Main equiptential conductor

[sheffieldelec]

Recently doing a periodic inspection, i came across a 10mm bonding conductor to a external building (valet bay) waterpipe. However the the main bonding conductor on the the water into the main bulding is 35mm (95mm Neutral), the water in the external building is fed by a plastic pipe underground from the main water supply. I am wondering if this is a fault and if so what code it should be? many thanks

 

[pushrod]

Not too sure about this but 20 views and no one has had a stab yet so... Are you talking a main protective bonding conductor? Think this depends on what the earthing arrangement is and whether the water supply, when it enters the valet bay, is an extraneous conductor or not. If it is a PME then the main protective bonding conductor is correct at 35mm but if it is not PME then it need only be 25mm copper. If it is not an extraneous conductor ie IR to MET is greater than 23 MΩ (because it is plastic coming out of the ground) then does not need bonding. If it is extraneous then the size should be... the same as the other one and a 2 requires improvement?

Assume it is not part of a petrol station and under other regs

Maybe this might encourage some one else to have a go

edit : oh and welcome to the forum as it's your first post!

 

[sheffieldelec]

it is a TNCs system and its bonded with a 10mm cable will IR next time i go back thanku!!

 

[pushrod]

Is there structural metalwork coming out of the ground as well, as that will also need main protective bonding.

 

[sheffieldelec]

no but there is gas also from main building also in plastic

 

[pushrod]

Just a thought - are these circuits rcd protected?