Supplementary Equipotential Bonding Q

[CEC]

I am having my house completely rewired and replumbed. Part of the new plumbing is a non-metallic pipe through the thatched roof void to avoid the need for the plumber to use a torch in the roof space. If he'd had to use copper and torches, we wouldn't be insured for fire. All good, so far. This creates two separate zones of pipework. The first, is connected back to earth in the CU via continuity, the second is completely isolated from the CU, because of the plastic pipe.

The pipework at the end of the house that is fed by the plastic roof pipe is not in any way bonded to the main pipe work. My electrician says that bonding is no longer required (every circuit is protected by an RCBO), yet my reading of the Regs is that bonding is required if the circuit doesn't meet the requirements of ADS (which I think it does) , OR it is a special location. The en-suite shower room at the far end of the house is surely a special location?

I checked the radiators and pipework in the end of the house that is served by the plastic pipe, against the sockets at that end of the house, and the is no continuity to earth.

Do you think I need bonding, in which case my electrician is wrong, or is ADS through RBCOs sufficient, even in bathrooms?

Many thanks

 

[JohnW2]

....My electrician says that bonding is no longer required (every circuit is protected by an RCBO), yet my reading of the Regs is that bonding is required if the circuit doesn't meet the requirements of ADS (which I think it does) , OR it is a special location. The en-suite shower room at the far end of the house is surely a special location? .... Do you think I need bonding, in which case my electrician is wrong, or is ADS through RBCOs sufficient, even in bathrooms?

Your electrician is almost certainly right.

The current regs now require supplementary bonding only in a 'special location' (room containing a bath or shower) and, even then, it is not required if all circuits in the bathroom/shower room are RCD (or RCBO) protected, if any extraneous conductive parts (e.g. metal supply pipes) have main bonding where they enter the building (which almost certainly will be the case), if any extraneous conductive parts in the room are 'effectively connected' to that main bonding (which almost certainly will also be the case, if applicable) and if the requirements for ADS are satisfied (which, as you say, they almost certainly will be). Provided your electrician can confirm those couple of points, there would be no need for any supplementary bonding.

Kind Regards, John

 

[Taylortwocities]

Your electrician is correct. Supp bonding no longer required - even in bathrooms - providing circuit is protected by RCD/RCBO (they are) and circuits meet ADS requirements (they will).

 

[ban-all-sheds]

The current regs now require supplementary bonding only in a 'special location'....

Supp bonding no longer required...

The regs never required the bonding of items which were not extraneous-conductive-parts.

the second is completely isolated from the CU, because of the plastic pipe.

 

[JohnW2]

The regs never required the bonding of items which were not extraneous-conductive-parts.

True, but the fact that the (seemingly copper) pipework at one end of the house is 'isolated' by sections of plastic piping does not, in itself, prove that there are no extraneous-c-ps in bathrooms/shower rooms. The OP says that he has found no continuity to earth from pipework and radiators at the 'isolated' end of the house, but the electrician should confirm that (amongst the other things I mentioned, if applicable) before concluding that SB may be omitted in special locations.

The insurer's concern about soldering in the roofspace suggests that the house may well have a thatched roof. If that is the case, this would probably indicate a property of appreciable age which might have metal waste pipes (which may not be being replaced as a part of the re-plumbing), which might represent extraneous-c-ps - as (although unlikely) could things unrelated to plumbing such as structural metal etc.

In passing, copper plumbing can be installed without the use of gas torches. For a start, 'push-fit' fittings could be used. Secondly, for those who do not trust such fittings and want soldered joints, electric soldering pliers/tongs can be used ...

Kind Regards, John

 

[davelx]

The insurer's concern about soldering in the roofspace suggests that the house may well have a thatched roof.

Part of the new plumbing is a non-metallic pipe through the thatched roof void to avoid the need for the plumber to use a torch in the roof space

 

[bernardgreen]

In passing, copper plumbing can be installed without the use of gas torches. For a start, 'push-fit' fittings could be used. Secondly, for those who do not trust such fittings and want soldered joints, electric soldering pliers/tongs can be used ...

