10ml or 6ml main bonding conductors

[Tapouchoke]

Hi guys

I have carried out works on a kitchen, altered cooker cct, altered socket circuit to suit new lay out
Installed rcbos to circuits as they have got socket outlets on them lest than 2oamps
All tested ect
16ml main tails 16ml main earth
now the main gas and water is only 6mml do I have to upgrade this or can I leave it as 6ml and put a comment / departure on the cert as code 4

All comments appreciated good and bad
Cheers

 

[spamwize2]

hi mate
depends what earth system is being used
6mm ok for tt system
10mm for others

 

[adamh]

asfaik anything over 4 if it is existing 10 if your fitting it.

 

[spamwize2]

if he's paying i would put 16mm to be safe maybe 32mm if he's rich!
got to be futureproof!!!

 

[Tapouchoke]

Hi guys

Tncs supply main bonding existing, just altered the sockets and cooker circuits
Thanks for the Input
cheers

 

[just add water sparks]

yes i agree with spamwize 10mm except for t.t What i cant understand is how come peeps are still putting in 16mm tails when this changed to 25mm when part p came out????If i am wrong please correct me,but pages 31-33 of the Electricians Guide To The Building Regulations 2005 back me up on this?????

 

[spamwize2]

i think youre right 25mm tails are in, dont forget £1 a foot for 25mm tails!

 

[Tapouchoke]

Sorry gents
16ml tails are original

You are right if installing new 25mm was just giving a brief insight into the supply parameters

 

[Mike P]

As I understand when undertaking new work on an old TNC instalation it should be part of the job to up the MET and main equipotential bonds 16mm and 10mm respectivlly.

 

[DYCHE4230]

As I understand when undertaking new work on an old TNC instalation it should be part of the job to up the MET and main equipotential bonds 16mm and 10mm respectivlly.

Really? Even if everything tests ok and all disc times, Zs's etc are met ???? That sounds a bit harsh!

 

[Mike P]

It's What I was informed to do when I did my 16th. TT supplies are 6mm Equipotential bonds

 

[jaldred]

You should really be checking your earthing arrangement and csa's of main and protective earthing conductors, before you carry out new installation or alteration.
If you earthing arrangement isn't up to min requirements it's a code 1 to me, not 4. There are (not very interesting) reasons for minimum csa's of earthing conductors within different earthing arrangements and not all directly related to meeting minimum Zs.
The main reason inadequate bonding is a code 1 and should be verified at quotation stage is this..... the NICEIC man will make you go back and put it right for free if he picks that job to look at and it's wrong, oh yeah and if another spark does work in that customers house and sees that the bonding is undersized and the customer tells him you were the last spark in he'll probably bad mouth you to the customer while quoting to upgrade the installation.
As a rule of thumb i'd always check the supply and arrangement before quoting the work.

 

[Tapouchoke]

hi guys
thanks again for the input any chance of spark doctor or dan givving ther view as it is much apricated
thanks

 

[Tapouchoke]

Again cheers for advice
Can we get a member who is good with the regs?
As I do work for the local authority and when you go into a job they want the bare minim to keep installation safe keep the cost down

TapouT

 

[jaldred]

You could call your regulatory body. The organisation you are registered with to self certify your work as required by Part P of the building regs.
Tell them that you are doing/have done work in a domestic dwelling with a PME supply - they will tell you that you need to upgrade the bonding to services (gas and water) to 10mm.

If you don't want to do that you can always invest in a copy of the regs and flick to page 134, reg 544.1.1 which basically says that main protective bonding conductors are required to be atleast half the csa of the main earthing conductor at a min of 6mm.... except in PME circumstances whereby you select the size of conductor based on the size of the main neutral conductor in table 54.8 (on the same page) 35mm Neutral or less = 10mm Main protective bonding conductor.

Hope this clarifies it for you?

 

[smoggy]

Again cheers for advice
Can we get a member who is good with the regs?
As I do work for the local authority and when you go into a job they want the bare minim to keep installation safe keep the cost down

TapouT

You don't have to change bonding, code 4 is ok, but like has been said don't risk getting bad mouthed, just change it to 10mm, make the cost up elsewhere.

