Pme installations in 18th edition with additional rod.

[David Rann]

It's proposed in the 18th edition that any new pme installation is to have a rod added by the electrician that has has a resistance of 30ohms or less. What are people's thoughts on this? My main concern is the amount of services that are going to get hit with everyone driving rods in.....also my lowest reading on a rod ever was 40 ohms which I thought was good.

 

[123]

Is it earth electrode for TNCS or for all TN systems that's being proposed?

 

[Risteard]

Presumably any TN system.

 

[stevethesparks]

What worries me is how are we going to quote on that?

 

[KEV 1 N]

last year on a gypsy site, i got 30 ohms on a 1m rod (sandy soil). when i had fitted 6 rods, one at each pitch and all linked with the SWA armour and 3rd core cpc, total Ra /Ze was 5.2 ohms.

Bet all the rods have been pulled out now!

 

[Deleted member 9648]

My feeling is it wont happen. There are simply too many buildings where the installation of an electrode is not practical due to location and the risk of hitting unknown services. In my area recently a 2 mtr coupled rod got 186 ohms, achieving 30 ohms would have been a mission on that bit of ground.

 

[Des 56]

So when the new earth rod stubbornly stays well over the 30 ohms,the guidance will then explain,in detail, how we tell the client why we are removing that shiny socket we just installed

 

[Deleted member 26818]

Not hard to get below 30 ohms on TN systems.
Just hook the rod up to the incoming Earth conductor.

 

[Leesparkykent]

Doesn't it also say something along the lines of for new buildings earthing of the foundations should strongly be considered...so a connection to the rebar/metal grid before the concrete goes in. Could be one way of achieving a low RA I suppose. I think if it stays in the Book when published it will be written as strongly advise/consider....Then they will try and enforce it in later editions of the 18th.

 

[Gavin John Hyde]

I wouldnt at all be surprised if come the 2nd release of the 18th edition we will stop a lot of this European conformity stuff as by then we will be out of the EU, I agree with @Leesparkykent though that this is going to have exceptions and considerations galore that will mean its not enforceable as it stands too many ifs and buts... but given 7671 is not legally binding and advisory could we not do individual risk assessments? I do not see how the industry are going to convince homeowners that they need a rod before you can sign the certificates off when doing a job... If it gets to that stage i am buying rods in bulk and setting up shop as a wholesaler... .
Down side is that you will get your local transient community and junkies pulling them up for scrap value when not put in well.

 

[snowhead]

we will stop a lot of this European conformity stuff as by then we will be out of the EU,

No we won't, don't mix up E.U and European.

We'll still be in all the European agreements for standards, they're nothing to do with the Economic Union.

 

[Wilko]

If it ends up that a new PME must have a 30 Ohm or better rod, I'm guessing many places won't be able to achieve it and would have to refuse DNO earth and fall back to TT ? (where your average 100 Ohm rod is perfectly ok) Doesn't really seem like a forward step to me ... Or have I misunderstood?

 

[Gavin John Hyde]

No we won't, don't mix up E.U and European.

We'll still be in all the European agreements for standards, they're nothing to do with the Economic Union.

Point taken. Its hard to know where the EU stops and other agreements start these days.

 

[Midwest]

As the draft has been closed, I can't verify, but I do recall the proposal of adding earth rod to supplement any earthing supplied by a DNO (542.1.201). And I think it related only to PME supplies, but I might be wrong there. There is also a proposal for foundation earthing in new builds (542.2.2).

Or did I just wake up in a cold sweat from a nightmare

Edit; those reg numbers are from some notes I made when reading the draft, so don't quote me on them!

 

[Ian1981]

As the draft has been closed, I can't verify, but I do recall the proposal of adding earth rod to supplement any earthing supplied by a DNO (542.1.201). And I think it related only to PME supplies, but I might be wrong there. There is also a proposal for foundation earthing in new builds (542.2.2).

Or did I just wake up in a cold sweat from a nightmare

Edit; those reg numbers are from some notes I made when reading the draft, so don't quote me on them!

No it’s applicable or maybe in this case , to any TN system were the supplier has provided an earth.

 

[Deleted member 26818]

Is this not just where PME conditions apply?
Can't actually see why a rod would now be necessary for TN-S.