Main Earthing Conductor

[m4tty]

Hi,

Been round to quote on a Board Change old BS3036 (TNCS) and the main earth comes from normal place through to the board. Meter on outside wall and Board in cupboard next to stairs head height. It looked like 4mm or maybe 6mm at a push. This goes straight into CU so theres no MET.

I understand that were not allowed to change that main earth as this is DNOs property? (Ze is 0.14 btw)

So all ill have to do is install 10mm to water as gas already has 10mm. Water is not bonded at all atm.

Cheers in advance for any help on this one.

Matt

 

[NozSpark]

A TNCS earth will usually go to a block with screws... sometimes it comes directly out of the head and then to the CU, if that is the case then I'd probably cut it so that there is only a few inches left and put that in an earth block and then take your 16mm earth from there!

 

[m4tty]

What if it meant tearing too much of the customers decorated house apart and they didnt want it changed. Is there any way it can be left. I thought that was dnos property and were werent allowed to touch it? Have i got this wrong?

Cheers

 

[SLIPSHOD & SLAPDASH]

The same person who previously cut the seals off must have done it

 

[m4tty]

The same person who previously cut the seals off must have done it

It was sealed up mate and looked untouched. No work has been carried out in this house for years. The rewirable fused board in this house looks original from when it was built.

Cheers

 

[NozSpark]

Matty,,

You cannot avoid upgrading the main earth just because your customer doesn't want their decoration messing up!

How about a different route?? maybe straight through the wall and then through conduit to the meter box?

 

[m4tty]

Theres a toilet the other side of the wall from mainfuse all tiled etc. Laminate floor all way through. Mid Terrace. Tiled bathroom above. Its not going to be possible. The water bond is going to be a nightmare. Maybe a job to avoid. I thought the earth into the cutout was not allowed to be touched, am i wrong then? thanks

 

[NozSpark]

I'd say it's your customers cable, it's just that you are not allowed to "tamper" with the main connection in the head.. therefore cut at 4" long and connect into an earth block and then your new earth into that.. leave enough slack in your new earth so that it can be terminated into the head correctly...

It's just like the tails really, they're yours, but you are "not allowed to" tamper with the meter connections

 

[ianmacd]

Don't forget though that if you put a new Earth connecting block before the CU then the Earth Block in the CU is no longer the MET and the new one becomes the MET so all bonding needs to go back to that.

 

[Lee321]

how i larffed

 

[ianmacd]

No as indevidual final circuit CPC's are connected via your ET in the CU which is connected back to the MET.

 

[jl-heating]

there is always a way,

we did some were the gas as on the front of the house and there cu on the back, 10mm up the front through the roof and down the back wall. looked horrendous but complies .

trunked to first floor.

find which way the boards run and fish it anything can be done its just a time factor

 

[ianmacd]

Nope its not fine. The Main Earth Terminates at the MET and what you are taking to the CU after that is a CPC for that part of a distribution circuit. All bonding have to be at the MET not at some random earth bar bacause its easier. CPC's are connected though the CPC to the CU. The regulation does not state that all the cpc's of each final circuit needs to be in the MET.

 

[Lee321]

there is always a way,find which way the boards run and fish it anything can be done its just a time factor

:Applaud

 

[Lee321]

Nope its not fine. The Main Earth Terminates at the MET and what you are taking to the CU after that is a CPC for that part of a distribution circuit. All bonding have to be at the MET not at some random earth bar bacause its easier. CPC's are connected though the CPC to the CU. The regulation does not state that all the cpc's of each final circuit needs to be in the MET.

:_|

 

[jl-heating]

if you think getting a 10m cable to a stop tap is hard, try getting 2 x 15mm pipes to a radiator in a fully tiled bathroom or kitchen or 6 pipes out of a cylinder cupboard and down a hall to each room .

you sparkies dowt know the meaning of difficult lol.....

(awaiting abuse)........!!!!!

see below.

 

[Lee321]

if you think getting a 10m cable to a stop tap is hard, try getting 2 x 15mm pipes to a radiator in a fully tiled bathroom or kitchen or 6 pipes out of a cylinder cupboard and down a hall to each room . you sparkies dowt know the meaning of difficult lol.....

(awaiting abuse)........!!!!!

see below.

pffff anyone with more than 3 brain cells can work out if you put water down a pipe it will come out at the other end

:x

 

[ianmacd]

And that cpc may also act as an combined cpc/bonding conductor can it not?

regards chris

Nope its a CPC. Bonding goes directly to the MET not via random places.

You are mistaking main earth that terminates at the MET with the CPC connection from the MET to the CU when there is an external MET. If there is no external MET then the earth bar in the CU becomes the MET and the Main Earth is takin directly to it.

 

[matt.leung]

Main earthing conductor from supply to MET

Water and Gas bionding to MET (10mm)

all cpc's back to the CU

16mm earth from MET to CU

JOB DONE - LOOK IN THE OSG Page 15

 

[Lee321]

you can take your bonds to the cu so then what matt