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.
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.
