I have a single story lean to downstairs loo that needs the light rewiring.  I’ve found the feed in from the previous light and I’ll be moving the switch, but I have no access to the ceiling void to run the cable  I suspect it’s just ply and plaster ceiling under the asbestos roof (old 50s garage which was converted)

If the wiring is like the rest of the place it will be clipped with tin clips so no chance of using it to feed the new wire.

any ideas? is my only option to cut some small holes in the ceiling to feed the new wire?  is rather not disturb if I can avoid it.  walls are all fully tiled so a pita to, and used to be a kitchen which still seems to have a live mains loop buried in there somewhere (which I will be making safe)  so basically wall lights are out.

someone has managed to add a fan (modern colours) to the circuit (with no isolator) but that means they got in the void to do so I cannot see how they did it unless it was prior to the ceiling going up?

bit stumped

Is there not a hole where the light fitting is?

Below the floor of an adjacent upstairs room?

I assume that you know about these (linky)

Additional holes made good will look nicer than a length of trunking 🙂

Take a look at the Super Rod Gekko.  It’s a pair of magnets and a string that allows you to feed cables through inaccessible cavities and around obstructions.  A sparky yesterday I met on a job was raving about these.

hiya, I have a set of rods I’ll take a look at those magnets sounds like the business.

yes very small hole where the light fitting is, and the entry feed is via an adjacent room but through an external wall and cavity.  I believe the switch and fan cables are likely chased in under the tiles and which is a right pain so I just plan to disconnect and move the position whilst I’m at it.  (who puts a switch for a bathroom in a cupboard outside it??)

so plan is relatively big hole in cavity wall under floor parallel to existing feed to run the switch live in to the light hoping I can fish it through.  it’s only a couple of metres tops.

likelihood it’ll take me all day and I’ll loose some rods, very high!

If I make an access hole in the ceiling what the best approach? something like a 75mm holesaw and then make good with a ply/plasterboard circle glued back and filled?

For an exit 75mm should be ok. For access bigger is better. Keep a light clockwise pressure on the rods