Street Lighting Control Systems: Understanding Methods and Their Evolution

5 Minute Read

Street lighting plays a pivotal role in ensuring the safety and aesthetics of our urban landscapes. With advancements in technology, there are now two primary methods to manage these lighting systems: group (or segmented) control and individual control.

Street Lighting Control Systems: Understanding Methods and Their Evolution

Group Control Method

The group control approach involves managing lamps in clusters, where they are grouped together and operated simultaneously. This method does not offer the flexibility of individual lamp control.

Individual Control Method

Contrarily, the individual control method provides a unique system for each lamp, allowing for tailored lighting adjustments on a lamp-by-lamp basis.

A Brief History of Lighting Control

A Brief History of Lighting Control

Lighting control has seen remarkable transformations throughout history, from the simplest manual methods to technologically advanced systems. Understanding this evolution gives context to the current state of street lighting control.

Early Beginnings: Torches, Candles, and Oil Lamps

Historically, lighting control started with rudimentary systems, such as torches, candles, and oil lamps. In these times, controlling light was primarily about manual lighting and extinguishing these sources.

Gas Lamps

In the 19th century, gas lamps marked a significant leap forward. Developed to utilize liquefied hydrocarbons to produce light, they still relied on manual operation but represented a shift from the ancient methods.

Electric Lighting

As the 19th century ended and the 20th century dawned, electricity paved the way for innovative lighting systems. This period witnessed the invention of switches, enabling more convenient control of electric lights, including centralized systems for turning them on or off.

Introduction of the Photo Relay

The mid-20th century heralded an era of electronic and technological advancements. The photo relay, a crucial innovation in lighting control, was born. The inaugural street photo relay was developed in the mid-1930s. Acting as the main control element, a photo relay employs a light-sensitive sensor or photo element. This allows for automatic toggling of street lighting based on ambient light levels, ensuring optimal illumination when needed.

The Impact of the Photo Relay on Street Lighting

The integration of the photo relay into street lighting systems marked a transformative moment in their history. It not only brought about enhanced efficiency but also paved the way for significant energy savings.

With the invention of the photo relay, there was a notable improvement in the efficiency of street lighting. The capability to automatically shut off lights during daylight hours meant a considerable reduction in energy consumption. As a result, cities found street lighting more economical and user-friendly.

The photo relay also highlighted the first major divergence in approach between Europe and the USA. In European regions, the infrastructure favored the installation of photo relays on groups of lamps, leading to segmental or group control. In contrast, the USA's distinct infrastructure and specifications for street lighting promoted the installation of photo relays on individual lamps.

Evolution of Group Lighting Control Systems

Evolution of Group Lighting Control Systems

Over time, advancements in lighting control mechanisms have pivoted towards more precise and energy-efficient systems. From photo relays to time-relays, the journey has been intriguing.

Time Relays and Timers: Addressing the Photo Relay Limitations

In Europe, control systems based on time relays and timers became a popular choice. The shift was driven by the challenges associated with photo relays— these could become dirty and might respond to unnatural light sources, such as car headlights, causing false activations. This problem, in a group management setting, could skyrocket electricity consumption and reduce the longevity of the system.

An early testament to group lighting control using timers was the system employed in Paris in 1889 for the Eiffel Tower's lighting. Mechanical timers were leveraged to automate the lights' switching process.

However, in the US, control was predominantly individual, with a strong inclination towards photo relays for a prolonged period.


Group Lighting Control
The Qulon Controller Example

But what does contemporary group lighting control resemble? Take the Qulon controllers (Mini, C, C1, C2) as illustrative examples. Generally, such a controller is placed in the lighting control cabinet and governs one or several lighting groups through starters. It is equipped with diagnostic functions and connects to an electricity meter, serving as a part of the electricity accounting system and helping diagnose lighting lines.


Scheduled lighting. The system can operate based on a preset schedule.

Group diagnostics. While pinpointing a specific malfunctioning fixture might not be possible, the problematic group can be precisely identified.

Quick installation without changing the lighting setup.

Cost-effective in both implementation and operation.


Lack of precision in identifying malfunctioning fixtures.

Limited energy-saving options due to group-based controls.

In the daytime, poles remain unpowered, limiting their infrastructure project potential.

Rare applicability in the US, influenced by infrastructure and historical factors.

Individual Control

Individual Control

The hallmark of individual control is the allocation of a distinct controller (replacing the photo relay) for every light fixture, enabling independent operation. One of the prevalent light fixture controllers is the GSM Node. Available with NEMA or Zhaga connectors, it introduces functions like on/off, dimming, and status checks.


Comprehensive control over the entire lighting system.

Varied energy-saving modes.

Facilitates interactive functioning with diverse sensors.


High initial implementation costs.

Complexity and expenses associated with managing numerous equipment pieces.

Typically preferred when there's a complete overhaul of the lighting system.


Given the diverse nature of urban infrastructure and the strengths and weaknesses inherent to each lighting control method, a one-size-fits-all approach is not the most efficient. It's recommended to adopt a flexible stance, considering the application of both group and individual control methods where they best fit within the city's framework. This integrated approach is likely to yield optimal results, combining the benefits of both systems.