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 under the ceiling so I didn't add a silicone bead on the back of the box before attaching it to the outlet. When covering an outlet that is fully exposed to the elements, it is imperative that you attach a silicone bead to fully protect the back of the box from dripping water. Looks safe, my box is in the shadows. , so I'm not worried about fading from sunlight or weathering.