Amp (Ampere)
- A unit that measures the strength/rate of flow of electrical current.
Armored Cable
- Electrical wires protected by metal sheathing.
Branch Circuits
- The circuits in a house that branch from the service panel to boxes and devices.
Breaker
- A switch-like device that connects/disconnects power to a circuit.
Buss Bar (also Bus Bar)
- Separate, metallic strips that extend through the service panel. Breakers slide onto the "hot" busses and neutral and ground wires screw down in their respective busses.
BX Cable
- An old type of armored cable now illegal.
Cable Clamps
- Metal clips inside an electrical box that hold wires in place.
Circuit
- A continuous loop of current (i.e. incoming "hot" wire, through a device, and returned by "neutral" wire).
Circuit Breaker
- The most common type of "overcurrent protection." A breaker trips when a circuit becomes overloaded or shorts out.
Conduit
- A protective metal tube that wires run through.
Duplex Receptacle
- The commonly used receptacle (outlet). Called "duplex" because it has two plug-in sockets.
Fuses
- Removable devices that link a circuit at the fuse box. Fuse connections blow apart and break the circuit if an overload or short occurs.
Fixture
- Any permanently connected light or other electrical device that consumes power.
GFCI or GFI (Ground Fault Circuit Interrupter)
- A specific type of circuit protection (commonly required in kitchens & bathrooms) that helps safeguard against shocks. GFCI protection can come from an outlet or a breaker.
Ground Fault
- Current misdirected from the hot (or neutral) lead to a ground wire, box, or conductor.
Hot, Neutral, Ground
- The three most common circuit wires. The hot brings the current flow in, the neutral returns it to the source, and the ground is a safety route for returning current. The ground and neutral are joined only at the main service panel.
Junction (Electrical) Box
- A square, octagonal, or rectangular plastic or metal box that fastens to framing and houses wires, and/or receptacles and/or switches.
Knockout
- A removable piece of an electrical box or panel that's "knocked out" to allow cable to enter the box.
Lead
- The short length of a conductor that hangs free in a box or service panel. (i.e. a wire end)
NM
- Nonmetallic-sheathed (plastic).
NMC
- Solid plastic nonmetallic-sheathing used in wet or corrosive areas, but not underground (see UF).
Ohm
- A unit that measures the resistance a conductor has to electricity.
Pigtail
- A short, added piece of wire connected by a wire nut. Commonly used to extend or connect wires in a box.
Romex
- A brand name of nonmetallic-sheathed cable made by General Cable Corporation. Often mistakenly used as a collective term for NM sheathed cable.
Rough-In
- Installing the boxes, cables, and making "in-wall" connections while the walls are still open. Later, final connections are made and the devices and appliances are installed during the trim-out.
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)
Travelers
- Wires that carry current between three-way and/or four-way switches.
UF (Underground Feeder) cable
- Cable designed and rated for underground, outdoor use. Cable wires are molded into solid plastic.
Volt
- A unit that measures the amount of electrical pressure.
Watt
- A unit that measures the amount of electrical power.
