Timers for Low Energy Lights

DIY Outlets sell replacement light switches which incorporate an on/off timer facility. These units only work on Incandescent bulbs for fairly obvious reasons. As Low Energy lights have a very high impedance in the off mode, replacing an On/Off switch with a timer type switch for Low Energy lights sounds to me like it is not possible - But has some 'Smart Arse' done it and produced such a replacement device , I doubt it, but it worth asking the question.

Probably has batteries.....

The "Smiths Timeguard" claims to be suitable for low energy lighting, I've only used it for incandescents, personally, but the instructions recommend it for anything other than "discharge lighting(e.g SON & Metal Halide)".

I must admit I have trouble seeing how exactly one without batteries could work without causing the dreaded 'my light is flickering when switched off' syndrome. Unless I suppose they also included a suitably rated capacitor to fit inside the rose

Or unless the earth becomes a bit more functional than it is normally (as the currents likely to be needed to power such a device, I suppose they might just be able to sneak it under the equipment standards that govern acceptable amounts of earth leakage, etc) but I'm not convinced that would be likely

neutrals at switches! thats the way its headed!

Hi Adam 151 and Lectrician and jj4091,
These type of timers need no batteries if the unit is used on incandecent lights. When you think about it, there will appear 240 V across the light switch in the off position and this will therefore power the timer with an extremely low current, with current being drawn through the light bulb as the timer is wired up as a direct replacement for the switch. When the timer swithces the light on then providing the input impedence of the timer is small in the on position, a sufficient Potential Difference could be generated to power the timer but not significantly effect the power output of the incandecent bulb. This is the problem with Low energy lights, the off impedance is extremely high approaching that of an open circuit (unlike Incandecent lights) and as such there is no voltage apparent across the light switch in the off position due to the open circuit nature of the low energy lamp when off, and as such any small current required to power the timer is not possible through the low energy bulb. If these timer units used batteries as a power source, then there would be no problem in getting them to work also on low energy lights. The 'no battery' feature of these timers is their big selling point.
I think there may be a solution by wiring a high value resistor across the low energy bulb such that a current can be drawn to power the timer. My problem is that I have no idea as to what the value of that resistor should be. Maybe someone has tried this possible solution.
It sounds like jj4091 has the answer and use the Smiths Timeguard, I will have to try one.
Thanks for your replies and interest

Sorry, if you misread my post, I understand where the current to power these things comes when a filament lamp is fitted,

When I wrote:

I must admit I have trouble seeing how exactly one without batteries could work without causing the dreaded 'my light is flickering when switched off' syndrome. Unless I suppose they also included a suitably rated capacitor to fit inside the rose

Click to expand...

I was refering to such an idea on a compact floresent lamp, I was pointing that any idea to do similar with this kind of lamp would cause the lamp to go into a cycle where the capacitor in the lamp slowly charges and the voltage across it rises, then the lamp tries to fire up, discharges the cap, (as its only being charges by a trickle through series impedance) and the cycle starts over

A resister could probably be used to solve the problem, but a correctly rated capacitor as I already alluded to in my previous posts would be a far more elegant solution (remember the point of the CFL lamp in the first place...)

I use timers and photocells with CFLs.

They work for me.

Perhaps they haven't read the instructions

CFLs work fine with time switches / photocells providing the device has actual proper switching contacts, rather than a solid state device which will cause CFL flicker.