DALI lighting control (IEC 62386)

DALI (Digital Addressable Lighting Interface) is a standardised digital lighting control protocol, defined in the IEC 62386 series of standards. Where a classic 0-10V dimming line drives all connected control gear or LED drivers simultaneously and identically, DALI can address each connected device individually via a digital signal on a shared two-wire bus.

Individual addressing, groups and scenes

Each DALI control gear unit (ballast, LED driver) is assigned a unique short address during commissioning, allowing it to be controlled independently of the other devices on the same bus line — up to 64 individually addressable devices per DALI line. Besides individual addressing, DALI supports:

• Groups: controlling multiple devices together as one logical unit (for example all luminaires in one room), up to 16 groups per line.
• Scenes: a pre-configured combination of dim levels per device or group, recallable with a single command (for example a "presentation setting" that dims part of the luminaires while setting another part to full output) — up to 16 scenes per line.

This makes DALI fundamentally more flexible than an analogue dimming line: the same physical bus can later be reconfigured into different groups and scenes without rewiring — purely through software/commissioning, not by changing the wiring itself.

Structure of the IEC 62386 standards series

The standard is built up from a series of linked parts:

• Part 101: general system requirements for the bus line.
• Part 102: general requirements for control gear.
• Part 103: general requirements for control devices (sensors, push-buttons).
• Numbered part standards for specific device types, for example LED modules, emergency-lighting control gear (self-testing variants, see also the guide on emergency-lighting self-test systems), colour control, daylight sensors and occupancy detectors.

DALI-1 versus DALI-2

An important practical distinction when selecting equipment:

• DALI-1 (the original, older generation) standardised almost exclusively the control gear — the side that actually drives the light. Input devices (sensors, control panels) were largely manufacturer-specific under DALI-1, so mixing input devices from different brands on the same bus line was not guaranteed to be interoperable.
• DALI-2 (the later extension within IEC 62386) also standardises input devices and adds a formal certification programme — a DALI-2-certified device carries its own logo indicating it has actually been tested against the interoperability requirements, unlike an uncertified device that merely claims to be "DALI compatible" without that formal testing.

Practical rule of thumb: when combining input devices (sensors, push-buttons) and control gear from different manufacturers, never simply assume interoperability — explicitly check that both sides are DALI-2 certified, particularly for input devices, where DALI-1 offers no guarantee.

Bus wiring: no SELV guarantee

The DALI bus line operates at extra-low voltage, well below normal mains voltage, and the two bus conductors are — unlike a mains supply — polarity-insensitive: swapping the two bus wires does not damage the system or disrupt its operation. That makes the wiring simpler than for many other bus systems, but it does not automatically mean the bus line may be treated as a SELV/PELV circuit under §414. Whether the actual separation from mains voltage meets SELV/PELV requirements depends on the construction of the specific DALI power supply/driver — installers must always follow the manufacturer's documentation rather than assume this based on the low operating voltage alone. For comparison, the guide on KNX bus installations covers the same kind of separation question for a different building bus system — the principle (a low bus voltage is not a guarantee of formal SELV separation) is relevant to both protocols, even though they are technically different systems.

Common mistakes

1. Assuming every DALI device automatically works with every other DALI device — especially for input devices (sensors, push-buttons), this is only guaranteed with DALI-2 certification, not under DALI-1.
2. Treating the bus line as a SELV circuit purely on the basis of its low voltage, without checking the actual separation construction of the power supply.
3. Wanting to change the physical wiring when reconfiguring groups/scenes — the whole point of DALI is that grouping is done through software/commissioning, not rewiring.
4. Exceeding the maximum number of devices or groups per bus line without checking this against the actual system capacity beforehand.

Related

• KNX bus installation and SELV separation
• §414 — SELV/PELV/FELV
• §559 — Lighting installations
• Emergency lighting — self-test systems