bathroom fan & old pull-cord switch

thaihobie · 28 May 2007

I am replacing an old noisy basic ceiling fan (installed when house built 13 years ago) with an inline loft mounted one over the shower cubicle. The new fan is timed - the old one wasnt.

The plan was to simply wire the new fan in to the existing pull-cord switch in place of the old fan which was connected to the pull cord switch with just red and black. The pull cord switch though seems oddly wired.

3X black in the earth post (including the black from the old fan). 2x red to L1 and one red from the old fan to 'Com'.
the 3 earths are twisted together and sheethed.

I have 3 core Plus earth wire but cant work out which way to connect the new fan in a way which enables the fan to run on on timer or why they have put the blacks to the earth post.

any advice available. thanks

Steve · 28 May 2007

The blacks SHOULD NOT be at the earth terminal. Reomve them immediately, and place the EARTHS there. Again, the earths SHOULD NOT be simply twisted together. Did the village drunk wire this up? Place the neutrals in a bit of terminal block.

Your fan requires a LIVE, a SWITCHED LIVE and a NEUTRAL. You have all 3 at the switch. If you cannot work it out, you shouldn't be doing this.

ColJack · 28 May 2007

asuming it's plastic then they have connected the neutrals into an un-insulated terminal.

they should be removed and put into a terminal block.

the 3 earths should be in the earth terminal..

from what i can tell from you description, you have live in, switch live and neutral out to the light and a switch live and neutral to the fan

you have 3 core to replace the current 2 core and earth to the fan..

you need to put the brown of the 3 core to the Com of the switch ( which should be the live in..

the black to the neutral ( sleeved with blue.. )

the grey to the L1 terminal..

these are then live, neutral and switched live repsectively..

you need to install a 3 pole isolator for the fan near to it..

this work comes under the scope of part P of the building regulation as it is in a bathroom..
you should have notified the LABC before comencing work..

thaihobie · 29 May 2007

Thanks for the quick responses.

Crafty, not sure who did it as it the wiring is untouched since we bought the house new 12 years ago. but since it had all approvals and was NHBC certified etc - it does make you wonder about some of the cowboys about.

The pull cord switch just powers/activates the the fan. There is a second pull cord for the light. We have the same set up in both bathrooms and I have had a look at all 4 pull cord switches.

In each bathroom the fan pull cord is as described (blacks to earth terminal), earths twisted and sheethed. For the pull cords for the lights the wiring is simple and correct for a switch as as I would have expected.

I think i will have to do as you both very wisely advise and get someone in to sort it out and get the needed approvals. Hopefully someone better than the original electrican.

Its painful though when a £50 fan looks like it will cost a fair bit - but the hole is already cut above the shower and theres no turning back now!

thanks again for the quick responses.

pdenni · 29 May 2007

just double checking is your new fan unit 12v?

thaihobie · 29 May 2007

no, mains driven.

but sits well away from the shower. the fan is half way along the inline exhaust trunking

a B&Q special.

ColJack · 29 May 2007

most fans with timers are run from the light so they come on when you turn the light on, and carry on for 15 mins when you leave and turn the light off..

just make the wiring for the old fans redundant by removing the wires and switches and putting any live cables into a JB ( ie the live in / live out ) in the loft or somewhere you can get at them later..

then wire the new fan off the back of the light..

thaihobie · 29 May 2007

Thats a good idea Coljack. thanks.

But as this an ensuite, I dont think my other half will agree because of the noise at night.

The ensuite has an opening & vented window and the fan is only for when we use the recently fitted power shower (no, not by me...) with the new fan duct positioned over the shower. (the old fan is ceiling mounted near the window).

so we still want to have the option of having the light on without the fan coming on.

ColJack · 29 May 2007

then i refer you back to my first post on this topic..

I told you how to do it there..

where are you based anyway?

thaihobie · 30 May 2007

in essex

thaihobie · 2 Jun 2007

fan now works fine!. (and earths & neutrals sorted)

many thanks for the help Coljack

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bathroom fan & old pull-cord switch

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