OpenEnergyMonitor Community

Emon TX + wifi shield 3 phase monitoring


I have an emon tx + wifi sheild I’ve been using at my house, but not longer really need.

I was considering installing it in another house, but they have 3 phase supply. Each phase appears to power different circuits of the house.

I’ve read there is a firmware option to handle 3 phase, but would it work if I just put 3 clamps on the 3 phases and monitor the 3 separately?

The reason to monitoring power is to get an idea of how much is being used at different times, but also get a rough daily/weekly/etc total and see if it matches what the house is being billed for.

(Note, I’m trying to get a photo of the 3 phase set up. I think it’s 3 old spinning meters, each phase powering separate circuits within the house, with just a couple of circuits heading out to a barn / green house. The metering/fuses board are quite old)

Welcome, Jonathan, to the OEM forum.

Are you sure you have three phases, not three separate meters on the same phase (maybe because the house was one under multi-occupation)? If you can measure 415 V between all three ‘phases’, then it really is 3-phase. (Take care if you do this.)

If it is 3 phases, in short, no. You can measure current correctly that way (but by default that’s not reported by the sketch in the emonTx), but your power and energy readings will be wrong, by a long way on two of the phases. If you don’t use the a.c. adapter, the emonTx should switch to “guessing” apparent power, but that won’t take the UK’s voltage that varies by the time of day and load on the system into account.

I may be wrong about the meter(s) that are in place. I’ll try and get a photo of the set up soon.

ok, so I was wrong. The 3 phases come into the house, all 3 go into an ‘elster a1100’ meter, then the 3 come out to 3 different fuse boards, each board running different circuits in the house.