DALI Overview
DALI is an industry standard protocol allowing digital control of lighting fixtures. DALI devices communicate over a DALI “Loop” which uses two wires to communicate between the DALI Master Controller (Gateway) and the lighting fixtures.
The DALI standard permits up to 64 fixtures to be connected to a single DALI Loop. Each fixture is assigned a unique DALI Address to facilitate bi-directional communication. The communication protocol permits standard commands such as intensity levels to be sent from the DALI Controller to a fixture as well as query commands to be sent to verify the state of a fixture. The latest DALI 2.0 standard adds additional commands including the ability to set the Color Temperature.
DALI communication takes place over standard, untwisted wiring using a low data rate. The low data rate maximizes communication reliability and minimizes wiring restrictions.
DALI fixtures are assigned to one of sixteen software defined “Groups”. A DALI Group is equivalent to a lighting zone. All Grouping can be performed from the DALI Master Controller post installation. Commands from the DALI Master Controller can be directed to a Group, triggering all devices assigned to that DALI Group to react.
The use of DALI Groups allows zoning of lights without the need for physically home running the fixture wiring, i.e. all lights in an area can be connected to the same power and data wires but controlled in smaller groups.
Primary Benefits of DALI System
- Reduced wiring compared to traditional home runs to a centralized dimming cabinet
- Ability to rezone without physically rewiring
- Color temperature control
System Design
Limit the DALI loop to be used for 50 fixtures. This will provide headroom for additional fixtures if required. All 50 fixtures can also be powered from a standard 15A residential circuit breaker.
Limit the total number of zones on the DALI loop to 14 to provide some headroom, to break up a zone in the future if required.
Wiring Guidelines
Fixtures require a 5-wire connection; Hot, Neutral, Earth, DALI, DALI
The DALI connections at the fixture are polarity independent.
Specialty 5-conductor, metallic and non-metallic cables are available from various vendors to facilitate a single cable being used for power and DALI communication. Examples:
- Southwire: Romex® Brand SIMpull® Type NM-B-PCS DUO™ Cable
- Southwire: MCAP® PCS Duo™ Power & Control/Signal Cable Type MC All Purpose
All wiring, including the DALI communication wires should be treated as Class 1 wiring, i.e. abide by all applicable NEC codes.
Wiring can be in a daisy-chain, t-tap or star topology. The only rule to follow is maximum wire distance between the DALI Master Controller and furthest fixture. Recommended limits are:
- 18 AWG: 500ft
- 16 AWG: 750ft
- 14 AWG: 1000ft
The wiring should run back to the lighting control cabinet where the DALI Master Controller is housed. The DALI communication wires will land on the DALI Master Controller while the AC Power connections will be fed from a beaker.