small size (dimensions) capacitative load?

[bernardgreen]

It is also a good idea to have a resistor in series with the capacitor to reduce in-rush current if the switch closes at the peak of the sine wave. The capacitor will appear as a short circuit until charged ( a few milliseconds ) meaning the switch contacts will sometimes be stressed beyond normal operating current when it closes. This may slightly reduce the life of the switch

 

[sparkybird]

Thanks folks - and for the shorthand lesson! I heart this forum!

An apparent extra load of 35 watts when the lamp is switched on.

That does sound right as each switch needs a min load of 40W, so if a CFL if say under 10 W is used then the capacitor would make up the difference.

Adam - thanks for that link. Can you just confirm that you've used them in practice with this type of switch and it worked OK?

http://www.tlc-direct.co.uk/Products/DNTLSW10ILM.html

Many thanks again, everyone for your time

SB

 

[sparkybird]

Rather blatant bump....


SB

 

[Adam_151]

Adam - thanks for that link. Can you just confirm that you've used them in practice with this type of switch and it worked OK?

Sorry SB, just read the post through properyu , my situation was a little different, I had a long two way switching arrangement causing CFL flicker when off and a 2D emergency fitting to be permantly on (obviously only used the switched live as a signal line)

So if you issue is the lamp is flikering when the switch is off, then it should do the trick, but if its that the switch isn't swithing on with such a low load, then probably not

 

[bernardgreen]

After a bit of research into the circuitry of some two wire switches it seems for some types the requirement for a minimum of 40 watts load only applies when the lamp is ON. This ensures the current flowing creates sufficient voltage drop across the switch to keep the electronics operating. When the switch is OFF it has the full 230 volts available with enough current capability providing the lamp resistance is low enough for the switch to have about a watt of power. In theory a resistor of less than 47 K ohms will adequately supply the electronics of some switches when the switch is OFF.

However stick with the manufacturers instructions.

 

[sparkybird]

Once again, thanks for responding both.

I spoke to the manufacturer today who confirmed that a capacitor of 2u2 is needed tfor the switches to operate - then spoke to rapid online (very helpfu, thanks Adl!) who said that they didn't sell one of this size and if they did, it would be BIG!

Back to plan B (not sure what it is yet...) but it may involve changing the light fitting - flameport's handy idea of a plasterboard back box I think won't work because of the age of the ceilings.....

Ta

SB