Just a note of thanks/success regarding my install.
My electric bill spiked by about $150 with no change in behavior. Some of that is seasonal but there was clearly something wrong. The house is from the late 1940’s but new to me and both it and the property are large, with a number of systems and some features that I’m not used to.
Purchased and installed the IoTawatt and found a failing sump pump within five minutes. The sump here has three pumps, so the overall system was working fine and it was not obvious that one pump was in distress. The pump was pulling several hundred watts 24/7 without actually working. Fortunately it was submerged at all times and not a fire hazard. Unplugged the seized pump and watched the wattage drop in real time.