PME and TT?

[Mattja]

Just checked the L-N loop at a fusebox and got a reading of 0.12ohms (great! ), so going to call up and try to arrange to get a PME system put in. Anyway I was just going though 5.4 regs and didn't spot where (assuming it's in there) it says if it's ok to have both PME and TT earth connections (going to the same CU), anyone else familiar with this or found it in the big book?

Basically do I need to get rid of the connection to that earth rod, or just hide it while the guy is on site to install the PME?

Little background on the place: it's currently got a whooping 800 odd (something up there, why count rotten eggs?) earth reading on a TT that as far as I can tell is a rod buried in mostly builders rubble. Sure that's still well under the 1667ohm mark, but of course there's no rcd in there and 850ohms on an rcd is still rubbish. The ground is so bad putting more rods in would be like throwing **** at a fan, long back-breaking ****s at a hard dry fan.

 

[westward10]

Wonder what the Ze (as is) was then?

I can only assume it is the 800 ohm figure he quotes.

 

[Midwest]

I can only assume it is the 800 ohm figure he quotes.

Arrrgh, re read OP again and bit clearer, thought he had DNO earth AND earth rod. See wot he's saying now. Told you I was easily confused

 

[Leyland30]

The earth rod sounds like it's stuffed. Bs7671 suggests anything over 200 ohms will be unstable.
Is a pme available if the system was previously TT?
Abscence of rcd is concerning.

Tread carefully Mattja - let us know how you get on.

 

[Leyland30]

The earth rod sounds like it's stuffed. Bs7671 suggests anything over 200 ohms will be unstable.
Is a pme available if the system was previously TT?
Abscence of rcd is concerning.

Tread carefully Mattja - let us know how you get on.

 

[sparksburnout]

The earth rod sounds like it's stuffed. Bs7671 suggests anything over 200 ohms will be unstable.
Is a pme available if the system was previously TT?
Abscence of rcd is concerning.

Tread carefully Mattja - let us know how you get on.

Mattja..........Mattja!!! Helloooooo!!!!!! I guess hes going to get back to us later?

 

[Mattja]

Sorry guys stopped getting notifications that people were still replying to this for some reason! Anyway yeah issue was settled, got the ukpowernetworks guy coming over later in the month to provide a PME, since I had just 0.12 ohms on the L-N loop that should fix the earthing nicely.

I'm just going to show up early on the day before he gets there and hide the wire to that old rod, so he doesn't think there's an adequate earth and skip the job (which there isn't obviously, but if he sees the wire and is of the mindset that earth rods are magic...).

 

[Des 56]

Hiding a wire to a rod seems to be completely pointless

The supplier will either have Pme available or not and they may or may not charge for their services
Having no earth visible will not make the slightest difference

If they see no earth at present and decided Pme was not available,the lack of any earthing facility will still not be their problem

 

[test electrical]

All they do is put a link in the cut out between N & E and do a ZE.It depends how far away the transformer is away and the cable type size etc is.You can do it your self putting the link in on your side of the meter and testing ZE. If its above the maximum permitted value, you could end up paying for a new service ie new cable or digging your way to a good earth.Its happened to me years ago in the sticks were the builder had to dig a 20 meter run because the house was on sandy soil. Ended up with just running in bare copper cable and two spikes.
Nightmare hope your not to remote and will depend on who's the DNO so and the engineer on the day.

Good luck

 

[Mattja]

Cheers, but fairly sure I'm in the clear for the maximum permitted reading of 0.35, as the first thing I did upon discovering the dodgy old earth was check the L-N loop and it came out as 0.12

I guess the final question is: do these DNO types prefer cake or biscuits?