CT Clamp for ESP

I would just go with a pzem004t v3 and save all the hassle for another project. Not only faster to setup (no calibration etc.) but also literally the same price as a coil (and it comes with a coil!). It also measures voltage, frequency beside current and all of that with a quite good accuracy (surely much better you can achieve with any coil because of the lack of RMS)

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Unfortunately disconnection of the wiring to install the CT is not an option, which is why I am looking at clip on CT units. Also, having a bare core isn’t allowed inside a mains junction box. Thanks anyway.

I use this one, it has clip on clamp and I have the unit outside of the FCU:

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Hi there… looks interesting. How did you connect it to HA?

Used an ESP32, but you can use a D1 mini or NodeMCU

You can use this using esphome:

Thanks again, I’ve ordered one of the units with the clip on CT.

Hi @Holdestmade, my Peacefair arrived, but I am a bit confused with the circuit diagram on the unit?

Here’s the diagram…


Did you connect the CT clamp and the AC connection, or just the CT clamp?

Also, the unit didn’t come with a cable with a plug that connects to the socket below. Did you end up buying one?


Thanks, Mark

Indeed that’s how the device works. The coil can only measure the current but that alone doesn’t help to get real power usage. The wires AC connection doesn’t use any high current but essential just does power the device and makes the pzem004t able to read the voltage (and probably some other values). If you like you could add a plug on it - the location where it is located in your circuit doesn’t matter as the coil decides where the power consumption is measured.

It also always comes with cable for the Tx/Rx side. You can easily work with dupont cables there or even use wire wrapping.

Can this be used also for 12v DC current?