Dimming protocols for decorative lighting: TRIAC, 0-10V, DALI-2, DMX512 and wireless

At a glance

Sources: standards bodies, the DALI Alliance and US government research, read on 5 November 2026. The method is for the lighting designer to choose; the driver and controller pairing should be tried before production.

Dimming is a pairing, not a feature

A decorative fitting does not dim by itself. The light source is fed by a driver, the electronic control gear, and it is the driver, not the glass or the metalwork, that decides what the fitting can be dimmed by. A US Department of Energy report puts it plainly for LED sources: a maker who claims an LED product is dimmable is claiming that its driver can take a dimmed signal from a specific type of dimming device (PNNL-22945, 2013). So the method has to be chosen before the shop drawings, because a driver built for one method does not simply take another.

Changing it late causes rework. A hotel-design trade article of 27 March 2026, written by a lighting maker, lists dimming protocols alongside finish changes and mounting details as small specification shifts that can trigger rework.

This sheet describes five families of control, what each is, where each snags, and what to ask. It does not rank them: no source read ranks them for decorative lighting, and the right choice depends on the room, the client and the people who will look after it. Make Bespoke Studio coordinates decorative lighting through partner workshops and has no delivered lighting projects to cite; the questions below are for the lighting designer and the workshop.

Phase-cut (TRIAC, leading edge; ELV, trailing edge)

A dimmer in the mains feed cuts part of each wave of the AC supply. The Department of Energy report calls forward phase-cut devices “TRIAC” or “leading edge” dimmers, which remove the front of each wave, and reverse phase-cut devices “ELV” or “trailing edge” dimmers, which remove the end of it. The reverse type was designed to improve the performance of low-voltage halogen lamps on electronic transformers (PNNL-22945, 2013). There is no separate control cable.

• The load rating does not carry over. Dimmer ratings in watts were set for incandescent lamps. LED drivers commonly draw current in repeated peaks 5 to 10 times their RMS current, so the rating no longer describes the stress on the dimmer. The report gives two US examples of the scale of the effect: a dimmer rated 600 W for incandescent lamps and 150 W for LED, and a lamp maker advising no more than eight 7 W lamps on a 600 W dimmer. Those are not UK figures.
• The listed failures. The report lists LED products that do not light, do not dim, dim erratically, turn off long before a halogen lamp would, shift colour, stay on or flash when off, flicker, or hum.
• Match the type. A driver may work with one edge type and not the other. The report advises specifying the dimmer type the light source maker recommends, derating the dimmer, and building a full mock-up of each circuit where possible.
• Standard. NEMA SSL 7A-2015 (R2021) sets compatibility requirements for forward phase-cut dimmers with LED light engines and says it is suitable for global use. Compatibility is defined for the light engine (driver and light source together), not for either part alone, and the standard is not meant to establish compatibility with dimmers already installed.

0-10V analogue

A pair of low-voltage control wires carries a DC signal from 0 to 10 volts from a controller to the driver; the mains feed to the driver is separate. The DALI Alliance describes it as one-way, and a US Department of Energy report notes that the current-sinking form in IEC 60929 Annex E has been used with fluorescent and HID lighting for over 35 years (PNNL-32949, 2023).

• Two forms. Current-sinking (IEC 60929 Annex E and ANSI C82.11) and current-sourcing (ESTA E1.3, used in theatre and entertainment dimming). A controller and a driver have to follow the same form, so ask which one the driver follows.
• Off is not specified. The older sinking standard gives maximum output at 10 V and an unspecified minimum at 1 V and does not specify an off state, so the supply to the driver is typically switched to make off.
• The lowest level varies. The report says most LED drivers can dim to 10% of full output, some only to 30%, some to 1% or lower, and some ambiguously claim to “dim to off”, which says nothing about the lowest level before turning off.
• A newer US standard. ANSI C137.1-2022 requires maximum output at 8 V or 9 V and a standby state at 0.5 V or below. In the report's test of 21 LED drivers in streetlights made before it, 9 of the 19 drivers evaluated did not comply, and the spread of response between luminaires was wide. A controller that assumes a straight-line response from 0 to 10 V can therefore give unexpected levels.
• Wiring. The DALI Alliance says polarity must be observed on 0/1-10V systems and that wiring errors are common there.

