TN-S main earth connection - who is responsible

[biotechpete]

Hi guys, I'm hoping someone can help me. I recently had my CU changed and bonding upgraded. The electrician told me that my supply side earth needed changing and I should contact my distributor (YEDL) who should carry out the work for free.

So I called YEDL who claimed that there was NO earth connection in their records and they would charge me for any work plus £45 call out. Since earthing was my responsibility.

I've posted a picture so you can see that the main earth cable (shiny and new- installed by the electrician) from the consumer unit (right) terminates at a block. Then another piece of uninsulated metal is connected from the block to the main supply. Does anyone know who is responsible for this?

Untitled

• biotechpete
• 9 Oct 2008
• 1

[/img]

 

[JohnD]

It looks to me like there is a poor and inadequate bit of wire to the cable armour or sheath. This is not much good but it is not unusual in an old installation.

Ask your electricity supplier if they will provide you with Protective Multiple Earthing (TNC-S) which they probably can. It might cost you £50 - £100 but will be money well spent. If not, ask if they can provide you with an earthing point, they might sweat a terminal onto the cable sheath for about the same money.

They are not required to maintain an earth point if they did not originally provide one, so they can charge you the first time they do it.

If they won't, you will have to get an earth spike, which will cost more and not be as good.

 

[aptsys]

If that wire attached to the sheath was originally provided by them, it is their responsibility to maintain it, so you shouldn't have to pay for them to solder a new bit of earth on.

 

[JohnD]

good point

and the way to prove it is?

 

[biotechpete]

Thanks. I think I understand now.

 

[oharaf]

That pathetic piece of boot lace is the earth, I have come across at least 10 of these this year in Yorkshire, I phoned the DNO and ordered up the earths never charged once

 

[ban-all-sheds]

One of those is mine, the other is the main earth for my neighbour's installation....

 

[oharaf]

Surely YOU have had some words BAS??????!!!!!!!!!!! That is pants even thou it may give an 'acceptable' Ze

 

[plugwash]

Does anyone know who is responsible for this?

They are not obliged to provide and earth but if they have provided an earth they are required to maintain it. So the question is did the DNO fit that tiny bit of wire or did someone else bodge it on. Furthermore the DNO may try to claim that the little bit of wire is actually an adequate earth.

 

[ban-all-sheds]

It's easy enough to check....

I've had a thought though - it's conceivable that you could get a PE fault in an installation upstream of all the protective devices on the consumer's side.

So what size does that earth cable need to be to withstand the fault current until an 80 or 100A fuse ruptures?

 

[Adam_151]

So what size does that earth cable need to be to withstand the fault current until an 80 or 100A fuse ruptures?

Assuming we are working on 5second disconnection, we are looking at a fault current of about 570A ish Amps to clear the fuse in that time... which gives a I²t of 1,624,500, so K²S² cannot be smaller than this, if you use 143 for K (the value for a PVC single earth), and re-arrange, you get a minimum S value of 8.91mm²

The figure will be lower for a bare conductor where insulation hasn't got to be protected, lower if fault currrent is higher (thus disconnection is faster), and lower still if you are looking at whether the wire blows clear or not, rather than whether it remains in sensible temperature bands....

 

[rssteve]

your electrician has cut the metter tails too long and there is single insulated cable on show.

 

[biotechpete]

your electrician has cut the metter tails too long and there is single insulated cable on show.

I realise that it is quite possible my electrician has messed up. I had to remind him of the regs on more than one occasion and I don't even own a copy. (It seems that a competent persons scheme isn't worth the paper it's not written on) but what from the picture makes you think that the meter tails are too long?

There is also an uninsulated earth attached to the same block as the insulated earth. this wire is soldered onto the sheath of the mains cable below the main fuse on the left.