Installation of sockets and lights outside

[skman]

Hi All,

Ok, I am looking to run 1 x twin socket and 1 x Single socket to outside (as radial circuit), and also an outside light on seperate circuit. I have done domestic electrics, but not with outside stuff, and also I will be fitting in a seperate CU next to the current one, to supply these (to save a complete CU change).

So.... I have got 2.5mm 3 core SWA running from the outside sockets in through the wall of the house, and into fused spurs. Then running 2.5 T+E through and down into a small CU next to the current one under the stairs. I also have Rubber sheathed Flex from the outside light into a switch then off to the CU under the stairs, running on 1.5 T+E

This is a TT system, and already has 100mA RCD protection in the main CU, and I have a garage CU with 40A 30mA RCD, and 2 MCB 1x6A (for the light) and 1x16A (for the 2 sockets whcih are radial).

Firstly, can you guys see anything wrong with what I have done so far, and also from the current CU to the new CU, I was going to run 6mm T+E from the 100mA RCD to the 30mA RCD to supply the power, but I have never installed a seperate CU before so wanted to check that bit was right too!!

(I am also going to run a seperate 10mm Earth Cable from new CU to the MET, as it is in the same cupboard.)

I know this is Part P notifiable, and have that in hand.

Whats your virdict???

 

[rebuke]

Socket and light wiring seems OK, however your plan to connect the new CU with 6mm T+E isn't...

The 100mA RCD does not provide overcurrent protection, so there is nothing to protect the 6mm cable, and if a fault were to occur in the new CU, it could potentially draw enough current to cause the cable to melt / catch fire before your main service fuse blows.

The correct way to do it would either be to split your meter tails using e.g. a henley block, and bring a new set of (appropriately sized) meter tails in to the new CU, or if there is space you could put an MCB in the existing CU to feed the new one.

Pics of your existing CU and service head etc might be useful...

 

[ban-all-sheds]

The correct way to do it would either be to split your meter tails using e.g. a henley block, and bring a new set of (appropriately sized) meter tails in to the new CU

Which can't be DIY'd if there's no separate main isolator for the whole installation...