TNC-S main bonding question...

[JohnnyG]

...before I walk away from a CU change & other work, not the end of the world but hey.
Existing is all 6mm, the gas is easy enough to sort but the householder is reluctant to accept the upheaval involved in sorting the water.
There's no sign of thermal damage & I'm aware of the regs & best practice guide's advice on the situation but is there anything I can do to help the householder in this situation apart from tearing his house apart?

 

[GaryMo]

6mm2 bonding conductors may well be compliant.

Calculate, via the adiabatic equation, the minimum size required for the earthing conductor, not necessarily the size that's been installed (543.1.1 (i))

The protective bonding conductors should be not be less than half the size of the earthing conductor that's required (544.1.1)


EDIT - the above doe NOT apply to PME supplies. I misread it for TN-S.

 

[JohnnyG]

That confuses me a bit as I read 544.1.1 as not pertaining to PME supplies & 543.1.1 as excluding protective conductors?

 

[GaryMo]

Damn - sorry - I read that as TN-S!!

I've edited my reply.

Is an external route a possibility?

 

[JohnnyG]

No worries

 

[JohnnyG]

Is an external route a possibility?

I don't think so but I haven't looked at that yet to be fair.
It's a terraced town house with the service head in the garage which is under their front 1st floor and the water intake at the back so it's unlikely.

Is there any provision for using the existing bonding if it meets max Zs?

 

[JohnD]

I did one like that where I had to run the main bond under the landing floor. I considered taking it up into the loft through a cupboard or plumbing duct but although there was one at the front of the house, there wasn't at the back. I also considered running it up the outside of the house, through the loft, then down the back wall, but the route I used seemed the easiest. The joists ran front to back which made it easier.

Found some interesting old curiosities under the floor. As it was for a relative I insulated the hot pipes which took the same route while I was at it.

 

[PrinceofDarkness]

JohnnyG, if that installation still has the original tails and service fuse, then the existing 6mm bonding is still acceptable, having been installed in accordance with the ESR Regs (that was).

The time to to upgrade PME bonding is when the supplier decides to upgrade his supply. The ESQCR Regs take precedence over the non-statutory IEE Regs and the 'OSG'.

It's a popular myth that the bonding has to be upgraded to 10mm when changing a CU even on PME supplies. There's no such requirement for older supplies - but the is an obligation to ensure that the existing 6mm bonding is safe and sound.........


Lucia.

 

[JohnnyG]

I respect your opinion PoD but have you got any facts to back that up?
I'm not about to lend my signature to some random internet info

 

[GaryMo]

Are you a member of one of the Competant Persons Schemes? eg ECA, NAPIT etc
If so, how about speaking to their technical support and see what their stance is?

 

[JohnnyG]

I am & am going to but they're closed until Tuesday and I'm not very patient when it comes to conundrums.
The advice on here is frequently as good anyway

 

[PrinceofDarkness]

I respect your opinion PoD but have you got any facts to back that up?
I'm not about to lend my signature to some random internet info

JG: What need do I have of facts, when it's you in need or reading the ESQ Regs?

I spent almost twenty years with the London Electricity Board, and then a few enjoyable years with Eastern Electricity as an agricultural contracts manager.

I'm here to tell you that an elderly PME bonding system has no need of upgrading unless the supplier decides to upgrade the supply.

Don't fall for that old nonsense, that all bonding must be upgraded at all costs. It simply isn't true for existing systems. Read the supply regs without relying on hearsay.

Take it or leave it - it's all the same to me.......


Lucia.

 

[JohnnyG]

You've no need of facts, I do, as it's my name on the EIC.
Your vocational history is fascinating I'm sure but that's of no help to me.
I'm not relying on hearsay, rather the current IEE regulations as far as I'm aware of them.
Now, if you're privy to a solution that supersedes them and allows me to solve my problem safely and legally it would be handy if you would share it instead of just telling me to read up on it.

 

[kevindgas]

I am & am going to but they're closed until Tuesday and I'm not very patient when it comes to conundrums.
The advice on here is frequently as good anyway

you talking rubbish!!!
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the advice on here is 100% more accurate!

 

[PrinceofDarkness]

I'm sorry that you've taken that attitude JG. I'm only trying to be helpful.

You won't find anything in BS7671 to oblige you to upgrade an existing bonding conductor installed to a former set of regulations.

The only obligation upon you is to make sure that the existing bonding is sound.

If you apply for a new PME connection, then of course you'd have to install appropriate bonding. But as you already have a PME supply, it has no need of further action.

Do you want that job, or not?



Lucia.