Ballasts have EMCIn the filter circuit, one end of the Y capacitor is connected to the live wire/neutral wire (L/N) of the power supply, and the other end is connected to the shell. Because the capacitor has a certain capacitive reactance, when the shell is not grounded, the hand will touch the shell. Feeling, multimeter measurement will have voltage;

In addition, the main components inside the ballast are inductors, transformers, and switch tubes. There are a large number of electromagnetic effects. The metal shell of the ballast will generate induced current, and the hand will feel tingling, so the ballast shell Must be grounded.