One: Why install electrical equipment grounding wire?
Because, when the motor has a leakage, the metal shell will be charged, if people come into contact with the metal body shell, the risk of an electric shock may occur if the electrical equipment installed ground wire, the leakage will flow directly into the earth through a ground wire, metal voltage equal to 0, and the human body come into contact with the metal casing, there will be no danger
Two: Why did you want to install the GFCI?
Reason as above, but more of a protection switch, when a leak occurs, the GFCI to trip off the power immediately, protective equipment and personal safety
Three: for distribution cabinets, switchboards safety