Stupid electician? Sky light and extractor fan

[plugwash]

you will wan't to remove the old switch cable (3)

at the light

the red of the 3 core switch cable goes to where the red of the current 2 core switch cable is

the blue of the 3 core switch cable goes to where the black of the switch cable is now

the yellow from the fan goes to the yellow of the 3 core switch cable (using a bit of terminal block


if you do not want timer overrun the red from the fan also goes to the yellow of the 3 core switch cable otherwise it stays where it is

at the switch

the red of the 3 core switch cable goes to the com terminal of both switches (with a short wire link)

the blue and yellow of the cable go to the L1 terminals of each switch

 

[benjiman]

Brilliant, absolutly blooming marvelous. Will give it a shot tommorow looks much more clearer now. Cheers plugwash and all

 

[ban-all-sheds]

1 is for the switch.

Yup. This is the one that you will be replacing with a 3C+E

1 for the extractor fan (3 core)

Yup - this is the one where you will remove the yellow from the rose and connect it with choc-block to the yellow from the switch

1 for the rose (I think)

One is the loop-in, i.e. the cable which carries the lighting circuit supply - it comes in from the previous rose in the circuit.

Whats the other one for?

This is the loop-out, i.e. the cable which runs to the next rose. See the reference section for details of how lighting circuits are wired.

You'll end up with this. As Lectrician says, the isolation switch is not essential, but it is a good idea.

 

[benjiman]

wicked, brilliant diagram BAS. Thanks alot. All sorted now. Just need to redo the decorating.

Running that 3 core was hard work

But got there in the end.

Thanks to all those that helped. I very much appreciate it, didnt think it was possible to sort it out personally but you guys gave me the confidence to smash the newly laid coving and break through the finnished plasterboard.

Very happy with the results. I particularaly like the live red linking cable used to supply both the switches Very clever indeed!

 

[pipme]

Sorry, But where's the fuse then ?

I know been here every time !! But every extractor fan I have looked at asks for a smaller value fuse than the lighting main ..... I know it complicates things (the two lives to fan) but why ignore this ?

I personally find more useful to have separate pull cord for fan, with over-run ... then fan not running when people just use light and loo or mirror (girls) .... Via FCU correctly fused.

The Manf options & calling for 2 amp fuse !! (Earth not shown for clarity ?)

The 'nub' of contention here being that in 3.3.3 The light is also controled by the 2amp FCU.
I will post, later a picture of my failed double insulated fan ... the burning is clear to see ... with the inner casing almost melted at a point ... There was, in the 'professional' installation NO 2 amp fusing. The lighting main fuse is of the correct value. I do not like the thought of anything overheating in my loft !!
Hammer me all you want ... no fuse as per Manf recommendation .. possible no valid fire insurance ... sue the installer ? I prefer Costa Brava not Costa Lot !!
P

 

[plugwash]

because there is no real need to fuse down fans and its a pita to do because of the two lives

i think in most cases the instructions are written by people who simply do not know what they are talking about

 

[pipme]

Sorry about all this chaps, but this is where I came in months ago, without the knowhow to get the sketch on forum.

My timed fan refused to start when light was switched on, light off, light on ... fan runs seemingly ok.
Not happy, must be a reason why non starting, I go to loft and strip fan ... ooer! bad burn mark and evidence of plastic deformation in one corner of inner plastic cover ( double insulated ) Also outer cover affected to a lesser degree.
Ok, fit a new fan ... Look up how it should be wired .... check the existing wiring ugh ! What you see in the sketch above is what I eventually deduced from close investigation (I added the red sleeves in sketch none in reality).... work done by spark 4 or so years ago. .. Ok it works, but no 2 amp fuse. No FCU, No triple pole isolator. Not coming from ceiling rose etc .. was a bit daunting at first.
We do have separate neutral cables in our lighting system late '60's built, given that the neutral is part of the same lighting circuit as the live I assume this is not a 'borrowed' neutral ?

P