I'll usually buy something like a Shelly (Plus) 1PM. It's all already done and in a nice isolated plastic enclosure, you just need to screw in the wires. Depending on the version you'll probably get an ESP32 inside. A 16A relay and power monitoring. And it doesn't cost more than the components bought seperately(?)
this post was submitted on 21 Jun 2026
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My idea was to use something like this:
Just with some sort of PM device integrated, I find it quite weird there are any available.
B.
Hmmh. I think the ACS712 or something similar would do. Or a power clamp around a wire. Just make sure you know what you're doing when messing around with mains voltage. I mean most people just buy something like a Shelly. They also have variants with 2 relais. Or a smart multi-outlet power strip. There's many options to buy. Tinkering with mains voltage and wanting it all exposed is a bit of a niche, I don't know if there's many PCBs out there. That's mostly cheap boards with just the relais.
Buy an ACS 712 ammeter, the integrated board should not cost more than $3, and you don't need any special high voltage isolation, it comes with 10 A terminals. You'll get a decently accurate current reading, multiply by your socket voltage to get power in watts (120 or 220, which is actually 240 volts nowadays, you should know), but you need to read it like 300-400 times per second for AC. Just beware that even the manufacturer says the chip itself is rated for 30 A, your terminals will become melted plastic at around 15 A, and you won't even fit the wires rated for more than 15 A into them.