Earthing from over head lines...

[infinity]

Need to do some work on a house, detatched with overhead lines supplying it.

There is a cut out in meter cupboard then tails inside the house to an RCD or ELCB, then into ccu.

There is no earth present just the tails going throught the RCD in the CU.

My question is.. How can i tell what the earthing system is supposed to be? I need to add a garage unit for solar should i earth stake it? i need to add bonding as its non existant so i could also add that to the stake earth but i dont want to add a potential difference between the earths. There is no existing stake.

Could the earth be taken from the neutral in the ccu to act as a PME type system?


Not come across this before so any help much appreciated.

 

[Silly Sausage]

I thought it had been raised, I’m bared!

No, definitely lowered Tony.

You're too big to get under it now! :crazy:

 

[Engineer54]

Do you want to have a think about that for a minute?

I've had a think about it, so how Do you get an earth Ze value at the cut-out/CU ?? You can get a neutral Ze, but nothing to compare it with, the installation doesn't even have any services bonding in place....

 

[Engineer54]

a good majority of the supplies up here are from over head lines and they are mainly TNCS ,occaisionally TT ,this may be a silly question but have you done a Ze , I bet the RCD you are talking about is an old brown one if im not mistaken they were outlawed in a change of the regs back in 1984 or around that time as jason has said contact the DNO for advice

I doubt it, they needed an earth connection to work!!

By the way, they aren't outlawed, they just have a recommendation to be changed for a current operated unit. They were never that reliable in general terms, but in certain conditions they worked pretty well, and some are probably working pretty well. The main trouble with them, were that parallel earth voltages set them off...

 

[adben]

Infinity, you had encountered a TT system (same to as we say multi-grounded system from the country I came from). Refer to your Electrician's Guide (updated to 17th ed, Chapter 3, it illustrates clearly the things you want to know.

 

[Spudnik]

I've had a think about it, so how Do you get an earth Ze value at the cut-out/CU ?? You can get a neutral Ze, but nothing to compare it with, the installation doesn't even have any services bonding in place....

If you test between line & earth, this would give you an indication that PME could be available.

 

[WPD Lad]

Where are you based? If you're mids just give WPD a ring and we'll pop out and tell you. Most of our lines are TNC-S, post a pic of the cutout!

 

[Engineer54]

If you test between line & earth, this would give you an indication that PME could be available.

That was the point, there is no earthing available anywhere to test!!

 

[WPD Lad]

That was the point, there is no earthing available anywhere to test!!

Can't rule out PME without seeing the cutout

 

[Engineer54]

Can't rule out PME without seeing the cutout

Don't think i've mentioned ruling out the possibility of a PME connection at the cut-out!!! That can easily be ascertained by contacting the local DNO. Doesn't stop a TT system being installed in the meantime, ...in fact it's a good idea to have another rod on a PME system earth at the installation.

 

[Spudnik]

That was the point, there is no earthing available anywhere to test!!

AAArrggghh!!! I meant line and neutral!!!

 

[infinity]

AAArrggghh!!! I meant line and neutral!!!

Yes i knew what you meant.
Just to clarify ( which is why the OP looks odd) the visit to property was late yesterday, i had no time to start testing etc so was physically just a visual.Which is why i asked as someone may have just had a simple answer i was unaware of.


I know once there i can figure it all out and il call the DNO as its SSE here and they are pretty good.

WPD Lad: the cut out is the same used for TNC-s with the neutral block on the side with room for earthing!

 

[Golden_Boy]

Had this about 3 months ago, overhead lines coming into property - 1 cable, just like pme, looking down the street every 3rd or so pole had earth cable coming down it, looking like pme, there was a 16mm earth at the cut out that went inside to the consumer unit, but not connected at either end, there was and old earth stake which was connected, so i'm thinking here we have an old TT installation, that the overhead wiring has been converted to pme but the house has not been, phoned e-on and got directed and re-directed, listened to lots of pretty music whilst "on hold" and the answer??? "we dont actually know what type of wiring we have in that area" !! jesus christ!!! suffice to say even though there could have been a lovely low pme Ze to be had, i left the installation as a TT because at least that way i could confirm the earth arrangement!!


So can sympathise with OP, cause sometimes things aint what they may seem, could be TT could be overhead pme, but obvious lack of any earth would dictate to rod it and TT it, oh and the DNO??? i dont know why people say to call them, next to useless advice in my experience

I rand my DNO just to find out what they would say when asked about earthing arrangements at my own home ( Its TT ) .. after being on hold for ages I WAS TOLD THAT MY SPARKS WOULD KNOW THE ANSWER....

 

[supasparxs]

Cant beleve how many electricians rely on a internet forum to carry out their jobs correctly

hmm what is the purpose of this forum, if we can't post our faults and ask advice from our faults and problems.....

 

[supasparxs]

only on a weekend mate,im steve through the week.:ninja:

it's Sunday ATM,
so we'll call you Sharon from now on

 

[alarm man]

it's Sunday ATM,
so we'll call you Sharon from now on

no comment:blush5:,i cant type anyway with me false nails on..

your on the list supa..:icon10: