What method switches street light circuits using a light-sensitive relay?

The method that switches street light circuits using a light-sensitive relay is the photoelectric cell control. This system relies on a photoelectric cell, which detects the ambient light levels in the environment. When the light decreases to a certain threshold, typically at dusk, the photoelectric cell activates the relay, turning on the street lights. Conversely, when the light levels increase at dawn, the cell will deactivate the relay, turning the lights off.

This automatic switching method enhances energy efficiency and ensures that street lights are only operational when needed, which is crucial for minimizing energy consumption and maintenance costs. The reliance on natural light for control means that there is no need for manual intervention or complex programming, making it a widely used and effective solution for street lighting systems. Other methods like manual switches and programmable timers lack the automatic response feature that the photoelectric cell provides, and while remote controls can be useful, they require direct operation rather than environmental sensing.