Wow. That's a substation! I'm honestly surprised that wireless works so well, at those levels I'd be very tempted to use industrial controllers that are all hardwired.

Agreed - in fact I did run Cat6 to all of those locations with the assumption of needing a direct connection. The IotaWatt doesn't have an ethernet interface, so wireless is the only way to connect. I have APs in most of the rooms (Using Ubiquity APs), so coverage is very good. I was concerned about the devices being in a sealed metal box, but wifi is surprisingly robust!

It is possible in the future I might switch to something else, but the units have been working really well without any glitches.