Dimmable LED lighting: what is the difference between TRIAC, 0–10 V and DALI-2
Dimming the lights to create a welcoming atmosphere or increasing brightness in a work area sounds simple. However, with LED lighting, installing a wall dimmer is not enough.
The bulb or luminaire, the driver and the control system must be compatible. This is where terms such as TRIAC, 0–10 V and DALI-2 come in. They all relate to dimming, but they do not work in the same way.
What happens when we dim the lights?
The dimmer sets the desired light level. The driver adjusts the power supplied to the LEDs to produce that level of light.
In LED bulbs that connect directly to the mains, such as many GU10 and E27 models, this electronics is built into the bulb itself. In other solutions, the driver is a separate component.
This is why dimmable does not mean “compatible with every dimmer”. You need to check which system is used.
TRIAC: dimming through the power supply
TRIAC dimming is associated with phase-cut control: the dimmer modifies part of the mains voltage waveform, and a compatible bulb or driver responds by adjusting the light output.
It is a common solution in homes, restaurants and small installations, usually using a wall dimmer without additional control wires running to the bulb.
It is also important to check the dimmer’s load limits and the number of bulbs it supports. An older dimmer designed for halogen lamps may not work correctly with LEDs, even if the total wattage appears suitable.
0–10 V: a separate signal to control brightness
In this system, the electrical supply and the dimming command have separate functions. A control signal, normally carried by two additional wires, tells the driver the desired light level.
This option is used in offices, commercial spaces and industrial installations, for example, to dim several luminaires in one area together.
You may also come across 1–10 V equipment. These two designations should not be treated as interchangeable: the minimum light level and the ability to switch the light off completely depend on the equipment. Always check these behaviours in the technical datasheet.
The 0–10 V refers to the control signal, not the voltage supplying the LEDs.
DALI-2: digital control and greater flexibility
DALI is a digital communication system dedicated to lighting. It allows devices to be controlled individually or in groups and lighting scenes to be saved, such as “meeting”, “presentation” or “cleaning”.
In a suitably equipped installation, it can also work with occupancy and light sensors. This allows different areas to be adjusted without all of them having to receive the same command.
DALI-2 identifies a certification programme that verifies requirements for operation and compatibility between devices. It does not simply mean smoother dimming, nor does it turn a luminaire into a wireless solution.
It is particularly useful when flexible control of several areas is required, but it needs suitable components and system configuration. Installing a DALI-2 driver alone does not create a complete system.
The dimming system is not the only consideration
When choosing a driver, you also need to check whether it operates at constant current or constant voltage, its output ratings, power rating and installation requirements. Two drivers with the same wattage and dimming system may not be suitable for the same LEDs.
See also our article How to choose the right LED driver.
The minimum light level deserves attention: dimmable does not necessarily mean a smooth transition all the way down to zero. If the light flickers, the equipment makes noise or the light switches off too early, the compatibility and operating limits of the complete setup need to be checked.
Which option makes sense for your space?
For straightforward dimming in a room, a phase-cut solution may be sufficient. To control groups of luminaires using a separate signal, 0–10 V may be suitable. When individual control, lighting scenes and sensor integration are required, DALI-2 offers further possibilities.
The best choice depends on the existing installation and what you want to control, not simply on which technology is the most advanced.
At Wattlamp, you will find a range of LED drivers. If you have any questions, send us the model references for your luminaire, driver and dimmer: ask Wattlamp.
The bulb or luminaire, the driver and the control system must be compatible. This is where terms such as TRIAC, 0–10 V and DALI-2 come in. They all relate to dimming, but they do not work in the same way.
What happens when we dim the lights?
The dimmer sets the desired light level. The driver adjusts the power supplied to the LEDs to produce that level of light.
In LED bulbs that connect directly to the mains, such as many GU10 and E27 models, this electronics is built into the bulb itself. In other solutions, the driver is a separate component.
This is why dimmable does not mean “compatible with every dimmer”. You need to check which system is used.
TRIAC: dimming through the power supply
TRIAC dimming is associated with phase-cut control: the dimmer modifies part of the mains voltage waveform, and a compatible bulb or driver responds by adjusting the light output.
It is a common solution in homes, restaurants and small installations, usually using a wall dimmer without additional control wires running to the bulb.
You may see the terms leading edge and trailing edge in the documentation. These describe different types of phase-cut control. TRIAC is usually associated with the former. You should not assume that a device supports both.
It is also important to check the dimmer’s load limits and the number of bulbs it supports. An older dimmer designed for halogen lamps may not work correctly with LEDs, even if the total wattage appears suitable.
0–10 V: a separate signal to control brightness
In this system, the electrical supply and the dimming command have separate functions. A control signal, normally carried by two additional wires, tells the driver the desired light level.
This option is used in offices, commercial spaces and industrial installations, for example, to dim several luminaires in one area together.
You may also come across 1–10 V equipment. These two designations should not be treated as interchangeable: the minimum light level and the ability to switch the light off completely depend on the equipment. Always check these behaviours in the technical datasheet.
The 0–10 V refers to the control signal, not the voltage supplying the LEDs.
DALI-2: digital control and greater flexibility
DALI is a digital communication system dedicated to lighting. It allows devices to be controlled individually or in groups and lighting scenes to be saved, such as “meeting”, “presentation” or “cleaning”.
In a suitably equipped installation, it can also work with occupancy and light sensors. This allows different areas to be adjusted without all of them having to receive the same command.
DALI-2 identifies a certification programme that verifies requirements for operation and compatibility between devices. It does not simply mean smoother dimming, nor does it turn a luminaire into a wireless solution.
It is particularly useful when flexible control of several areas is required, but it needs suitable components and system configuration. Installing a DALI-2 driver alone does not create a complete system.
The dimming system is not the only consideration
When choosing a driver, you also need to check whether it operates at constant current or constant voltage, its output ratings, power rating and installation requirements. Two drivers with the same wattage and dimming system may not be suitable for the same LEDs.
See also our article How to choose the right LED driver.
The minimum light level deserves attention: dimmable does not necessarily mean a smooth transition all the way down to zero. If the light flickers, the equipment makes noise or the light switches off too early, the compatibility and operating limits of the complete setup need to be checked.
Which option makes sense for your space?
For straightforward dimming in a room, a phase-cut solution may be sufficient. To control groups of luminaires using a separate signal, 0–10 V may be suitable. When individual control, lighting scenes and sensor integration are required, DALI-2 offers further possibilities.
The best choice depends on the existing installation and what you want to control, not simply on which technology is the most advanced.
At Wattlamp, you will find a range of LED drivers. If you have any questions, send us the model references for your luminaire, driver and dimmer: ask Wattlamp.
