We also control (or used to control) our street lights in AoNZ using ripple control (it was implemented with a tuned reed relay in some towns). Back in the 70s

We also control (or used to control) our street lights in AoNZ using ripple control (it was implemented with a tuned reed relay in some towns). Back in the 70s friends built a ripple transmitter and sent morse across Ōtepoti by turning on/off their suburb's street lights (at 2am)