PME & TNS supply in same building

[interlude]

Hello all,

Have been doing some work in a large building complex, the original building has a TNS supply but the large extension to the building has a seperate PME supply.

At present there are no main protective bonding conductors to water/gas/oil and these services are common to both old and new parts of the building. If these MPB conductors are taken to one of the origins (PME for example) I'm imagining that will cause issues by mixing two Earth potentials (PME potential on pipe work and TNS potential from cpc's). Have been looking through the BGB but can't find an answer to my question. Any ideas?

 

[Farmelectrics]

Re: TNCS & TNS supply in same building

take the earths of the gas and water back to the buildings own incoming supply how would you get them mixed up

 

[telectrix]

Re: TNCS & TNS supply in same building

IMO, if the extraneous parts are common to both areas, then you must combine the earthing arrangements . you don't want a pd between the 2 earthing systems. you could dis. the TN-S and connect the whole system to the PME.

 

[driverman]

Re: TNCS & TNS supply in same building

When new supply applied for, did the DNO know that it was to remain as one building? Is having 2 supplies in one building OK? 2 x points of isolation.

 

[Knobhead]

Re: TNCS & TNS supply in same building

The fun and games will start if the two supplies are on different feeders/transformers. It could cause quite bad circulating currents. Have a word with the DNO.

 

[SPARTYKUS]

Re: TNCS & TNS supply in same building

Whats that Tel? Dis. The TNS??? The mother, the king, the queen of all earthing???? :laugh:

 

[interlude]

Re: TNCS & TNS supply in same building

When new supply applied for, did the DNO know that it was to remain as one building? Is having 2 supplies in one building OK? 2 x points of isolation.

I don't know when the extension was built, but I believe that this is a question that surely should've been raised at the time.

The fun and games will start if the two supplies are on different feeders/transformers. It could cause quite bad circulating currents. Have a word with the DNO.

There is a substation on site, coincidentally the SSE where there on Wednesday with temporary backup generators as they were shutting down the onsite substation for ongoing works in a neighbouring village. I'm pretty sure that both supplies are coming from there.

Either way, I agree that they need to be contacted.

 

[Knobhead]

Re: TNCS & TNS supply in same building

I don't know when the extension was built, but I believe that this is a question that surely should've been raised at the time.



There is a substation on site, coincidentally the SSE where there on Wednesday with temporary backup generators as they were shutting down the onsite substation for ongoing works in a neighbouring village. I'm pretty sure that both supplies are coming from there.

Either way, I agree that they need to be contacted.

If it’s a transformer dedicated to what I assume is an industrial estate, I’m surprised it’s a mix of TN-C-S and PME. That said they could be on separate feeders from the transformer feeder pillar installed at different dates.

What is the rating of these supplies?

Before you do anything talk to the DNO. You’ve decided that anyway.

 

[Knobhead]

Re: TNCS & TNS supply in same building

IMO, if the extraneous parts are common to both areas, then you must combine the earthing arrangements . you don't want a pd between the 2 earthing systems. you could dis. the TN-S and connect the whole system to the PME.

I’m surprised at you for suggesting that Tel.

 

[netblindpaul]

Re: TNCS & TNS supply in same building

Is it PME or TN-C-S?
Does it have a PME label?

 

[Knobhead]

Re: TNCS & TNS supply in same building

Both from what the OP says. Two supplies.

 

[ImpededLoop]

Re: TNCS & TNS supply in same building

The first post seems to say the two supplies are TNS and PME.

 

[interlude]

Re: TNCS & TNS supply in same building

Is it PME or TN-C-S?
Does it have a PME label?

Sorry for the confusion, put TNCS in thread title but it has PME label at intake.

 

[Knobhead]

Re: TNCS & TNS supply in same building

The tread title says something altogether different ? ? ? ?


I give up!

 

[netblindpaul]

Re: TNCS & TNS supply in same building

Quite Tony, there are still some that assume that TN-C-S = PME!