Home›Lighting guides›Choosing the right dimmer
Advice
Which dimmer works with our LED spotlights?
A dimmer made for incandescent bulbs is not going to do it, but “an LED dimmer” is not enough either — those come in two flavours and only one of them is right. Which one is stated in the spotlight’s specification.
Every recessed spotlight we sell is triac dimmable. So look for a dimmer marked triac, leading edge or phase cut (often shown as R,L) and rated for LED loads, meaning it has a low minimum wattage. A dimmer that only does trailing edge (C) is the wrong one.
In this article
Why an old dimmer does not work
A dimmer left over from the incandescent era is built for a hefty load. It often states a minimum of forty watts. Back then that was a single bulb; now six Lesto spotlights on their 6 watt setting come to 36 watts between them and do not even reach that minimum.
Below that minimum the dimmer does not really know what it is doing. The result is flickering at low settings, buzzing, or spotlights that only strike once you have already turned the knob halfway up. Nothing is broken — the dimmer simply does not suit the load.
A dimmer sold as LED-compatible starts at a few watts and has electronics that can cope with the pulsed current an LED driver draws. That is the first requirement. The second is the technology.
Leading edge and trailing edge, in plain terms
The mains supplies alternating current: a wave that passes through zero a hundred times a second. A dimmer weakens the light by cutting a piece out of every half wave. There are two places to do that, and that is the whole difference.
Leading edge — phase cut
Cuts away the start of each half wave. It is switched with a triac, hence the name. Recognisable by R,L or triac on the packaging.
Cheap and robust, and it is what most LED drivers are built for — ours included.
Trailing edge
Cuts away the end of each half wave. Recognisable by C or trailing edge.
Runs quieter and often more smoothly, but only with drivers designed for it.
So it is not a question of which technology is better. It is a question of which one belongs to your driver. Put a driver made for leading edge on a trailing edge dimmer and flickering, or not striking at all, is the usual outcome.
Not sure? There are universal dimmers that handle both technologies and configure themselves. They cost a bit more, but if you do not yet know what will end up on that circuit, they are worth the money.
What our specifications say
| Range | Output | Dimmable |
|---|---|---|
| Lesto | 4W / 6W | Yes, triac |
| Lyvo | 5W / 7W | Yes, triac |
| Warmo | 5W / 7W | Yes, triac — and Dim2Warm |
| Quaro | 6W | Yes, triac |
You will find the same on every product page, in the specification table under Dimmable. Do check there, because it is the only place that is correct per item.
Two things that go with this:
- With empty fittings it depends on the lamp. If we sell a fitting without a built-in LED — a GU10 or G9 fitting, for instance — then the light source you screw into it decides whether the whole thing dims, not the fitting.
- The Warmo does something extra. It has Dim2Warm: the further you dim, the warmer the light gets, from 3000K towards an incandescent-like glow. That only works if it is genuinely being dimmed, so with a dimmer on the circuit. Without one you have an ordinary CCT spotlight.
How many spotlights on one dimmer
A dimmer has a lower limit and an upper limit. With LED you almost never hit the lower limit if you buy an LED-compatible dimmer; the upper limit is the one to plan for.
- 6 × Lesto at 6W = 36 watts
- 12 × Lesto at 6W = 72 watts
- 20 × Lyvo at 7W = 140 watts
That sits comfortably within what a common LED dimmer can handle.
The packaging often shows a maximum of a few hundred watts in large type. That figure is for incandescent bulbs. For LED loads manufacturers usually give a separate, far lower maximum — sometimes a quarter of it — because LED drivers draw a much larger inrush current. Find the line in the manual that says LED and work with that number.
It flickers — what now
Work through it in this order:
- Is the technology right? If the dimmer says C or trailing edge, that is the cause. Our spotlights want leading edge.
- Is there enough load on it? Two spotlights on a dimmer with a 20 watt minimum is too little. Putting more spotlights on the same dimmer helps more often than you would think.
- Are all the spotlights on the same setting? A group with the wattage switches set differently will dim unevenly.
- Does the dimmer have an adjustment screw? Many LED dimmers have a trimmer behind the knob that sets the lowest level. Turn it up slightly until the flicker at the bottom of the range disappears.
If it still flickers after those four points, the driver and dimmer combination simply is not a happy one. That happens, even between brands that both do what they promise.
Frequently asked questions
Can I control the spotlights with a smart dimmer?
Yes, as long as the module supports leading edge. Check that per model, because the same manufacturer often supplies both a leading edge and a trailing edge version. We do not sell wall dimmers ourselves, so you are free in your choice of brand.
Can the dimmer also change the light colour?
No. The CCT switch is a small switch on the driver that you set before installation. The dimmer only controls how brightly the spotlight burns. The Warmo is the exception: its colour gets warmer the further you dim.
What if I do not want a dimmer at all?
Then everything simply runs at full output. The wattage switch and the CCT switch are independent of a dimmer, so you still choose light colour and output without one.
Why do the spotlights not go fully off at the lowest setting?
At its lowest setting a dimmer lets a little voltage through. With few watts connected that is enough to make the LED glow faintly. More spotlights on the same dimmer, or adjusting the trimmer, usually solves it.
Dimmable spotlights
Every recessed spotlight in the range is triac dimmable and has a CCT switch on the driver. Each product page carries the full specification table, including cut-out size and recess depth.
Also useful: fitting recessed spotlights in a plasterboard ceiling