I have measured 240v using this IC. I used two 240v minature transformers in series across the mains to measure the voltage. This became ~6v on the (series connected) secondary side that I then fed to the NSC RMS to DC convertor IC.

I used the 'two transformer in series' trick as I had once read about it in Elektor as a way to improve the linearity of the small cheap transformers I was using.

It worked real well, only issue was the cost of the ICs. I also worked on doing various half wave and full wave recification schemes, but after smoothing found the lag was an issue.

Bill