The house we are buying is supplied by OVO, there is an electrical report saying it needs converting from TT supply to TNCS (PME) due to high reading and need to contact OVO for this. I don't really understand what these means but something to do with earth loop impedance and I am guessing safety cut outs? Are there options for us, does it need a full rewire, I've tried to google it and seems suppliers are often unable to help? Is there some way to check if OVO can upgrade the old tt supply?
Thanks for any advice
Best answer by Transparent
Firstly I'm not surprised there are earthing issues near your new home. The supply is from overhead wires and Western Power have already installed four additional earthing points on the 440v (3-phase) Feed running along Richmond Road from the sub-station in Manor Brook Close (Reference 93/7855).
For the sake of others reading this, the ELI which Hannah refers to is Earth Loop Impedance, and is a measure of how much resistance there is to electricity trying to flow to ground in the event of a fault within the home. It needs to be low enough to ensure that a safety trip will function. More info in this guide.
There's more detail about the range of acceptable values over here on the website of Professional Electrician. A reading of 24Ω is high for a TT system, but I'm not sure on what basis there has been a recommendation to use PME (Protective Multiple Earth) instead.
My house is TT and, when I bought it, had an earthing system dating from 1960's and was clearly "non-compliant". However I worked alongside a local electrician to solve the problem, and we fitted two new earth rods about 3m apart adjacent to a position where the soil was permanently wet.
Safety within the house will be provided by an RCD (Residual Current Device). This trips out when there is too great an imbalance between the current leaving the live connection and returning via the neutral. So it would operate even if the earth connection was iffy.
Hannah - you mention RCD unit(s). But you haven't confirmed whether you know if any are fitted. Since you don't yet own the property I'm assuming you can't post a photo of the consumer-unit here yet.
I'm still surprised that your solicitor hasn't requested that this be resolved by the vendor as a condition of your purchase. Perhaps you've already haggled all you can out of them!
If you want to talk to Western Power themselves about changing the connection to your new house, telephone their Contact Centre on 0800 096 3080 (Mon-Fri 08:30-17:00). They would normally start by asking for the Meter Number (MPAN) which I guess you don't yet know.
If you already know anyone in the area of Ibstock/Coalville, I suggest you start asking for recommendations of a good local electrician. Ideally you want a tradesman who relies on his reputation to provide ongoing business.