Any tips on a DIY solution to panel monitoring?

My electrical panel has separate breakers for three different baseboard heaters and each major appliance for two apartments in my house. It would be illuminating to be able to set up something central to get a view of what's contributing to my electrical costs.

I've seen "Eyedro EYEFI-4" and "Emporia Vue Energy Monitor" and a few others. Emporia's solution seems close, but it's a closed system and there's no API access to the raw data, everything requires manual control from the app.

But what I'm really hoping for just the basic hardware which might be connected to an arduino or a hat on a Raspberry Pi, and which I could monitor with my own software. I've found this split core current transformer on Amazon, but I'm left with two problems:

  1. I don't know what I'd need to do to convert its output to something that, say, and Arduino could understand (i.e. a voltage from 0 to 5V for an analog_in). And.
  2. Given that the arduino only has 6 analog_in ports, how do I switch a port so that it can alternately take reading from more than 6 CTs? Might there be ab IC that could take a binary number on one set of pins (driven for example by the arduino output pins) and control a switch based on the number selected? Or is there another better way of doing this that I haven't imagined yet? (I'm sure there must be.)

I would love to get any advice as to the approach I should take. (Maybe not even arduino?) Then I'll be able to direct my research so as to improve my next question here. :)

  • Most Amazon listings are actually Amazon "Marketplace", which is third party sellers similar to eBay. They are selling the cheap unsafe junk off Alibaba, that has never seen the inside of a testing lab and definitely does not have a CSA or UL listing. Letting any of that near mains wiring is Right Out. Not even so much as an RU (component UL listing) – Harper - Reinstate Monica Jan 10 '20 at 7:17
  • I agree with Harper if not UL listed or at least a reversed UL symbol it should not be used in the U.S. it may be “fine” in other countries, is fine or just ok that what you want in your house while sleeping? I prefer a listed device and if UL it will be allowed by any inspector in the U.S. TUV a 3rd party agency will also pass but this is mostly for international equipment we shipped overseas from my experience. – Ed Beal Jan 10 '20 at 7:40
  • I have one of these installed, and would be happy to talk about it in chat. Just @ my name there if interested. – JPhi1618 Jan 10 '20 at 15:29
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    Does this answer your question? How can I add an ammeter and/or voltmeter to my home breaker panel? – PhilippNagel Jan 10 '20 at 16:08

Your ambitions exceed your abilities... and there's a lot of problem scope you haven't really thought through.

Don't reinvent the wheel

First, really, seriously scour the market for existing consumer products which might provide an API. I'm seeing good signs that several consumer home power monitors can provide raw data streams. For instance neurio said in 2016 they were expecting to have this data. Sense has it in beta. It's around; look harder.

Also look into talking to your smart meter directly, which has the CT's in place. Some smart meters use Zigbee Smart Energy protocol.

Research the literature on the subject

If you can't find any datastream access, then research what's already been done in the field. I see plenty of halfway respectable efforts.

Use items that are actually UL-listed (CSA-listed, ETL, ЯU etc.)

CE is not a testing lab, it's the standard mark China puts on everything that will never see the inside of a testing lab because it's junk. It's a fake of a European self-certification standard, but without the actual self-cert. Everything you see on AliExpress, eBay or Amazon Marketplace will be rubbish from Alibaba.

For instance, Magnelab makes CTs with either ЯU or UL listing (component vs. product suitable for direct use).

Don't exit the panel with electrical wires of any kind

Any electronic equipment that lives inside the panel, stays in Vegas. You cannot have any wire between your homebrew stuff inside the panel and the outside world. The only possible communication scheme is wireless; and that's what all consumer home energy monitors do - they stick a WiFi antenna out a knockout.

That means you'll be doing Raspberry Pi and not Arduino.

Or both - the way you get >6 analog inputs into an Arduino is to use two Arduinos. They could be slaved to the Raspberry Pi.

Absolutely no signal wires in or out of the panel.

No running with your panel cover off - it's not a PC. The panel cover has a vital safety function other than the obvious; it holds the breakers in. Without it you can rock a breaker out by turning it off.

One more thing: On simple circuits, put the CT's on the neutral wire.

And lastly, no signal wires in or out of the panel.

  • 2
    Thank you for your reply. Yes, my ambitions exceed my abilities -- that's why I'm here, asking your advice and trying to learn\. And I hear you regarding "no signal wires in or out of the panel", the more I think about that, the more committed I am to live by it. Thanks for emphasizing it. – Graham Jan 11 '20 at 18:10

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