The Reliance Controls PB30 NEMA 3R Power Inlet Box is an outdoor/watertight electrical inlet for a 30 Amp L14-30 generator cord. It is designed to be located outdoors where the generator is running to prevent dangerous carbon monoxide fumes from the generator from entering your house. This inlet box is then safely hardwired through an outside wall directly to the transfer switch or panel, eliminating the need for cords running through windows or doors. It is designed to be wired directly to the transfer switch or panel by using one of the four combination 1/2-inch and 3/4-inch knockouts (one on each side, bottom and back). The exclusive patented design provides generous wiring space and facilitates rough-in. The face of the box is removable for easy placement and wiring. It is constructed of steel with rugged, anti-corrosive powder-coat paint and has a spring-loaded inlet cap to prevent moisture front entering the connector inlet when not in use. - The rain tight NEMA 3R PBN-Series steel power inlet box is designed for use with Pro/Tran transfer switches, Panel/Link transfer panels and generator-ready load centers. - The front entry inlet has a weatherproof spring cover which closes when not in use to protect the inlet from the elements. -It is designed to be installed outdoors in an open area where the generator is being used to avoid carbon monoxide hazard. - Constructed of powder coated steel, this traditional Reliance Controls series will not rust. - Using four combination 1/2-inch and 3/4-inch knockouts (one on each side, bottom and back) the power inlet box is designed to be wired directly to the transfer switch or panel. -cUL listed.