If only life were simple! If only we could buy an LED fitting, or retro-fit LED lamp, wire it in, connect it to a dimmer and hey presto – a perfectly dimming light. Unfortunately, as so many of you will have experienced, this is not always the case and lamentably, the answer is not always crystal clear. So how to stop LEDs from flickering? The following explanation in layman’s terms may help you resolve any problems you may have or, even better, avoid them in the first place.
Speak the Same Language
All LEDs have electrical control gear known as Drivers – even retro-fit LED lamps have tiny drivers in the base of them. These need to speak the same language as the dimming module. When using a simple Mains dimming switch there are two methods of dimming – one is Trailing Edge and the other is Leading Edge. Trailing Edge tends to be better; the dimmers are slightly more expensive but they are less prone to buzz and are generally more compatible with a wider range of fittings. The manufacturers of the LED driver or lamp should stipulate the dimming method recommended (some will say either) so then you can ensure that the correct dimmer is installed. Do check that the LED retro fit lamps are dimmable – not all of them are!
For large projects always check that the dimmers are compatible with the LED fixtures or lamps that will be used; I usually combine Philips MasterLED lamps with Varilight V-pro intelligent dimmers which currently work well together – please note the word ‘currently’ as specifications can change and manufacturers will always state that testing should be carried out to ensure compatibility. Forbes and Lomax combine beautifully styled fittings incorporating Varilight dimming modules but it always advisable to state that the dimmer will be used for LEDs when ordering
Don’t Overload the Circuit
A common mistake is to look at the maximum wattage on the dimmer, say 250 watts (in old money) and decide that, as the LED lamps are only 5 watts for example, you would be able to dim a multitude of fittings on that circuit. Wrong. Ideally you should downrate by 6-10 times so in this case you would be best running 5 – 8 max fittings of 5 watts each. It is possible to get larger load dimmers so it is best to check the number of fittings on each circuit before installation.
Don’t Underload the Circuit
Some dimmers, especially Leading Edge dimmers, need a minimum load in order to work, some as much as 40 watts before they will kick in. The more modern Trailing Edge dimmers will generally work from a lower load set point but be wary of trying to dim one or two LED fittings on one dimmer or you may need to incorporate a ‘dummy load’ to enable the dimmer to work.
Keep it Simple
Try to avoid using MR16 equivalent LEDs where possible when dimming as you then have three factors to bear in mind – the dimming module, the driver and the transformer which involves more ‘communication’ and more chances of incompatibility. GU10 retro fit LED lamps or GLS replacement lamps are much simpler altogether. However, on a positive note I have had success with using Philips MasterLED MR16 lamps with low voltage fittings on a Hamilton Mercury system but this was several years ago so may not be true today. Always best to check.
Phase Adaptive Dimmers
If you don’t know whether you are going to use Leading Edge or Trailing Edge drivers then go for a Phase Adaptive dimmer; more high spec but flexible. Try Lutron for the latest in cutting edge dimming technology. And if you’re wiring a new-build or self-build property it is worth considering a digital method of dimming such as DALI.
Favour Constant Current
Constant current LED drivers general work much better than constant voltage ones. The LED fittings for constant current drivers should be wired in series and your electrician should always check what products are specified before any wiring is done.
If you are still having problems with flickering lights and you have assessed all of the above then it may be time to check out the wiring in the property. Loose or faulty wiring or spikes and troughs in the electrical supply reaching the circuits in question could be having a knock-on effect so it is always advisable to check this out as well