Kitchen wiring question

[nobbynomates]

The LABC man is due to pay a visit next week before i start any work, everythings sorted apart from plans for kitchen wiring.
I need to swap a single socket for a double socket to power a combi boiler and the washing machine.
Thing is, the old wiring is a radial circuit, and running 2 x 2.5mm T&E cables is going to be a problem as the current wiring runs through the joists under a flat roof, so i can`t access it unless i take down the ceiling.
Can i run a single cable, perhaps 4mm or 6mm directly back to the new CU? (New CU is a dual RCD wylex)
Cable run would be approx 8 metres.
Thanks Chaps.

 

[jj4091]

What are you trying to achieve, turn the radial into a ring? You do not need to do that just for a C.H. boiler & washer if the current cable is 2.5 mm & correctly protected. If you cannot run 2 new cables how are you going to run 1x6mm?

 

[experience]

As jj4091 said, use the correct size breaker for the radial to protect the cable and you'll be fine

 

[nobbynomates]

Let me try to be a little clearer.
I`m rewiring the kitchen as i still have the old original wiring, the black rubber coated type.
At present, the single socket is fed by one single cable, direct to old CU.
The cable runs through joists, (through holes) in a flat roof above the kitchen.
Trying to pull 2 new cables through along the same route looks impossible without taking part of the ceiling down.
It looks like a single cable would be easier to pull through.
I can see the space above the ceiling from the side, from the upstairs bedroom, but can`t reach the cable as its too far away.
I can get to both ends of old cable, so joining a new single cable and pulling through looks the easiest option without taking the ceiling down.
If it comes to it, i could re-route 2 new cables within the safe zones, around top of kitchen wall within 150mm?

 

[holmslaw]

..

 

[nobbynomates]

As jj has pointed out, I don't see problem, just fit a 16Amp mcb and your sorted.

Sorry mate, read my 2nd post again, i edited as you posted.

 

[ban-all-sheds]

Let me try to be a little clearer.
I`m rewiring the kitchen as i still have the old original wiring, the black rubber coated type.

A significant factor - if it hadn't been for that you wouldn't have needed to replace or add any cables, hence the confusion.

It looks like a single cable would be easier to pull through.

Then pull a single one through...

I can get to both ends of old cable, so joining a new single cable and pulling through looks the easiest option without taking the ceiling down.

Easiest as long as you can actually keep the old & new attached, and they don't separate or get jammed in the process. Hopefully others here can provide tips on how to maximise your chances...

 

[nobbynomates]

Sorry for the confusion.
So is 4mm or 6mm direct to 16Amp mcb acceptable in this instance?

 

[holmslaw]

..

 

[ban-all-sheds]

Should you be DIYing if you don't have a copy of the OSG or the EGTTBR or the Wiring Regulations or any guide to them?

 

[davy_owen_88]

Sorry for the confusion.
So is 4mm or 6mm direct to 16Amp mcb acceptable in this instance?

If the cable doesn't run through any insulation a single 2.5mm² cable will carry 16A without a problem.

As mentioned, pulling a new cable through might sound easy, but if you have tight bends, undersized holes through joists, or worse still, the cable is clipped along the route then you are bug*ered and will need to run a new cable through a new, safe and convenient route (it might not be possible to satisfy the last 2 criteria at the same time unfortunately )

 

[nobbynomates]

So 2.5mm T&E it is then.
No lagging, just a straight run through joists.
Thanks all for your help.