4 Wire Gfci Outlet Wiring Diagram Edit DIY outlet improve to GFI. I performance how to determine line and load wires using an inexpensive lightbulb tester. Share this post Related PostsElectrical Circuit Diagram Considering BuzzerJacuzzi Electrical Wiring DiagramElectrical Wiring Diagram Software OnlineHvac Electrical Circuit DiagramControl Panel Wiring Diagram SoftwareLift Control Panel Wiring DiagramXs650 Clear Wiring DiagramElectric Circuit Diagram Terrify