Tail Sizing and Bonding

[smithjim0001]

Hi All

On inspection of any ccu am i to understand that it should be noted on the test sheet that the tails should be 25mm obviously most installs that are a little old will have 16mm or less so should this be noted as undersized incoming tails.

Also regarding searching for the main water bond if it is there but cant be found ie behind cupboards how far do we go and how is it noted on the test sheet.

Thanks All

 

[SirKit Breaker]

Hi All

On inspection of any ccu am i to understand that it should be noted on the test sheet that the tails should be 25mm obviously most installs that are a little old will have 16mm or less so should this be noted as undersized incoming tails.

Also regarding searching for the main water bond if it is there but cant be found ie behind cupboards how far do we go and how is it noted on the test sheet.

Thanks All

It all depends on the size of the cutout fuse. If it is 100a then 25mm Tails, 16mm Earth, 10mm main bonding and 6mm other bonding.

If it is 80amp then 16mm tails are OK and suitably sized earth and bonding at min 50% CSA as above.

I always fit 25mm just to be on the safe side.

Cheers........Howard

 

[smithjim0001]

Hi Thanks for that ill quote the full section regading page 17 Meter tails which is throwing in some level of confusion on the matter reg 514.3 in on site guide states that Polarity should be indicated by the colour of the installation and the minimum cable size should be 25mm

 

[Sintra]

Also regarding searching for the main water bond if it is there but cant be found ie behind cupboards how far do we go and how is it noted on the test sheet.

Thanks All

If you can't find the main bonding then how do you know that it is there.

 

[Des 56]

Hi Thanks for that ill quote the full section regading page 17 Meter tails which is throwing in some level of confusion on the matter reg 514.3 in on site guide states that Polarity should be indicated by the colour of the installation and the minimum cable size should be 25mm

The on site guide is a catch all guide, and may not dig too deep into whats permitted, rather what is best

If it is a new installation,for various reasons it would be wise to use 25mm

On an existing installation where 16mm is used,it would serve little purpose inflicting work and cost on somebody to upgrade tails for a loading that may never be available or needed if the 16mm is adequate

Anybody doing additions or alterations has a duty to assess this before adding to them


I was puzzling myself over a colour coded installation

 

[smithjim0001]

Yer was ment to say colour coded insulation.

Regarding the water and gas bond if i have 2 x 10mm bonds leaving the ccu then i would assume that they are going somewhere but if concealed in a non access riser of cupboard how far do you go.

 

[Des 56]

If they are not visible for inspection
Continuity test between the 10m at the consumer unit (dis connected) and an avilable water pipe nearest to point of entry or where you think they may be connected
If it tests ok

Note it on the certificate,what you tested and code it accordingly stating in the limitations what could not be inspected

 

[Sintra]

Yer was ment to say colour coded insulation.

Regarding the water and gas bond if i have 2 x 10mm bonds leaving the ccu then i would assume that they are going somewhere but if concealed in a non access riser of cupboard how far do you go.

Reason i mentioned that is while doing a pir i came across 2 16mm cpc's going out from met.
After doing continuity tests to pipework and not getting a reading climbed into roofspace above db and found the 2 cpc's connected together in a jb.

 

[smithjim0001]

Ill tell you what your absolutly bang on with that last comment you never can tell what is leaving the board.

Thanks for your help