Which Dimmer Works With LED Lights? Rotary vs Electronic LED Dimmer

If the lamps you want to dim are LED, buy a dimmer that is rated for LED and check its minimum load, not its maximum. A classic rotary dimmer such as the Aling-Conel Experience Art. 72206 is listed by the manufacturer for incandescent and halogen lamps only, with a 40 W minimum. Swap the halogens for four 7 W LED spots and you have 28 W on a dimmer that needs at least 40 W to work, which is exactly why LEDs on an old dimmer flicker, buzz or refuse to switch off. The Aling-Conel Experience Electronic LED Dimmer Art. 72208 is rated 4 to 160 W for dimmable LED, incandescent and halogen, so one 5 W lamp or twenty 8 W lamps both sit inside its range. The one condition that no dimmer can get around: the lamp itself must say "dimmable" on the box.

In this article

• Why do LED lights flicker on a normal dimmer?
• Rotary dimmer vs electronic LED dimmer: what is the difference?
• How many LED lamps can one dimmer handle?
• Which lamps can you dim at all?
• What else goes in the wall box?
• When is a wall dimmer the wrong choice?
• FAQ

Why do LED lights flicker on a normal dimmer?

Three things go wrong, and they usually go wrong together.

The load is below the dimmer's minimum. A dimmer is not a simple tap. It is an electronic switch that chops part of every mains cycle, and it needs a certain amount of current flowing through the lamps to keep its own circuit stable. Halogen lamps supplied that current easily: a single 50 W spot already covers a 40 W minimum. An LED spot draws 5 to 8 W, so a whole ceiling of them can still sit under the floor. The result is lamps that flicker at low settings, glow faintly when "off", or jump straight from dark to bright.

The dimmer is the wrong type. Older rotary dimmers are leading-edge designs, built around a TRIAC that was designed for the simple resistive load of a filament. An LED lamp is not a filament, it is a small power supply (the driver) feeding the chips, and that driver reacts badly to the sharp cut a leading-edge dimmer makes. As lighting retailer Lyco puts it, trailing-edge dimmers "tend to work better with the capacitive load of an LED driver", and leading-edge units "may require multiple LED lamps in order to even have a chance of working".

The lamp is not dimmable. A non-dimmable LED has a driver that expects a clean, full sine wave. Put it on any dimmer and it will flash, buzz or die early. BLT Direct's advice is blunt: "If it does not state this you should assume that the bulb is not dimmable."

Rotary dimmer vs electronic LED dimmer: what is the difference?

Both Aling-Conel units below are 1-module Experience devices, 250 V~, built to IEC 60669-2-1, and press-fit into the same mounting frame. What separates them is the load the manufacturer will stand behind.

Spec (manufacturer figures)	Rotary Dimmer Art. 72206	Electronic LED Dimmer Art. 72208
Lamps listed	Incandescent and halogen; halogen with standard transformer	Dimmable LED, incandescent, halogen
Load range	40 to 800 W incandescent or halogen; 40 to 400 VA with transformer	4 to 160 W
Minimum load	40 W	4 W
LED listed by the maker?	No	Yes, dimmable LED
Control	Rotary knob with on/off indication	Electronic, with on/off indication
Size	1M, 22.2 x 45 mm	1M, 22.2 x 45 mm
Price (white)	$7.95	$40.74

Read the table from the bottom up and the price gap makes sense. The rotary unit is a high-power dimmer for the lamps of twenty years ago: 800 W of halogen is sixteen 50 W spots. The LED unit handles a fifth of that wattage but goes ten times lower, and that low end is what an LED installation actually uses.

How many LED lamps can one dimmer handle?

Add up the wattage printed on the lamps and keep the total between the dimmer's minimum and maximum. On the Art. 72208 that window is 4 to 160 W, which covers almost any room:

• One 5 W dimmable LED bulb in a bedside pendant: 5 W, inside the range.
• Six 7 W dimmable LED spots over a kitchen island: 42 W, inside the range.
• Twelve 10 W dimmable LED downlights in a large lounge: 120 W, inside the range.
• Twenty-five 8 W lamps: 200 W, over the limit, so split them across two dimmers and two circuits.

Two cautions. First, many dimmer makers tell you to leave headroom below the maximum with LED, because an LED driver draws a short surge of current every time it switches on. Aling-Conel do not publish a separate LED derating for the 72208, so treat 160 W as the ceiling and stay well under it. Second, mixing lamp brands on one dimmer is a classic cause of uneven dimming; once you find a lamp that dims cleanly, use the same model on the whole circuit.

Which lamps can you dim at all?

This is where most dimmer purchases go wrong, so check the lamp before the switch.