My insurers say "no hot work" in the roof space of ny thatched cottage, and that would almost certainly include anything hot enough to melt solder.

As tp the original question.

The pipework at the end of the house that is fed by the plastic roof pipe is not in any way bonded to the main pipe work.

My opinion is that it should be bonded to the MET ( main earth bar ) as a single fault at the end of the house could make exposed metal pipes and taps Live. With no route to Earth there will be no leakage current and hence the protective RCD with not operate.

Given that, in a few extreme fault situations, fires have been started by over-loaded bond cables I would not run bonding cables through the roof space either.

 

[John D v2.0]

My opinion is that it should be bonded to the MET ( main earth bar ) as a single fault at the end of the house could make exposed metal pipes and taps Live. With no route to Earth there will be no leakage current and hence the protective RCD with not operate.

Stop the thread!
We need a definitive link to summarise all previous discussions on this topic so we can just post that whenever the subject of bonding random bits of metal comes up! As it's a repeated theme

 

[bernardgreen]

so we can just post that whenever the subject of bonding random bits of metal comes up!

There is no fit all solution / requirement as to the need for bonding. Random bits of metal on one building may be zero hazard ( electrically ) but similar bits of "random" metal in another house could be potential hazards.

Specifically in a old building with stone walls and no damp proof course where the walls are damp. These walls can be conductive enough to be a hazard to a person in contact with the wall and an un bonded metal item that is Live due to a fault. The current through the person and wall to Ground may be enough to harm the person but not enough ( due to the impedance of the wall ) to trip the RCD. Hence pipe work and similar metal items that might become Live due to a fault should be bonded to MET ensure the RCD trips immediately the fault occurs and thus remove any hazard to persons who may touch that metal item.

 

[John D v2.0]

There is no fit all solution / requirement as to the need for bonding

Hence the need for a summary/FAQ.

 

[bernardgreen]

Hence the need for a summary/FAQ.

A summary / FAQ has the risk of someone using an existing "answer" from the FAQ that appears to be a close fit ( or even perfect match ) to their circumstances.

It appears to be the answer but is not applicable to the situation due to some factor that either (1) the FAQ compiler was not aware of or (2) the person asking was not aware of the importance of that factor.

 

[ban-all-sheds]

Or (3) the person answering has got a mania for making anything metal which he can see or touch into part of an electrical installation.

 

[bernardgreen]

Or (3) the person answering has got a mania for making anything metal which he can see or touch into part of an electrical installation.

Knives, forks, spoons, saucepans, frying pans, baking trays, roasting dishes......
Probably a total into the hundreds in my kitchen.
My God - it's a death trap!

Hence pipe work and similar metal items that might become Live due to a fault should be bonded to MET ensure the RCD trips immediately

Knives, forks, spoons, saucepans, frying pans, baking trays, roasting dishes......are very unlikely to come into contact with a Live conductor.[/QUOTE]

 

[ban-all-sheds]

Hence pipe work and similar metal items that might become Live due to a fault should be bonded to MET ensure the RCD trips immediately the fault occurs and thus remove any hazard to persons who may touch that metal item.

That is not what equipotential bonding is for.

Metal items cannot become live due to a fault unless they are exposed-conductive-parts.

 

[JohnW2]

My opinion is that it should be bonded to the MET ( main earth bar ) ...

Even Supplementary Bonding, when required, does not require a direct connection to the MET.

As has been said, we've been over this ground umpteen times with you in the past, and it is important that people understand that your view is somewhat out on a limb.

The point that often gets missed is that to follow your approach and create lots of unnecessarily earthed metal will increase the risk of electric shock in the event of some types of fault. Yes, it facilitates operation of an RCD if that occurs, but without the earthed metal an appreciable shock would not, in that situation, occur in the first place - and I would personally prefer not to have a shock than to have a shock which an RCD might prevent killing me.

It is a matter of swings and roundabouts. Your approach is safer in the presence of some types of fault, whereas it is more dangerous in the presence of other types of fault. It's therefore a matter of deciding which type of fault is considered to be the more likely and, as you know, a lot of people have a different view of that from you.

Kind Regards, John