TNCS bonding for additions and alterations

[Deleted member 9648]

Was reading the spring 'Connections' mag today. In the 'questions' section the query was is it ok to carry out an alteration or addition to a TNCS install if the bonding is in 6.0mm and not practical to upgrade.
The answer was a definite no, it must be upgraded to 10.0mm. The article even suggested a way round this would be to convert to TT! Of course in the vast majority of situations we would all upgrade....
But I always thought the guidance on this was that if it really is not practical to upgrade, that if the 6.0mm has been in place for some time,and there is no sign of thermal or other damage, then a competent and qualified person can make the decision that the existing bonding is adequate.
Now I have not upgraded on very few occasions, but took our NICEIC assessor to a DB change where the 6.0mm remained in place on his last visit,and he was quite happy that there was good reason to leave it in place.
Another scenario may be with perfectly fine 6.0mm bonding in place...and just an additional socket to be added. That is hardly going to affect existing bonding arrangements or change anything.
'No madam, the bonding has been absolutely fine for 20 years,but because of that new socket you want You'll have to spend £200 putting a slightly bigger bonding wire in, but first you'll have to take up all that oak flooring you've just had laid on the landing, that OK?'
Has something changed or is that Connections article boll****?

 

[HappyHippyDad]

I've always thought the same Wirepuller.

Best practice Guide Number 6 (issue 2), page 5, section 6.1 (see notes 2 and 3) states that :

"A 6mm bonding conductor could be deemed adequate if the bonding conductors have been in place for a significant time and show no signs of thermal damage."

Who is the author of connections?

 

[davesparks]

I've always thought the same Wirepuller.

Best practice Guide Number 6 (issue 2), page 5, section 6.1 (see notes 2 and 3) states that :

"A 6mm bonding conductor could be deemed adequate if the bonding conductors have been in place for a significant time and show no signs of thermal damage."

Who is the author of connections?

The same author as writes the best practice guides, the almighty and all powerful NICEIC

 

[stevethesparks]

How strange, I spotted this article earlier this evening and thought exactly the same thing. I checked up on the latest best practice guide 1 - issue 3 (although not regs), and yes it still states the same as HH's post.
Maybe a call to the NICEIC to clarify this if I get a chance tomorrow.
And to add, what a great work-around, to convert TNCS to TT FFS.

 

[jeremy]

Is TTFFS a new earthing system?

 

[stevethesparks]

Is TTFFS a new earthing system?

I think its a new system NICEIC are introducing for undersized main bonding conductors, you put a 5 ohm resistor between the PME and the MET :wacko:

I am not going to get the chance to phone anyone today, so have emailed both the NICEIC and the magazine for clarification, I'll post any replies I get.

 

[Welchyboy1]

Same old really, one minute its fine to leave it next minute its a deadly hazard

i wonder what napit and others opinion would be ?

 

[Octopus]

So a 6mm is now dangerous

How pathetic

Strikes me that the author is trying to generate work for them selves

 

[Pete999]

The same author as writes the best practice guides, the almighty and all powerful NICEIC

A work of fiction then

 

[Midwest]

wirepuller, I read that piece as well, and your post made me ring up and ask - Elecsa technical.

As you said, previous recommendation, was 'when making a site visit for a quotation, provision of bonding must be included....should you find the bonding installed is undersized to the current regulations, you can proceed with the works if there is no sign of damage or deterioration'. Goes on to say about recommending to client of upgrading & cost implication etc, and noting comments on certificate.

So I rang technical, and obviously a few electricians have already queried the new recommendation, which is;

When carrying out ANY work on a domestic property, where the bonding is found to be inadequate, it should be upgraded to current regulations. If for any reason, e.g. accessibility for cable runs, the upgrade is not carried out, that is the contractors decision, or the work is declined (not verbatim account of conversation).

The recommendation now, is it must be upgraded (reg 132.16 + 544.1.1). I asked why the change in advice, and was told it has come after research, which wasn't expanded on.

Seems like someone's done some research on litigation!

 

[YoungBart]

It strikes me as if NICEIC have just taken 'The Bigger the better' approach to earthing. We'll all be installing 50mm earths before long, Just in case....

 

[hightower]

Be interesting to hear what other schemes say since Elecsa is essentially NIC anyway.

 

[Deleted member 9648]

We have our annual NIC visit in may....will raise the point then and report back.

 

[Deleted member 26818]

It all boils down to whether the earthing and bonding arrangements are adequate for the protective measure/s you intend to install or use.
If you intend to rely on ADS, is bonding required?
If you intend to rely on earth leakage, is bonding required?
If you intend to rely on double insulation, is bonding required?
If you intend to rely on placing out of reach, is bonding required?
If you intend to rely on equipotential bonding, is bonding required?

If the answer to any of the above is yes, then you have to determine whether the CSA of the bonding conductors is sufficient?
If yes, then the bonding is adequate.
If no, then the bonding requires upgrading.

 

[GEOFF S]

Hi all

Sounds like a strange decision, must of caused a fire in London?

What if i have 2 x 6mm feeding 2 extraneous parts of the same resistance to earth, and then replace it with 1 x 10mm?

Cheers