• Incandescent and halogen: always dimmable, on either dimmer. These are the lamps the rotary 72206 was built for.
• LED bulbs and spots marked "dimmable": dim on the 72208. Not marked dimmable means not dimmable.
• Integrated LED panels, downlights and ceiling lights: usually not dimmable from the wall. Their built-in driver expects full mains. A ceiling light with a remote control dims through its own electronics; a wall dimmer in front of it can damage the driver.
• 12 V and 24 V LED strip: dimmable, but never with a mains dimmer. The strip runs on DC from a driver, so the dimming happens on the low-voltage side with a strip controller.
• Fluorescent tubes and CFL: not on either of these dimmers.

What else goes in the wall box?

Both dimmers are modular mechanisms supplied with their coloured front, so you do not need a separate button cover. You do still need the two parts every Experience point needs: a mounting frame that screws into the wall box (from $0.57) and a cover frame that clips over it (from $0.52). If the dimmer shares a 3-module box with other functions, a blank module ($0.41) fills any empty slot. Wiring is the same as a one-way switch: live in, switched live out to the lamps. The 72206 is specifically wired "as a single-pole switch" in Aling-Conel's catalogue, so it cannot sit in a two-way circuit; for a landing controlled from two places, keep the 2-way switches and forget about dimming that circuit.

When is a wall dimmer the wrong choice?

A dimmer is a cheap upgrade when the lamps suit it and an expensive mistake when they do not.

• Your LED fittings are not marked dimmable. Most integrated LED panels, slim downlights and corn bulbs are not. No dimmer fixes that; the fix is a dimmable lamp or a plain switch.
• The circuit is LED strip. Use a strip controller on the 12 V or 24 V side instead. The Aura Dimmer and Controller for CCT strips ($14.40) handles 5 to 24 V at up to 10 A per channel and also sets the colour temperature, and the Aura 24 V 8 W strip ($10.40) is sold as dimmable for exactly this setup.
• You want the lights to switch themselves. In a corridor or stairwell, the real saving is not dimming but turning off. The Experience Infrared Motion Detector ($47.85) switches up to 500 W of lighting on movement, with a 10 second to 10 minute timer and a 2 to 2,000 lux daylight threshold.
• The lamps are still halogen and you are not changing them. Then the $7.95 rotary dimmer is the sensible buy, and the LED dimmer's 160 W ceiling becomes a limit rather than a feature: three 60 W halogens already exceed it.
• The load is a fan, a transformer-fed lamp of unknown type, or anything with a motor. Neither unit is listed for inductive loads beyond the halogen transformers in the table. Ask before you buy.

One more point on the room itself. Dimming changes brightness, not colour. A 6000 K daylight lamp dimmed to 20 percent is a dim cold light, not a warm one, so pick the colour temperature first using our guide to 3000K vs 4000K vs 6000K in each room, then add the dimmer.

Frequently asked questions

Can I use a normal dimmer switch with LED bulbs?

Only if the dimmer's manufacturer lists LED as a supported load and your bulbs are marked dimmable. The Aling-Conel rotary 72206 is listed for incandescent and halogen only, so for LED use the 72208, which is rated 4 to 160 W for dimmable LED.

Why do my LED lights still glow when the dimmer is off?

That is usually a leading-edge dimmer leaking a small current through a load far below its 40 W minimum. An LED driver needs very little to light faintly. A dimmer with a 4 W floor, or a plain switch, stops it.

Why do LEDs buzz on a dimmer?

Buzzing comes from the lamp's driver or the dimmer coil reacting to the chopped waveform. It is common with leading-edge dimmers on LED and far less common with a dimmer designed for LED, provided the lamps are dimmable and the total load is inside the rated range.

How do I know if my LED bulb is dimmable?

It says "dimmable" on the packaging or the lamp body. If it does not say so, assume it is not. Integrated LED fittings with no replaceable lamp are usually not dimmable from the wall unless the fitting's own datasheet says they are.

Can I dim an LED strip with a wall dimmer?

No. LED strip runs on 12 V or 24 V DC from a driver. Dim it with a strip controller on the low-voltage side, or with a driver that is itself marked dimmable, never with a mains dimmer in front of the driver.

What is the minimum load on a dimmer and why does it matter?

It is the smallest total lamp wattage the dimmer needs to work correctly. Below it the dimmer loses control and the lamps flicker. Halogen installations rarely drop below 40 W; LED installations often do, which is why a 4 W minimum matters.

Sources: Aling-Conel Experience catalogue extracts for Art. 72206 and 72208 (linked on each product page); Lyco, Dimmers: Trailing vs Leading Edge; BLT Direct, Why do LED lights flicker on a dimmer switch.