Replace consumer unit - unidentified Radial Circuit

[dazzlerpalmer]

I have just replaced my consumer unit (old wylex) with a newer split board.
Whilst doing it I noticed that there was a wire (looks like 2.5) coming from the downstairs lighting circuit? I now have wired it to a 32AMP fuse as a separate radial and turned it off since it appears to do nothing.

Everything in the house works ok. I have no idea what this is or where it goes. My worry is that is is somehow linked to one of the other circuits even though it was in with a bulk standard 5AMP radial(1.5mm) . We have a downstairs shower room and fan. The fan seems to be on the radial lighting circuit. There is no electric shower (it is gravity fed non-electric). I wonder if there is anyway I can do some continuity testing to see if this cable is linked to any of the others.

In the meantime I have switched it off from the main baord.

Any ideas guys would be really appreciated. Thanks for your time.

 

[Spark123]

What size fuse was supplying this cable pre board change? Is it possible it is an immersion heater cable? If everything is working, the only viable way to trace the cable is either with cable detection equipment and a signal generator or rip the floor boards up.

 

[towman]

Could also be a direct feed for an alrm transformer, bell transformer etc - I found one of these on my old board - I think "Wiggy" put it in!!

The other alternative is that it is actually the other end of the lighting RING - it could be you haven't got RADIALS? Though if you've disconnected it you might have now! Just because it's 2.5mm doesn't mean it wasn't the other end of the lighting ring- maybe the installers ran out of cable?

 

[mapj1]

put a test lamp on the end. If it becomes live when another circuit is energised it is clearly part of it and shoudl be under that MCB.
If not, pull it out of the way and terminate it in a junction box or similar, and label it as 'spare-dead'
Leaving it attached an MCB invites someone to turn it on by mistake.

 

[dazzlerpalmer]

cheers guys - I will test it as suggested and disconnect it if not a ring.

If it is an alarm or bell cable (which would make sense since it was the downstairs lighting circuit) I will try to locate the other end.

If you hear a big bang from my neck of the woods, I've found it!

 

[dazzlerpalmer]

checked it last night - its dead.

So I am going to connect it back to its own 6amp mcb turn all other circuits off and see if my old meter is a spinning.

Short of that I will have to go around all the possible locations with a tester (although the one I have got is not that good)

 

[securespark]

I often find cables attached to a CU which "do nothing" and find they are chopped off under the floor etc...

Give it a gentle tug (and the cable too, for that matter! ) with the power off, and see if it gives any.