CU Change - No main earthing on water main. Polypipe incomer

[AMC]

Hi, Have completed consumer unit change. However there is no main bonding on incoming water and doesnt look like there ever has been. Have managed to locate incoming water supply and it is 20mm polypipe, the rest of the house is mainly run in copper. Im assuming it is my responsibility to get an earth sorted out, or am I able to list it as a deviation? (im using the job for my part p inspection on Tuesday!!!!)

 

[djb_1983]

Na you will have to make sure the earthing is in place yourself, otherwise the trade body your using will prob fail you for energising the supply without the adequate earthing in place.

 

[AMC]

I thought that may be the case! what a ****!!!

 

[johnboy6083]

if it is polypipe, then why bond it? its plastic. You are not bringing another potential into the installation, so imo no need for bond. Just note it on the Cert.

 

[AMC]

My main concern was really that pretty much the entire installation other than the incomer is in copper,including immersion heater etc, apart from the pipework under the bath which is Hep20 plastic. So do you think my inspector will accept this?

 

[johnboy6083]

if the installation is protected by 30ma RCD, then you dont need to bond the pipes, ie the old way of doing it under the boiler and sink. bu if its not too much hassle, then bond it anyway.

 

[AMC]

The new board is a Wylex dual rcd 30mA board. I understand having the 30mA RCD's pretty much covers me on supplementary bonding, is it ok for main bonding though?

 

[johnboy6083]

if the incoming is plastic then IMO, no need for a main bond. fresh water does not conduct electricity.

 

[Sintra]

Agree with above no need for main bond to a plastic service pipe.

 

[ringer]

Try phoning whichever scheme you are joining and ask their opinion. That way if your assessor says you done it wrong, you can say you took advice (from his employers). You've already paid your money - and advice is part of what you have paid for, so use it. Better than arguing "well guv, the lads on the forum said...."

 

[johnboy6083]

Try phoning whichever scheme you are joining and ask their opinion. That way if your assessor says you done it wrong, you can say you took advice (from his employers). You've already paid your money - and advice is part of what you have paid for, so use it. Better than arguing "well guv, the lads on the forum said...."

have to agree! its not our opinion that counts, its your assessors, and his heirarchy.

 

[ezzzekiel]

run a bond to where the copper starts and note it down

 

[telectrix]

if fresh wter does not conduct, then it's s waste of effort chucking an electric fire in the wife's bath

 

[johnboy6083]

The conductivity of a solution of water is highly dependent on its concentration of dissolved salts, and other chemical species that ionize in the solution. Electrical conductivity of water samples is used as an indicator of how salt-free, ion-free, or impurity-free the sample is; the purer the water, the lower the conductivity (the higher the resistivity). Conductivity measurements in water are often reported as specific conductance, the conductivity of the water at 25 °C

from wikipedia.

I used to install control equipment for water features. the method of telling th pumps when to empty a tank of water, was to use liquid level relays. these will tell you when the water is at a preset point by measuring its resistance. on these relays, there is a dial to set at which resistance the relay will activate. On tanks fed from mains, the relay would not work unless we set this dial at over 150,000 ohms. however i would not try to test this with your wife

 

[johnboy6083]

i would like to add to above, that i have been in a situation where i have meggared a cable where the ends were in dirty water, and it gave me a dead short. the dirtier water is, the better its conductivity.

 

[telectrix]

also depends on how fast you crank the handle on the megger

 

[Hawk81]

Well in my humble opinion to bring it back to the main question there is no need to bond the water pipe. as it is plastic then it is not needed. we bond as to stop a potential earth difference not to make sure that the rest of the copper pipes is earthed. surely any assesor will understand this or he should not be in his job.

 

[pushrod]

Not sure at all about this but isn't there a resistance value between the pipework and earth which shows whether or not something is an extraneous conductor or not and so if it will need bonding -> 20 KΩ and you don't need to bond??? or am i thinking of something completely different

 

[antimatter]

Section 4.4 OSG

The is no requirement to main bond an incoming service where the incoming service pipe and the pipework within the installation are both of plastic. Where there is a plastic incoming service and a metal installation within the premises, main bonding is recommended unless it has been conformed that any metal pipework within the building is not introducing earth potential. All bonding connections are to the consumers side of any meter, main stopcock or insulatinf insert.

 

[pushrod]

Section 4.4 OSG

unless it has been conformed that any metal pipework within the building is not introducing earth potential.

so how do you confirm that - is it what i said above? (on reflection is the figure 22 kΩ?)