Dimming LED lamps: the dos and don'ts

The adoption of dimmable LED lighting for new installations is rising fast, but with a vast retrofit market to address, there is an opportunity for further growth if the user experience can be optimised. LED lighting has already captured the imagination of consumers in a way that CFLs never did with LED lamps offering many of the energy-saving benefits of compact fluorescents but in a much more familiar package.

Consumers are able to buy lamps that look like the incandescent lamps they are replacing, which makes for a more comfortable switch. However, they are also expecting the dimming performance to be replicated and this is where a lack of information can lead to disappointing results.

Here are our top tips for getting the best out of retrofit dimmable LED lighting.


It is a common misconception that any LED lights can be dimmed with an LED dimmer"

DO choose dimmable LEDs
The number one rule for successfully dimming LED lighting might sound obvious but it is a common misconception that any LED lights can be dimmed with an LED dimmer. In reality, the driver circuitry must be designed with dimming in mind. Therefore, it is essential to choose lamps that the manufacturer describes as ‘dimmable’. The lack of an industry standard for dimmable LED drivers has, though, led to a myriad of different approaches by lamp manufacturers, some more successful than others.

Choose ‘dimmable’ lamps but be aware that this in itself is not a guarantee of a good dimming performance. It is, however, a good starting point.


DO stick to recognised brands
There is a lot of variation in the dimming performance, under test, of LED lamps described as dimmable. In particular, the achievable brightness range and stability of output are the features most likely to disappoint with unbranded lamps.
Some manufacturers are happy to label their lamps as dimmable even if they can deliver only the smallest change in brightness. Choose lamps from established lighting manufacturers. Aside from dimming considerations, established brands are also more likely to offer better product warranties, longer lamp life and more customer support.

Top tip: Stick to brand names that you can have confidence in and don’t be tempted to make false economies.


The escalating brightness of retrofit LED lamps has made dimming much more relevant"

DO read the label
To deliver a true retrofit comparison with incandescent lighting, it is important to consider the brightness range. Significant advances in LED lighting technology have been made in recent years, achieving far higher lumens per watt, even for the halogen-mimicking warm white lamps, where lamp output is often compromised for the more familiar incandescent hue. There is little point in connecting a dimmer to an LED light if it is dim enough already, so the escalating brightness of retrofit LED lamps has made dimming more and more relevant. Brighter lamps can give customers a greater dimming range.

Top tip: Read the label and select the dimmable lamps with the highest maximum lumen output.



DO ask manufacturers about compatibility
Most established lighting brands publish compatibility data on their websites. Dimmer switches are tested with various loads and the lamp performance graded. These grades are a useful reference point and can help when choosing a dimmer. It can be confusing though, when navigating the websites of international brands, to find dimmers listed that are not available in the UK. If in doubt contact the company to ask about their recommendations.

Top tip: Manufacturers want customers to experience the full potential of their lamps and will often be happy to recommend the best dimmer switch to use.

DON'T use a standard dimmer
Some lamps manufacturers may boast that their dimmable LED lighting can be controlled using a standard dimmer, but where this claim is borne out, it is likely to be true only when some very narrow criteria are met. Standard dimmers will be underloaded in most LED applications, exacerbating flickering and strobing effects, which, in turn, can drastically shorten lamp life. Standard dimmers are also not equipped to exploit the full brightness range, resulting in a disappointing user experience.

Top tip: Take claims of compatibility with standard dimmers with a pinch of salt.


DO choose a dimmer designed for LED lighting
Sophisticated dimmers are available to deliver the best possible performance from dimmable LED lighting. Some have several dimming modes to enable smooth dimming across the diverse driver technologies in the market. The brightness output a lamp produces from the same power input varies markedly between brands. For this reason, some manufacturers now include an adjustable minimum brightness setting so the user can access the full brightness range of a given lamp. An adjustable minimum brightness also ensures that any instability a lamp might exhibit at its lowest level of illumination can be avoided.

Top tip: Dedicated LED dimmers are equipped to exploit an LED lamp’s full dimming potential, better replicating the dimming behaviour of an incandescent lamp.

