On Thursday, May 16, 2013 1:00:35 PM UTC+1, jkn wrote:
Hi All
The recent thread about blowing bulbs reminded me of this:
Some years ago I fitted a pair of touch dimmer switches from TLC:
http://www.tlc-direct.co.uk/Products/VLIDQ1401MS.html
These are for for ceiling lamps in our living room. These were originally 'standard' light bulb fitting; I have since replaced them with two fittings each with 3x Halogen g9 40W bulbs.
Cut to a number of years later, and over a period of a year or som, both dimmers got less reliable (light would cut out on its own etc.). Eventually I replaced them both with the same item.
One of these works fine. The second dimmer seemed to fail after a week or so (light failed to turn on when touch place pressed) and I returned it to TLC for a replacement.
However there seems to be more to it than that; What seems to happen is that after a few days the replacement dimmer also stops working. If I then trip the mains MCB for that lighting circuit, and re power it, it is fine .... for a few days.
The wiring to the dimmer is solid and I don't think anything else has been changed in the lighting circuit.
Assuming I've not just been unlucky with dwo dodgy dimmers, any thoughts as to what might be causing this? I originally wondered if the load might be too little but the switches are rated at 60W minimum...
I'm not sure how this minimim works, but I have noticed that if my dimmer (rotate to dim, push for on/off) is set to mininmum and I push for ON the lights don't come ON, even on turning it 'up' but if I switch push off/on again then they light and I can then dim them to miniumum without a problem.
I assume they still use SCRs so maybe they need a certain current flowing through thier gates in order for them to conduct properly, if not they stay off. The current needed might equate to a 60W of load.
Remebring that they don;t reduce the current to the load but switch off or on depending what part of teh sine wave cycle ...
I don;t have an MCB's just fuses so not sure about that side of it.