Is it possible for a light to be wired wrong and still work?

[Kkiernan09369]

At my father in laws house, for the last 5 years two of the bedrooms lights haven’t worked. The bedrooms that the lights don’t work all seem to wired correctly.

apart the landing, which does work. But appears to be wired incorrectly?

rather than having a live in, 3 red loops, and black line, it spears the light fitting is hooked up to a red cable and black. And I can only see 2 blacks.

 

[westward10]

Is that the landing light which works.

 

[Kkiernan09369]

Is that the landing light which works.

Yes this is landing light. I though maybe the loop looking incorrect might have the knock on effect as to why the bedroom lights won’t work.

 

[westward10]

If that is what as known as a three plate wiring system I would expect to see another red in the bottom connector however it is difficult to say for sure.

 

[telectrix]

landing light usually 2 way, so there might be a JB in the attic.

 

[davesparks]

As its the landing light and probably 2 way switched from downstairs you may find that the switched live is a single red coming from the upstairs switch. The downstairs switch would have a permanent live coming in from the downstairs circuit.
The upstairs lighting feed is only providing the neutral to this light, the live just looped through.

If this is the case it is called a borrowed neutral and is a potentially dangerous situation which you should get an electrician to investigate and rectify, make sure you tell them that you suspect it may be a borrowed neutral.

If you are going to attempt any work yourself then make sure to isolate all lighting circuits, not just the one you are working on, a borrowed neutral can cause an isolated circuit to become live due to the connection to another circuit.

 

[Taylortwocities]

Do you have a two-probe voltage test device (not a magic wand/neon screwdriver) or a multimeter. If so, do you know how to use it?

If not then, I'm afraid, it's a job for an electrician on site.

 

[telectrix]

As its the landing light and probably 2 way switched from downstairs you may find that the switched live is a single red coming from the upstairs switch. The downstairs switch would have a permanent live coming in from the downstairs circuit.
The upstairs lighting feed is only providing the neutral to this light, the live just looped through.

If this is the case it is called a borrowed neutral and is a potentially dangerous situation which you should get an electrician to investigate and rectify, make sure you tell them that you suspect it may be a borrowed neutral.

If you are going to attempt any work yourself then make sure to isolate all lighting circuits, not just the one you are working on, a borrowed neutral can cause an isolated circuit to become live due to the connection to another circuit.

that makes a lot of sense. explains why there are only 2 reds in the loop terminal.