Design your lighting installation to ensure you don’t exceed the maximum load of the dimmers available"

DON’T buy your luminaires without first selecting a dimmer
Like all dimmer switches, those designed for LED lighting have minimum and maximum load recommendations. Design your lighting installation to ensure you don’t exceed the maximum load of the dimmers available. Splitting the load across more than one dimmer could provide a solution and give greater control by allowing light levels to be zoned in a multi-functional space. Until recently it was difficult to find a dimmer capable of controlling more than 100W of LED lighting, but some recent products open up the possibility of dimming much larger LED loads, up to 600W.

Top tip: It’s important to select a dimmer that can control the total wattage and quantity of lamps you want to dim.

DO read the instruction leaflet
LED dimmers often come with features designed to enhance their performance, but you may have to program the dimmer to access them. Don’t be tempted just to ‘plug and play’ because you may be missing out on features that will give greater expression to your lighting. For example, with some remote-controlled dimmers, enhanced scene-setting features may be unlocked using the dedicated handset. Some manufacturers have released how-to videos on their websites.

Top tip: Read the instruction leaflet or you may miss out on features and benefits.

  • Dr Anthony Doyle is the chairman of Doyle & Tratt, manufacturer of Varilight dimmer switches


  • See the latest LED lighting at LuxLive 2017, Europe's largest annual lighting event this November. The show takes place on Wednesday 15 November and Thursday 16 November 2017 at the ExCeL London. Entry is FREE – see the full programme of events and register to attend by clicking here

Comments 13

Was without exterior lighting on deck and over kitchen sink due to blown bulbs. Finally got money to hire an electrician (not cheap!) to install 2 new decklights and fix kitchen light, ending up costing $350. DECK: Removed the housing on the new fixtures to find LED panels with rows of about 4 x 5 resulting in too bright of lights off my dining room. How does one reduce the wattage with a wall switch from inside? Young (licensed) electrician said "I've never seen anything like that" when he took the fixtures apart and saw a warning to "Do not touch" the tiny bulbs. KITCHEN: Turned out NOT to be a replaceable tube of which I had 2 new ones on hand, rather the entire neon fixture which the big box stores no longer carry. Had to replace the hard-wired light fixture with an LED fixture so now when that little row of dots "blows" I'll have to call an electrician to install yet ANOTHER LED light fixture instead of replacing a simple bulb! What have the "Evil, and Stupid Parties" done to us??? Do they want us to return to candles, or just perish in the darkness? (That may actually be a metaphor.)

I purchased Sunbeam 60watt/9watt LFD light bulbs that say not dimmable. In a single ceiling light they were not dimmable, but in a chandelier with 5 bulbs and using a standard dimmer they did dim without blinking unless at maximum dimming.

Your website suggested do's and dont's for dimmable LED lighting would be available, but the text is partly obscured by large grey shapes in three areas which seem to be entirely useless and obstructive. Readers should not have to guess at the advice which is missing. Very disappointing

I bought the Legrand LED Dimmer, and almost no led dimmable lamps are compatible. The Philips 4.5W gu10 led flame never shuts down completely. The philips gu 5w 2700w led shuts down, but its light is too white not a true 2700k lamp. I phoned asking what lamps are compatible with what dimmers no one knows. Its a really frustrating market, nothing works with anything

Here's an idea. Tell your Congressman to repeal the ridiculous "Energy Independence and Security Act of 2007," a bipartisan act of The Stupid Party and The Evil Party, so the average consumer can go into the Wal-Mart and buy a light bulb without having a degree in electrical engineering.

