bonding needs relocating on to the remaining lead pipework... (an extraneous conductive part).  Despite any plastics 'break' inserted.  Probably.

To Bond or not to Bond may be relevant reading, and your insurer's emergency people may need to consult an electrician to be sure one way or the other.  The current cable will go back to the MET (main earth terminal) by your meter/consumer unit.

TBF you really want the lead pipework from the suppliers external stop tap / meter replaced entirely with MDPE plastic (when the bonding then won't be needed). But that will be at your cost.

Section62

hatt55 said:

...
Years ago I attempted to have a water meter installed (didn't happen, long story) and I remember asking an electrician about something similar. I must have read something on line to prompt the question. I feel like he said something that suggested my current electrical set up - the consumer unit is quite new - meant that these wires might be redundant and it would be fine. But, I wouldn't like to guarantee that.
...

"Might be" is a bit of a worry, but for a definitive answer you'd need a qualified electrician to inspect the system and advise.

The need for bonding isn't simply about the type or age of your consumer unit... it is a lot more complicated than that, which is why if you ask 10 people you'll probably get a dozen different answers.

My personal take on it would be similar to Rodders53's - if part of the (underground) lead pipe is remaining inside the house then it has the ability to act as an 'earth'.  Which means it could be at a different potential to other exposed metal pipework (and other conductive items) and therefore carry the risk of someone coming into contact with it and getting an electric shock.

The fact the lead pipe would be shorter than it currently is doesn't change the risk.

On the other hand, bonding things which shouldn't be bonded can create different risks.  Hence the need for professional advice.

The stand out for me is them proposing to connect new pipework to lead pipe.  The skills to properly work lead pipe don't really exist any more, so I'd guess

they are proposing to use some form of proprietary connector.  Which is what would concern me the most - lead pipe isn't as uniform in size as modern materials, and being soft it deforms easily.  So you can't really use fittings which 'clamp' (in the way olives do on copper pipe), and fittings using a rubber seal (like those used for plastic pipe) will only seal if the pipe diameter is correct for the fitting and the pipe hasn't been deformed already.  I would avoid cutting lead pipe unless there was absolutely no alternative... so it will be interesting to see what method they will use to join on to it.

hatt55

Thanks all. I'll mention it to the plumbers, but I really don't want the pipe repair to be delayed if they need to call out an electrician. Water isn't pouring out of the stop tap and it seems to be soaking away through the soil, but the flow is constant. 

From the slightly varying responses, it seems like this isn't totally clear cut and probably needs someone to at least double check. But also, no one is screaming that this could suddenly make the water pipework electrocute me/the plumber, which is good. 

Keep_pedalling said:

Make sure this is just a bonding connection, in some older houses the lead pipe was used to provide the main earth connection. 

The documentation I have from when the previous owner when they had the consumer unit replaced says that the means of earthing is "via distributor's facility", but obviously there are various bit of information in that document and for the most part I don't know what they mean! 

Rodders53 said:

The current cable will go back to the MET (main earth terminal) by your meter/consumer unit.

Just pre-empting what might happen here, and also emphasising that I don't know anything about electrics - if they didn't clip the bonding wire to anything and just left in lying in what is currently some quite damp soil, would there be an issue (assuming no wider electrical fault occurs today)?


 Rodders53 said:

TBF you really want the lead pipework from the suppliers external stop tap / meter replaced entirely with MDPE plastic (when the bonding then won't be needed). But that will be at your cost.

Agreed! But just at this moment I'm more interested in stopping the leak and that's a big job. Things are complicated (and why I can't really use an external stop tap at the moment) because I'm on a shared supply as well. 

hatt55

Section62 said:

hatt55 said:

...
Years ago I attempted to have a water meter installed (didn't happen, long story) and I remember asking an electrician about something similar. I must have read something on line to prompt the question. I feel like he said something that suggested my current electrical set up - the consumer unit is quite new - meant that these wires might be redundant and it would be fine. But, I wouldn't like to guarantee that.
...

"Might be" is a bit of a worry, but for a definitive answer you'd need a qualified electrician to inspect the system and advise.

The need for bonding isn't simply about the type or age of your consumer unit... it is a lot more complicated than that, which is why if you ask 10 people you'll probably get a dozen different answers.

My personal take on it would be similar to Rodders53's - if part of the (underground) lead pipe is remaining inside the house then it has the ability to act as an 'earth'.  Which means it could be at a different potential to other exposed metal pipework (and other conductive items) and therefore carry the risk of someone coming into contact with it and getting an electric shock.

