How-To Electrical
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Trans 1) Getting Started Trans
2) Electrical System Basics
3) Service Panel
4) Running Cable
5) Outlets
6) Switches
7) Installing Light Fixtures
8) Common Electrical Codes
9) Replacing Switches & Outlets
10) Repairing Lamps & Cords
11) Glossary

Glossary of Terms & Definitions

AFCI (Arc Fault Circuit Interrupter)
Simliar to a GFCI, an AFCI shuts down power to a circuit when it detects an arcing situation, such as when frayed or broken wires brush against each other and create a spark or arc. AFCIs help protect against fires. An AFCI circuit breaker is the most common way to provide AFCI protection. Electrical codes require AFCI protection for all outlets in bedroom areas and, depending on the interpretation of the codes, may also apply to lights and smoke detectors. AFCI protection requirements can be expected to expand to other areas of the home.

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.

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.


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.

A protective metal tube that wires run through.

Duplex Receptacle
The commonly used receptacle (outlet). Called "duplex" because it has two plug-in sockets.

Removable devices that link a circuit at the fuse box. Fuse connections blow apart and break the circuit if an overload or short occurs.

Any permanently connected light or other electrical device that consumes power.

GFCI or GFI (Ground Fault Circuit Interrupter)
A specific type of circuit protection that helps safeguard against dangerous shocks. GFCI protection can be provided by a GFCI outlet or a GFCI circuit breaker. GFCI protection is generally required by code for most outlets in a kitchen, all outlets in a bathroom, all exterior outlets, and certain outlets in garages, unfinished basements and laundry areas.

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.

A removable piece of an electrical box or panel that's "knocked out" to allow cable to enter the box.

The short length of a conductor that hangs free in a box or service panel. (i.e. a wire end)

Nonmetallic-sheathed (plastic).


Solid plastic nonmetallic-sheathing used in wet or corrosive areas, but not underground (see UF).

A unit that measures the resistance a conductor has to electricity.

A short, added piece of wire connected by a wire connector. Commonly used to extend or connect wires in a box.

A brand name of nonmetallic-sheathed cable made by General Cable Corporation. Often mistakenly used as a collective term for NM sheathed cable.

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)

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.

A unit that measures the amount of electrical pressure.

A unit that measures the amount of electrical power.