How to Install an Electrical Outlet from Scratch. In order to install an electrical outlet and circuit from scratch you need a roll of 14-2 or 12-2 Romex® cable (depending on how much load you need from the outlet) and either a new work box, or an old work box.Ad.f a 14-2 cable is run from the panel to the outlet, then a 15 amp circuit breaker is the largest that can be used to protect that circuit. If a 12-2 cable is run from the panel to the outlet, then a 20 amp circuit breaker is the largest that can be installed to protect the circuit. 5. Support cable.