Bathroom Extractor Fan & Low Energy Bulbs

[Gingerswine]

We have an existing 3 way spotlight in our bathroom and an extractor fan connected to it. This has been working fine - when the lights are switched off the fan continues to run for a few minutes and then stops. Doing her part for the environment my wife decided to buy 3 low energy bulbs (the 'spiraled' fluorescent type) to replace the existing spot light bulbs. When the lights are switched on they and the fan all come on. When the lights are switched off the fan continues to run and wont stop. It runs for hours! But putting the original bulbs back in makes the fan work normally and it stops after a few minutes. I've switched the bulbs over a few times to prove its not a one off. Any ideas what the problem is and what can be done about it?

 

[cheesepuff]

could be a faulty batch of cfl's getting power from the fan thus keepling the fan on all the time.

random thought

 

[bernardgreen]

The timer requires 230 volt or neutral potential on the switched live to indicate lamp on or lamp off. Anything in between these will confuse it.

Incandescent lamps have filament which means there is a resistance path between switched live and neutral. When the switch is OFF the switch live is connected vie the lamp filament to neutral.

Energy saving lamps do not have the filament so when the switch is off the switched live is floating and will not be at neutral potential meaning the timer cannot recognise the lamp as being OFF.

Keep one bulb as a filament (incandescent ) lamp is the easiest solution.

A resistor between switched live and neutral will solve the problem.

A 470 Kohm (470,000 ohms ) 1 watt is effective on most timers. A lower value may be needed on some timers. The resistor should not be less than 100 Kohm. It must also be capable of having 230 volts applied to it.