TT Earthing and Cut outs

[Milodog]

Installed a MK 18th edition duel board and went to test what looked like a TNS system but the ohms were 2-4. Had the supplier check for PME options but it reads .9, so they have told the customer get an earth rod installed.
As we now have a metal enclosure needed and whether i install a 30mamp or TD RCD a the front, we have 2 problems. My rod would be approx 15m away and likely reads of 20omhs or more giving super low V returns thus the supplier fuse will not break. Aside of this, should the cable between the supplier fuse and consumer unit get damage and touch the metal box there would sufficient risk to life and property as this would be before the RCD's

How do we get around this? Which regs and physically what are people installing as typical NICEIC website down and contact page fails. This is a domestic single phase property.

 

[westward10]

Is it or isn't it a TN-S supply, if if is the DNO is obliged to maintain it.

 

[davesparks]

went to test what looked like a TNS system but the ohms were 2-4.

What does this mean?

 

[Milodog]

Is it or isn't it a TN-S supply, if if is the DNO is obliged to maintain it.

It has an earthing wire from the incoming bulk head, screwed to board. The DNO said no
[automerge]1583994923[/automerge]

What does this mean?

Looks like a TN-S as the stranded earthing already there bolted to the DNO metal casing lead to the old board. Tested it but come back between 2 and 4 ohms

 

[Midwest]

I’ve heard a DNO is obliged to maintain an earthing facility if it’s in place. But practically, I’ve also heard other members in similar situations where the DNO have declined to do so.

I wonder what regulations this falls under, and what right of appeal a consumer has?

 

[Baddegg]

Got any pics @Milodog.....

 

[snowhead]

Looks like a TN-S as the stranded earthing already there bolted to the DNO metal casing lead to the old board.

The DNO should have arranged replacement of this "Metal casing" (Cut out, presumably)

 

[westward10]

They are obliged to ensure the metal head is effectively earthed.

 

[davesparks]

Looks like a TN-S as the stranded earthing already there bolted to the DNO metal casing lead to the old board. Tested it but come back between 2 and 4 ohms

If the DNO equipment is metal then it will have had an earth supplied originally and they need to maintain it.
Also they will usually replace metal cutouts as a matter of course.

 

[Milodog]

If the DNO equipment is metal then it will have had an earth supplied originally and they need to maintain it.
Also they will usually replace metal cutouts as a matter of course.

All guys saying DNO should do. I have somewhere in my books the actual regulation which states the DNO, unless unsafe to do so is responsible for the earth. On another job a few years ago, i stated the reg but a supervisor countered with reg blah blah and that was his final position on the matter??

 

[westward10]

Regulation 10 ESQ&CR 2002.

 

[Lister1987]

Regulation 10 ESQ&CR 2002.

Earthing of metalwork
10.—(1) Subject to paragraph (2), and without prejudice to any other requirement as to earthing, a generator, distributor or meter operator, as the case may be, shall ensure that any metalwork enclosing, supporting or otherwise associated with his equipment in a network and which is not intended to serve as a phase conductor is, where necessary to prevent danger, connected with earth.

(2) Paragraph (1) shall not apply—

(a)to any metalwork attached to, or forming part of, a wooden pole support, the design and construction of which is such as to prevent, so far as is reasonably practicable, danger within 3 metres of the ground from any failure of insulation or failure of insulators; or

(b)to any wall-mounted metal bracket carrying an overhead line not connected with earth, where the line is both supported by an insulator and the part of the line in contact with the insulator is itself surrounded by insulation.

 

[richy3333]

Why has this come to light after a board change?

I had a high Ze on a TNS and my DNO said they wouldn’t action until (I think) over 1.5 ohms. The Ze measured was 0.95 ohms in my instance.