The fact the lead pipe would be shorter than it currently is doesn't change the risk.

On the other hand, bonding things which shouldn't be bonded can create different risks.  Hence the need for professional advice.

The stand out for me is them proposing to connect new pipework to lead pipe.  The skills to properly work lead pipe don't really exist any more, so I'd guess

they are proposing to use some form of proprietary connector.  Which is what would concern me the most - lead pipe isn't as uniform in size as modern materials, and being soft it deforms easily.  So you can't really use fittings which 'clamp' (in the way olives do on copper pipe), and fittings using a rubber seal (like those used for plastic pipe) will only seal if the pipe diameter is correct for the fitting and the pipe hasn't been deformed already.  I would avoid cutting lead pipe unless there was absolutely no alternative... so it will be interesting to see what method they will use to join on to it.

Missed this whilst I was typing my other reply.

The previous electrician may have said it with more certainty than I've conveyed here. It was a long time ago, so I can't quite remember, I just recall that I queried something about having a plastic bit of pipe associated with the meter and was told it wouldn't be an issue. Not sure why though, and this is a bit of a different situation.

I think my plan is to follow up with an electrician and ask that they come and take a look. If no bonding is required, great. If it is, then hopefully just moving the clip onto the remaining piece of lead is an easy job for someone that knows what they're doing.

Section62

hatt55 said:

The documentation I have from when the previous owner when they had the consumer unit replaced says that the means of earthing is "via distributor's facility", but obviously there are various bit of information in that document and for the most part I don't know what they mean!

'Means of earthing' and 'Bonding' are two different things, although both get called 'earth' and use wires with the same green/yellow sheath.

The wording "via distributor's facility" probably (but not definitely) means you have a "PME" system, which means the earthing is done via a combined earth/neutral wire back to the supplier's substation.  Bonding means connecting relevant conductive parts within the property (such as copper pipes) so they are at the same potential.  With PME getting the bonding right is essential, because you don't want a situation to occur where you or someone else becomes the connection between the PME earth and 'true' earth in a fault situation. It can be extremely dangerous... hence the need for a professional to be involved.

hatt55 said:

Just pre-empting what might happen here, and also emphasising that I don't know anything about electrics - if they didn't clip the bonding wire to anything and just left in lying in what is currently some quite damp soil, would there be an issue (assuming no wider electrical fault occurs today)?

Can you clarify where the lead pipe needing repair is located.... I'd assumed this was inside your home, but if the bonding wire/clamp could be left in damp soil this suggests it might be outdoors or in an outbuilding?

hatt55

The lead pipe is just inside the threshold of the house, under the floorboards in the hall. As its a Victorian terrace, the subfloor is just soil (I would say 'earth', but in a discussion about electrics that will confuse things even more!). The soil has become damp because water has leaked into it, but its inside the door. I don't know if the soil is bone dry normally, but its damp at this point because water has leaked out. 

So my thinking is that if they haven't thought through what to do with the bonding wire, they could just discard it and not attach it to anything. That's just speculation on my part though. 

Section62

hatt55 said:

The lead pipe is just inside the threshold of the house, under the floorboards in the hall. As its a Victorian terrace, the subfloor is just soil (I would say 'earth', but in a discussion about electrics that will confuse things even more!). The soil has become damp because water has leaked into it, but its inside the door. I don't know if the soil is bone dry normally, but its damp at this point because water has leaked out. 

So my thinking is that if they haven't thought through what to do with the bonding wire, they could just discard it and not attach it to anything. That's just speculation on my part though. 

Makes sense

I'd suggest if the bonding really isn't required then the cable should be properly terminated (insulated) and labelled (both ends if possible).

Leaving the end laying on/in the ground/earth/soil could result in it acting as a poor quality (and variable) means of earthing which might be problematic in a fault situation, and at best could give spurious results for testing/inspection so a nightmare for someone to figure out what is going on.

Rodders53

Check out your water company's website wrt lead pipe replacement and removal of a shared supply.  You may have missed a boat though wrt the costs of doing both/either. (See Lead in drinking water for my supplier, Anglian)

The bonding cable if not required / used can be identified / traced and disconnected from the MET end (and if removed / recovered entirely is worth a few bob for the copper). 

It won't come to much harm; nor do any harm if left under the floor and the lead pipe is not at a different earth/ground potential to the end of that green yellow cable and both are touched by a person at the same time.  If there is a potential difference then it must be connected to the lead pipe of course!