Bathroom timed extractor fan wiring question

[Flybywyre]

I am in the process of fitting a bathroom extractor fan in an area that used to be a window but I am now boarding up and tiling over. I am taking the electric supply from the wiring supply to the bathroom wall mounted light so that the fan comes on when the light is turned on.
Getting the permanent live supply for the timer is a problem as the switch is situated in the hallway outside the bathroom.
However there is a live supply that used to supply an old wall heater that I have removed and is in exactly the right place. Can I use this supply as the permanent live connection to the extractor fan?
Thanks in anticipation,
FBW

 

[ColJack]

no you can't..

 

[londonboy]

Are you sure theres not a perm live at the light fitting, or in the loft?

 

[ban-all-sheds]

The permanent live to the switch has got to come from somewhere....

 

[Flybywyre]

Thank you for your replies................
The property is a purpose built (1969) ground floor flat situated in a block of 8. I do not have a loft.
The supply for that bathroom light switch comes from some trunking that winds it way around the lounge and kitchen.
Would I be right in thinking that the only practical way of overcoming this problem is to wire the extractor fan up without using the timer facility ?
Regards,
FBW

 

[plugwash]

how does power get from the swtich to the light currently? can you draw a diagram of the complete setup?

 

[londonboy]

Thank you for your replies................
The property is a purpose built (1969) ground floor flat situated in a block of 8. I do not have a loft.
The supply for that bathroom light switch comes from some trunking that winds it way around the lounge and kitchen.
Would I be right in thinking that the only practical way of overcoming this problem is to wire the extractor fan up without using the timer facility ?
Regards,
FBW

Thats the easy way yes

 

[flameport]

Option 1: Put a new cable in - vertically from the light switch up to the ceiling, through the wall then around the top of the bathroom wall(s) to the fan?

Option 2: Forget about the lighting circuit. Get a fan with a humidistat and connect it to the old heater supply?

 

[ban-all-sheds]

Option 1: Put a new cable in - vertically from the light switch up to the ceiling, through the wall then around the top of the bathroom wall(s) to the fan?

And the neutral comes from.........?

 

[sjwkmje]

Option 1: Put a new cable in - vertically from the light switch up to the ceiling, through the wall then around the top of the bathroom wall(s) to the fan?

And the neutral comes from.........?

We really need some photos. BAS, if its looped in looped out at the switch the neutral could be there. If you show us a photo of the wiring inside the light we can advise better. You need to take the permanent live switched live and neutral all from the same circuit via a three pole isolator located outside the bathroom.

Adam

 

[ban-all-sheds]

if its looped in looped out at the switch the neutral could be there.

 

[Hibbo]

Erm, why can't he power the fan from the old heater supply, and take only the switched live from the light?

 

[Flybywyre]

Pictures as requested.
Behind the boxed in area I have two power feeds. 1 from the old light fitting and the other one is from the removed bathroom light and heater.
Regards,
FBW

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• Flybywyre
• 27 Dec 2009
• 1

Wiring behind the light fitting

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• Flybywyre
• 27 Dec 2009
• 1

Close up

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• Flybywyre
• 27 Dec 2009
• 1

Bathroom light switch situated in hallway with trunking up to the ceiling and across to the...

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• Flybywyre
• 27 Dec 2009
• 1

Wiring from trunking into the airing cupboard and through the messy hole into the back of the...

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• Flybywyre
• 27 Dec 2009
• 1

The current view (White cable to ceiling is my temporary lighting)

For a description of the photo's take a look at my album
//www.diynot.com/network/Flybywyre/albums/

 

[ColJack]

Erm, why can't he power the fan from the old heater supply, and take only the switched live from the light?

because then he would have a shared neutral..with the light circuit back feeding into the neutral of th heater circuit.

it could be done with the use of a relay but then you would need a neutral form the lighting circuit for the relay..

 

[ColJack]

so you have a trunking in from the switch?

then it's a simple matter of swapping the existing T+E from the switch to the light with a 3C+E..

as it's fed from the rear of the airing cupboad and wall mounted then it's a really simple job that you seem to be making over complicated..