Difficult one this without seeing the actual job I know but I was hoping for some general advice.
I’m fitting out a bathroom and have come to the shower rail. The rail fixes at two points on the wall and needs a third support at the corner to the ceiling.

The ceiling is sloping, I can make an angled bracket, piece of wood for that but the main issue is that the ideal attachment/fixing point falls pretty much right between the two ceiling bulkhead lights, as shown by the sketchup sketch below..
Excuse the rubbish drawing. Trying to bosh it out quick in my lunch twenty minutes!

Firstly, I am using a stud detector, set to detect ac current but am just not really confident as I keep getting inconsistent readings, something which I can see is very common with these detectors.

As a starting point, where are the cables likely to be?
The lightswitch is outside the door. I imagine there would be a run of cable horizontally between the two lights but where else? Would the cable likely go upwards to the meeting of the vertical wall, along the wall top and then outside to the switch?

Is there any tips anyone can offer when faced with a lack of confidence in your wire detector?
The most obvious of course is to get a sparky in but you know, I’m pretty competent in most practical stuff and want to save money where I can, just happen to be a little clueless on electrics being a humble furniture maker… 🙂

Anyone offer any advice?
Cheers.

Incidentally, I can see the shower rails are not level and the bath is the wrong way around. Please try to ignore that… 😉

If you aren’t sure then the only way is to have a look – drill a couple of inspection holes?

There are officially safe zones where wiring should go but once a cable goes up into a ceiling cavity all bets are off. I’d remove a light fitting, cut the cable hole a bit bigger and see what’s what with a small mirror and torch.

If it’s sloping I assume there’s a roof above. It’s easier to run cable under there than through the wall so I’d expect the trunking to go straight up from the switch then to the lights. Take the switch out to see where the trunking heads. If there is only one trunking to the socket and only two wires the power comes in from wherever the trunking heads too.

drill a couple of inspection holes?

Without going through the cables obvs..
Suggest how?

Without going through the cables? Suggest how?

as I mentioned. Remove the light and enlarge the cable hole. Use a pad saw. Should all be covered by the fitting.

Your worst case scenario is that someone has checked the cables into the timber structure then plasterboarded over it. More likely to be lying between the timber battens or drilled through the middle of them (in which case a you should be fine if you only go 25mm into the timber with your screw. If ceiling is old style lathe + plaster the cable will be woven through the 25mm gap between the lathes and the joists (in which case fix into the perpendicular Brander that the lathe is nailed to) or if the joists run the other way the cable will be in space.

Without going through the cables obvs..
Suggest how?

By above suggestion or simply by drilling/cutting holes manually/carefully. Assuming it is a plasterboard ceiling then you know how thick that is so it would be pretty difficult to cut through electrickery cables.

Of course you could also isolate the mains before cutting the holes so if you do happen on a cable there will be no chance of electrocution.

Or go and buy a cheap inspection camera – like the ones used in garages .
Useful and now very reasonably priced – get one with alight on the end – most have.
edit – just to give an idea how easy/cheap the options are put:

android endoscope into ebay – select uk only – change from £10 ok ?

Endoscope bought. Had no idea you could get these. Might do a few medical checks while I’m at it. 😀

Thanks for the tips folks.