chasing cables in/behind wall

benson1980

Hi all, some advice on the above would be much appreciated....

I'm redecorating our bedroom and we have a cable that has been run through some plastic trunking which I obviously want to get rid of. Definitely a live cable and believe it is for our security light attached to the front of the house.

What is the easiest method of chasing this back into the wall? To the right hand side of the photo this is all just plasterboard, where we have the dormer window, so is there some way of working the cable around the back of this? No issues making holes at some suitable intervals but just couldn't work out really how you easily route the cabling behind if that makes sense?

Presumably the other option is to chase into the solid gable end wall close along the edge where the trunking is presently?

Third option is obviously to get an electrician to do it. I'm reasonably happy with [very] basic electrics and where the cable goes up into the loft I can probably disconnect it somewhere and then feed it back through when done.

Thanks

grumbler

Chasing is easy with right tools (angle grinder + SDS), but messy.

Running it behind the plasterboard is doable, but depends on what's behind it.

Why not to run the cable outside, around the corner?

fenwick458

benson1980 said:

 To the right hand side of the photo this is all just plasterboard, where we have the dormer window, so is there some way of working the cable around the back of this? No issues making holes at some suitable intervals but just couldn't work out really how you easily route the cabling behind if that makes sense

Only way to find out is start making holes, there are ways of getting cables around the back and it involves cutting holes and feeding access rods through. I normally use 5" hole saw and cut access holes, then afterwards put a small batten in and screw the bit of plasterboard back in and easyfill over the top. but the problem with this method is(unless you either built it or know how it was built) there's no guarantee any of the holes you make will be of any use to you. sometimes you might make one hole, and feed the cable from A to B and B to C and thats in job done, other times you make 4-5 holes and none of them are any good as you hit timbers, steel beams, insulation etc.. and you havent achieved anything and just created more work in that you just have to patch up 4-5 holes

benson1980 said:

Presumably the other option is to chase into the solid gable end wall close along the edge where the trunking is presently?

that's definitely the simpler option, no disconnecting of any cables, just chase a small channel for the cable, put it in it and plaster over the top of it

benson1980 said:

Third option is obviously to get an electrician to do it. I'm reasonably happy with [very] basic electrics and where the cable goes up into the loft I can probably disconnect it somewhere and then feed it back through when done.

Probably the easiest option as you will just be paying someone to do the job. If you get a good one their experience will help 

benson1980

Ok thanks both for the advice. Much appreciated. Hadn’t thought about the insulation issue so chasing it into the solid wall seems to be the way to go. I’ll probably avoid routing it outside unless I’m struggling with the above for any reason but I have the tools I need. Just not done this particular job before and wanted to make sure there wasn’t an easier option before making a mess.

FreeBear

Please pay attention to permitted safe zones for the cable (within 150mm of a corner or ceiling). You should also consider running the cable through conduit (makes life easier if it ever needs replacing). At a minimum, use a steel capping before slapping plaster on.

grumbler

FreeBear said:

Please pay attention to permitted safe zones for the cable (within 150mm of a corner or ceiling).

Is this if the cable is parallel to a corner or a ceiling?

Section62

benson1980 said:

Definitely a live cable and believe it is for our security light attached to the front of the house.

I think the starting point should be finding out for sure what the cable does, and working out why it comes down from the loft.  Is there a switch anywhere which controls the light?

If it was me, and the cable is for an outside light, I would look to having it rewired so that it is fed from a circuit under the floor of that bedroom - e.g. from the downstairs lighting circuit.

That would mean lifting the flooring in that bedroom (what type?) but would reduce the amount of chasing of walls to 9" or so. (i.e. coming up from the floor rather than down from the ceiling)

Lifting flooring isn't usually the preferable way to do things, but I think the mess created by chasing all the way down and across from the ceiling is likely to be a lot less desirable than the aggro of lifting and replacing the flooring.  As the room is being decorated it is the ideal time to do it.


I'd also use conduit in all of the chasing, and ideally sink in a suitable back box where the cable goes through the wall to enable a connection to be made inside the house if the light fitting is replaced with a pre-wired one at some point in the future.