Per the IEC standard, Safety capacitors are divided into two classes X and Y. Remember, X capacitors are connected from line to line or line to neutral and Y capacitors are connected from line to ground. They are further divided into subclasses such as X1 X2, and Y1 Y2. For each sub class, AC voltages are designated to provide the overall capacitor class and rating for the application. For example, a typical Safety Capacitor can be listed as X1 400 VAC Y2 250 VAC. This means that the customer can use this part type as an X1 capacitor at 400 V or a Y2 capacitor at 250 V. Each of these sub classes has peak voltage, rated voltage, application, and impulse voltage requirements that are specified by the IEC safety standard.