Bathroom mirror lights don't work without main light switched on

[Pete77]

Hi all, apologies if there is a more appropriate forum, I just can't seem to find a definitive answer!

I have 2 bathrooms, each of which has a mains-wired mirror with lights, shaver socket and demister. Downstairs, the mirror lights etc. only work if the main light is switched on. Upstairs, the mirror works independently of the main light.

I'm assuming the latter is the correct setup? i.e. the mirror should work without the main light on. If so, can anyone suggest a likely reason for the downstairs mirror working that way?

Any advise appreciated
P

 

[Andy78]

It works like that because someone wired it like that. It could probably be altered to work independently of the main light.

 

[Pete77]

Well worth signing up to the forum for that calibre of advice!

Perhaps I should have asked 'can anyone suggest why it might have been wired like that?' The neighbour's bathroom is wired the same way.

 

[DefyG]

Obviously 'looped' off of the main lighting s/l. Maybe in the light fitting, switch or a hidden junction box.
As for why, you'll have to ask the original installer!

 

[ferg]

It sounds like someone made a mistake either at 1st or 2nd fix.

Correcting it could be as simple as altering wiring at a switch or may need part of the circuit rewired

Impossible to tell which from here.

 

[ruston]

Well worth signing up to the forum for that calibre of advice!

Perhaps I should have asked 'can anyone suggest why it might have been wired like that?' The neighbour's bathroom is wired the same way.

Probably when they were fitted the permanent live was not accessible and they could only tap into the switched live to avoid major disruption and damage to the decor.

 

[Andy78]

Well worth signing up to the forum for that calibre of advice!

Perhaps I should have asked 'can anyone suggest why it might have been wired like that?' The neighbour's bathroom is wired the same way.

Any depth of answers on here tend to reflect the depth of supplied information

 

[Pete77]

Cheers guys. I think that tells me what I wanted to know - that it's more likely a mistake than intentional.

 

[MJPD29]

Should be easy fixed if you can find where it is connected to the lighting circuit and connect it to the permanent live rather than switched

 

[DjMadness]

Hi,

I think it was a stress mistake made by the electrician. The reason for the udesired behavior of lighting downstairs is because: live wire that must be headed to mirror switch is taken from the output terminal of the previous main switch instead of taking it directly from live feeding the entire bathroom lighting. On the surface mounted box in which the main switch takes place, notice the output terminal (screwdrive junction) it must contain 2 red wires. If you could identify which of refers to the mirror, detach it from where it is and plug it to the other terminal. This is while assuming you have SPST switches.

Dj

 

[Deleted member 26818]

Might have been intentional.
Seen Shaver sockets wired off the Switched live because the transformers can buzz if left permanently live.