My new abode is currently TT with a reported Ze of 190 ohms. It's sitting on granite and the prospect of driving in multiple rods is not particularly appealing (which, presumably, is why we haven't been able to locate from the previous owner). I've contacted WPD and they confirm that PME is available. Is there any reason why I would not accept it? (Apart from the fact that WPD want to charge £163.03 whereas my previous DNO did it for free!) We're very rural and the supply is overheads with a pole mounted tx in the garden.
Firstly does the 190 ohms cause you any problems ? You may not need to do very much assuming RCDs and so on are operational.
If there is no discernible earthing, it may be using water pipes and so on, but then actually I'd expect a lower figure, though it may be at least partly the electrode at the pole pig transformer that is contributing to the reading. I presume the transformer is not just for you - if it is it will end up as PNB anyway. Can you see how that earthing is done ?
I suppose drilling an electrode in is not funny, and probably pointless, but is there no soil cover at all ? A J" bent electrode or even one laying sideways in a trench can still be quite effective.
Unless you have outbuildings or plan to have an electric car you want to charge on the drive, then converting to PME makes sense in terms that writing a cheque is less work than installing an electrode..
Succinct as ever Mike! I found the writing of cheques easy work, it was the next bit that got tricky. I was asking as I seem to remember JP being critical some while ago and that he put a rod in with his PME system.
Nice one Andy but a life spent peering under other people's floorboards doesn't give rise to swimming pools, stables and electric gates! Sadly!
Presumably if the Tx is in the garden then their earth electrode is as well, it might even be by the wall of the house, so there might not be much separation between the DNO earth electrode and installation rods anyway.
When ground conditions prevent driving of earth rods, I have achieved good results by use of bare copper earth tape buried in a trench, the material used fir lightning conductor down leads.
A reasonable length gives a good low resistance connection, much better than burying a short rod.
In the case of extending a TT system to an outbuilding via buried SWA , a copper tape buried at the same time serves the dual purpose of an earth electrode, AND a substantial bonding conductor that will handle any diverted neutral currents.
Thanks Broadgage, I did ask in an earlier post if adding an earth tape in the trench I was digging for the submain to the garage would be a good idea but I felt that received a luke warm response.
So where am I now, take the PME, take the PME and and run the tape or ignore PME and improve my TT with more rods or tape in trench.
