Detached garage and regs

[Sintra]

If you have no other services in the garage and provided the earth in the sub main can handle the PEFC you could remove the earth rod and connect the earth from sub main into garage cu.

 

[Adam W]

If Ze at the garage CU is <100Ω why bother ripping out the electrode and running in another earth?
The garage is effectively it's own installation with it's own earthing system.
Surely better than transporting the earth from TNCS?

 

[Sintra]

Personally i would leave as is also.

 

[nickblake]

I hope this is in the right section.

I am hoping someone can refer to the correct section in 7671.

Incoming TNCS/PME

Brother in laws house 80's, set in CU with type 1 breakers no RCD protection at all.
( No funds for new board )

this could be done using a budget board ie:cpcConsumer Units & Enclosures not brilliant boards but great where budget is tight ,also could form part of your part P assesment
Detached garage T&E comes out of board to outside in to an adaptable box and continues into garage in SWA. 2 Way rewire-able fuses Looks like SWA is only 2 core but difficult to see

As per the old regs ( I think ) they have run no CPC from the dwelling instead earthing is provided by rod. IE a TT system

Additional protection is provided by a 30 mA oldd rccb, RCD tested trips on both 0/180 well within limits.

Measured Ze in garage is high at 68 Ohms but I believe this falls within the parameters for TT.

I want to submit this a board change for Part P assessment, I think and this is where I need the help guys that I should be looking at running a 16mm csa main earth back to the board or a met block in the outside meter box ( this would be easier as the main Earth from the PME disappears into the cavity ) as I am paying for the project I was planning on a 4 way board + MS with an RCBO for lights/sockets/pond/spare.

I do have all the readings ie Ze/Zs and pfc's for both buildings if this in anyway makes any difference to the answer given

As always thankful for your advice guys !

ATB Steve

hope this helps

 

[Jimmy Boy]

I am grateful for time and trouble you have taken to read this thread fella's .

I am not one to follow regs blindly I want to understand the principle behind a regulation and then adopt it based on my understanding of it, perhaps I am too ---- and should just follow the carrot, I now understand the principle of other services entering and the need for them to be EB back to to MET.

If this was a cottage in the middle of nowhere I wouldn't even be having this discussion I would assess it as TT, deal with it as TT and move on, the reason I am being so paranoid about it is because the garage is less than 3 foot from the house, has outside supplies to garden pond, and I can't seem to reconcile in my mind the the poor Ze compared to the house, but I except this is within the regs and and see if I can get the main CU changed instead, and just earth the CPC on the supply side only.I think I would prefer to have an mcb at CU and a D/P RCD in garage as opposed to an RCBO. Thanks again.

ATB Steve

 

[Jimmy Boy]

Nick that link doesn't seem to work mate.

Steve