Are LED streetlights dimmable?
The vast majority of modern LED streetlights support dimming, though this must be explicitly specified. Common dimming methods include:
1. 0-10V Dimming: The most universal method. It uses two dedicated signal wires (typically purple and pink) to apply a 0-10V DC voltage; 10V represents full brightness, while 0V represents the lowest setting (often down to 0% or 10%). This requires an external 0-10V dimmer or controller.
2. PWM (Pulse Width Modulation) Dimming: The LED driver uses pulse width modulation to adjust brightness by varying the duty cycle. This offers a wide dimming range without color shift; however, the PWM frequency should be ≥1000Hz to avoid visible flickering.
3. DALI (Digital Addressable Lighting Interface) Dimming: A digital, addressable system where each light has a unique address, allowing for complex scene control and status feedback. It is well-suited for large-scale lighting systems.
4. Resistance Dimming: Brightness is adjusted by changing the resistance value via an external potentiometer (10kΩ). While simple, it offers lower precision.
5. Scheduled (Timer-based) Dimming: The LED driver contains a pre-programmed schedule, automatically adjusting brightness at specific times without the need for an external controller.
6. Wireless Dimming: Dimming commands are received via wireless signals such as Zigbee, LoRa, or NB-IoT. For roadway lighting, the most common approach is to combine 0-10V or DALI dimming with scheduled or remote control. The benefits of dimming include significant energy savings—for instance, by reducing brightness (e.g., to 50%) during late-night hours when traffic is light—as well as an extended lifespan for the LED components.
Not all LED streetlights support dimming, so it is essential to verify this at the time of purchase. Additionally, dimming signal wires should be routed separately from power cables to prevent interference.
