Living waaaaay out in the middle of nowhere (it isn't a joke that I have an underground laboratory in the middle of the rainforest on a Pacific island) we have a well and a septic system. One of the problems we face is too-frequent minor electrical glitches that can trip circuit breakers. That's annoying for in-house stuff but if the breaker/gcfi for the septic system pump trips then poop don't pump and after a day or two a shrieking alarm wakes us up - because of course it happens at night.
So to monitor the power actually at the pump and get a warning when it is absent - before the shriek - I adapted one of the little ESP8266 wifi SBCs I've been using for temp/humidity monitoring in the house. Since I don't really care about the outside temp/humidity for this purpose I just removed the sensor and the relevant code and reflashed a board so it simply reports status; and of course if there is not power it can't report anything. At the Squeak end I simply track the last timestamp received from that unit and if nothing has come in for 30 minutes it notifies me.
Of course this is really nothing like as sophisticated as the usage LabWare put an extension of my MQTT code to; that's monitoring the power grid for Scottish Power and apparently several US states.
tim -- tim Rowledge; tim@rowledge.org; http://www.rowledge.org/tim Strange OpCodes: XER: Exclusive ERror