Shower Room Fan (with timer)

[drewks]

Firstly - sorry - I know that this topic has been discussed before but I can't find any discussions that includes my questions!

I'm replacing a knackered fan of the same basic type but the existing wiring has me confused as I can't now understand the wiring diagram on the new fan instructions.
I know it needs to have a double pole fused spur (old one didn't have one)..... is it ok to put this in the roof space?

Basically the existing set up has 2 cables into the light fitting (one from switch, one from mains), then 2 cables out from the light fitting to the fan.

If someone could give me simple instructions on how to wire the new fan in with this set up I'd be very grateful.

Many thanks!

 

[riveralt]

I take it for the old extractor the light and the shower came on at the same time.
To introduce a dual pole fused connection unit into the circuit you need to intetrupt the live neutral and earth to the fan and probably the light as well, for the timer model, a three pole isolation switch. Though where on the circuit will depend on the manufacturers instructions.

From your comments it sound as if you have a ceiling rose at the light with a Twin and earth cable going to the light switch - is this a standard light switch?

The simple arrangement for a shower extractor and light is that a live is taken from the ceiling rose down to the light switch and a switch live returns to the ceiling rose light live terminal.
At the ceiling rose a three core and earth cable then is terminated so that one conductor is connected to the switch live terminal, one conductor is connected to the permanent live and the third conductor is connected to the neutral. The earth is also connected.
At the fan the permanent live, switched live and neutral are connected to their respective terminals and the sleeved earth (usually not used) is terminated in terminal block.
That means when you turn the light on the fan will switch on and when you turn the light off the fan will remain on for a set time limit.
Have a look at this and see if you can work out the most appropriate way to wire your fan.
//www.diynot.com/wiki/electrics:lighting:fan

 

[drewks]

Thanks v m for your reply riveralt:

Yup it looks like a standard light switch that I'll be replacing with a pull cord, and yes, the light and FAN came on together with a delay on the fan going off (same as the new one).

The double pole fuse on the instructions looks like it's before the light switch.

I'm still a tad confused by your explanation of the wiring -
"At the ceiling rose a three core and earth cable then is terminated so that one conductor is connected to the switch live terminal, one conductor is connected to the permanent live and the third conductor is connected to the neutral. The earth is also connected.
At the fan the permanent live, switched live and neutral are connected to their respective terminals and the sleeved earth (usually not used) is terminated in terminal block."
DON'T WORRY IT'S MY SHORTCOMINGS NOT YOURS!!

Is there a way to explain it EVEN more simply for a tiny mind like mine?!

I very much appreciate your time and effort - thank you.

 

[drewks]

PS
Attached (hopefully) is a picture of the ceiling rose wiring if it helps at all...//media.diynot.com/34000_33291_42309_97553766_thumb.jpg

 

[ban-all-sheds]

The double pole fuse on the instructions looks like it's before the light switch.

You could do that, i.e. put an FCU in the supply to the bathroom light, but that means that if the fuse blows you'll have no light.

Is there a way to explain it EVEN more simply for a tiny mind like mine?!

//www.diynot.com/wiki/electrics:fan

There's also a diagram there showing how to use an FCU without having the light go through it - you would need to change the light switch as well.


I would advise against putting the FCU in the loft - best to have it easily accessible. If you use the double-pole light switch idea it will obviate the need for a 3-pole fan isolator - another reason for having it accessible.

 

[riveralt]

It is very difficult to try and explain exactly what is required via the forum.
The problem is the dual pole fused connection unit that manufacturers have introduced without any good reason other than to give them a get out clause on their warranty.
What type of fan is it by the way - wall mounted, ceiling mounted or an inline fan in the loft.

Looking at your photograph from left to the right. The leftmost three block contains your live wire to your light, the switch live wire(black - though it should have a red sleeve on) and your switch live to the extractor fan (red). One of the centre wires to the fan will be your permanent live. One of the wires to the right 2 terminal block will be the extractor fan neutral.

A photograph of what is at the extractor fan would help.

 

[drewks]

Thanks a lot for your replies!

Does this wiring diagram (fan) help?

//media.diynot.com/34000_33291_42310_32530186_thumb.jpg

And this is an inline fan.

Ta v m.

 

[riveralt]

Unfortunately its too small and blurred,

What is the make and model number?

 

[drewks]

Soz re the picture!
It's from Intervent (think this is Manrose?) - VSF100T Timer Model

 

[ban-all-sheds]

Unfortunately its too small and blurred,

Should have gone to specsavers - looks OK to me.

View media item 42310

 

[ban-all-sheds]

I can't now understand the wiring diagram on the new fan instructions.

Having see the diagram, the only thing I can say to that is "you need to get an electrician".

 

[riveralt]

Okay I have found a legible drawing that is similar to the blurry one.
I am working on the basis that this in line fan sits in the loft and you want a pull switch and fused connection unit as per diagram. The pull cord will operate the light and shower.

Firstly make sure the shower room lighting circuit is dead and tested dead.
You are going to have to interupt the power supply to the shower room ceiling rose by removing the incoming live neutral and earth from the ceiling rose and connecting it to the supply side live neutral and earth on the the fused connection unit (fcu). You should also remove the old extractor fan cables from the ceiling rose.
From the load side of the fcu connect 3 Core and Earth 1mm2 brown to live, grey to live, black to neutral and earth to earth - this cable is going to your extractor fan through your pull switch.
At the pull switch you need to cut the three core cable. Connect the grey cable from the fcu to the Common on the switch and the grey cable to the extractor fan to L1 on the switch. Put the two browns, two black and two sleeved earth into their own terminal blocks which will stay inside the pull switch cover. If the pull switch has an earth terminal then use that instead.
You now need to connect 1mm2 T&E to the ceiling rose with shower room light.
At the pull switch connect the 1mm2 T&E brown cable to the L1 terminal and the blue cable to the black neutral terminal block. At the ceiling rose connect the brown cable to the lamps live terminal and the blue to the lamps neutral terminal.
At the extractor fan connect the brown to the permanent live, grey to the switched live terminal and black to the netural terminal - there may be somewhere to house the earth if not sleeve it and put it in a terminal block .
Couple of things.
There are other ways to wire this.
Generally Fcu's are supposed to be accessible if the loft is the only place you can put then as long as you can access it.
If you do not fully understand what I have said or do not feel confident in conducting this work then do not start it. Get an electrician in to sort it out for you.

 

[drewks]

Riveralt, you're a star - thanks very much for this detail; even I can follow it so that's great.
I greatly appreciate your time and expertise - many thanks again.

 

[drewks]

riveralt - have wired up and is not working....
....have just gone through steps again and I note that you say:

'At the extractor fan connect the brown to the permanent live, grey to the switched live terminal and black to the netural terminal - there may be somewhere to house the earth if not sleeve it and put it in a terminal block.'

As I understand it this is the 3 core & e cable from the pull switch; I've connected the black to the 'neutral' terminal block in the pull switch too but still no joy on the fan OR the light (the other lights on the same circuit are ok).

Any suggestions?? Pulling my hair out here!

 

[riveralt]

I done a rough and ready drawing here.
Two Core and Earth to the FCU (could be red and black instead of brown and blue)
Three core and Earth from the FCU to the Pull Switch.
Three core and Earth from the Pull Switch to the Extractor fan.
Two Core and earth from the pull switch to the light.

Untitled

• riveralt
• 7 Feb 2012
• 2