Bonding gas supply

[oldbutnotdead]

Apologies-I've waded through all the posts on this subject and i think i know the answer to my question but would appreciate confirmation.
Situation- EICR on rental, bonding undersized- whoever renewed the CU in 2010 put the proper size from MET to CU but didn't bother upgrading the rest.
Oddity- the gas meter is under the stairs near the CU, so is cold water stopcock and heating pipes. There's a bit of 6mm from MET to the house side of the meter and onwards to cold water and heating pipes-all fine, easy to replace.
There's another bit of 6mm that drops into the floor void. Supply is TN-S so not an earth rod. DMM had lowest impedance between 6mm and gas pipe so I suspect it runs under the hallway and is clamped to the gas pipe where it enters the house (under the front door somewhere).
My reading of the several posts tells me that since the meter is inside, bonding should be on the customer side of the meter before any branches, visible, mechanically sound, marked. So I don't need to upgrade that 6mm dropping under the floor. True or false?

Ta

 

[Taylortwocities]

6mm is adequate bonding for TN-S supply.

 

[conny]

You are correct in that it should be on the customers side of the meter before any branch offs etc and, I think, within 300mm, (maybe 600mm but I don't think so), of the meter.
It must also use a recognised clamp and be clearly marked stating Safety Earth. DO NOT REMOVE. (or something similar)

 

[oldbutnotdead]

@Taylortwocities bloke who did previous EICR in 2017 thought so as well, alas he's stopped doing them cos of scheme costs. TBH it might be 4mm, haven't counted the strands. Path of least resistance is to upgrade, the visible ones are easy, that stray could be a sod, see below
@conny ta, i'll disconnect the stray and park it under the floorboards. Can't think of anything it could be connected to except the gas- water used to come in thru kitchen which is in the opposite direction, its going the wrong way for bathroom.

 

[Taylortwocities]

Bonding in 4mm would be very unlikely.

 

[EFLImpudence]

bloke who did previous EICR in 2017 thought so as well, alas he's stopped doing them cos of scheme costs.

Scheme membership is not required to do EICRs.

 

[EFLImpudence]

You are correct in that it should be on the customers side of the meter before any branch offs etc and, I think, within 300mm, (maybe 600mm but I don't think so), of the meter.

That is what regulation 544.1.2 states but it is electrically incorrect.

The bonding should for electrical reasons be made at the point of entry where practicable.

 

[EFLImpudence]

Also people always seem to mention stop-cocks as if they are in some way relevant.

They are not and are nowhere mentioned in the regulations regarding bonding.

 

[JohnW2]

You are correct in that it should be on the customers side of the meter before any branch offs etc and, I think, within 300mm, (maybe 600mm but I don't think so), of the meter.

As often discussed, this is one of those crazy situations in which, in order to satisfy an EICR inspector (without the need for argument) one may have to do things which are not necessarily sensible, nor even necessarily safe.

The regulation in question (which has not changed much for decades) appears to have been written by someone with no understanding of the concept/purpose of main bonding and says (with my emboldening):

544.1.2 The main protective bonding connection to any extraneous-conductive-part such as gas, water or other metallic pipework or service shall be made as near as practicable to the point of entry of that part into the premises. Where there is a meter, isolation point or union, the connection shall be made to the consumer’s hard metal pipework and before any branch pipework. Where practicable the connection shall be made within 600 mm of the meter outlet union or at the point of entry to the building if the meter is external.

For a start, the point which is probably most commonly overlooked is that IF there is no electrical continuity across the "meter, isolation point or union", then pipework on the consumer's side of that "meter, isolation point or union" is NOT an extraneous-c-p and therefore does not require main protective bonding at all (i.e. reg 544.1.2 does not apply at all).

There is also a theoretical argument that to 'unnecessarily' bond (resulting in a connection to 'earth') the consumer-side pipework would, by introducing 'unnecessarily earthed things' into the house increase the risk of electric shocks. However, in practice, pipework is almost inevitably 'earthed' via boilker etc., so that 'unnecessary bonding' does not actually make the situation any less safe.

However, worse (and potentially dangerous), again IF there is no electrical continuity across the "meter, isolation point or union", then IF there is a significant length of pipe (which IS an extraneous-c-p which needs to be bonded) within the building on the supplier's side of that, then complying with the regulation (by bonding on the consumer's side of the meter etc.) would leave the pipe (extraneous-c-p) on the supplier's side of the meter unbonded, hence theoretically presenting a risk of electric shock.

Kind Regards, John

 

[oldbutnotdead]

As often discussed, this is one of those crazy situations in which, in order to satisfy an EICR inspector (without the need for argument) one may have to do things which are not necessarily sensible, nor even necessarily safe.

The regulation in question (which has not changed much for decades) appears to have been written by someone with no understanding of the concept/purpose of main bonding and says (with my emboldening):
For a start, the point which is probably most commonly overlooked is that IF there is no electrical continuity across the "meter, isolation point or union", then pipework on the consumer's side of that "meter, isolation point or union" is NOT an extraneous-c-p and therefore does not require main protective bonding at all (i.e. reg 544.1.2 does not apply at all).

There is also a theoretical argument that to 'unnecessarily' bond (resulting in a connection to 'earth') the consumer-side pipework would, by introducing 'unnecessarily earthed things' into the house increase the risk of electric shocks. However, in practice, pipework is almost inevitably 'earthed' via boilker etc., so that 'unnecessary bonding' does not actually make the situation any less safe.

However, worse (and potentially dangerous), again IF there is no electrical continuity across the "meter, isolation point or union", then IF there is a significant length of pipe (which IS an extraneous-c-p which needs to be bonded) within the building on the supplier's side of that, then complying with the regulation (by bonding on the consumer's side of the meter etc.) would leave the pipe (extraneous-c-p) on the supplier's side of the meter unbonded, hence theoretically presenting a risk of electric shock.

Kind Regards, John

Yeah, that bit above. If I were to bond the gas pipe at point of entry only, it would be invisible (under the floor). If I leave the 6mm connected to the MET I'll (presumably) get another tutting and C2 from the EICR bloke. So I've gone with my original plan (which makes limited electrical sense but complies with regulations so I'll get a big fat tick in that box). The visible supply pipe to meter is only about 500mm (including the anaconda), crappy DMM indicates continuity across the meter so I'm not going to lose a lot of sleep over it. And when the box has been ticked, that bit of 6mm might end up back in the MET......ta for the input

 

[oldbutnotdead]

Scheme membership is not required to do EICRs.

I may have used the wrong words, he certainly told me he wasn't doing EICRs because of some sort of costs- might have been PLI or something, didn't push it, none of my business. Shame, think the defects list would have been a lot shorter

 

[JohnW2]

Yeah, that bit above. If I were to bond the gas pipe at point of entry only, it would be invisible (under the floor). If I leave the 6mm connected to the MET I'll (presumably) get another tutting and C2 from the EICR bloke. So I've gone with my original plan (which makes limited electrical sense but complies with regulations so I'll get a big fat tick in that box).

Yep, as I said, a totally 'wrong' reason for doing it, but an approach which leads to less heartache.

The visible supply pipe to meter is only about 500mm (including the anaconda), crappy DMM indicates continuity across the meter so I'm not going to lose a lot of sleep over it....

At least that means that following the regs (rather than electrical sense) has, in your case, not actually introduced any significant danger!

And when the box has been ticked, that bit of 6mm might end up back in the MET......ta for the input

Kind Regards, John