Writing cert for two DB's

[Oli]

Hi Everyone,
Thanks for all your input for other posts.
Writing out my certificate for a job and was wondering how best to approach it.
Previous sparky made provisions for the garage wiring by putting in a small distribution CU direct from henley block and a wire to the then proposed garage area. This is all on TN-CS

Garage has now been built and I have taken his feed and wired up garage with a CU in the garage. I have terminated the earth from TN-CS and installed TT.

I tested at CU in house up to my CU in garage, and then did all my tests again for final circuits at CU in garage.

When it comes to the cert do I need to do two completely separate ones or just the one concerning final circuits or can I somehow combine both.

Many thanks.

Oli

 

[ipf]

It looks like, with different earthing details, you won't just be able to add detail and results for the second board. But why is the garage TT?

 

[Oli]

That was my thought.
Garage is more of a shed separate from house, I have always been told to not export TN earth.
Additionally it will have car charger, but I would have serperated earths anyway.

 

[Deleted member 9648]

You would not be 'exporting' a TN earth, you would be extending it to an outbuilding. Don't listen to the 'cant export' brigade, they are talking rubbish. These same people will 'export' the earth to outside sockets, pond supplies and garden lighting without a thought, and yet get all silly when a shed is mentioned. But if the garage is to have a car charger then you are correct to TT.

 

[Oli]

I know, I know, my Stroma guy who checked me told me not to export so I went with him, but I can't see the issue, I've not checked with my DNO in this area but allegedly some don't accept it. The only other thing is do you have to make sure you take a 10mm earth back to MET.

 

[Harry_P]

I know, I know, my Stroma guy who checked me told me not to export so I went with him, but I can't see the issue, I've not checked with my DNO in this area but allegedly some don't accept it. The only other thing is do you have to make sure you take a 10mm earth back to MET.

I'm guessing your stroma assessor told you it needed to be TT because of the çar charger?
Ps if you TT it you wont need to take a 10mm earth back to the board

 

[Deleted member 9648]

I know, I know, my Stroma guy who checked me told me not to export so I went with him, but I can't see the issue, I've not checked with my DNO in this area but allegedly some don't accept it. The only other thing is do you have to make sure you take a 10mm earth back to MET.

The minimum bonding size is 10mm for a PME/TNCS system. If there are any main bonding requirements in the outbuilding then you would need to meet the requirements right back to the MET if you use the PME/TNCS. If there are no main bonding requirements then there would be no need for a minimum 10mm back to the MET.