6mm main earthing conductor and main bonding conductors

[pistolpete]

Been asked to install an extractor in bathroom. Installing 30mA rcd spur outside covering all lighting and ext fan. Obviously notify building control and installation cert. what's people's opinions of listing as a departure from bs7671 on installation cert. obviously recommend upgrade to 16mm. supply is TN-C-S and DNO connected 6mm to service head. Thanks in advance

 

[GLENNSPARK]

as far as the earthing is concerned.....then you need to know the size of the bullit in there....and then do the adiabatic for it...

when it comes to the bonding.....as long as its visually good for continued service (and this includes any connections)...and it tests OK...then just note it....it isn`t a fail....although i would personally be recommending it be upgraded...

 

[Geoffsd]

If it's wrong it would not be a departure.

A 'departure' is a different (than BS7671) method of achieving a safe electrical installation.

 

[Sintra]

If its wrong you shouldn't be carrying out any additions or alterations.

 

[Welchyboy1]

Been asked to install an extractor in bathroom. Installing 30mA rcd spur outside covering all lighting and ext fan. Obviously notify building control and installation cert. what's people's opinions of listing as a departure from bs7671 on installation cert. obviously recommend upgrade to 16mm. supply is TN-C-S and DNO connected 6mm to service head. Thanks in advance

If your install is out of zones 1 and 2 you need not notify anymore either!

 

[brman]

for what it is worth I decided to ask Elecsa their stance on this recently. In my case I was doing a CU change and the bonding and earth were 6mm (TNCS).

Their response was:
1) Does the adiabatic work for the main earth?
2) Is the bonding in good nick with no signs of overheating?

If yes to both the above then tell the customer it should be upgrade and give a quote. However when the customer refuses the extra cost/hassle crack on and do the work but put a note on the cert that it is undersized but ok and the customer did not want it upgraded.

Which is basically what Glenn said

 

[sima24]

Am i right in thinking that if you can prove a reading of 0.05 ohm or under you can cover yourself that way.

 

[davethsparky]

No, that's just a bit of an old wives tail as far as I'm aware

 

[brman]

0.05 is the value given in guide note 3 for the testing of bonding but I would not take it on its own as evidence of good bonding.

 

[Richard Burns]

Am i right in thinking that if you can prove a reading of 0.05 ohm or under you can cover yourself that way.

No.....

 

[pistolpete]

Brought this up with Nic Eic engineer, they said if it meets sizing calculated by adiabatic equation note it on cert and notify customer recommended upgrade to main earthing conductor. Thanks for responses

 

[GLENNSPARK]

Brought this up with Nic Eic engineer, they said if it meets sizing calculated by adiabatic equation note it on cert and notify customer recommended upgrade to main earthing conductor. Thanks for responses

hmm...
i`m sure i said that someware...

 

[pistolpete]

Yep thanks. I thought I'd read it somewhere too but always good to get a second opinion.

 

[GLENNSPARK]

try post #2 pete..