Touch sensor switch

[derwent]

Firstly, I understand normal domestic electrics, but not electronics.
I have a 240v 'capacitance touch sensor' light switch, see http://www.ebay.co.uk/itm/I-LumoS-Luxury-Crystal-Glass-1-Gang-1-Way-Touch-On-Off-LED-Light-Switches-/231567893060?var=&hash=item35ea85a244 The blurb states a minimum load of 3 watts. It works perfectly when used to switch a 15 watt light bulb on and off. However, I wish to use this switch to operate a 240v ventaxia bathroom extractor fan, rated at 4.3 watts and it doesn't work. If I connect both the bulb and the fan, they both work, but not the fan when connected on its own. The extractor fan is to be wired separately to the bathroom lighting, and I don't want to have to switch an additional light bulb on every time I switch the fan on. I'm guessing that I need to add a capacitor or resistor into the circuitry, in parallel with the fan, that will act as a 'substitution' for the light bulb. Please advise.

 

[makkem]

Hi
I am not familiar with that particular unit but I strongly suspect it works in a similar manner to a domestic dimmer switch.
These are not connected to neutral but are in series with the light bulb (as domestic light switches generally have no neutral wire to them) they rely on the light bulb having a low resistance to neutral when cold but a high resistance when hot.
The fan however has a high resistance to neutral and this is why your switch will not work with the fan in the circuit but will work with the light bulb.
Unfortunately no combination of resistor or capacitor will make this work.
The standard way to wire a bathroom extractor is to connect it in to the lighting circuit, often with a timer built in to the fan which continues to run for a period after the light has been turned off.

 

[derwent]

Hi
I am not familiar with that particular unit but I strongly suspect it works in a similar manner to a domestic dimmer switch.
These are not connected to neutral but are in series with the light bulb (as domestic light switches generally have no neutral wire to them) they rely on the light bulb having a low resistance to neutral when cold but a high resistance when hot.
The fan however has a high resistance to neutral and this is why your switch will not work with the fan in the circuit but will work with the light bulb.
Unfortunately no combination of resistor or capacitor will make this work.
The standard way to wire a bathroom extractor is to connect it in to the lighting circuit, often with a timer built in to the fan which continues to run for a period after the light has been turned off.

Thanks for taking the time to reply . You're correct that the switch is wired in series with the fan, and appreciate the info re high / low resistance. From this, it would seem that I need a component that has a low resistance to neutral, wired parallel to the fan, if such a component exists The reason I want to have the fan wired separately to the lighting is because I don't want the fan to come on every time the lights are turned on - only when required.

 

[makkem]

If you fit a component with a low resistance to neutral in parallel to the fan you will cause a short circuit,light bulbs work because the resistance increases as they heat up.
The only way you will get it to work as you want is to have a separate switch for lights and fan and your fan switch would need to be a conventional switch,which in a bathroom situation would need to be either sited outside the bathroom or be a pullcord switch.

 

[derwent]

Ok - thankyou for your replies.