ADE-7880 Voltage Divider Circuit

At 440V RMS with a 2MOhm : 1KOhm voltage divider brings the voltage at the adc input to 0.22Vrms which is within range. For 600V RMS a 2MOhm : 1kOhm voltage divider results in 0.3 V RMS at the ADC input which is still in range. In order to have the output be at the same level as 440V RMS you would change your voltage divider to  2.7MOhm : 1kOhm.

When picking the voltage divider resistor values you want to ensure that the voltage after the divider will not exceed +- 500mV at the ADC input.  With a a 2MOhm :1 KOhm divider you meet this requirement for both 440VRMS and 600V RMS.