Epson 4500 - Manual (Page 47)

Connecting the Printer to Your Computer
4. If your cable has a ground wire, connect it to the ground screw
beneath the interface connector.
5. Plug the other end of the cable into the computer. If there is a
ground wire at the computer end of the cable, attach it to the
ground connector at the back of the computer.
Setting Up the Printer 1-25