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“Since writing up the article on how to build a simple Arduino home energy meter which measured the energy consumption for a single phase, I’ve had a number of people ask about doing a 3 phase energy meter. While there is a range of commercially available single phase energy meters available, the 3 phase meters aren’t nearly as common and tend to be quite expensive. So I decided to take the opportunity to build a 3 phase energy meter and fix up a couple of areas in the original energy meter’s code which could have been done better. Again, with this meter I was going for simplicity. Sure, for perfectly accurate measurements you need to measure both the supply current and voltage but for this application and in the interests of keeping the energy meter simple and safe – only requiring a non-contact connection to your mains – I’ve decide to stick with a simple current measurement which gives you an estimate to within a couple of decimal points of a kilowatt hour. This meter measures the supply current through each phase using a CT (current transformer) and then does a few calculations to give you the current, power, maximum power and kilowatt hours consumed for each phase. With a few changes to the code, you can also add your local tariffs and display the cost of electricity used to date.”

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