Electrical System Basics
Electricity is supplied by a local utility to a house through three underground or overhead wires (two "hot" leads and one neutral lead) that enter the house through a conduit and a meter .Those wires connect to their respective buss bars inside the service panel -- usually two hot, one neutral, and one ground buss .Circuit breakers slide/snap onto the hot buss bars. They act as safeguards against short circuits and overloads by "tripping" off. A breaker also functions as a switch; turning the circuit on and off as desired .Breakers also connect to outgoing "hot" wires. The hot wires deliver power to a device (like a light) and normally have black insulation. Cable with two hot leads also have a red hot lead .Once the electricity has done it's work, it goes back to complete the circuit on the "neutral" wire, which is most often white. Electricity needs this completed circuit to work properly -- a way OUT through the hot wire, and a way BACK through the neutral wire .In addition to the neutral, the green (or bare copper) ground wire offers current another path back should an electrical short or overload happen .From the service panel, the ground has two safe paths to divert electricity: connected to a long metal rod buried outside the house and/or the house's water pipes .All the wires, called cable, are often housed by a flexible plastic sheathing. It's nonmetallic-sheathed (NM) cable, but is often mistakenly called "Romex" which is a brand name made by General Cable Corporation. Cable is also identified by gauge (thickness) and the number of leads it has. For example, NM 14-2G means that the cable is nonmetallic, 14 gauge, has two leads (1 neutral, 1 hot), and a ground wire.