 

[jaldred]

Still think you're best checking with your registered body, NICEIC, ELECSA or whoever. The regs are pretty clear on minimum requirements but i do concede that they aren't retrospective and there are 'advisory' codes given on some other documentation i've seen (it's the regs they'll hold up in court though).
I have mates who have had to go back to properties to upgrade the bonding where there has only been 6mm, admittedly it was before the advent of the 17th edition, maybe the new regs have changed requirements?
Does anyone know if there is a reg in there giving this leeway?

 

[smoggy]

Still think you're best checking with your registered body, NICEIC, ELECSA or whoever. The regs are pretty clear on minimum requirements but i do concede that they aren't retrospective and there are 'advisory' codes given on some other documentation i've seen (it's the regs they'll hold up in court though).
I have mates who have had to go back to properties to upgrade the bonding where there has only been 6mm, admittedly it was before the advent of the 17th edition, maybe the new regs have changed requirements?
Does anyone know if there is a reg in there giving this leeway?

Correct me if i am wrong, what is basically being said here is everytime you do a job no matter how small you have to upgrade bonding if not current regs.?

 

[coxy]

Hi I would say if the main fuse in the cut out is 100 A should be 25mm tails & 16 mm earth if 60 Amp 16.mm tails ok.If tt 6mm earth ok if tn 10 mm earth.

 

[heathelect]

As a matter of course i always change mains tails to 25mm & 16mm earth, with 10mm to gas and water etc, i know other other sizes are ok for different installations, but you dont always know what the main incomer fuse size is, so i always go for the max, regards dave

 

[coxy]

Hi Sorry read the post wrong,I would always install 10mm main bonding whatever supply.

 

[saveloy]

FWIW. On surveying a potential job I ALWAYS check to see if there is the correct bonding (10mm) in place before giving an estimate and then advise on an upgrade if required. In most cases it is no big job to upgrade anyway. I just feel that it is good practice to make sure that the whole installation meets current regs when I have finished my work.

 

[laney06]

I spoke to the niceic on this very subject as i had the same issue with one of the jobs i was using for my assesment.
Basically, if tns or tt you can use the adibiatic equation to prove what size conductor you can use for your bonding ( i squared t over k, square rooted). If tncs (pme) then you refer to table 54g. (could be table 54h, i forget!) which states in a round about way you must have 16mm and 10mm bonding.
The nic position on this is thus: you MUST make sure the bonding is up to CURRENT regs BEFORE you commence work.
Therefore an installation cert cannot contain any 'codes' as you should have done this work as part of your job.
Hence me quickly selecting a new job for my assesment!!

Hope this helps.

 

[jaldred]

That's how i've experienced this subject too Laney.
It's all about the combined neutral/earth at the supply with a TNC-S. The supply authority worry that they may lose the earth somewhere down the line and that should there be any stray currents the path of least resistance could be the Final Circuit CPC's. By have 'oversized' Main Protective conductors the stray currents should exit down those instead of the casing of your kettle.

 

[TPES]

FWIW. On surveying a potential job I ALWAYS check to see if there is the correct bonding (10mm) in place before giving an estimate and then advise on an upgrade if required.

What do you do if you advise them of the upgrade to gas and water supplys and they dont want to pay for you to do it.

Do you leave the 6mm bonding in place and continue with your work, just adding a note on the cert you recommend a 10mm upgrade?

Or tell them before you start that the bonding HAS to be upgraded before you will carry out ANY alterations or additions?

 

[saveloy]

What do you do if you advise them of the upgrade to gas and water supplys and they dont want to pay for you to do it.

Do you leave the 6mm bonding in place and continue with your work, just adding a note on the cert you recommend a 10mm upgrade?

Or tell them before you start that the bonding HAS to be upgraded before you will carry out ANY alterations or additions?

TBH I have never had a customer who won't pay to have the main bonding done. And if I ever do get someone who doesn't want to pay to have work done properly then I don't lose sleep over it. I give them a quote to do the work properly, they take it or leave it. Anyone who wants to skimp on electrical work in their house probably isn't worth working for anyway. At the end of the day it's my name on the certs and my neck on the line, so I won't drop my stantards or do a half####d job just to earn a few extra quid.

 

[ezzzekiel]

I spoke to the niceic on this very subject as i had the same issue with one of the jobs i was using for my assesment.
Basically, if tns or tt you can use the adibiatic equation to prove what size conductor you can use for your bonding

The adiabitic equation is Not used to calculate the size of Main Bonding conductor 543.1.1


as an afternote, Napit allow min 6mm on tns if permission not given to upgrade and note on eic, pme rules apply