I use Shelly EMs and EM Pros and they are excellent. My favourite feature is that they work on non-networked firewalled VLANs and don’t need the internet to work.
this post was submitted on 23 May 2025
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Home Assistant is open source home automation that puts local control and privacy first. Powered by a worldwide community of tinkerers and DIY enthusiasts. Perfect to run on a Raspberry Pi or a local server. Available for free at home-assistant.io
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I'm using off-the shelf CT-clamps with an ESP. Obviously it's a fair amount more work, but it's cheaper than a commercial solution, fully offline and no subscriptions, you know exactly what you are getting, and you can build a solution that is just the right size for your application, and infinitely modifiable if your needs change.
I think one day, I might go with something like that.
But admitting my own time limitations: It would probably sit in a drawer until I got around to it, joining the RGBW strip and similar ESP I bought a few years ago!
I bought one last year and and that's exactly what happened. It's in a box. I'd love to install it, but have to build a little external box because it did t quite fit.
I have the Shelly Pro 3EM 120A and I have nothing but good things to say about it, installation is easy if you know what you're doing, integration with HA was trivial and it's very customizable. Before purchasing it I was worried about the update frequency of the values, but I was happy to see that it updates about a couple times per second, which is great. I'm happy to answer any questions you might have!
Ah, brilliant. In that case, I may have the confirmation to make the order.
It's just a shame the 120A is so much more expensive! £70 vs £120.
As there is a low chance I'll be pulling more than 50A on a circuit, but I know it'll 100% happen one day if I cheap out!
Yeah the bigger toroids are quite expensive, you can always buy just the toroids by themselves later on though, I think Shelly even sells them separately
Second question actually; How did you find the installation?
I'll probably get an electrician to fit, but if there are any gotchas it'd be good to know before I instruct.
My dad is an electrician so he did it for me, from what he told me it was pretty straightforward. The easiest thing to mess up is the orientation of the toroids, which is easy to notice because the values will be negative. The 120A toroids are also kinda bulky, if your panel is on the small side it might be a bit difficult getting them in there.
They only seem to sell the 50s separately, which is a shame. £50 worth of calibrated iron, hooray (!).
They do sell the big ones on Amazon Spain at least https://www.amazon.es/Shelly-EM-120A-Current-Transformer/dp/B08HM4735J/262-6285131-6774253
@GreatAlbatross Unfortunately I can't say anything about the given Shelly clamp meter.
But I'm using several of Shelly Plus Plug devices in german version.
https://shellystore.co.uk/product/shelly-plus-plug-uk/
I'm a big fan of Shelly, because it can be configured and used completely without sending data to the cloud.
The integration in Home Assistant is very good and my data is only local at my self hosted Home Assistant instance.
Appreciate the response.
It's good to get some feedback on the integration.
I also currently use some (cheap) zigbee plug monitors, which I might replace with these down the line, thanks!
This is something I’ve looked into in the past as well and with about 35 circuits to monitor, the Vue seems like a good one and done solution except it’s way too small, AND there’s mucking about with firmware which I’m none too excited about. I’m waiting for something better.
Shelly, if you're listening: Smart RCBOs would be interesting to explore.
As would a product that can handle, say, 16 clamps, and you buy the clamps separately.