Technical information about DALI for Electricians

Listed below is the information an Electrican should know when installing DALI based products

• DALI is not defined as a SELV (Safety Extra Low Voltage) system. This means that normal wiring rules that would apply to normal power circuits will apply to DALI wiring.
• DALI cables can be wired next to normal mains carrying wires reducing the need to segregate the control wires.
• The DALI bus can be run up to 300m using 1.5mm squared cable as the DALI specification allows for maximum 2V drop in the communication signal. 
• The DALI bus does not require termination of the line and supports all wiring typologies except rings and closed loops (trees, branches, chains are all acceptable)
• The DALI bus is a 4 or 5 wire system (requiring active, neutral and two control wires). An earth wire is required in single insulated devices.
• A DALI bus can be connected to a maximum of 64 DALI type devices. Every DALI bus requires a DALI power supply. The DALI power supply is a current limited device ensuring that the bus current does not exceed 250ma.
• A DALI power supply can be wired at any position along the bus wire and is used to facilitate communication between the DALI devices and the control system. The DALI power supply will continue to put between 9.5 and 22.5 volts on to the control wires while there is no communication. DALI devices will respond to the control system by shorting the two control wires together.
• A DALI control system can be connected at any position on the bus. If the control system adheres to the full DALI standard protocol, multiple control systems can exist along the same bus.
• Thanks to a high signal to noise ratio and wide ranges for the digital signal, it is virtually impossible for the DALI data signal to be affected by interference.