Earth Provision - who's responsibility is it anyway??

[sparkybird]

Hi all

Just wondered if I could rack your collective brain about this one. Sorry it's lengthy, but might have implications for many of you!

Recently tested out my system and Ze (External Loop Impedance) came in at 1.01ohms. I'm on a TNS so the regs state the max permissable is 0.8. In addition, my next door neighbours share my earth, so they were also 'at risk' (In fact I have a suspicion that the Ze was only obtained because they have bonding to their gas/water pipes - I don't)

So I phoned the supply company, who came out to retest and just confirmed what I had found (suprise, suprise!). However, on speaking to their engineer, he said that
1. He didn't think this was an unsafe reading (despite the fact that the regs say otherwise, which he admitted)
2. As the company had not supplied the earth, it was not their responsibility to correct it anyway. (When I asked how he knew it wasn't their's, he just said - that's not how we'd do it)

His advice to me was to put up with the reading or install an earth rod in my garden (I live in central London and doubt whether I'd get any better Ze). I also don't want my lights on and RCD

This is not the first time I have come across this - and it's p*ssed me off as basically I think the supply companies are passing the buck either back to the consumer or to their electrician. Is this as a result of privatisation/deregulation??

Has anyone else encountered this? How did you get it resolved (if at all??)

SB

 

[securespark]

I come across dodgy main earth connections all the time: I should post some photies, but keep leaving my camera in the office!

If I have to work on an install with a dodgy connection, I just ask the householder to ring the provider and ask for the connection to be made good. If the provider kicks up a stink, I ring them and tell them they have a legal responsibility to provide a sound earth connection (providing it is not TT).

It used not to be their problem, but now they have a responsibility to provide an MET.

Usually, the dodgy connection is made with an EC14 (usually loose!) on the sheath of the cable so they sweat a braid onto the sheath, terminating it in a 3 or 4 way block.

You can imagine their response when you say OK, then, I'll just tighten up this earth clamp........

Can you post a piccy?

 

[mapj1]

The electricity regulations supply have been updated in 2002, so
and the supplier must make an earth available if he can do so safely.
But 'safely' is open to interpretation. If it is open circuit they should correct it, if it is so high resistance it cannot blow their service fuse in reasonable time, they should correct it. The rest depends on how well you can shout down a 'phone and threaten legal action, sadly you are probably in that grey area.
good luck Mike.

Statutory Instrument 2002 No. 2665
The Electricity Safety, Quality and Continuity Regulations 2002

and

Equipment on a consumer's premises
24. - (1) A distributor or meter operator shall ensure that each item of his equipment which is on a consumer's premises but which is not under the control of the consumer (whether forming part of the consumer's installation or not) is -
(a) suitable for its purpose;

(b) installed and, so far as is reasonably practicable, maintained so as to prevent danger; and

(c) protected by a suitable fusible cut-out or circuit breaker which is situated as close as is reasonably practicable to the supply terminals.
(2) Every circuit breaker or cut-out fuse forming part of the fusible cut-out mentioned in paragraph (1)(c) shall be enclosed in a locked or sealed container as appropriate.

(3) Where they form part of his equipment which is on a consumer's premises but which is not under the control of the consumer, a distributor or meter operator (as appropriate) shall mark permanently, so as clearly to identify the polarity of each of them, the separate conductors of low voltage electric lines which are connected to supply terminals and such markings shall be made at a point which is as close as is practicable to the supply terminals in question.

(4) Unless he can reasonably conclude that it is inappropriate for reasons of safety, a distributor shall, when providing a new connection at low voltage, make available his supply neutral conductor or, if appropriate, the protective conductor of his network for connection to the protective conductor of the consumer's installation.

(5) In this regulation the expression "new connection" means the first electric line, or the replacement of an existing electric line, to one or more consumer's installations.

full text here http://www.opsi.gov.uk/si/si2002/20022665.htm#8

 

[sparkybird]

Here's the pic securespark (sorry it took so long, I'm not very web wise!)

Oeer - that came out a bit big!

