TNCS & TT system’s mixed in same building

[cliffed]

What’s your thoughts on this both systems are accessible & contact could be made between metallic service‘s, been in service-for ages & only spotted on an EICR

 

[timhoward]

Mixed, how? More info needed.
i.e. is it earth rods connected to TNCS, or two entirely separate earthing systems that could be touched at the same time?

 

[cliffed]

Mixed, how? More info needed.
i.e. is it earth rods connected to TNCS, or two entirely separate earthing systems that could be touched at the same time?

Two different earthing systems either end of building & yes they can be touched @ the same time

 

[timhoward]

Two different earthing systems either end of building & yes they can be touched @the time

I wouldn't be happy.

 

[cliffed]

I wouldn't be happy.

Nor am I …. Would you actually link the 2 Earthing systems together
Knowing the Zs would be lowered on the TT System
Maybe no difference to having TT & TNCS in close proximity of each other or accidentally linked
The other option would be to disconnect the REC TT supply & reinstate with sub main from the TNCS … no idea the work’s involvement in that

 

[davesparks]

It is very wrong and should never have been left like that.

Do you have any idea why there is a TT system installed? Is there a part of the installation which is unsuitable for connection to a TNCS earth?

You can't just connect the two earthing systems together as you could be introducing a potential danger by having a TNCS earth present in a location it shouldn't be.

 

[cliffed]

It is very wrong and should never have been left like that.

Do you have any idea why there is a TT system installed? Is there a part of the installation which is unsuitable for connection to a TNCS earth?

You can't just connect the two earthing systems together as you could be introducing a potential danger by having a TNCS earth present in a location it shouldn't be.

Thinking the 2 buildings were separate @ some time, then linked with building works making into 1 building
Agree on the danger if being linked with Earthing
THE other option would involve the REC to convert to Tncs…or leave it like it’s been & reported over decades

 

[davesparks]

Thinking the 2 buildings were separate @ some time, then linked with building works making into 1 building
Agree on the danger if being linked with Earthing
THE other option would involve the REC to convert to Tncs…or leave it like it’s been & reported over decades

DNO's will not normally provide 2 TNCS earth connections to the same building as that can cause all sorts of problems with diverted neutral currents through bonded metalwork.

 

[cliffed]

DNO's will not normally provide 2 TNCS earth connections to the same building as that can cause all sorts of problems with diverted neutral currents through bonded metalwork.

Ok maybe disconnection of the TT supply