Bathroom Extractor Fan

[womble35]

My current Bathroom extractor fan is wired to a switched FCU outside the bathroom door. As it is now very noisy it is time to change it, so I want to install a new one, which has a timer on it. I would prefer to wire the new one to the light so that when the light is turned on the extractor fan starts.

The Bathroom light is currently wired into a chock block in the loft and then two core cable goes through the plasterboard to the light.



The extractor fan is in the ceiling connected via some flexible ducting to an external grille. The new extractor fan has three connections. L, L/S, N.

Can I connect the new fan to the straight to the chock block i.e L to the mains loop, L/S to the switch wire, then N to the Neutral. Or do I need to connect via a unswitched FCU.

 

[ericmark]

The chock block should be in an enclosure of course not just open. The wiring you propose is OK if no window in the bathroom or if the fan is not required anyway i.e. opening window. But to comply with building regulations you need to be able to run fan without the light. Standard is a pneumatic push button.

You also need an isolator so the fan can be turned off should it become faulty otherwise you would lose lighting if the fan fails.

There are two methods common one uses a three contact switch to isolate the other uses a double contact switch for lights so although switched with lights it's not actually connected to lights. The latter method will also allow a push button in parallel to run fan without lights but likely also needs a FCU.

Much depends if the fan is required by building regulations or if it's an extra.

Clearly if not like for like then also Part P raises it's head.

 

[PrenticeBoyofDerry]

Clearly if not like for like then also Part P raises it's head.

Naughty boy, you'll be in trouble for that!
womble35
Have you looked at Wiki
//www.diynot.com/wiki/electrics:lighting:fan
If you do alter or install new cabling then notification will be an issue, as far as replacing the extractor schedule 4 will allow you to do this.

 

[sergeantash]

Just my opinion but I wouldn't wire it direct to the light because then you lose your option to isolate it if needed.

When we have people staying, the fan can be noisy if someone's using the toilet at night, so generally we'll turn it off via the fan switch.

Having it linked to the light without the ability to exclude it would be a pain in the arse, for me anyway.

In my fan related thread, I was told that it should run through an FCU.

 

[holmslaw]

..

 

[riveralt]

In my fan related thread, I was told that it should run through an FCU.

You should have been told to follow the manufacturers installaion instructions - which most times indicate the requirement of an FCU and three pole isolator for a timer model.

 

[riveralt]

My current Bathroom extractor fan is wired to a switched FCU outside the bathroom door.

Can I connect the new fan to the straight to the chock block i.e L to the mains loop, L/S to the switch wire, then N to the Neutral. Or do I need to connect via a unswitched FCU.

Yes you can but I would utilise the switched FCU you already have. This will give you the opportunity to isolate the fan while still keeping the light on.
From the chock block (enclosed in a choc box) clear of any insulation run three core and earth from the PL/N/SL/E terminals to the FCU.
On the supply side of the FCU connect the SL (grey core with brown sleeve) to the Live Terminal, the N (black core) to the Neutral Terminal and the Earth to the Earth Terminal.
Put the PL (Permanent Live - brown core) in a terminal strip (you call them chock block).
Then run three core and earth from the FCU to the fan.
On the load side of the FCU connect the grey core (with brown sleeve|) to the L, the black core to the N terminal and the earth to the earth.
Connect the brown core to the terminal strip with the PL and place that inside the FCU back box.
At the fan PL to PL - SL to SL and N to N. Most fans do not require the earth so put it in a terminal strip and tape up.

Since all of this work is taking place outside the bathroom it is my view that there are no notification issues involved but I'm sure that will be challenged.

 

[ban-all-sheds]

Clearly if not like for like then also Part P raises it's head.

Part P applies to any work whatsoever on fixed electrical cables or fixed electrical equipment located on the consumer’s side of the electricity supply meter which operate at low or extra-low voltage and are—
(a) in or attached to a dwelling;
(b) in the common parts of a building serving one or more dwellings, but excluding power supplies to lifts;
(c) in a building that receives its electricity from a source located within or shared with a dwelling; or
(d) in a garden or in or on land associated with a building where the electricity is from a source located within or shared with a dwelling.

 

[ban-all-sheds]

And that would not comply with regs.

Which one(s)?

 

[womble35]

Thanks for all the replies

I have altered the naming on my pictures, to try and avoid confusion. Choc Block to me is a terminal block (Connector Strips) enclosed in a plastic box. In my picture I show just the terminal blocks (Connector Strips) so I can show the connections.

Regarding Part P, I knew this would come into play. I am not worried about it though as I have a qualified sparky coming down at the weekend with 40 years experience, who will be helping. Although I expect I will do most of the work, while he watches drinking tea

Anyway, after reading these posts, and the installation instructions of the extractor fan, I think I have worked out how to wire it correctly. Nothing will be done till the weekend, but I like learning how things like this should be wired correctly and legally.

The picture below is how I would do it. Would it pass ? Kind Comments please

 

[riveralt]

Yes that appears okay but you don't really need the three pole isolator if you wired it way I suggested earlier.