Service Entrance (SE) - The location where the incoming electrical line enters the home.
Service/Supply Leads - The incoming electrical lines that supply power to the service panel.
Service Panel - The main circuit breaker panel (or fuse box) where all the circuits tie into the incoming electrical supply line.
Short Circuit - When current flows "short" of reaching a device. Caused by a hot conductor accidentally contacting a neutral or ground. A short circuit is an immediate fault to ground and should always cause the breaker to trip or the fuse to blow. (also see ground fault)
Surge - Transient current or voltage associated with lightning or switching
Switchgear - A general term covering switching and interrupting devices and their combination with associated control, metering, protective and regulating devices; also assemblies of these devices with associated interconnections, accessories, enclosures and supporting structures, used primarily in connection with the generation, transmission, distribution and conversion of electric power.

Three Phase Power - Three separate outputs from a single source. There is a phase difference of 120° between any two of the three voltages and currents.
Transformer - A static electrical device which by electromagnetic induction transfers electrical energy from one circuit to another circuit usually with changed values of voltage and current in the process.
Travelers - Wires that carry current between three-way and/or four-way switches.
Turn Ratio - The ratio of the number of turns in the high voltage winding to that in the low voltage winding.

UF (Underground Feeder) cable - Cable designed and rated for underground, outdoor use. Cable wires are molded into solid plastic.