MAIN EARTH BONDING domestic installation

[piz]

Hello
When we are asked to change a CU i have been told on pme and tns the main earthing conductor is the responsibilty of the electricity board.
so if this is the case why is a 16 mm earth sold on packs of 2meter tails?,
example change board 25mm tails or 16mm if 80amp main fuse 10mm to gas and water but only sometimes 4 or 6 mm main earth do we just record this on an EIC
Cheers

 

[Engineer54]

Because none of the rods around me are buried, they are always exposed and Regs state 25mm for none protected and none buried rods

Pretty pointless exercise then, to have an earth rod that's not buried!! lol!!!

 

[Spazz]

Pretty pointless exercise then, to have an earth rod that's not buried!! lol!!!

I know your taking the **** - its driven into the ground but the top is exposed - therefore not buried and not protected against mechanical protection - regs states 25mm - I cant be bothered to get OSG or BGB out for the Reg number

 

[Spazz]

Burry it it's not hard ! Drill , then get good old lumpy out for that bit your drill won't do!

It is when someone has put a concrete path around it - I have a SDS with a Rod driver attachment but that wont drive it past the concrete

 

[MDJ]

I thought a 4mm2 unprotected and a 2.5mm2 protected ie (in conduit) was adequate for a TT system, I may be wrong again of course.

Mike

 

[Spazz]

I will go get my regs in a bit

 

[spark 68]

I know your taking the **** - its driven into the ground but the top is exposed - therefore not buried and not protected against mechanical protection - regs states 25mm - I cant be bothered to get OSG or BGB out for the Reg number

Nicholas I think you have mis-read the OSG.

it says min 25mm if buried but not protected against corrosion

2.5mm if not buried but protected against corrosion and mechanical damage,
4mm if not protected and not buried

 

[Des 56]

Nick,if the earth conductor is protected against corrosion, its not buried,its not mechanically protected,then 10.0mm is ok

542.3.1

 

[spark 68]

Nick,if the earth conductor is protected against corrosion, its not buried,its not mechanically protected,then 10.0mm is ok

542.3.1

I usually use 10mm Des, seeing as how I carry that size anyway.

 

[sparks1973]

I'm wondering when the thread title will be relevant to the thread

well i think we may struggle there Des....
i mean whats `earth bonding`?...

 

[spark 68]

More to the point, how do you terminate 25mm into a domestic CU ?, unless it get's a 'haircut' (Geordie sparks term LOL)

 

[Engineer54]

Nick,if the earth conductor is protected against corrosion, its not buried,its not mechanically protected,then 10.0mm is ok

542.3.1

More than OK for a domestic installation!! lol!!!

 

[Spazz]

542.3.1:
Protected against corrosion and mechanical = 2.5mm copper
Protected against corrosion and not mechanical = 16mm copper
Not Protected against corrosion and not mechanical = 25mm copper

Most properties in Pembrokeshire with TT are not protected against corrosion or mechanical protection so must be 25mm

To terminate 25mm into a CU is a pain I had to split the cable to 4/3 wires and terminate that way over 2 connections - NAPIT said that was the best way

 

[spark 68]

542.3.1:
Protected against corrosion and mechanical = 2.5mm copper
Protected against corrosion and not mechanical = 16mm copper
Not Protected against corrosion and not mechanical = 25mm copper

Most properties in Pembrokeshire with TT are not protected against corrosion or mechanical protection so must be 25mm

To terminate 25mm into a CU is a pain I had to split the cable to 4/3 wires and terminate that way over 2 connections - NAPIT said that was the best way

That reg refers to the cable being buried directly in the ground, see the extract from the OSG I posted earler

 

[Spazz]

Either way in Pembrokeshire its not possible because all the rods have been concreted to make a path - i will take the trunking idea into consideration next time

 

[spark 68]

see reg 543.1.1 on the next page of the BGB:wink_smile: