no mixing of earths?

[topquark]

What is the problem if you two types of earthin system in one building?

Which one would you use for any bonding of the metal in the barn? You have two possibly differing potentials. The situation could be made even worse if the supplies are on differing phases as well.

Safest option has to be to TT the barn.

 

[Engineer54]

Which one would you use for any bonding of the metal in the barn? You have two possibly differing potentials. The situation could be made even worse if the supplies are on differing phases as well.

Safest option has to be to TT the barn.

Going by the OP's description of the Barn build, it's probably is a TT system in it's own right!! The problem being, is isolating the two differing earthing/bonding supply types. This is a DNO's total cock up, and it's they, that should be sorting this problem out, especially if these two supplies come from separately derived TX's....

 

[topquark]

Going by the OP's description of the Barn build, it's probably is a TT system in it's own right!! The problem being, is isolating the two differing earthing/bonding supply types. This is a DNO's total cock up, and it's they, that should be sorting this problem out, especially if these two supplies come from separately derived TX's....

Good point mate, hadn't thought about the frame itself effectively TT'ing it.

 

[jason121]

If there of the same trany shirly it wont matter go with the best eath path ie TNCS

 

[moggy1968]

it's the potential(?) for introducing different potentials in the same building.

I had this in my parents business when they expanded into a shop next door, one was TNS, one TCNS and the DNO put them both onto TNCS

 

[jason121]

isnt that the answered to this thread

 

[PeteC]

thanks all for your comments!

SMA17000TL meets DIN VDE 0100-712 and does not require B type RCD fault protection, but if RCD required 100mA per inv. min, because of differential currents. As a barn 300mA max.

It could be the DNO need to address their supplies~ there is a good IEC thread in progress on PNB TNS supplies. But even if both supplies come from the same Tx then they should still need earth systems seperated? maybe that's a DNO call.

If both became TT then what means to earth? The bonded array to the structural framework certainly could have a low Ra. If low enough then I could seek permission from the building engineers to use?