How do street lights work?

11 December 2019, 11:58

A street light in London
A street light in London. Picture: PA

Do street lights turn on and off by themselves or is someone controlling them?

Mystery Hour Question

How are street lights operated? 
Cara, Edinburgh


Name: Tom, Romford  
Qualification: Electrical contractor and I maintain and repair street lighting
Answer: Solar cells are quite an old system now, and many of the local authorities are now employing central management systems. In these cases it’s not just a photo cell, it’s a complicated device that transmits and receives radio signals. These central management systems send a signal to turn the lights on and off. 

Name: Brandon, Watford 
Qualification: Electrical engineer
Answer: Streetlights are run by photovoltaic (solar) cells. So when the light of the sun comes up, there’s enough electricity generated within the component, which opens the circuit, to make the light switch off, and vice versa.