DALI-2

DALI is a two-way digital protocol. Commands can control, configure and query a device, and can be sent to one device, to a group or to all devices on the bus (DALI Quick Start Guide v1.1, 2023). It is specified in IEC 62386, whose Part 101 (2022) covers system components in a bus system for digital control of electronic lighting equipment. DALI-2 is the DALI Alliance's certification programme, launched in 2017, based on the latest version of the protocol; the Alliance verifies test results before certifying, and lists every certified product in a public database.

• Limits per bus. 64 addresses for control gear and 64 for control devices; 16 groups for control gear; 16 scenes in each control gear; a bus power supply of up to 250 mA, typically about 16 V; 1.5 mm2 cable recommended, with 300 m the most between the two farthest-apart devices; daisy-chain or star wiring, never a closed loop. The two bus wires are not polarity sensitive except at a bus power supply.
• Several addresses in one fitting. A driver with two independently controlled outputs uses two addresses, so a fitting with several channels, tiers or colours can use up several of the 64.
• What to look for. All control gear complies with Part 102 of IEC 62386, Part 207 covers LED control gear and Part 209 colour control. DALI-2 adds fade times from 0.1 seconds to 16 minutes. The Alliance guide describes levels from 0.1% to 100%; how low a given fitting actually goes depends on its driver and light source.
• Certification is of the driver. The Alliance does not certify luminaires. A luminaire containing certified DALI-2 control gear may carry the logo, and a product not in the database is not DALI-2 certified. Version-1 products are not recommended for new designs; DALI-2 gear in an older system is expected to be fine, but bus power supplies and control devices that pre-date DALI-2 have no tests behind them.
• Commissioning. Addresses, groups and scenes are set up after installation with a commissioning tool or a suitable controller. Say who does it and who keeps the record.

DMX512

ANSI E1.11-2024 (USITT DMX512-A) comes from entertainment lighting. It describes digital transmission between controllers and controlled equipment including dimmers: one controller sends a repeating stream of values, in up to 512 data slots per link (one “universe”), to one or more receivers over a terminated RS-485 (EIA-485-A) link at a nominal 250 kbit/s.

• One sender, terminated line. A data link has a single active driver and a terminated line. The terminator is 120 ohms between the two data conductors, and the total load is limited to 32 unit loads.
• No guaranteed delivery. The standard does not require error checking, says there is no assurance that all packets are delivered, and says DMX512 is not an appropriate control protocol for hazardous applications.
• Not a building network. It says it is not intended to support a venue-wide network carrying lighting, sound and scenery on the same wire, and that cable requirements and premises wiring are outside its scope. Equipment is marked DMX512-A.
• Patching. Each product uses a “slot footprint”, the number of data slots it takes, and someone has to keep the schedule of which fitting listens to which slots.

Wireless

Wireless is a way of carrying the control, not a dimming method in itself: something in or on the fitting must receive the signal and set the driver. The bodies behind the main standards describe them this way.

• Bluetooth mesh. The Bluetooth SIG primer describes a many-to-many network in which messages are relayed, calls networked lighting control a key application, lists lightness on a perceptually uniform scale and scenes among its functions, and says security cannot be switched off.
• Zigbee. The Connectivity Standards Alliance describes a self-healing mesh and four certification programmes. Its overview page does not describe lighting.
• DALI+. Introduced by the DALI Alliance in 2024, it carries DALI-2 commands over wireless and IP media instead of the two-wire bus.
• Power for the receiver. The DALI Alliance Quick Start Guide describes a 24 V auxiliary supply for control devices, such as a wireless node attached to a luminaire, that cannot be powered from the bus.

Each body says its certified products interoperate; we have not tested any claim, and a certification listing is evidence, not a guarantee.

Compatibility checks before you fix a method

Ask for these in writing, per fitting, before the shop drawings are approved.

What to ask the lighting designer and the partner workshop

Of the lighting designer or electrical engineer

• Which control method does the project use, and for which rooms? Is it fixed before the fittings are ordered?
• Who supplies and sets up the controllers, dimmers or gateways, and who commissions and keeps the schedule of addresses or channels?
• What is the lowest level wanted, and what happens at off, and when the power is lost and restored?
• Is a mock-up of one fitting on the real control chain planned, and who signs it off?

Of the partner workshop

• Which driver is in each fitting, and which dimming methods does its datasheet say it accepts?
• Number of independently controlled channels per fitting, and how each is wired and labelled.
• The lowest light level the fitting reaches with that driver and light source, and whether it flickers or hums at low levels.
• For DALI-2, the database listing of the driver. For 0-10V, sinking or sourcing. For phase-cut, the dimmer types it has been tried with. For wireless, the standard, the certification listing and where the receiver sits.
• Can the driver be replaced without taking the fitting apart, and is the same driver available later?

