Exported earth

[Apache]

Here now!TNCS on an overhead and no-one has noticed an issue with this?!

I have overhead PME!

I like the idea of TT the whole lot, the argument for why makes a lot of sense!

 

[Larnacaman]

Nothing to stop anyone putting a rod in and connecting to the MET at the origin on a PME system,......insist on it in some countries!!! Far better than relying on a rod for the whole installation, ...now that IS a fact!!!

But then i'm not afraid of shadows, so never listen to the scaremongers that worry about things, that in reality stand little chance of ever happening....

 

[steptoe]

You sure that its allowed to mix earthing systems,? That to me under UK regs would simply be asking for trouble. !

 

[Larnacaman]

Well that's basically what the old boards used to do when they converted all the old TT systems to PME, they left the original rod connected to the CU or MET, ..so you tell me?? All this scaremongery of a PME supply is old hat now. Replacing it for a TT system on the other hand, ....now that IS scary!!!!

And on that note, time for bed ...lol!!!

 

[ADS]

Nothing wrong with 'rodding' the PEN conductor at the incommer - you wouldn't rod the installation 'earth', though, ( i.e. the EMT of the second building), and still have it connected to the PME supply 'earth'.

 

[binky]

Some exra info - there are two phases of supply, and judging by age of installation I would say this is TT conversion to PME (most of the DBs also have RCD incomers). Given the pipework which is 35mm copper running between the 2 buildings which are only 5m apart I think I want to stick to one earth system for both buildings. I will be checking continuity between buildings on my return to site just to check continuity which i suspect will be very low. Given the above I think I will install a couple of nice earth rods cos the pipework must be an excellent rod anyway:^O

 

[steptoe]

Nothing wrong with 'rodding' the PEN conductor at the incommer - you wouldn't rod the installation 'earth', though, ( i.e. the EMT of the second building), and still have it connected to the PME supply 'earth'.

We are not talking about rodding the PEN conductor though, its SEPARATE when we get it, so we can only rod the E , and only the DNO can rod the COMBINED side.

 

[ianmacd]

Really, Ian.And yet every time we've discussed this kind of thing, (and disagreed ha ha), the 'Rod-brigade' insist that if you TT part of the installation, then this becomes a seperate earthing system and you don't connect the MET of the TT install to the MET of the PME supply install..........GN8 also states this

And 542.1.8 would disagree with that. You have to keep them seperate (not possible with this one and the commin pipework) OR follow 542.1.8 and install a large enough conductor to link the MET to the 'earth marshalling point' in the out building.

 

[ADS]

And 542.1.8 would disagree with that. You have to keep them seperate (not possible with this one and the commin pipework) OR follow 542.1.8 and install a large enough conductor to link the MET to the 'earth marshalling point' in the out building.

Ian, 542.1.8 is to do with 'Earthing' and 'shared' protective conductors of seperate installations - it has nothing to do with 'Bonding', which is a totally seperate issue, as you should well know.

It doesn't matter if 10 buildings share pipework, they can still have seperate earthing systems - the pipework is 'bonded' where it enters the building, to that buildings earthing system, that's how you create an 'equipotential zone' - nothing to do with 'earthing'.

 

[Chr!s]

Nothing wrong with 'rodding' the PEN conductor at the incommer - you wouldn't rod the installation 'earth', though, ( i.e. the EMT of the second building), and still have it connected to the PME supply 'earth'

In some instances its advisable, placing a rod in a suitable impedance will reduce the touch voltage on a broken pen to that below 50v if designed correctly

---------- Post Auto-Merged at 12:22 ---------- Previous post was made at 12:19 ----------

Ian, 542.1.8 is to do with 'Earthing' and 'shared' protective conductors of seperate installations - it has nothing to do with 'Bonding', which is a totally seperate issue, as you should well know.It doesn't matter if 10 buildings share pipework, they can still have seperate earthing systems - the pipework is 'bonded' where it enters the building, to that buildings earthing system, that's how you create an 'equipotential zone' - nothing to do with 'earthing'.

I agree ads, 542 .1.8 has nothing to do with it, any common extraneous conductive part is treated the same as anu other, as you said, you make an equipotential zone

---------- Post Auto-Merged at 12:26 ---------- Previous post was made at 12:22 ----------

And 542.1.8 would disagree with that. You have to keep them seperate (not possible with this one and the commin pipework) OR follow 542.1.8 and install a large enough conductor to link the MET to the 'earth marshalling point' in the out building.

So are you say the pipework forms part of the electrical installation Ian? That would mean your pipe work is now an exposed conductive part?

 

[binky]

It doesn't matter if 10 buildings share pipework, they can still have seperate earthing systems - the pipework is 'bonded' where it enters the building, to that buildings earthing system, that's how you create an 'equipotential zone' - nothing to do with 'earthing'.

This is a very good point, if this was a terrace of houses linked by metal water/gas pipes I wouldn't give damn what was going on next door cos I wouldn't know. However houses don't share electrical supplies so It doesn't seem right to have two different systems off the same supply, but then I've TTed a few sheds and garages in my time so what's the difference? :|

 

[safedepth]

You would need to check with DNO about exporting their Earth. If you TT the barn then you would need to run a 16mm CPC from the Barn's new MET back to the MET in the supply building (reg 542.1.8) if the supply building is still TN-C-S.

Probably easiest to TT the lot as you suggested.

---------- Post Auto-Merged at 22:02 ---------- Previous post was made at 22:00 ----------

542.1.8 may apply to this.

Binky, the last time I rang WPD about exported earths they said since it was on the consumer side of there head they didn't care. Not in a don't give a s..t kind of way, simply weren't concerned as it wasn't theirs.

 

[Larnacaman]

As soon as anyone mentions outbuilding, garage, or shed, and all the old myths are revived and the scaremongers come out to play ...Amazing!!!!

In this case even more so, as the main property and barn have an ''Existing'' PME system and ....blow me down, it's being suggested that a perfectly sound system be ditched, in favour of a bunging in a couple of rods!!!!! Jeezus!!!! Commonsense has surely just left the building...Amen

 

[binky]

Binky, the last time I rang WPD about exported earths they said since it was on the consumer side of there head they didn't care. Not in a don't give a s..t kind of way, simply weren't concerned as it wasn't theirs.

Sounds about right :^O

---------- Post Auto-Merged at 22:26 ---------- Previous post was made at 22:19 ----------

As soon as anyone mentions outbuilding, garage, or shed, and all the old myths are revived and the scaremongers come out to play ...Amazing!!!!In this case even more so, as the main property and barn have an ''Existing'' PME system and ....blow me down, it's being suggested that a perfectly sound system be ditched, in favour of a bunging in a couple of rods!!!!! Jeezus!!!! Commonsense has surely just left the building...Amen

The existing supply to barn doesn't meet requirements for PME. What I am looking for is cost effective correction to problem. What I haven't mentioned is owner is looking to sell and move abroad to retire, ergo unlikely to do more than Code 1s on PIR, which would mean not replacing FTE on catenary wire. Easiest option therefore is to TT barn I wam just concerned about bonding and pipework link between buildings. However in between the arguments I think I can see a clear way forward that meets regs and cost implications.

Thank you all for your input and opinions :Applaud :Applaud:Applaud