To calculate the max allowable AC voltage on an MLCC, KEMET recommends the following rules. Rule number one: the peak AC voltage plus any DC voltage must be less than the rated voltage of the MLCC. This means that, at no time can the rated voltage of an MLCC be exceeded. Rule number two: the peak-to-peak value of the AC voltage must be less than the rated voltage of the MLCC. In other words, the RMS voltage must be less than the rated voltage divided by 2 times the square root of 2. When looking at the example of a C0G 1210, 33nF MLCC with a DC voltage rating of 500V and given the voltage rules above, the maximum AC voltage that can be applied to the MLCC is 176V_RMS.