Have you invested in Megaman Modo GU10 dimmable LED lamps? Are you finding those dimmable lamps are... well.., just not dimming? Never fear, I have here a quick and curious fix. Just don’t ask me to explain how it works...

I’ve been favouring the Megaman Modo LED lamps recently after my primary supplier ran short of the Sylvania lamps I’d been fitting over the last year or so. I have to say, I like the Modo lamps; they have an attractive physical appearance which suits most fittings and they provide a good light output. I suspect many people wouldn’t be able to tell them apart from a halogen lamp, especially when they’re on.

The only issue is that they come as ‘dimmable’ out of the box, however I find that out in the real world their dimming function isn’t great.


Now, dimming LED lamps is a flippin’ minefield, and most dimmer switches out there, especially those already fitted into people’s homes, were made for incandescent lamps and therefore have minimum load requirements that are unlikely to match a sporty new LED lighting arrangement.

So, I installed nine Megaman downlights in a house last week under the agreement with the homeowner that his existing dimmer switch may not work with them. Sure enough, twiddling the dimmer after installation yielded very little alteration in the light output. Interestingly, with only one Modo lamp fitted it worked quite well, but by the time all nine were in place there was hardly any variation in brightness over the full range of the dimmer control.

A little disappointing, but not at all unexpected. Then I spotted a loose Screwfix GU10 LED lamp rattling around on the back of the van which also claimed to be dimmable. Now, I don’t normally use store own-brand lamps and wouldn’t go out of my way to fit the Screwfix LAP range of products, but I thought I’d replace just one of the Modo lamps with this Screwfix fellow just for shits n' giggles to see how it reacted to the dimmer.

Imagine my surprise... nay, astonishment when I found that all nine lamps were now dimming with much more range simply as a result of this one lamp being changed out. How could this single Screwfix lamp, rated at 5W just like the Megaman Modo models, be affecting the other eight lamps causing them to all dim with the same linear brightness over a wider twiddle-range of the dimmer switch?


It certainly raised an eyebrow or three, enough in fact for me to post it onto my knobby YouTube channel for the world to see.


Surely a freaky one-off you may think? Well, I had another site which exhibited the same problem. Another sparkie, who shall remain nameless, had installed sixteen Modo LED downlights with a Zano adjustable dimmer on an MK grid switch some time ago. I’d been there to perform other work and the homeowner mentioned to me their trouble with dimming the downlights in that room. I tried adjusting the Zano dimmer, and I replaced it with the MK equivalent to see if that would work, but no dice – and no dimming, or at least, very little dimming, so the Zano went back into place and I went away scratching my (admittedly handsome) head, as with it being a grid switch it wasn’t easy to fit just any old LED dimmer and be done with it.

That was a few weeks ago, and I admit I’d chucked it onto the back burner not really knowing where to go next, short of throwing the baby out with the bathwater and trying different lamps, but after stumbling across this trick I went back to site today armed with another Screwfix lamp. Lo and behold, changing out a single Modo for my Screwfix model now caused all sixteen lights to dim evenly across the full range of the Zano dimmer much to the delight of the homeowner.

lapandmodoNot exactly twins in the looks department, although light output is about the same.

There are another two sites I know of with this problem, one is mine and the other is with a builder I know. We’ll be trying this trick on both of those installations, only I’ll be trying it with a couple of other dimmable LED lamps made by Integral and Sylvania to see if they also have the same effect.

So what’s happening electrically to make this work? Well, I’m not exactly sure. By playing with a power meter, it seems that the Screwfix lamp has different characteristics to the Modo model, and as it dims it appears to use less power. How that sets the dimming level for other lamps connected in parallel I can’t figure out. I’d have thought that a standard electromechanical dimmer reduces the voltage as it is adjusted down and the electronics in the lamp decreases the light output in sympathy, but why swapping out just one single lamp should affect all others when they are presumably all receiving the same input voltage I just don’t know.

If you have Modo models with difficulty dimming, then a quick trip to Screwfix armed with order code 3797G may just see you get a quick and dirty fix without the need for employing a sparkie. Unfortunately, the Screwfix lamps are sold in packs of five, but if this trick does turn out to work with the Sylvania or Integral lamps then that may indicate there are all sorts of alternative makes and models which could also do the job. I’ll know more after Thursday, so watch this space...



Hunh? It's Thursday already?? Why, it only feels like it was.. uh.. two days ago that I was writing the above. How time flies when you're installing downlights!

I returned to a third site today where Modo lamps had been installed and weren't doing the do when it came to doing the dim. In this instance there were five downlights and adjusting the dimmer largely meant they were either on or off rather than them varying in brightness. Micro adjustment of the control meant you could twiddle them down, but then there was some flickering going on at the lower end so that wasn't ideal.

This time I tried an Integral lamp and a Sylvania lamp to see what effect they would have on Modo performance. The former made little difference, while the Sylvania worked quite well but remained noticably brighter than its Modo counterparts when the dimmer was turned down. Both the Integral and Sylvania lamps also eliminated the flicker of the Modo models at lower light levels.

Again, the results were posted on YouTube should you wish to see for youself.

Unless I come across anything else, it seems the Screwfix lamp remains the best for the job. It looks physically similar at a glance, its light output is comparable to the Modo lamps when dimmed, and it did the best job of making the Modo's work over a wider range of the dimmer control.

I'm still going to continue fitting the Modo lamps as they are nice, they're well regarded by the suppliers and installers and their price is right, but when it comes to a dimmable installation I'll keep a pack of Screwfix lamps to hand should I run into trouble.