Where this meets Part L

Approved Document L (England) has guidance on lighting controls: paragraphs 6.62 to 6.65 of the 2021 edition and 5.68 to 5.72 of the 2026 edition. They point to Building Research Establishment Digest 498, ask for automatic controls that turn general lighting off in unoccupied spaces, ask for daylight controls such as photo-switching and dimming, and ask for display lighting on circuits that can be switched separately. The 2026 edition adds key-card or occupancy controls in hotel bedrooms (5.70). Whether a chandelier falls under those paragraphs is a separate question, set out in Part L and chandeliers; the control method chosen for the rest of the room is part of the same decision.

Dimming method: [DALI-2 (IEC 62386, control gear to Part 102, LED Part 207) / 0-10V current-sinking / trailing-edge phase-cut / DMX512-A (ANSI E1.11)]. The workshop is to state on the shop drawing, for each fitting: driver make and model [ ]; dimming types its datasheet accepts [ ]; number of independently controlled channels [ ]; lowest light level reached [ ] % and whether it dims to off. For DALI-2, the driver is to be listed in the DALI Alliance product database and the listing reference given.

The lighting control supplier [ ] is to confirm in writing that the specified driver and the [dimmer / controller / gateway] are compatible, the maximum number of fittings per [dimmer / bus / link] [ ] and the lowest level achievable. One fitting is to be tried on the real control chain over its whole dimming range, and signed off by [lighting designer] before production. Any change of driver or control method after approval of the shop drawings is a variation.

[Controls supplier] is to set up and commission addresses, groups, scenes or channels, and to hand over a schedule of addresses or channels per fitting, the wiring diagram and the driver datasheets. The workshop is to label each fitting with its address or channel where it is not set on site.

Standards and sources

• DALI Alliance: Quick Start Guide v1.1 (April 2023) and Specifying with DALI, DiiA(SE)001a: read. Designer's guide: sections 3, 4, 6, 7.
• IEC 62386-101:2022, DALI system components: IEC listing read; standard text not read.
• ANSI E1.11-2024, USITT DMX512-A (ESTA): scope, topology, slots, loading, termination.
• Dimming LEDs with Phase-Cut Dimmers, PNNL-22945 (US DOE, 2013): US report. 0-10V Control for LED Streetlights, PNNL-32949 (US DOE, 2023).
• NEMA SSL 7A-2015 (R2021), Phase-Cut Dimming for Solid State Lighting: foreword, scope and contents only.
• Bluetooth mesh networking primer (Bluetooth SIG): read to section 8. Zigbee: Connectivity Standards Alliance overview.
• Approved Document L, Volume 2 (England), 2021 edition: 6.62 to 6.65; 2026 edition, 5.68 to 5.72.

Questions we are asked

Can I put any LED chandelier on a standard dimmer?

Not safely. A US Department of Energy report says a dimmable claim means the fitting's driver can take a dimmed signal from a specific type of dimming device, and lists failures, from no dimming to flicker and hum, that depend on how well the source and the dimmer suit each other. Ask the workshop for the driver's dimming type and the dimmer maker for the maximum number of fittings, and try one on the real circuit.

What is the difference between leading-edge and trailing-edge dimmers?

A leading-edge (forward phase-cut, TRIAC) dimmer removes the front of each AC wave and a trailing-edge (reverse phase-cut, ELV) dimmer removes the end. A driver may work with one and not the other, so the driver's datasheet decides which to specify.

What does DALI-2 certified mean?

It is a certification by the DALI Alliance against the latest version of the DALI protocol in IEC 62386, with the test results verified by the Alliance. Only products in its public database are certified. The Alliance does not certify luminaires, so check the driver inside the fitting.

Is 0-10V or DALI better for a hotel or restaurant?

No source read ranks them. 0-10V is a one-way analogue signal whose response and lowest level vary from driver to driver. DALI is a two-way digital bus with addressing, groups and scenes, and needs a bus power supply and commissioning. The lighting designer decides, and it should be settled before the fittings are ordered.

Is DMX512 suitable for dimming a chandelier?

It is a lighting control protocol from entertainment, and a fitting needs a driver that takes it. The standard says it has no required error checking and is not meant as a venue-wide network, so ask the lighting designer whether it suits the room.