Hi guys
Im after some advice on an installation im doing some work on. The installation has 2 supplies into the same building. The supplies are side by side and both TPN, one 300A and the other 200A. They are TNCS and supplied from the same tx although im unsure if its PME or just TNCS as there is no sticker and the tx is literally a few meters away.
My concern regards the earthing. Each supply's meter cabinet has a terminal on the side for connection of an earthing conductor. One supply has an earthing conductor present that runs to the buildings local structural steelwork. The other supply cabinet has no earthing conductor present although there is a lugged 'wire rope' connected to the terminal which disappears underground with the supply cable and is obviously something to do with the DNO. It could possibly be the old remnants of a TNS supply i guess. There is no MET at all for the installation. There is one set of (undersized) bonding in place which also runs back to the structural steel.
It appears therefore that the install is only using the earthing conductor of one supply via the one cabinet. Supplies can be simultaneously touched at many parts throughout the install. Steel nature of the building means the earthing of everything is effectivelly all connected together anyway. All Zs readings fine. But this surely isn't right and the whole setup comes across as a lash up with no thought or regs in mind.
So, is this something i really need to take up with the DNO and request an engineer visit? In my experience they are generally hard work. Has anyone any suggestions as to the solution? I think both supplies would require bonding together. Would this be best achieved with a single MET with 2 earthing conductors run to it (one from each supply) or is it better to have 2 MET's (one for each supply) and then connect these together with what would probably be a decent size cable.
Its a situation ive never come across and as im replacing a couple of DB's and moving some circuits about, i feel obliged to sort the earthing out as i have scope to do this. Appreciatte the view's on this (long) post guys.
Cheers.
Im after some advice on an installation im doing some work on. The installation has 2 supplies into the same building. The supplies are side by side and both TPN, one 300A and the other 200A. They are TNCS and supplied from the same tx although im unsure if its PME or just TNCS as there is no sticker and the tx is literally a few meters away.
My concern regards the earthing. Each supply's meter cabinet has a terminal on the side for connection of an earthing conductor. One supply has an earthing conductor present that runs to the buildings local structural steelwork. The other supply cabinet has no earthing conductor present although there is a lugged 'wire rope' connected to the terminal which disappears underground with the supply cable and is obviously something to do with the DNO. It could possibly be the old remnants of a TNS supply i guess. There is no MET at all for the installation. There is one set of (undersized) bonding in place which also runs back to the structural steel.
It appears therefore that the install is only using the earthing conductor of one supply via the one cabinet. Supplies can be simultaneously touched at many parts throughout the install. Steel nature of the building means the earthing of everything is effectivelly all connected together anyway. All Zs readings fine. But this surely isn't right and the whole setup comes across as a lash up with no thought or regs in mind.
So, is this something i really need to take up with the DNO and request an engineer visit? In my experience they are generally hard work. Has anyone any suggestions as to the solution? I think both supplies would require bonding together. Would this be best achieved with a single MET with 2 earthing conductors run to it (one from each supply) or is it better to have 2 MET's (one for each supply) and then connect these together with what would probably be a decent size cable.
Its a situation ive never come across and as im replacing a couple of DB's and moving some circuits about, i feel obliged to sort the earthing out as i have scope to do this. Appreciatte the view's on this (long) post guys.
Cheers.
