Introduction

The Digital Addressable Lighting Interface (DALI) is one of the most widely adopted lighting control standards, offering flexibility, reliability, and easy integration with building automation systems. But to unlock the full potential of DALI, correct wiring and topology design are essential. Unlike traditional analog dimming systems (like 1–10V), DALI uses a two-wire digital bus for communication, making it easier to design, expand, and maintain.

In this guide, we explore the wiring rules, topologies, limitations, and best practices for DALI installation as per IEC 62386 standards, ensuring smooth commissioning and reliable long-term performance.

DALI Wiring Basics

• Bus Type: Two-wire, polarity-free – installers don’t need to worry about cable polarity, reducing wiring errors.
• Voltage: Nominal 16V DC (supplied by DALI power supply) – stable low-voltage communication ensures reliability.
• Current Limit: 250 mA per DALI line – exceeding this can cause instability or device failures.
• Maximum Devices: 64 ballasts, drivers, sensors, or controllers per line – suitable for medium-scale projects.
• Cable Length: Up to 300 m per line (depending on cable cross-section) – extendable with gateways for larger systems.
• Control: All devices connected to the bus can send and receive messages – unlike 1–10V where control is one-directional.

DALI Topologies

1. Bus Topology

• All devices are connected in a linear fashion along a single backbone.
• Common in corridors, long office floors, or warehouses, where luminaires are aligned in series.

2. Star Topology

• All devices connect back to a central junction point.
• Ideal for large rooms, open-plan offices, or spaces with many fixtures, making troubleshooting easier.

3. Tree / Mixed Topology

• Combination of bus and star.
• Flexible and practical for real-world building layouts, allowing engineers to mix wiring approaches as needed.

???? Unlike DMX, DALI does not require termination resistors at the ends of the line, which simplifies installation.

Cable Requirements

• Type: A 2-core twisted pair cable is generally recommended for DALI wiring because it enhances noise immunity and maintains reliable signal transmission. This ensures smooth communication even in large installations. Using a standardized cable type also simplifies design, installation, and troubleshooting.

• Cross-Section: Larger cross-sections reduce voltage drop over long runs.
  • 0.5 mm² = max 300 m
  • 1.0 mm² = max 600 m
  • 1.5 mm² = max 1000 m

• Shielding: Shielded cable is generally not required for DALI networks, as the protocol is designed to resist common interference. However, in environments with heavy machinery, airports, or high electromagnetic noise, shielding helps maintain reliable communication. Using shielded cables ensures signal stability in such demanding conditions.

• Segregation: The DALI bus can share conduits with mains wiring if the insulation meets safety standards, reducing cabling effort. This lowers installation costs and simplifies wiring layouts. Proper compliance with electrical codes must always be ensured.

Power Supply Requirements

• Each DALI line requires one power supply (16V DC, 250mA max).
• Do not connect multiple power supplies to the same line, as this can cause conflicts.
• Large projects use multiple lines, interconnected via gateways to maintain scalability.

Connection & Ports

• DALI Bus Terminals: 2 wires for communication (no polarity), making wiring simpler.
• AC Input Terminals: Provide mains power for the driver/ballast to run lamps or LEDs.
• Emergency Terminals: Used in DALI emergency drivers for self-test and compliance reporting.
• Auxiliary Ports: Some modern drivers provide connections for sensors, switches, or IoT gateways.

Comparison: DALI vs Other Protocols

Best Practices for DALI Wiring

• Keep total line current under 250 mA to prevent instability.
• Use a dedicated DALI power supply instead of sharing with other systems.
• Avoid loops or short circuits in the bus, which can cause communication errors.
• Choose the correct cable cross-section for the required run length.
• Label each DALI line and device during installation to simplify commissioning and maintenance.
• For large buildings, use DALI gateways to connect multiple lines into KNX, BACnet, or IoT systems.

Example Applications

• Office Buildings often use a tree topology with central gateways on each floor, simplifying system expansion and centralized monitoring. This approach allows facility managers to integrate lighting with HVAC, blinds, and sensors for greater energy efficiency and flexibility.

• Hospitals benefit from a star topology in patient rooms, where each luminaire connects directly to a central point. This setup allows independent fault detection and quick maintenance without disturbing critical operations.

• Retail Chains leverage cloud-connected gateways to ensure uniform lighting settings across all outlets. This centralized control improves brand consistency, simplifies scheduling, and reduces maintenance costs.

• Smart Cities adopt DALI-enabled street lighting with IoT integration, enabling predictive maintenance and energy optimization. Flexible topologies support large-scale deployments while ensuring real-time monitoring.

Conclusion

DALI wiring and topology design are the backbone of reliable, scalable, and energy-efficient lighting control systems. Using a simple two-core bus, DALI enables both power and communication to run through the same pair, significantly reducing installation complexity and cost. Its flexible topology allows star, tree, line, or mixed layouts, making it adaptable to office buildings, hospitals, retail chains, and smart city projects. Each line supports up to 64 devices, with straightforward addressing and grouping that simplify commissioning and maintenance. This versatility makes DALI suitable for both standalone systems and large-scale integrated automation projects.

Following IEC 62386 standards ensures interoperability across devices from multiple vendors, avoiding vendor lock-in and ensuring long-term reliability. Proper planning of cable routing, power supply sizing, and address assignment during the design phase reduces commissioning issues and enhances system performance. When combined with gateways, DALI integrates seamlessly with KNX, BACnet, or IoT platforms, enabling advanced features such as centralized monitoring, daylight harvesting, occupancy-based control, and predictive maintenance. By applying these best practices, engineers can build future-proof lighting infrastructures that balance efficiency, flexibility, and resilience.