Unit will initially operate on a single GFCI circuit but comes with adapters for other outlet configurations (e.g. light switch, regular non-GFCI outlet). Very easy to install, simply remove the existing panel on the socket, loosen the mounting screws (or replace the mounting screws with screws provided), align the box with the loose screws, slide the box into place, pull tighten the screws. super easy. The lid snaps straight on and the lid seals tight to keep moisture out. My outlet was underβ¦