Help needed again pls - Lighting fault tracing

[westward10]

Removing the ceiling exposes all risks. You state you are no plasterer so you would not attempt this, you are clearly no electrician however you are happy to peruse this and I'm sure Confucius would have a opinion on this. A poorly finished ceiling poses little risk, poor electrical installations pose a significant risk to life. Plastering requires a great deal of skill with a modicum of knowledge, electrical works require a great deal of both, think on it.

 

[AJB Temple]

Thank you. That doesn't answer my question though. A camera accessing the ceiling also exposes all risks. Removing the wires via existing holes also removes all risks. What is the logic for demolishing the ceiling if wires can be stripped out without that?

 

[timhoward]

Thank you. That doesn't answer my question though. A camera accessing the ceiling also exposes all risks. Removing the wires via existing holes also removes all risks. What is the logic for demolishing the ceiling if wires can be stripped out without that?

If there is nothing dangerous upstream of where you tap into the circuit, and no other wiring/circuits with previous DIY efforts then you might get away with it.
You have rather eloquently described this house as an electrical disaster waiting to happen, hence the comments that this is a chance to make sure this area is ok that should be seized.
Ceiling board isn’t expensive, and if you are converting into two rooms won’t there be a plasterer on site anyway at some point?

 

[AJB Temple]

Thank you Tim. We have had the house for nearly 9 years and said in previous threads (I had one fault fining recently in room connected to this on) that we have worked our way through. Much of it is new and finished and was professionally rewired (where it was not new), though the electrician who did this has moved to Eire recently. The old kitchen was the last room to do because it has been a workshop for the past year or so. One of the refurb jobs has been to remove all sockets from this area as it becomes a bathroom. The laundry room has a new 13 amp radial direct to secondary CU in this case with AFDD. That room is finished apart from some shelving and decorating (in progress). No plastering is done or planned because internal stud walls and 200mm of extra insulation have been added throughout the old part of the property, with membrane and panelled insulated walls over that. This has obviously made rewiring a great deal easier. The new bathroom is fully insulated and has cement board walls against membraned insulated stud for full tiling. Hence no need for plastering. I do the tiling.

I agree that ceiling board is cheap and I have installed plenty. However, the excellent plasterer we trust and have used in the past for the new build parts is booked until July /August as we are in an area where they are putting in very large numbers (thousands) of new build. Reliable trades are in short supply - same applies to brickies for instance.

I will inspect the void today, having relocated the track saw bench.

 

[AJB Temple]

SOLVED
Thanks for all the help. It was nothing to do with the smoke detector. In this new hole (where there will be a light fitting) three white T&E wires were fed from this "junction" (see pic if it loads). One supplied the redundant smoke detector and the other two run round the lights in two different directions with a further radial connection at another light point.

There was no junction box at all. CPC connections made by uncovered twisting, and everything else crammed into a strip connector, where there was a short and a bit of blackening (hard to see in the photo). I've traced point to point and there are no other junctions that are not at a former light fitting point. The old wires have then been used to pull through new wires in the whole room and back to the CU. (The pull through proves there are no other junctions). The switch segment buried in the wall (quite short) has been removed as it will be replaced by a quinetic controller anyway. A new wire has been run from an unused lighting rated spare MCB for now (CU will be replaced with another all RCBO and possibly AFDD set up when an extension is built). So this cable feeds only the bathroom lights and nothing else (apart from the controller).

I think this lot may be the original wiring from the developer when the house was first converted and is pretty much the last remnant left in the building. What I thought was a mains fed smoke detector in the laundry area, was in fact a dummy and not actually connected to anything at all. Amazing. The one in the new bathroom was fine. It's hard for a layman to understand how developers and employed trades can do this kind of work, with poor terminations and no junction boxes.