settle an earthing argument

[markymark2406]

A mate of mine is installing mains to his shed 40metres away from his house using 10mm 2 core swa

Hi house is PME earthed are we right in saying that the shed should have its own earthing arrangement using a stake (TT)?

 

[ricicle]

It will need TT if there are extraneous conductive parts entering the shed as the armour will not be big enough for a bonding conductor

 

[RF Lighting]

Unless there are extraneous conductive parts in the shed, then it is fine to use the PME earth in the shed.

 

[ricicle]

Or you could say it the other way round like Rob

 

[RF Lighting]

I'm bit slow on the keyboard tonight!

 

[securespark]

You can export PME even if there are extran. cond. parts IF you also run a large CSA earthing conductor with the SWA, but it's a lot of fannying around.

 

[ricicle]

You can export PME even if there are extran. cond. parts IF you also run a large CSA earthing conductor with the SWA, but it's a lot of fannying around.

Or if the armour is of sufficient conductance to act as a bonding conductor. With a resistance ratio of approx. 9:1 you would need armouring of around 90mm² which off the top of my head is around 95mm² 2 core swa.

 

[securespark]

Hence mentioning the additional earthing conductor.

Can you imagine the bend radius of SWA that big?

 

[Paul_C]

Running a suitably sized earth is by far the better arrangement than the combination of adopting inferior TT and having what are effectively two separate earthing systems within the same installation though.

 

[ColJack]

or just run 3 core.. unless it's already bought and run ( does say "running" )