Switching a fan from a shower switch

[shedbuilder]

Hi folks,

I have a customer who currently has a bathroom fan switched from the room's lighting circuit. The fan has a timer, and so is also has a permanent live. All of this supplied through a fan isolator, so perfectly correct.

The guy is annoyed at night by other people using the bathroom, switching the light on, and then having the fan run on for 10 mins. Rather than reduce the timer time, he'd like the fan to be switched by the power to the electric over-bath shower. The switch is a ceiling mounted pull-cord, and the fan wiring is in the loft, so all perfectly doable.

I've no problem with this. I was going to take the fan power from the permanent side of the shower switch & the fan switched from the switched side of the shower switch (and obviously neutral also from the shower). The slight inconvenience is that it means installing two fuses, one per line conductor (I was just going to use 2x FCUs, heavily labelled as to what their function is) to protect the 0.75mm^2 fan wiring, since upstream will be the 45A shower MCB.

However, it got me wondering... Is there a better solution? The product I'd really like to find is some sort of switch that will sense current in one circuit (the shower), and switch current in another circuit (the fan) while keeping the circuits electrically seperated. That way I could leave the fan on the lighting circuit (no need to bother with the additional FCUs), and have the fan switched by the shower actually being operated, rather than just when it receives power.

Anyone know if such a product exists, or offer any better solutions?

Thanks in Advance.

 

[Spudnik]

Not cheap but i would install a fan controlled with a humidity sensor:

4 Inch Humidity Wall Extractor Fan

That way, very little in the way of wiring needs to be altered.

 

[shedbuilder]

Thanks Jason. I actually have such a thing installed in my bathroom at home.

Unfortunately it's not an option for my customer I'm afraid, since (1) the fan is already pre-installed, and (2) it's not a wall fan, but an in-line fan in the loft ducting between the bathroom ceiling mounted extract grille, and the outlet tile on the roof.

I'm not sure whether a remote humidity sensor is available for these, but as I say the client is really after it being switched by the shower.

Thanks again.

 

[bazza2541]

You could fit a relay into the shower circuit, or if the client would allow , fit another pull switch to isolate fan so it could be turned off seperate to the lights.

 

[pushwire]

All the guy has to do is isolate the fan when the shower is not in using the isolation switch. Lots of people do.

 

[mags1972]

Hi folks,

I have a customer who currently has a bathroom fan switched from the room's lighting circuit. The fan has a timer, and so is also has a permanent live. All of this supplied through a fan isolator, so perfectly correct.

The guy is annoyed at night by other people using the bathroom, switching the light on, and then having the fan run on for 10 mins. Rather than reduce the timer time, he'd like the fan to be switched by the power to the electric over-bath shower. The switch is a ceiling mounted pull-cord, and the fan wiring is in the loft, so all perfectly doable.

I've no problem with this. I was going to take the fan power from the permanent side of the shower switch & the fan switched from the switched side of the shower switch (and obviously neutral also from the shower). The slight inconvenience is that it means installing two fuses, one per line conductor (I was just going to use 2x FCUs, heavily labelled as to what their function is) to protect the 0.75mm^2 fan wiring, since upstream will be the 45A shower MCB.

However, it got me wondering... Is there a better solution? The product I'd really like to find is some sort of switch that will sense current in one circuit (the shower), and switch current in another circuit (the fan) while keeping the circuits electrically seperated. That way I could leave the fan on the lighting circuit (no need to bother with the additional FCUs), and have the fan switched by the shower actually being operated, rather than just when it receives power.

Anyone know if such a product exists, or offer any better solutions?

Thanks in Advance.

Where is the grill position in the ceiling in relation to the shower? I fit bathroom electrics for a bathroom company around here and alot of customers are now having the showerlight fan kit off of a seperate switch to the main lights so the fan only comes on when needed, i.e with the shower light, or just add a seperate pull switch for the fan as someone said earlier or turn the fan isolator off at night, much easier than the extra work involved in taking it from the shower isolator, don'y forget your feeds for the seperate FCU's would have to be either 6mm or 10mm depending on the shower rating, those isolator pattress boxes don't usually allow for much wiggle room with cable that size, especially 10mm!!!

 

[stretchyboy]

you could come off of the switched shower supply as long as you fuse it down with a fused connection unit or similar and that you have enough capacity in the shower supply (i'd be surprised if there isn't room for 100W) The cable from the shower feed to the FCU only need to be large enough to take the load and blow the shower over-current protection therefore a 2.5 could be suitable if this calculates ok