Splitting workshops.

[ChrisElectrical88]

I am after a bit of advice for a job I am quoting.

The current set up is 2 workshops next to each other. Both units are fed by 1 2x5x5 split load board. Each workshop has a socket Circuit, couple of heaters and a lighting circuit. No issues there.

The landlord is now renting each workshop out to seperate businesses and wants to bill them seperatly. So my plan is for unit 1 to have the current split load board. Off this (non RCD) a submain circuit for a new RCBO board for unit 2 via a MID Approved Check Meter which can then be billed as necessary.

My issue here is the board is fed in 16mm T&E cable buried less than 50mm in the wall. So needs an upfront RCD. I'm not keen on 2 workshops running off 1 30mA RCD thats in accessible. A 100mA Type S crossed my mind but obviously I need 30mA to protect the submain.

Is everyone in agreement that a new submain with a upfront Wylex 80A Switch fuse is the best Option? This will probably go down like a sack of poop due to costs but I can't see any way around it?

 

[James]

Split the supply between dno meter and current db
Run into 2 meters.
Mater A supplying current board
MeterB supplying new board in second workshop.

Alternatively if all party’s are happy, identify the circuits going to second workshop and run all the live conductors for them through the same ct coil that is fed to a meter?

 

[ChrisElectrical88]

Thanks for your suggestion. I did think a Ct coil, but I think all parties would prefer there own mains board.

I think splitting the supply at the DNO point I to 2 meters and then a submain out to each board via a Switch Fuse is the best way. Its just the cost of it the landlord won't be happy with.

My main headach to get it done within their cost is this submain buried less than 50mn in the wall needs 30mA RCD protection, unless anyone can think of a reason why not. It currently doesn't have it even though it was only wired up 5 years ago.

 

[Wilko]

My main headach to get it done within their cost is this submain buried less than 50mm in the wall needs 30mA RCD protection, unless anyone can think of a reason why not. It currently doesn't have it even though it was only wired up 5 years ago.

Hi - I may be misunderstanding, but if you don’t touch the existing sub main you aren’t required to fix the “cable in walls” problem its got.

 

[ChrisElectrical88]

The current switch fuse is looking a bit worse for wear and is chipped. Ideally I want to put a Wylex DSF80M upfront and tidy up the mainsm tails which are just thrown in.

 

[telectrix]

if you are using the existing 16mm T/E buried in the wall , there's no requirement to RCD protect it, although current regs demamd compliance with 522.6.204 BYB. Amd.3. (not got 18th). if it's a short buried<50mm, could you cap over with some 2mm steel plate?

 

[ChrisElectrical88]

It is up to 6 meters buried although I think it's likely to be 2-3 meter, cant 100% verify cause I can't get into the roof space far enough.

 

[telectrix]

i'm thinking that as the regs. are not retrospective, you are not obliged to make existing parts of the installation compliant with current edition. as such, a comment on your EIC as a departure should cover it.

 

[ChrisElectrical88]

Cheers tel.

Its just with me changing the switch fuse up front I want the whole installation covered.

I popped there on my way in this morning. Identified the exact route white was about 3.5m. The landlord is happy for a length of 2x2 metal trunking to go over the top of the run. I can then put warning labels inside this trunking of the reason it's there.

Just means chipping out some plaster behind in a few places so I don't hit the cable haha