TT Earthing using DNO Rod at Transformer??

[bmines67]

Hi Guys, I was called out to a house in the countryside to do a shower replacement. The homeowner had already got the plumber to install the new shower, (an 8.5 kw to replace a broken 9.5 kw model) and wanted me to connect the shower an issue a Minor Works Cert.

I do all my tests on the wiring (6mm T+E fed from a 32amp type B MCB protected by a 30ma RCD) and everything seemed normal. R1+R2 is 0.13 ohms, Insulation Resistance is 500M.

I turn power on and check the EFLI and it turns out to be 0.54 ohms?? This is strange i think on a TT, so i look at the service head, no earth connection. 16mm earth from the Consumer Unit to a Henley block in the meter cabinet, and a 16mm earth going into a duct and underground. No sign of any earth electrode??

I do a Ze and it is 0.47 ohms. So i ask the homeowner if he knows the position of any earth rods and he tells me "the ground was too rocky, so my father-in-law connected the earth to the earth at the pole"

I've not come accross this before and dont know how to proceed so any opinions or advice would be appreciated.

 

[Leesparkykent]

Does it have it's own dedicated transformer mounted on the pole?

 

[davesparks]

Call the DNO and get them out to sort it out.
There may well be a very good reason they did not make their earth connection available to the consumer so making a DIY connection to their transformer's earth is not good!

 

[uksparks]

I have seen the very same thing in a house in a village not to far from here, they were on the end of a run in the middle of nowhere, tranny on the pole, earth connected to the pole, I just called the DNO and they sorted it.

 

[bmines67]

Does it have it's own dedicated transformer mounted on the pole?

Yes Lee, it has it's own transformer on the pole. There are no houses nearby.

 

[bmines67]

I just called the DNO and they sorted it.

When you say they sorted it, what exactly happened? Did the provide a PME connection or did they just disconnect the diy connection and tel you to TT the installation?

 

[uksparks]

Yes they just did a PME which is what I presumed they would do.

 

[malcolmsanford]

DNO's are now supplying overhead PME systems to rural areas providing a stable earth for customers. These are easy to spot following the line of the overhead poles and at about every 3rd pole you will see an earth coming down the pole into the ground.

The earth though is the property of the Network provider and can only be issued with there permission. After all ithey have to guarantee it's stability to the ESQCR. So your FIL "nicking" the earth is not a goer.

You will have to contact the DNO before they find out to be honest.

 

[mhar]

Are you sure it isn't pnb? A quick earthing enquiry of the dno should be your first port of call

 

[Leesparkykent]

Are you sure it isn't pnb? A quick earthing enquiry of the dno should be your first port of call

That what I was thinking but the rod should be adjacent to the property/head if it's PNB.

 

[mhar]

I have only encountered pnb once, in similar circumstances as described in the opening post. I couldn't see where the earth was taken to. For the sake of a quick call to the dno a lot of speculation could be avoided

 

[GEOFF S]

You need to contact the DNO, the TX will be either hot or cold with regards to earthing, you could see some dangerous voltages on your installation if a fault on the TX occurs.

Cheers