They’re not that hard to install, but it requires taking the cover off your electric service panel box and installing the clamps directly onto the live wires, which if I’m not mistaken, remain energized even if you switch your main breaker off, see the diagram below. That gives you a total measure of your electricity use.
If there’s a chance you might screw up somehow during that kind of installation process, then an electrician should do it for you. That’s who installed mine, although he was already upgrading the entire panel so the time spent installing the HEM clamps added essentially nothing to what I was paying him anyway. But I don’t think I would have attempted it on my own regardless.
The clamps can also be installed on a single circuit to measure only that circuit’s energy usage. It’s somewhat harder to kill yourself that way, since if you switch off the main breaker, the wires you’re applying the clamps to are no longer live.
Devices like iotawatt are generally installed with multiple similar clamps to measure multiple circuits.
