Hope this is posted in the correct place, I am looking at using Zigbee hardware to complete the following task.
I want to switch off a domestic water pump after a certain amount of energy is used per day (kWHr). Essentially so that the house does not flood when I am out
The relationship between kWHr and flow rates is directly proportional so I want to have it setup that the Zigbee power meter removes power after 400Wh is used.
It depends on your situation. Zigbee works best when you have lots of mains-powered devices (lights, sockets) to forward messages round the network. It’s not good at simple point-to-point connections. You might be better looking at wi-fi.
Not knowing how much power your motor needs, as an EE you’re probably aware that any relay you use for a motor will have to be spec’ed as much as 3x higher to accommodate startup inrush current.
That said, here’s a nice write up for a Zigbee high-power (30A) relay that provides energy monitoring in HA. There are also several WiFi devices available with similar features, but look for locally-controlled (cloud-independent) WiFi like Shelly, Tasmota, or ESPhome for best results. Here is a 10A option, for example.