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OK, I am at wit's end over this supposedly easy project, advice would be appreciated.

So, my goal is to drill into the wall of my hobby room in my flat, in order to mount a pegboard for paint racks. All the walls in my flat are lathe & plaster over masonry(old Victorian tenement). The wiring was all redone at the same time years ago by a trade pal of my grandad's, and he specifically did all the plugs under the floors and behind the skirting, and all of the lights go straight up & down at the lightswitches themselves. Using one of those electronic wire finder doodads works exactly as I would expect it to based on that information, ie it finds no wires in the walls anywhere except directly above and below lightswitches.

Except on the one sodding wall I actually want to drill into, where it seems to detect multiple live AC wires inside the wall, running in multiple directions(one lengthways about head height, two or three spots where one appears to run downwards from there, nothing above it), which there's no actual reason for that I can see; I opened the one plug socket on the wall and right enough the cables come up from under the floor, none of the vertical detection points align with the plug, and it goes off at the lightswitch as it should. Checking the same wall from the opposite side(it's internal) and it detects nothing unexpected.

Obviously I'm now somewhat hesitant to drill into the wall, but I'm wondering if anyone can suggest some reason why I might be running into this?

I found this

https://www.youtube.com/watch?v=wzl2C7HjAW0

So it could be picking up a pipe in the wall, or indeed any metal as from what I can gather they pick up the wires by looking for metal.

Of course you can work around that, just mark the wall and identify the shape of what its detecting. Also if you're in any way worried shut the power off fully to the house that way you at least safe yourself from electrical harm.


Automatically Appended Next Post:
https://www.youtube.com/watch?v=RsRtlM8VvLU

This might help too though he doesn't really get started until around 6 mins in




Interestingly this is probably a good thread for me to notice! I grew up in an old house so all the cables and pipes, for the most part, are external to the wall and often have pretty clear in and out parts where they do duck behind. So thinking about cables and pipes hiding behind and witihin walls is one of those "stupidly obvious but never really had to think/do it before" kinda situations for me.

The thing that jumped out at me was that you say you're living in a flat, and therefore.must have up and/or downstairs neighbours and possibly adjacent ones.

Consequently could what you're picking up be feeds running into another property in the building?

 Overread wrote:
I found this

https://www.youtube.com/watch?v=wzl2C7HjAW0

So it could be picking up a pipe in the wall, or indeed any metal as from what I can gather they pick up the wires by looking for metal.

According to the listing on Amazon it specifically detects live AC, it has a separate mode for detecting metal pipe. I also can't fathom why there would be pipe in an internal wall between a bedroom and the front living room, almost exactly as far away as you can get from both the bathroom and the kitchen. It's not a gas pipe since I can see where that comes in from the stairwell across to the meter, which is out in the hall on the opposite side of the flat. The radiator pipe goes into the floor and the central heating is definitely under the floorboards. Like I say, there's zero reason there should be anything there.

Of course you can work around that, just mark the wall and identify the shape of what its detecting. Also if you're in any way worried shut the power off fully to the house that way you at least safe yourself from electrical harm.

Unfortunately the cheapo detector isn't really that precise, it goes off at different spots each time I recalibrate and sweep over it(but the same spots have come up several times). There seems to be an area of the wall about 1m square where something is setting it off, unfortunately thoroughly overlapping the ~1m x ~0.5m section I want to screw the pegboard to

 Azreal13 wrote:
The thing that jumped out at me was that you say you're living in a flat, and therefore.must have up and/or downstairs neighbours and possibly adjacent ones.

Consequently could what you're picking up be feeds running into another property in the building?

I suppose it's technically possible? I don't see why it would be though, below me is a retail unit, and the wall is right in the middle of its open shop floor, above me the flats are all built to the same pattern with the bathrooms and kitchens about as far away from this wall as they can be at either end, and its an internal wall to my flat so there's no neighbour abutting it. The main soil pipe for the property is several walls over in the bathroom. And it's not as if above or below can run things through my wall without me knowing since the wall is solid as I said, masonry with lathe & plaster cladding.

Honestly? Might be worth getting a handyman in on this one.

That way, you can benefit from their liability insurance if things go Grot sharped.

If it's an old property you may have a bunch of gas pipes in the walls from when they were how the place was lit.

Typically when the gas lighting was junked and the place switched to electric the old gas pipes would have been capped off and left in place in the walls, later gas work can then remove the main underfloor supply pipes leaving a bunch of orphan pipes in the walls

Could be. I've decided not to risk it - I've got a load of old laminate flooring left over, so I'll construct some kind of jig and backing board out of that that I can fix directly to the back edge of my work desk, and just screw the pegboard into that. Not the best solution, but it might do the job. Thanks for the suggestions.

Good call. You don't want to take any risks with electricity.

Could you perhaps attach that backing board to the wall, away from where the mystery wires are, instead of onto your desk?

 AndrewGPaul wrote:
Could you perhaps attach that backing board to the wall, away from where the mystery wires are, instead of onto your desk?

Nah that would defeat the object, which is to have all my paints easily accessible right in front of my hobby area. To clear the area where the detector keeps going off I'd have to move it several feet off to one side or the other.

I've never really used them, but it's my understanding that these wiring-detector devices are sorta prone to giving false positives, especially cheaper ones. Can you change the sensitivity settings on it?
If so, measure again with a lower sensitivity (that still lets you find the wires you already know about).

 Yodhrin wrote:

 AndrewGPaul wrote:
Could you perhaps attach that backing board to the wall, away from where the mystery wires are, instead of onto your desk?

Nah that would defeat the object, which is to have all my paints easily accessible right in front of my hobby area. To clear the area where the detector keeps going off I'd have to move it several feet off to one side or the other.

Oh, so the whole wall is inaccessible? I was thinking you could mount a large sheet, then position the racks on that board.

 AndrewGPaul wrote:

 Yodhrin wrote:

 AndrewGPaul wrote:
Could you perhaps attach that backing board to the wall, away from where the mystery wires are, instead of onto your desk?

Nah that would defeat the object, which is to have all my paints easily accessible right in front of my hobby area. To clear the area where the detector keeps going off I'd have to move it several feet off to one side or the other.

Oh, so the whole wall is inaccessible? I was thinking you could mount a large sheet, then position the racks on that board.

Well, that could work, but then I'd have to fork over for a big MDF sheet, whereas I can make the desk mount with some odds & sods I already have.