Another "exporting PME post"...

[Wilko]

The DNO supply comes into the green cabinet, and within this cabinet there is a 4w 3ph dist board.
The 4c 25mm SWA runs from here to the garage, to another 3ph dist board, then from here to the house.
There is a duct from cabinet to garage, so an additional bond could be pulled in, but as I say, the incoming water is plastic.

My worry is : if the DNO supplies the means of earthing (TNCS) and their cutout and fuse is in the green box at the boundary, then the installation's MET should be there. So if you are using SWA armour from green box to garage then it's insufficient for bonding to the garage too.

 

[dmcturk]

My worry is : if the DNO supplies the means of earthing (TNCS) and their cutout and fuse is in the green box at the boundary, then the installation's MET should be there. So if you are using SWA armour from green box to garage then it's insufficient for bonding to the garage too.

Thanks, but if the incoming water is plastic, there is no gas/oil, RSJ's are enclosed, and there is no other exposed metal work, what do you bond to?
Like I said, it would be possible to pull a 10mm in (using the SWA as cpc).
So providing there is no bonding requirements, using the PME earth is ok.

 

[LeeH]

Can you 100% guarantee the metal work is enclosed throughout and will remain enclosed?

 

[Wilko]

Can you 100% guarantee the metal work is enclosed throughout and will remain enclosed?

This is my thought too. From description there is a solar array and a 3phase ground source heat pump ...

 

[LeeH]

I don't know the specifics, please tell me somebody.

If you have an extraneous conductive part, is it relevant wether it's exposed or not? I would have thought you would have bond it regardless. I certainly would personally.

 

[dmcturk]

I don't know the specifics, please tell me somebody.

If you have an extraneous conductive part, is it relevant wether it's exposed or not? I would have thought you would have bond it regardless. I certainly would personally.

The garage and house are timber framed, with the rsj in the house resting on timber supports, so not going to have a potential to earth.

 

[dmcturk]

The garage and house are timber framed, with the rsj in the house resting on timber supports, so not going to have a potential to earth.

Would you bond individual radiators if supplied via plastic pipes?

 

[Deleted member 93172]

My feelings for what they are worth are, pull in another CPC from the incomer position to the garage then onto the house, terminating at each point in a single way service block. This means you have covered all bases, you know what they say assumption is the mother of all ****up's.

 

[westward10]

I agree with yo

Would you bond individual radiators if supplied via plastic pipes?

No need to.

 

[westward10]

Can you 100% guarantee the metal work is enclosed throughout and will remain enclosed?

It would difficult to achieve if the metalwork was extraneous, you often see it partially boxed in for aesthetic purposes or given fire protection but as you say to totally contain it 100% would be all but impossible especially on large structures and not cost effective, you may as well bond it. From what the op says it doesn't sound extraneous.

 

[Leesparkykent]

I would use 16mm due to table 54.1 even though its ducted as I doubt the ducting will protect against mechanical damage.