Thanks 'GetItGoing' but you didn't go far enough: there are a lot of 'innocents' like Wayne that don't know what a stew of hazmat an incandescent lightbulb is. The list of hazmat is long including toxic and carcinogenic material; in fact, the average consumer probably doesn't notice because although incandescent lamps are a statutory hazardous product, the law allows batches of less than 100 to be disposed of in general waste streams (more than 100 must get hazardous waste disposal). The list of course includes lead , lead oxides, leaded glass frit, chromium oxides, bromine and depending on manufacturing process mercury vapor. Since several of the hazardous substances serve merely to diffuse and whiten the light, they are deemed unnecessary and banned in many jurisdictions e.g. where only clear glass bulbs can be sold. Even tungsten is hazmat: for a while it was thought safe but then the military replaced lead bullets with tungsten and soon enough discovered a new environmental hazard i.e. tungsten. Comparatively, the hazardous content in LED lamps is almost entirely in the lamp ballast i.e. electronic assembly and shares the same issues as any modern electronic devices which are capable of compliance with current ROHS standards, unlike incandescent lamps. Beyond hazmat, fire statistics show that ~35% of all residential fires are due to incandescent lamps including proven and suspected cases. A major problem in the North American market is that many fixtures are rated for 60W or 75W maximum but can easily by fitted with 100W+ lamps. Also, many recess fixtures are only rated for properly reflectorized lamps but can easily be fitted with non-compliant lamps - this is one area where package and fixture labeling is woefully inadequate.

For LEDs or CFLs to function at all in a system that includes either a dimmer or a semiconductor switching device, those bulbs MUST be DIMMABLE! The destruction of a non-dimmable CFL in a motion detector system with a solid state switch was almost instant. LED lights can be destroyed inthe same way. The problem is not with the name brand suppliers, but rather with the very cheap imports , whose labels are often a list of lies. Reputable makers will clearly mark which products are dimable, and it they are not marked they probably won't function correctly in a dimmed installation. Some folks do want that pale-yellow light for some applications, so selection of the color temperature is now important, while it used to be there was not much choice with incandescant lights.

Hello - I am changing over all my bulbs to LED and have just discovered you need to have an LED dimmer switch for your LED bulbs - you cannot use the standard dimmer switch it must be a LED one - can you recommend where to buy. I am having a problem in finding a LED dimmer switch (Phone 0203054 9018) Thank you

"LED bulbs are crap, almost as bad as "we make with hazmat materials" fluorescent bulbs spewing mercury into the environment" This is a completely ridiculous statement, and has NO basis in fact. LED bulbs are not "crap", which you would know if you weren't biased against new technology. Facts: - LED bulb quality does greatly vary between manufacturers and bulb types and styles. - LED bulbs are now available with far better color production than incandescents. For example, I can now get LED bulbs with neutral white range (3000K, 3500K) which is much better than they dingy, yellowish, almost-orange "soft white" incandescents that are almost the only choice for household bulbs - LED bulbs are very safe and do not have any post-use hazardous materials to be concerned about. - Now LED bulbs are available with light source elements that mimic vintage or modern incandescent bulbs too, and look great, for those who prefer the glow of those older bulbs It's not a perfect technology but has gotten MUCH better in a short time. Incandescent bulbs are hugely inefficient and make my small work office get too warm. Much better to have nice, clear lighting with less heat.

Hi Jeff I suspect you dimmer is really designed for a higher load as taken by 4*40W filament lamps. With a single filament lamp and 3 LEDs there is probably still enough load on the dimmer but once that is a low power device too then the dimmer doesn't work correctly. This is a common problem and one I am facing in a 'new' house with about 100 halogen lamps in many many circuits!

Why not just admit LED lights can't get to low light levels? LED bulbs are crap, almost as bad as "we make with hazmat materials" fluorescent bulbs spewing mercury into the environment.

Hi I'm looking for led downlight dimmable all sizes Thanks Best regards  ABDULLA AJLAN  Blue fox electric  Mobil: +973 36566965 Land line: +973 17260091 Fax: +973 17260019 Email: abd_ajlan@yahoo.com

I recently bought a house with what appears to be an electrical anomaly to a layperson like myself. I replaced two fixtures (each with two bulbs) powering incandescent bulbs that are connected to a dimmer switch. In my replacement fixtures I put Edison-style LED bulbs. When I have 3 of the 4 bulbs replaced with the LED bulbs, they are very bright and appear to be working correctly. However when I replace the 4th bulb with the new LED one, the entire system immediately gets dimmer. Do you believe this to be an issue with my dimmer switch, and that it might need to be replaced with an LED compatible switch? Thank yoU!

Leave your comment