Q&A: LED downlights and power problems

I have been told by a sparkie that dimmable LED lights cope better with power fluctuations than non-dimmable ones. Is there any truth in this? Also, I was told by a salesperson that if a fairly expensive LED four-light track failed I would have to replace the whole fitting. This doesn’t seem right to me. Presumably you could replace globes with most fittings, or replace the driver or driver parts if this were the problem, rather than throwing away the entire fitting?
Lynn Atkinson

How well a fitting copes with power problems depends on the quality and design of the driver. Dimmable fittings will be designed to handle a range of voltages and ‘chopped’ waveforms, so they handle spikes well, but a properly designed fixed-output driver should work just as well. It also depends on what you mean by fluctuations, such as long-term (minutes to hours) variations in mains voltage, or short-term spikes caused by motors etc, or both.

The advantage with a dimmable driver is that it does give you the option to add dimming later should you want or need to.

Regarding the track light, that depends on how it is designed. If it has replaceable bulbs, then no, you wouldn’t have to replace the whole unit. Many suppliers are selling standard halogen track lights with LED retrofit bulbs, so the combination is fairly common.

If the fitting is designed from the ground up as a LED fitting then it will have one or more drivers driving the embedded LED arrays, so if you get a LED failure, you will have to live with that light being out unless you can get a replacement array and find someone to install it. If the unit uses a single driver to drive four arrays (unlikely, but I’ve seen poor designs like that) and the driver fails then, again, you would need to find an equivalent driver and have it fitted by a technician (with LED experience—all electronics techs are not created equal).

As it depends on the fitting design, you’ll need to get technical details or have a close look at the fitting you are proposing to use so that you can see how it’s configured.
This is one of the aspects that is working against LED lighting at the moment—there are so many variations and you need to understand what you are buying.
Lance Turner

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