berkinet wrote:Indeed. However. I would think the two ends are compatible, but different. So, I would then suggest that your real need is to measure the internal temperature of the fridge. Because, everything else is really just analogous (to a greater or lesser sense) to the temperature. In your case, I would still monitor the circuit to see that current was available and then place a temperature sensor (RTD, thermocouple, or thermistor), in the fridge. You could also measure AC at the fan or current draw on the hot wire to the fan. But, as noted, those two indicators will not guarantee the fridge is actually cold.
Yes, that would most certainly work. The fridge is but one example, however. Sump pump, septic pump, randon system, etc. are all 24/7 things I'd like to monitor. Each of them plugs into a receptacle and it would be wonderful to (safely) monitor them from the plug.