How to sense if a heater is plugged and on

Question

I want to remotely check if one of my home sockets (which happens to power a heater) is transmitting current or not. I do this as a hobby project, so my main priority is to learn through the process of building it, therefore I don't want to buy 'ready-to-use' devices. Also, this is a heater and I have carpet so, for safety reasons, I would like to not need to peal and connect wires that carry several amps. In particular, my heater is 2000W at 230V, so it will be using ~8.7 amps if I'm not mistaken.

I have been looking at different alternatives. Ideally, I would like to have a socket adaptor that sits between the wall socket and the heater, and the only thing it does is producing 3.3V or so on an external pin when it detects for instance 1 amp going through it. I can then feed that signal to an MCU and do whatever I need. At this point, I'm interested in the step of sensing when there is current flowing through the socket, but I don't need to measure the exact amount of current.

The alternatives I have found (that are safe enough) are:

• Hall effect sensors This is not ideal, but it's safe as I don't need to manipulate any part transferring a respectable amount of amps.
• Socket adapter with LED: I could break the LED part and solder a wire to it to use it as an input signal for my MCU.

Am I looking at the right parts? What are other options I could use?

Answer 1

After reading all the comments, the adapter with LED is discarded. That leaves 2 main options:

• Current transformer
• Hall-effect detector

Both devices work by passing a current carrying wire through the hole they expose, thus it's necessary to, somehow, expose only one of the wires that go to the target device (such device will have a single cable with, at least, 2 wires in it: phase an neutral).

Still, out of the 2 options, the hall-effect detector seems safer as the output it generates is a low voltage, which will vary depending on the amount of current going through the sensed wire. The current transformer induces a current on the output, which has a problem: it's necessary to solder a burden resistance in between the outputs to avoid a (theoretical) infinite voltage between them. There are online burden-resistor calculators but again, this is an added difficulty and, if by any chance the burden resistor is damaged or the solder points fail, it can be unsafe as far as I can see.