As you can see from the wiring diagram, a three-prong plug is designed to supply electricity to several other electrical appliances safely. As per the wiring diagram here, the third prong grounds the electricity to protect anyone who uses the metal-encased appliances from getting electric shock or electric current. It should be noted here that in a three-prong 240v plug wiring diagram, the black wire is the hot wire and becomes energized the moment you insert the plug into a socket. The black wire is usually covered with the golden brass screw as a general rule of thumb. At the same time, the white wire is known as the neutral or return wire. The white wire hooks around the silver screw, and the green wire goes to the ground screw
