Technical Rundown of DALI Wiring
DALI wiring is the biggest advantage of the DALI system. The wiring of the ballasts (regulates power to the lights) does not determine the grouping of the lights and switches. Instead, changes can be made to the system.
Lighting fixtures can easily be grouped. For example: dimmed hallway lights and brighter kitchen task lights. These can be programmed to fit the lighting needs of the space. Modification of a DALI system is as simple as re-adjusting the system, avoiding complicated wiring changes.
Below are things both you and your electrician should be aware of when wiring a DALI network:
Things to Be Aware Of When DALI Wiring
At the design phase, other lighting control systems may require wiring based on the expected needs of the space. That is, what the space would be used for, whether as an office or a dining room etc. DALI offers flexibility because groups can be assigned at any time regardless of how the fixtures are wired. If a space was originally a dining room but gets converted into a study, there will be no need to change the lighting because the problem can be resolved with a simple reprogramming of the digital interface.
For example, 0-10V dimming systems require ballasts to be installed in parallel and controlled simultaneously by a single control unit. On the other hand, DALI systems can be installed in series, in a star configuration, or in a combination of the two. This combination provides a potential reduction of the amount, and distance of wiring needed.
Below, various wiring configurations are shown in Figure 1.
Standards to follow
Normal wiring standards are applicable to the DALI systems as they are not classified under Safety Extra Low Voltage (SELV) system. However, there are specific standards to follow such as:
- The ballast must be a current source.
- The ballast must provide a minimum current of 0.2 mA and a maximum of 1 mA.
The standards also set requirements for the wiring and the properties of the wires. No special wiring, such as twisted pairs or special cables, is required. However, in most cases, wires should be:
- 300m for maximum cable length
- 250mA as the maximum DC supply
- 1.5mm2 in terms of diameter
Figure 2 shows a typical DALI wire.
To connect the DALI wiring to the main light source, you will need a ground wire, a main wire, a shielded wire and two wires from the controller. The line voltage and bus bar are usually routed in the same cable found in the controller. The five wires mentioned make up 5-core cables which include neutral, earth, live (or hot) and two DALI wires.
The control wires and main supply wires should be rated 2 kV and double insulated. The controlled devices, such as light bulbs or electronics, have to withstand power supply of ±30 V without being damaged.
For DALI systems, there is no need to separate the wires or control system. Why? Because the DALI control cables that are 1.5mm2 can reach a maximum length of 300m. Also, switches and sensors can be connected directly to the wires or control units running between the ballasts.
In figure 3, sensors and switch panels (or a ballast loop) are connected directly to the DALI.
In figure 4, sensors and switch panels are connected directly to the control unit
Need for an independent power supply
It is imperative that every DALI installation has its own power supply. The power supply boosts all DALI systems and devices, like motion sensors. Being a low voltage system, it only requires a low voltage power supply for the system to operate. The output of the unit (e.g motion sensor) is dependent on the low voltage wiring that allows communication between the control unit and ballasts.
DALI ballasts and devices are connected to the power supply and to the DALI circuit. If there is more than one DALI circuit, check that the ballasts are connected to the right DALI circuit. Some configurations, when used for setting up the DALI installation, provide the option of checking whether all the ballasts are connected to the right DALI circuit.
Other things to know
The need for Low Voltage Wires
Low voltage wires are run between the control unit, power supply, and ballasts. These wires are needed to boost the performance of the DALI system while preventing electric shocks to the user. They can be designed in a series layout, a star connection, or a combination of the two as shown earlier.
Distance and Voltage Drop should be monitored
It is important to keep the distance or voltage drop in mind when wiring a DALI network as this may affect its performance. The maximum voltage drop that is allowed for a DALI loop to keep a clear message all the way to the end of the loop is 2V. As a rule of thumb for typical wiring and installation, the maximum distance between any devices on the loop should not exceed 300m.
Emergency lighting testing on the DALI network
The unique method of DALI wiring also makes it possible for emergency lighting to run on the DALI network. This is done with a computer system. Moreover, these DALI-compatible emergency fittings can be scheduled for automatic testing and reporting.
When building standards require each emergency fixture to be tested for its performance and battery condition on a regular basis, time can be saved if a DALI lighting control system in combination with a computer software is utilized. There is a software available which can test the performance of an emergency lighting as it relates to the lamp, ballast faults and battery status and reports their performance back to a computer.
The fixtures can be set to be tested periodically or continuously. Because the testing procedure is performed by a computer, testing can be done during off-hours without requiring the presence of maintenance staff. When there are concerns about productivity issues and potential distractions, after-hours testing is important.
Below is what a simple DALI system wiring will look like: