Guys if you could help I would be eternally grateful.....

[withnail69]

I didn't eat last night and hardly slept due to mains having been off whilst I tried to sort this....

A few days back I tried to replace my bathroom light switch (outside the bathroom) with a dimmer switch. This worked but the fan (which I foolishly hadn't thought about) only turned on when the light was off. (The fan also has its own seperate large switch which is permanantly on. Obviously the fan was controlled by the standard light switch. I tried changing up the wires a bit but I couldn't get the fan to come on with the dimmer (I now know I shouldn't have attempted this but the lights in the bathroom were so harsh). So last night I went to put my normal light switch back and then the problems started. I didn't take a picture of the original configuration cause didn't think I would need to switch back... These are the wires I have.... one white/grey and one brown going in to the common and two other brown cables. I can't remember where these went. There is common and one way and two way holes for the four cables to go into. It seems like whoever originally installed this wasn't very good to leave three cables the same colour. I tried the following combo..... two in the common (90% sure this is how it was) and both other browns in the one way... This resulted in the light being permanently on (regardless of switch) but the fan working with the light switch. I then tried the same two in common and one brown in one way and one brown in two way and then the light was off and wouldn't turn on with the switch but yet again the fan works with the switch turned on. My friends who work in this field say to just try different combos until it works. Do you think its possible that I got the brown that goes in the common mixed up with one that doesn't? Any help would be really gratefully recieved I now have no bathroom light and am exhausted.

 

[Iggifer]

the easiest way to work this out will be to just use two pairs of wires at a time,

so start with the grey in common and bown 1 in L1 see what that does, then brown 2 and so on.

This should help you identify what wires do what, mark them with a pen as you go, then when you've figured out what does what it should be a simple enough job to connect them back up properly

 

[viewer]

Also likely the fan will not work with a dimmer.

 

[Iggifer]

I read it as he'd already established this through it not working and that's why he's trying to put the switch back on, I could be wrong though

 

[withnail69]

iggifer is right. Thanks for trying to help guys. Would it be usual for two wires to go in the common and one to go in the one way ( I take it this is what you mean by L1?). I'm pretty sure all four wires were connected when I first took this switch off. For the dimmer I had two in the common one in one way and another in two way and the lights worked ok. Just can't remember the config of the four wires for the original normal switch to get fan and lights turning on and off at same time....

 

[Iggifer]

it's not necessarily standard for two wires in the common, but it depends what setup there is, it's certainly not wrong by definition.

A multimeter would make your life a lot easier!

 

[PrenticeBoyofDerry]

Do you have any approved test equipment that can safely test for voltage?
and a meter that can test for continuity?
Firstly finding the permanent live would be a major help.
What core colours are at the fan isolator?
Also is there a CPC/earth cable or two at the switch?

 

[withnail69]

from the top of the switch (ie:- looking like it is coming down from ceiling into box is a large white plastic wire. Inside that is the grey wire and the brown wire (because these came into the box together I thought they both went in the common (at least this is how I remember it but it looks like I am wrong). From the bottom of the switch ie:- Looking like they are coming into the box from the floor direction are two loose brown wires (which are currently in the one way and two way holes) as previously stated with this configuration the fan works with the light switch but the light doesn't

 

[withnail69]

doing some googling. I realise the grey cable has a bit of electrical tape on it which looks like it should be going into the L1 and not the common. I think I am getting there! thanks for your help .. Source.....

http://www.flameport.com/electric/lighting_circuits/switchwires_2way_both_newcolour_T.png

 

[ban-all-sheds]

Plan A:

Continue doing electrical work by trial-and-error, without knowing what you are doing, hoping to hit on the right combination before you hit on one which results in bad things.

Plan B:

Equip yourself with the right tools, and the right knowledge, and get it safely right first time.



I recommend Plan B.

 

[withnail69]

I wouldn't be here asking for help if it hadn't gone wrong. I think that much is clear. I'm not sure how you pointing it out to me again helps?

 

[ban-all-sheds]

1) Because your whole attitude to electrical work needs adjusting.

2)

• http://www.google.co.uk/search?q=electrical+circuits+101
  
  
• http://www.google.co.uk/search?q=multimeter+101
  
  
• http://kevinboone.net/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• //www.diynot.com/wiki/electrics
  
  

 

[withnail69]

1) Because your whole attitude to electrical work needs adjusting.

2)

• http://www.google.co.uk/search?q=electrical+circuits+101
  
  
• http://www.google.co.uk/search?q=multimeter+101
  
  
• http://kevinboone.net/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• //www.diynot.com/wiki/electrics
  
  

some links which is helpful thanks. As previously stated if I'd taken a photo at the start then I wouldn't need to ask for help here. I've been talking to professionals and they can't give me definitive answers without being there in the flesh so its not a simple problem its seems like a pretty complex switch. I've really appreciated some people taking the time out to help but if this is one of those flex your muscles and attack the ignorant newbie forums then so be it.

 

[ban-all-sheds]

Not at all.

I advised a more sensible approach than guesswork, and provided information to facilitate that.

Maybe it does need someone there in the flesh, but if you knew what you were doing then you could be that person, and you could sort this out even if you had lost track of which wire originally went where. And IMO knowing what you are doing is utterly essential. I'm not "attacking" you, but you do deserve to be admonished.

 

[riveralt]

Ignore BAS he seems to be in a different world from the rest of us at the moment. His more recent apoplectic response to the standard of workmanship just highlighted this fact.
While it would be nice for everyone to have the knowledge required for fault finding electrical circuits, the reality is that is just not the case - get over it BAS.
Waits patiently for the flame Sorry admonishment.
To OP the most important lesson you have learned from your experience is that you should always photograph or write down and mark how the cables are connected before you start any work - especially on lighting circuits which seem to catch out a lot of DIYers.
Back to your problem - which you may have solved already.
Can you tell me how the bathroom light and extractor fan operated before. I.e. did the fan come on with the light and did it go off with the light. Or did it come on with the light and stay on for a few minutes after the light was turned off.

Can you also photograph the conductors in the new/old dimmer/switch and the ones in the 3 pole isolator (big switch).