In short
DALI is an international standard (IEC 62386) for digital control of luminaires: each one receives commands over a two-wire bus and can be dimmed, grouped and queried. In an industrial building it allows lighting by zone, dimming according to the daylight coming through rooflights, switching off aisles with no activity and knowing which luminaire has failed without going up to check.
What is DALI and what are its limits?
A large building needs several lines, joined through gateways to a higher-level system such as KNX or to a controller with a network connection.
| Characteristic | Value |
|---|---|
| Wiring | Two wires with no polarity, which can run in the same cable as the mains supply |
| Luminaires per line | Up to 64 addresses |
| Groups and scenes | 16 groups and 16 scenes per line |
| Maximum length | About 300 m with 1.5 mm² cable |
| Feedback | Status and failure of each luminaire |
| DALI-2 | Certified version that includes sensors and push-buttons on the same bus |
Which control strategies are used in an industrial building?
- Zones: production, warehouse, aisles, loading bays and offices are switched separately.
- Presence: racking aisles drop to minimum or switch off when nobody is there. At height, specific detectors are needed.
- Daylight: near rooflights and doors, luminaires dim to hold the set level.
- Schedules per shift: each shift has its zones and levels.
- Maintenance level: slightly more light than needed is installed and dimmed down; as luminaires age, this is compensated.
- Cleaning or security lighting, at a reduced level.
DALI, 1-10 V dimming or simple on/off?
| System | What it allows | Limit |
|---|---|---|
| On/off by circuit | Fixed zones defined by the wiring | No dimming; changing a zone means rewiring |
| 1-10 V dimming | Dimming by circuit | No addresses and no fault information |
| DALI | Dimming and grouping each luminaire by programming, with fault reporting | Requires luminaires with DALI drivers and commissioning |
| Wireless DALI | The same without running the bus | Manufacturer-dependent; suitable for buildings in use |
Which mistakes are common?
- Buying LED luminaires without dimmable drivers and finding out when you want to control them.
- Using office detectors at a height of ten metres.
- Defining zones by the distribution board and not by how people work.
- Not documenting addresses and groups: any later change becomes complicated.
- Forgetting emergency lighting, which has its own rules.