Long Tails

[eckersecker]

The meter is on the outside wall. The tails will come across the kitchen between the joists and down to consumer unit under stairs, approx 8metres run.
Have looked at past posts and answers are conflicting. Am I correct in assuming a fused isolator is required at the metre and then i can use ordinary tails?
I read someone who recommended SWA and an RCD. How would an RCD work if you are using RCD spilt board. There would be no discrimination ? The whole house would go down every time a downlight blew!

 

[malcolmsanford]

Yes you will need to protect those tails with most likely a switch fuse. It is highly unlikely the DNO will allow their protection device to cover anything over 3-5 metres.

Think you may have the SWA and RCD thing confused unless it was for a TT system. If you have a TN system then there is no need to have RCD protection for the tails. If you have a TT system then yes the chances of having a low enough Zs to trip a fuse is nearly impossible, so you would need an RCD, but you would use a 100mA S type for the discrimination.