I recently purchased 2 little voltmeters they look like the sort that would go in a control or instrument panel they are connected with just 2 wires which provide the operating supply ( they light up green and red) however the green one states it will work between 20and 500 volts and the red one between 60 and 480 volts. When they are both on the green one indicates normally around 241 volts the red one shows 235 volts why the discrepancy I know it's not much but makes you wonder if one of them is lying. Secondly I've noticed that the green one tracks voltage changes faster than the red one and that a few times the green one jumps down to 238 then up to 241 multiple times while the red one stays the same and I think can see a slight flicker in my filament lamps when this is happening incidentally both meters are connected to the same plug a 2 pin 5 amp one
Actually these days even in residential areas, harmonics can make the waveform all kinds of nasty. Put a scope on the mains a while back (via an isolation transformer which i would have thought would've smoothed over the worst, and the waveform was distinctly 'flattish' at the peaks and had some odd angles on the sides (ie sharp changes in slope). I suspect the reason is the time of day, fairly low load which would have been mostly electronic loads, from home PC's, modern tv's etc through to LED bulbs.
Actually these days even in residential areas, harmonics can make the waveform all kinds of nasty. Put a scope on the mains a while back (via an isolation transformer which i would have thought would've smoothed over the worst, and the waveform was distinctly 'flattish' at the peaks and had some odd angles on the sides (ie sharp changes in slope). I suspect the reason is the time of day, fairly low load which would have been mostly electronic loads, from home PC's, modern tv's etc through to LED bulbs.
