Submain Earth/Bonding question?

[Flakey]

Hi guys/girls

Just some clarification needed. I have an house where there is sub board in the garage , and also a boiler in the garage. The water copper pipe that connects to the boiler is continuous from the house. I am aware of the exporting PME situation so plan to drop out the 3rd core of the 10mm swa that is feeding the board as well as the glanded armour currently connected to the sub board and TT the garage then bond services to the garage from MET in garage. What would be the best course of action with regards to the pipe being connected to the house as well as the garage? Would a length of plastic pipe be suffcient to to seperate both zones. Also where would be the best place to insert the plastic bit of pipe. for example before it leaves the house or anywhere?

Thanks in advance

 

[DPG]

No. That is not correct. As someone said above, check the diagram and notes on p70 of GN8. I think you will be surprised.
Daz

 

[bigspark17]

Use the 10mm earth inside the swa to connect from house MET to EMT in garage and from there 10mm bond to pipe. Youre very lucky to find a 10mm 3core in place underground if only every outbuilding was like that. When getting telephone calls about armoured cables to garage/shed if you suggest to the customer to bung a 10mm 3c in this will usually save alot of drama when you come to connect up and future proofs the install for minimal extra cost.

 

[Ib≤In≤Iz]

Just extend the equipotential zone of the original

 

[Octopus]

I'd rather extend the TNCS than rely on a twig in the ground.....

 

[Flakey]

Thanks a lot guys for your input I think my understanding was a bit off!!

 

[DPG]

Thanks a lot guys for your input I think my understanding was a bit off!!

We all have gaps in our knowledge. Nothing to worry about.
Daz

 

[Octopus]

^^ hit, nail and head spring to mind

 

[bigspark17]

Thanks a lot guys for your input I think my understanding was a bit off!!

It shows your willing to learn and not to proud to ask the question, good signs for a top spark.. keep at it mate!

 

[mache]

sorry no actual input to give but was wondering if the existing boiler is powered from a supply direct from the house and therefore is earthed via the house supply with presumably the copper piping mechanically connected to this earth. I have no idea if this has any implication with regard to your bonding of pipework to your new garage supply.

 

[Midwest]

sorry no actual input to give but was wondering if the existing boiler is powered from a supply direct from the house and therefore is earthed via the house supply with presumably the copper piping mechanically connected to this earth. I have no idea if this has any implication with regard to your bonding of pipework to your new garage supply.

The metal pipe may be earthed, but as it is a re-appearing metal pipe it needs to be bonded as per Chapter 54. Sorry haven't got the reg no, as don't have BS7671 with me