Voltage reading for over the past week and a bit never drops below around 228 and never higher than 237
From that, as youâre measuring downstream of the auto-transformer, you should NOT remove it. Doing so would take your mean voltage to around 250 V, and the peak to over 256 V, which is above the statutory maximum - assuming youâve calibrated your emonPi accurately.
What information do you need to verify its been set up correctly?
Calibrated?
If you have, or have access to, a reasonably good a.c. voltmeter thatâs in calibration, check the voltage reported by your emonPi against that meter. I know itâs hard, because (where I live at least) the mains voltage fluctuates quite widely and quite rapidly, and not helped by the default averaging period of the emonPi being 10 s and that of the meter more like ½ s or even less.