bonding to water service pipe

[harry olee]

IET wiring regulations with regard to TT-S requires earthing arrangement bonding to the water service pipe. Does this need to be near the stop cock or could any convenient cold water pipe near the CU which has continuity with the stop cock pipe do.

 

[Geoffsd]

Do you mean TN-S?

As near as practical to point of entry on consumer's hard pipework before any branches.

 

[Engineer54]

IET wiring regulations with regard to TT-S requires earthing arrangement bonding to the water service pipe. Does this need to be near the stop cock or could any convenient cold water pipe near the CU which has continuity with the stop cock pipe do.

TT system bonding requirements, are exactly the same as TN system requirements!! Earthing cable from rod to MET may differ but not bonding cable sizes

 

[harry olee]

Do you mean TN-S?

As near as practical to point of entry on consumer's hard pipework before any branches.

sorry a typo -I did mean TN-S

 

[harry olee]

So it is unacceptable if there are any branches? My stop cock is 5 metres away from the CU. I understand this connection should be no more than 600mm

 

[Engineer54]

The bonding point should be at a location before any branch off's in the pipe work occures, generally stated as within 600m of entry!!

 

[Engineer54]

So it is unacceptable if there are any branches? My stop cock is 5 metres away from the CU. I understand this connection should be no more than 600mm

Sometimes it's just not physically possible, in such cases commonsense is called on to determine an alternative connection point!!!

 

[harry olee]

That seems me logical to me, but is that in accordance with BS7671 from an inspectors point of view.

 

[Geoffsd]

As near as practicable to point of entry on consumer's hard pipework before any branches.

is what the regulation states.

 

[Engineer54]

I did say commonsense is called for. Alas not ALL the answers to all situations will be covered by BS7871, but an inspector with experience will be fully aware of such incidences....

 

[harry olee]

The pipe work closest to the CU is the end of a long length of copper pipe with some soldered yorkshire joints but i have tested it for electrical continuity with a DMM and some cable. I can run a earth bonding cable to the stop-cock which will be 5M approx -it is feasable although a pain.I know what is easiest but I'm not sure what is the best option from an inspection point of view.

 

[Geordie Spark]

The pipe work closest to the CU is the end of a long length of copper pipe with some soldered yorkshire joints but i have tested it for electrical continuity with a DMM and some cable. I can run a earth bonding cable to the stop-cock which will be 5M approx -it is feasable although a pain.I know what is easiest but I'm not sure what is the best option from an inspection point of view.

The best option from an inspection point of view would be: "As near as practical to point of entry on consumer's hard pipework before any branches".

 

[harry olee]

So the 5M length bonding cable is the only option in my situation.Would 16mm squared earth cable be the best choice.

 

[Octopus]

Why 16mm?

 

[Geordie Spark]

Why 16mm?

I used 16mm on one of my last jobs, the reason being I had the remains of a roll of it but had no 10mm and as I was retiring, thought it more sensible to use-up what I had rather than buy a new roll of 10mm which would add to the collection of things that I would probably never use again !!

There is - as far as I know - nothing wrong with using cable bigger than that specified, but I wouldn't really want to use anything less i.e. 6mm

 

[Octopus]

I was wondering why the OP said 16mm as 10mm is the reg and most of us have a reel of 100m available.

 

[colshaws]

I had my Elecsa assesment recently and brought up this subject with the assesor, in my house the C.U and boiler are in the same cupboard in the kitchen, the gas meter is about 3m away in a seperate cupboard and the incoming water about 6m from C.U under the sink. The assesor was quite happy with the idea of bonding to gas and water at the boiler and confirming continuity to the incoming gas and water, as he said not ideal and not before branches in pipework but it is as close as practibly possible so he would accept it on an assesment, but to note this on any paperwork.

 

[harry olee]

I was wondering why the OP said 16mm as 10mm is the reg and most of us have a reel of 100m available.

4mm is recommended for supplementary bonding but as the cable length is 8x recommended length then a larger cable could be appropriate, but thinking about it 10mm would be fine.

 

[Octopus]

4mm is recommended for supplementary bonding but as the cable length is 8x recommended length then a larger cable could be appropriate, but thinking about it 10mm would be fine.

But this is equipotential bonding

 

[harry olee]

Yes it is, a larger cable is unecessary. I will be bonding to the nearest cold water pipe now after seeing colshaws post anyway.

 

[D Skelton]

4mm is recommended for supplementary bonding

Whaaaaaa???

but as the cable length is 8x recommended length

I didn't know there was a recommended length for a main equipotential bonding conductor???

I understand this connection should be no more than 600mm

Am I right in thinking that you are mistaking 600mm as the length of bonding conductor/maximum distance allowed between DB and services???

but thinking about it 10mm would be fine.

What do you mean "but thinking about it"? It is either correctly sized or not, there's no thinking about it??? Use the regs to size the conductor and where applicable an adiabatic equation.

Without wanting to sound like the sort on here I detest most, are you an electrician? If not, please step away from one of the most important parts of an electrical installation :whatchutalkingabout

 

[Deleted member 9648]

I had my Elecsa assesment recently and brought up this subject with the assesor, in my house the C.U and boiler are in the same cupboard in the kitchen, the gas meter is about 3m away in a seperate cupboard and the incoming water about 6m from C.U under the sink. The assesor was quite happy with the idea of bonding to gas and water at the boiler and confirming continuity to the incoming gas and water, as he said not ideal and not before branches in pipework but it is as close as practibly possible so he would accept it on an assesment, but to note this on any paperwork.

Yes it is, a larger cable is unecessary. I will be bonding to the nearest cold water pipe now after seeing colshaws post anyway.

The problem with this approach is that if alterations are made to the pipework between the point of bonding and the point of entry resulting in a loss of continuity the whole point of main bonding is defeated. If the incoming service is bonded at the point of entry the whole point of main bonding remains in place regardless of alterations made upstream of the bond. THIS is why there is a requirement to main bond at the point of entry,it's not just 7671 trying to make our lives harder. If it's not possible to bond at the point of entry...(and it nearly always is...it's more cant be bothered) IMO it is not sufficient to note on the cert....plumbers and clients dont read certs. I think it should be a requirement to place a notice at the CU stating that following alterations to plumbing a test of the effectiveness of main bonding should be carried out.

 

[shocking_eg]

Iv always done the bonding just after the stop cock or after the gas meter, before any branches off. as regs state - yes they can be a pain to do. but surely "as close as practical" could mean anywhere? depending on different peoples views on whats easier for them to do.

 

[Octopus]

Iv always done the bonding just after the stop cock or after the gas meter, before any branches off. as regs state - yes they can be a pain to do. but surely "as close as practical" could mean anywhere? depending on different peoples views on whats easier for them to do.

No. "as close as practical" means if its under the floor you should bond as soon as it emerges and not 3 meters along where lazy people can cut corners.

 

[shocking_eg]

No. "as close as practical" means if its under the floor you should bond as soon as it emerges and not 3 meters along where lazy people can cut corners.

just what i thought.