PLC in Street lighting: How it works and when to use it

Lighting control without extra infrastructure. That’s the PLC advantage

Power Line Communication (PLC) is a technology that transmits data through the same cables already used for supplying electricity. In other words, you use the same power cable not only to power luminaires but also to control them — with no need for additional wiring or radio equipment.

How PLC works
At the heart of PLC is signal modulation: a data signal is overlaid onto the existing electrical waveform without disrupting the base frequency. Simply put, we don’t change the supply voltage — instead, we modulate the shape of the wave by adding controlled high-frequency oscillations. These modulations are picked up by receivers in the luminaires and interpreted as commands (e.g., on/off, dimming, switching scenes).

It works similarly to how sound is transmitted over radio waves: the core energy powers the system, while the modulation carries the data.

Where PLC is used
The technology is ideal for centralized lighting systems, where:

All luminaires are powered from a single source (such as one control cabinet).
A single cable can serve 50, 100 or more lighting poles.
Power and control signals travel over the same wire, making installation as simple and cost-efficient as possible.

Typical scenario: a new city street or highway where all lighting is wired to a central point, and the cable is used only for lighting.

Why PLC can’t always be used

The technology performs best under two key conditions:
1. Centralized power supply — luminaires must be connected to one cabinet.
2. Cable is used only for lighting — without extra loads like:

billboards
traffic lights
public outlets
pumps, etc.

When other loads are added to the circuit, they interfere with the PLC signal and distort the modulation — leading to control failures.
However, there is a technical solution that can help mitigate this issue in many cases — a noise filter. It eliminates interference and stabilizes the PLC signal when non-lighting devices are present on the line.

It's a common misconception that noise filters are always required. In practice, they are only necessary when:

More than 15–20% of the connected load comes from third-party devices
The line includes high-interference equipment, such as LED screens or industrial pumps