Bonding conductor

[socket2me]

Im doing some alterations in part of a school. I noticed a water stop cock that has no bonding conductor. Its not the main stop cock as that is another part of the school. I carried out an R2 from the local sub board i am working from and got 0.32.
Am required to bond it to bring it within the 0.05 requirement or is it ok with the main bond at the main stop cock? I would just do it but its a bit of a job so if its not required then i will leave it...
Cheers

 

[Geoffsd]

The stop-cocks are irrelevant.

The supply pipe should be bonded 'where practicable' at the entry point to the premises.

 

[Richard Burns]

Unless you are certain that this stop cock is introducing an earth potential, independent of the main water supply, then leave it.

 

[Toby Kuhnert]

Test and see if it is an extraneous conductive part

 

[Risteard]

0.05 requirement

There is no requirement for a main protective bonding conductor to have a resistance not exceeding 0.05 Ohms. A low resistance (e.g. not exceeding 0.05 Ohms) is between the clamp and what it is connected to in order to ensure that there is an adequate connection.

 

[telectrix]

thanks for pointing that out. so many guys erroneously have this silly figure of 0.05ohms as the max. resistance of a bonding conductor.

 

[Risteard]

thanks for pointing that out. so many guys erroneously have this silly figure of 0.05ohms as the max. resistance of a bonding conductor.

Indeed. Would be curious as to which Reg. they believe requires it! Only mentioned in GN3 (in the context mentioned above) as far as I am aware.

 

[telectrix]

sadly a case of reading things wrong. for a long time, many sparks thought it was not done to extend pme to a garage/shed and so spent hours banging in useless short thin rods.

 

[jaypp]

Mr D Skelton gave a very good explanation of the 0.05 figure in this thread;

http://www.electriciansforums.co.uk...89470-main-protective-bonding-conductors.html

 

[socket2me]

Thanks guys so the higher value i recorded is probably quite good given the distance of the main bonding conductor to the stop cock.

 

[telectrix]

estimate the length of the bonding conductor. look up the resistance/m for the csa then you can guesstimate what it should be.

just wondering what mary whitehouse has to do with it ( she wanted to stop cock)

 

[SimpleSimon]

I was always taught that to guesstimate what the resistance should be on a bonding conductor is 0.05 ohms per meter so on a reading of 0.32ohms your run should be roughly 6.5m.

However like said said previous I think you should check if this could bring an earth potential otherwise you should be fine.

 

[Geoffsd]

If 10mm² conductor, 0.32Ω would be 173m.

Page 182 OSG.