mystery cable - adding a socket

[markburns]

hello,

i am looking to add a new electrical socket in my bedroom - three storey house, the bedroom is the only room on the top floor. this new socket will mainly be used for a hairdryer.

there is no existing socket anywhere nearby to take a spur from.

up in the loft there is an unidentified 2.5mm cable which i could break into with a junction box - but i am not sure what this cable is currently used for.
using a voltage detector and turning off the consumer unit switches one by one i was hoping to narrow down what it was....but none of them seemed to kill this cable. the only time it went 'dead' was when i turned off the main switch in the consumer unit. can anyone advise how:
a) i can work out what this cable is, or
b) if i am ok to add my new socket to it anyway?

thanks in advance for any help!

 

[safesinbad]

Sounds like the problem lies inside your dist board, cable connected in same terminal as main tails or into incoming of MCB assuming its not a quickline board. Get an electrician in to do the job as it will have to have its own ciruit(if this is the problem) and it must issued with an electrical installation certificate.

Do not put a socket onto this cable if you don't know where an if there is overload and RCD protection to it.

it could also be that the circuit that that cable is on has a faulty MCB. Try switching off all MCB's but leave the main switch on and test the outgoing on all MCB's to prove this.

 

[markburns]

ok, all understood thank you for the quick reply

 

[sparkwright]

this 'voltage tester' wouldn't happen to be the voltstick variety which glows up would it? if so they are prone to false results like you have just described. you need a better way to test out the cable. can you see where it goes to? could it be an immersion cable?

 

[spark1]

Mark . A job for an Electrician !