In 1994, my new Townhouse when I lived in Midrand, had an odd "box" just outside the front door. On enquiring with the complex electrician, he advised me that it was designed for a ripple control relay.
This was apparently a device that could be used by the Local Municipality, to switch off just the geysers in a suburb, to prevent maximum demand charges.
It might only be necessary to shed the geysers for 15 or 20 minutes, which would have absolutely no effect on hot water, but have a huge reduction on power demand, given that the average geyser is 3Kw per house.
Went back to have a look. Box still there with loose wires.
What ever happened to that simple principle of load shedding, without the need to shut down a suburb completely.