Class-X and Class-Y capacitors are safety-certified and generally designed for and used in AC line filtering in many electronic device applications. The Class X capacitors are designed to be used across the line (line-to-line or line-to-neutral); they are rated based on the peak voltage pulse, as shown in the table here. The Class Y is also known as a line-to-ground capacitor. These capacitors have a higher rating when compared to X capacitors. The X2 and Y2 are most commonly used when the device will be removed from the power outlet used in common appliances plugged into wall sockets. The X1 and Y1 are commonly used in industrial settings where the circuit is not removed from the power outlet, like an industrial lighting ballast connected to a 3-phase line. Class-Y can be used in place of Class-X, but not vice versa, as Class-X capacitors do not meet the line-to-ground safety standards, are less robust, and withstand lower peak impulse voltages.