Electric bathroom mirrors from lighting ring

[Oli83]

I’m putting a new en suite bathroom in.

Behind the old plasterboard the developers have left a loose cable which is giving a very low reading when I test it, I’m assuming it’s a spur from the lighting ring.

The en suite is adjacent to another en suite I plan to refit in future.

I want use the cable to power low amp led mirrors in this en-suite and the adjacent one when I get around to doing that refit.

I connected a 13amp socket to the wire and plugged in a light, it didn’t come on and the RCD tripped. This is why I’m assuming the spur is from the 6amp lighting ring. There isn’t enough space in the loft for me to get a look at it to confirm.

If I connect a 5 amp fuse to the wire, creating a fused spur, then into a junction box to split the connection onto the two low amp led mirrors, will that work and is it safe?

 

[robinbanks]

What do you mean by "low reading"?

it didn’t come on and the RCD tripped

Assuming you made the connections correctly, I doubt the wire you have found is wired as you expect (if it were a good spur it should have lit any random light you found, even a 500w halogen flood light)

There isn’t enough space in the loft for me to get a look at it to confirm.

I think you may need to hand over to a smaller, sparkier person

If I connect a 5 amp fuse to the wire, creating a fused spur, then into a junction box to split the connection onto the two low amp led mirrors, will that work and is it safe?

Not wishing to rain on the bonfire, but my vote is no; you've a wire of unknown provenance that appears to promote a short when loaded, or possibly bridges multiple circuits, and doesn't strike me as a good candidate. You're assuming a lot, verifying little and tacking a 5 amp fuse into a circuit will do nothing for protection that a 6amp breaker won't do better.