Anyway, the big cable on the right is the supply, which comes into my house. The earth clamp around this is rubbish as none of the outer sheathing has been stripped back. The green sleeved conductor is my main earth. The group of bare copper conductors are actually next door's main earthing conductors. The newer cable on the left hand side is next door's supply, which comes out of the big black 'box' into which mine goes. I guess at some time we shared a supply which has now been split...?

My argument is that is next doors were given this new supply didn't the company have a duty to provide them with a safe earth? Which they clearly didn't, as they are just relying on my rubbishy one.

I'd also be interested to know what Ze readings are likely for a TT system in central London if anyone has this info.

Hope you can help
SB

 

[JonB]

I have just had a new supply installed for the very same reason, old cloth covered cable no earth and fed from next door, at no cost to us.

JonB

 

[sparkybird]

JonB - that's interesting - did they supply your neighbours at the same time for free?
SB

 

[plugwash]

iirc they aren't allowed to feed from one house to another like that anymore so if someone complains they have to rectify it.

 

[Nige F]

Guys, does that aply to overheads too......can`t supply from one house to next...because a friend has just that setup and wants his incoming moved for an extension...thought the buggers would charge a fortune..

 

[JonB]

Sparkybird,

No just disconnected us from them.

JonB

 

[mapj1]

A normal 4 foot by 3/8" TT earth rod, driven into damp soil, will typically give 20 to 100 ohms depending on time of year and salt content. If the soil dries out, or the rod corrodes away, it could be in the high hundreds.
AFIK the 0.8 ohm figure for TN-S is not a regulation limit, it is just a value that can be assumed if no contrary information is available. It is what they usually tell you if you ring up to measure 'by enquiry', and they have no measured figure.
Trying to lower 1 ohm to <0.8 by hammering in extra rods in shunt is likely to be very tiring, as you will need many (perhaps 20-50 !! )of them, and probably cannot get them the rod length or so apart required for parallel combination of resistance, before you run out of land.
300mA RCD for the lights, and call it TT?
BUT 1.1 ohms will meet the disconnection times OK for 6A breakers, and even 16A type B, so only the ring main and showers etc will need to be on RCDs to meet the disconnection time - perhaps no bad thing anyway?

 

[sparkybird]

Thanks for all your replies folks, makes for interesting reading.

Plugwash - so maybe I should get my neighbours to complain, and at least they might then get their own supply, with proper earth.

Mapj1 - the earth loop at my sockets is too high, although this might be to do with my oldish wiring, but the higher than normal Ze ain't helping (I've downrated to 16A for the meantime and will be replacing the ring at the weekend). I'm more worried that the main earth is so rubbish that the Ze reading we are getting is actually due to my neighbours bonding (ie to gas and water pipes) but without messing around with them I can't establish this. If this is the case though, I feel a bit vulnerable as this is outside my control!

I'm gonna make some more enquiries with OffElec (or whatever they are called) and will update soon

Cheers
SB

 

[mapj1]

I presume you have contacted your DNOs technical dept and described the installtion and got no joy, good luck with the regulator..
As regards your high earth impedance on socket circuits, if you can't win any other way, just RCD protect the ring - then the breaker can be B32, or even C32 if you are feeling enthusiastic, as the earth impedance is then only required to fire the RCD in the disconecction time, not the MCB as well, so the impedance is then allowed to be 30mA/50v or nearly 1600 ohms, which you clearly meet.

 

[ban-all-sheds]

Which is what you'll have to do anyway when your DNO, after having been harried by you and the regulator, re-designate your supply as TT...

 

[sparkybird]

Hi all

Although I'm reviving an old(ish) post, I just wanted to let you know what happened re my lack of decent earth.

After arguing the toss with the electricity company, which basically said that whilest my Ze was outside the regs it wasn't so far outside that they would bother doing anything about it - lo and behold at 9 am on a Monday morning just as I was about the leave the house, two geezers from EDF turn up annoucing that they are here to 'sort out' the earth! I've now got a much better reading - hurrah. And I didn't have to pay a penny.

So the moral of the story is - don't give up.

SB

 

[ban-all-sheds]

And I didn't have to pay a penny.

Or even spend one:

http://www.screwfix.com/talk/thread.jspa?forumID=23&threadID=494