Advice on consumer unit / flat re-wire

[kenai36]

Hi all,

Just recently set up on my own and potentially have a flat re-wire to contend with. Customer has just moved in and wants to get everything right before decorating etc.

The flat has gas central heating so no need to worry about the old storage heater wiring. Only 4 circuits for the sockets, lights, cooker and boiler.

I was wondering if you could advise me on the following?

1. The supply to the flat is fed via imperial 6mm equivalent twin and earth from a sub main on the floor below. If changing the board, would this need to be replaced / upgraded and if so, by who?

2. There is no main earth from the meter cupboard, earth is provided by the twisted tinned copper cpc on the existing installation. Would this need to be installed?

3. Nothing is bonded at all, would I need to run 10mm to where the water and gas enters the flat and run that back to the consumer unit, or to the meter cupboard?

4. Realistically is there any way around chasing out in the safe-zones below the ceiling to carry out the rewire of the property? No CPC on the lighting circuit so figured it would make sense to replace everything as i'd be chopping out the lighting circuit anyway.

5. Would it be acceptable to just replace the board with a small 4 way consumer unit and advise the customer to keep the plastic light switches (I think this is what she wants to do but I'm not keen)

Sorry, there's a lot there but not done much work in flats, especially ones with the meter downstairs and running off a sub main.

Cheers in advance,

Rich

 

[Midwest]

First question, is your customer a tenant, freehold or leasehold?

And does she pay for any maintenance services if freehold or leasehold?

 

[Octopus]

Small fuseboard = rcbo board

Keep plastic switches- don't understand what you mean

 

[westward10]

Small fuseboard = rcbo board

Keep plastic switches- don't understand what you mean

Lighting circuits don't incorporate cpcs but if being rewired then yes, ???

 

[Octopus]

Lighting circuits don't incorporate cpcs but if being rewired then yes, ???

As I said, I don't understand ...

 

[HandySparks]

What's the earthing type?

What's the construction of the walls and floors?

What's the rating of the circuit protection of the submain?

 

[kenai36]

Cheers guys.

TNCS at the main incommer downstairs. Then fed up to the flat via a 50a MCB via what looks like 2 x 6mm T + E

Ceiling and floor are concrete

If I can / just change the board and leave the lighting circuit alone then I'd have to notify the customer that they can't change to metal fittings and mark that on the board wouldn't I?

 

[Octopus]

Hum..... You need to give them a written quote outing the scope of the works.

Leaving the lighting circuit as is means it's only a partial rewire.

 

[Strima]

As the ceiling and floors are concrete are the circuits not run in conduit?

 

[Wilko]

Hi Rob, personally I would insist all things are addressed. For example 6mm is for a cooker, not a flat. TNCS needs earthing conductor to be based on incoming neutral from DNO into the building, check out Reg 544.1.1 and Table 54.8. If the building DNO neutral is 70mm (say) then it needs to be 25mm. And it needs to be connected to the building MET, not some other sub main, if I've understood you correctly.

Instead of chases you could look at putting cornices to get cables around the room, but they will have to drop somewhere

 

[The Ghost]

Far too many questions. Are you sure you are up to this?

 

[ChrisElectrical88]

Why 2 6mm coming into the flat?

 

[Toneyz]

Why 2 6mm coming into the flat?

looks like one for standard 24hr supply other for off peak E7 heating.

 

[Dave OCD]

I'll probably get shot down for this but if both sub-mains are 6mm [look more like imperial equivalent 10mm to me] and the 'off peak' is no longer required, if both cables test out spot on you could consider altering at source and doubling them up, but a lot also depends on whether incoming pipework is actually extraneous and requires main bonding, if so even the doubled-up cpc would almost certainly be undersized for both earthing and bonding.

 

[Midwest]

I'll probably get shot down for this but if both sub-mains are 6mm [look more like imperial equivalent 10mm to me] and the 'off peak' is no longer required, if both cables test out spot on you could consider altering at source and doubling them up, but a lot also depends on whether incoming pipework is actually extraneous and requires main bonding, if so even the doubled-up cpc would almost certainly be undersized for both earthing and bonding.

 

[kenai36]

Cheers for all the replies. I had a look at the flat next door and they've had new tails and 16mm main earth ran through the building. The flat above has has an SWA ran up to it and no separate earth so looks like everyone has taken a different approach.

I've left it with the customer to ask / let the building owner know that she wants to board changing and will take it from there.

On further extensive testing (by knocking on the roof), turns out it's a false ceiling so that should help matters.