DALI vs 0-10V Dimming: Which Control Protocol to Spec

0-10V and DALI both dim LED drivers over low-voltage control wiring, but they work in opposite ways. 0-10V sends an analog voltage that sets the light level for everything on the control circuit. DALI sends digital commands over a bus that can address each device individually and read status back. The choice comes down to how much control the space needs and how much it is likely to change. (If you are dimming through the power wires instead, that is phase-cut dimming, covered in our TRIAC vs ELV vs MLV guide.)

How 0-10V works

A separate pair of low-voltage control wires runs between the control and the drivers, and the voltage on that pair sets the light level. In the US, ANSI C137.1, published by NEMA, specifies the interface. As Lutron describes it, it is "an optional standard that controls and drivers can follow which defines the interface and performance requirements for 0-10 V controls and drivers".

Three practical points for the installer:

• Drivers on the same control pair get the same level. They dim together, so the wiring defines the zone.
• Current direction. Lutron's 0-10V application note cites IEC 60929, which "dictates that the load (driver) shall be the source of the current and the control should sink that current." The same note says a sourcing dimmer is "typically NOT the case." Match the control to the driver's documentation.
• Polarity matters. In Lutron's words, "the low-voltage control wires are polarity sensitive, meaning if the wires are switched, the driver and the entire 0-10 V link will not function properly."

The DALI Alliance's own comparison is that "analogue systems provide minimal diagnostic information, leading to longer downtime during maintenance." And changing zones on a wired 0-10V system generally means changing the wiring: Lutron notes that digital options such as DALI and Lutron EcoSystem "provide more flexibility to re-zone spaces that a wired analog 0-10 V solution cannot." Our post on what 0-10V dimming is walks through 0-10V wiring in more detail.

How DALI works

DALI stands for Digital Addressable Lighting Interface, specified in the multi-part international standard IEC 62386. Instead of a voltage level, DALI sends digital commands over a two-wire bus, and every device on the bus has its own address. Addresses, groups and scenes are set up during commissioning, using software or a commissioning tool. As the DALI Alliance puts it, "individual and group control enables DALI systems to adapt to changing lighting needs without the need for extensive rewiring."

The key figures and rules, from the DALI Alliance:

• Devices per subnet: "Each DALI subnet can have 64 control gear AND 64 control devices." Control gear, typically an LED driver, receives commands to control at least one output. Control devices send commands and "are application controllers and/or input devices," such as sensors and push buttons.
• Scenes: "Each control gear stores up to 16 scenes."
• Feedback: DALI supports two-way data exchange, so a controller can query things like a driver's current light level or a lamp failure.
• Bus power: the bus must be powered for devices to communicate, with a 250 mA maximum bus power supply. That supply "can be a standalone product or integrated within control gear or a control device."
• Polarity: "Except for devices containing a bus power supply, where the connection will be marked 'DA+' and 'DA-', the wires in a DALI system are not polarity sensitive."
• Topology and length: daisy-chain, star or a combination is allowed, and "the total cabling distance is limited to 300m (except in cases where the cable layout and characteristics are specially designed and selected)."

DALI-2 and certification

DALI-2 is, in the DALI Alliance's words, "the certification program which is based on the latest version of the DALI protocol," with "much more comprehensive testing than DALI version-1, with a strong focus on device interoperability." The earlier program "applied primarily to control gear and did not include devices such as application controllers, sensors, or bus power supplies." DALI-2 covers all of those. Products are tested by the manufacturer or an accredited test house, the results are verified by the DALI Alliance, and only then are products listed in the DALI Product Database and allowed to show the DALI-2 logo. The DALI, DALI-2 and D4i marks are trademarks "in various countries in the exclusive use of the Digital Illumination Interface Alliance."

For a mixed-vendor job, specify DALI-2 certified parts and check each model in the Product Database before you order.

Side by side

• Signal: 0-10V is an analog control level; DALI is digital commands.
• Zones: on 0-10V, the wiring sets the zone; on DALI, up to 64 control gear per subnet are addressed individually and grouped in software.
• Diagnostics: 0-10V provides minimal diagnostic information; DALI supports two-way queries such as light level and lamp failure.
• Polarity: 0-10V control leads are polarity sensitive; DALI wiring is not, except at devices containing a bus power supply (DA+ and DA-).
• DALI bus power: DALI needs a powered bus, from a standalone supply or one built into a driver or controller.
• Changing zones later: 0-10V generally means rewiring; DALI is regrouped in software.

Which to specify

0-10V fits spaces where zoning is simple and stable and nobody needs to know the state of each fixture.

DALI fits spaces that need individual fixture control, scenes, regrouping without rewiring, or diagnostics such as failure reporting.

A building can use both, each area with drivers and controls for its own protocol. If one system has to control the other, confirm the interface with both manufacturers before you specify. For how either fits a broader control strategy, see our commercial lighting controls buyer's guide and our comparison of wired vs wireless controls.

Spec it with Rock

Rock Lighting & Electric carries fixtures and drivers with DALI dimming options, including Elco Koto and Oak products and Westgate ULR ribbon, alongside our range of lighting controls. Create a contractor account, request a quote, or send us your control plans and we will help match fixtures and drivers to the protocol your project uses.

Frequently asked questions

What is the main difference between DALI and 0-10V? 0-10V is an analog control interface: the voltage on a pair of control wires sets the light level, and drivers on the same pair dim together. DALI is a digital bus defined in IEC 62386 that can address each device individually and supports two-way data exchange.

Is DALI better than 0-10V? Neither is better in every case. DALI offers individual addressing, software grouping, scenes and diagnostics, which suit spaces that need fine control or will change. 0-10V suits spaces where zoning is simple and stable.

How many devices can a DALI bus control? The DALI Alliance states that each DALI subnet can have 64 control gear, such as LED drivers, and 64 control devices, meaning application controllers and input devices such as sensors. Each control gear stores up to 16 scenes.

What is DALI-2? DALI-2 is the DALI Alliance's certification program based on the latest version of the DALI protocol, with more comprehensive testing than DALI version-1 and a focus on interoperability. It covers control gear, application controllers, sensors and bus power supplies. Certified products are listed in the DALI Product Database.

Does 0-10V wiring polarity matter? Yes. Lutron's 0-10V application note states that the low-voltage control wires are polarity sensitive, and if they are switched the driver and the whole 0-10V link will not function properly. DALI wiring is not polarity sensitive, except at devices containing a bus power supply, marked DA+ and DA-.

Does DALI need a power supply? Yes. The DALI bus must be powered for devices to communicate, with a 250 mA maximum bus power supply. The DALI Alliance notes the supply can be a standalone product or integrated within control gear or a control device.

Can I use DALI and 0-10V in the same building? Yes. Each area uses drivers and controls for its own protocol. If one system has to control the other, confirm the interface with both manufacturers before you specify.

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