Electrical Glossary

AFCI (Arc-Fault Circuit Interrupter)

A breaker or outlet that detects dangerous arcing in wiring, a common cause of house fires, and shuts the circuit off. Required on most living-area circuits in new work.

Alternating Current (AC)

Current that reverses direction many times per second (60 times per second in the US). Homes and businesses run on AC.

Aluminum Wiring

Branch-circuit wiring used in some homes in the 1960s and 70s. It expands and loosens at connections, so it needs special connectors or remediation.

Ampacity

The maximum current a conductor can carry continuously without exceeding its temperature rating.

Amperage (Amps)

The amount of electric current flowing in a circuit. Breakers and panels are rated in amps.

Arc Flash

A dangerous release of energy when current jumps through the air between conductors. It is why live panel work is left to trained electricians.

Automatic Transfer Switch (ATS)

A switch that senses a utility outage, starts the standby generator and moves your home or business to generator power, then switches back when power returns.

Backfeeding

Sending power from a generator back into the home wiring without a transfer switch or interlock. It is illegal and can electrocute utility workers.

Ballast

A device that regulates current to fluorescent and some HID lamps. LED retrofits often remove or bypass it.

Bonding

Connecting metal parts (pipes, panels, frames) together so they stay at the same voltage, reducing shock risk.

Branch Circuit

The wiring between the final breaker and the outlets, lights or appliances it feeds.

Breaker (Circuit Breaker)

A switch in the panel that trips automatically when a circuit is overloaded or shorted, protecting the wiring.

Bus Bar

The metal bars inside a panel that breakers clip onto to draw power.

Cable

Two or more insulated conductors bundled in a single jacket, such as NM (Romex) cable.

Circuit

The complete path electricity travels from the source, through a load and back.

Code (NEC)

The National Electrical Code, the safety standard for electrical installations. Georgia currently enforces the 2023 NEC with state amendments.

Color Temperature (Kelvin)

How warm or cool white light looks. About 2700K is warm and cozy; 4000K to 5000K is crisp and bright.

Conductor

Any material that carries electricity easily. In wiring it usually means a copper or aluminum wire.

Conduit

Metal or plastic tubing that protects wires, common in commercial work, garages and outdoors.

Continuous Load

A load expected to run for three hours or more, such as an EV charger. Circuits for it are sized at 125%.

CRI (Color Rendering Index)

How accurately a light source shows colors, on a scale to 100. 90+ is ideal for kitchens and baths.

Dedicated Circuit

A circuit that serves one appliance only, such as a refrigerator, microwave or EV charger.

Dimmer

A control that varies light output. LED fixtures need LED-compatible dimmers to avoid flicker or buzzing.

Disconnect

A switch that cuts power to equipment for safe service. Required within sight of many appliances and at the exterior of new home services.

Double Tapping

Two wires under a breaker terminal designed for one. A common inspection defect that can cause overheating.

Electrical Panel (Load Center)

The metal box that receives power from the utility and distributes it to breakers and circuits.

EMT (Electrical Metallic Tubing)

Thin-wall steel conduit used widely in commercial buildings.

Equipment Grounding Conductor

The bare or green wire that gives fault current a safe path back to the panel so the breaker trips.

EV Charger (EVSE)

Electric Vehicle Supply Equipment. A Level 2 charger uses a 240V circuit and charges far faster than a standard outlet.

Federal Pacific (FPE) Panel

A brand of panel installed for decades whose Stab-Lok breakers have a reputation for failing to trip. Replacement is widely recommended.

Feeder

Conductors that run from the main panel to a subpanel or large piece of equipment.

Fixture (Luminaire)

A complete lighting unit: housing, lamp or LED, and wiring.

Footcandle

A measure of light falling on a surface: one lumen per square foot.

Four-Way Switch

A switch wired between two three-way switches so one light can be turned on and off from three or more places, such as a long hallway or a stairway with several landings.

Fuse

An older overcurrent device that melts to open a circuit. Fuse boxes are often upgraded to breaker panels.

GFCI (Ground-Fault Circuit Interrupter)

An outlet or breaker that trips in milliseconds when it senses current leaking to ground, protecting people from shock. Required in kitchens, baths, garages, outdoors and more.

Ground

A connection to the earth. A grounding electrode system (rods, water pipe) stabilizes voltage and helps protect against lightning and surges.

Ground Fault

Current flowing to ground through an unintended path, sometimes a person.

Grounding Electrode

A rod, plate or metal water pipe that connects the electrical system to the earth.

Hot Wire

The conductor that carries current from the source. Usually black or red insulation.

Interlock Kit

A mechanical device on the panel that prevents the main breaker and generator breaker from being on at the same time, allowing safe portable generator use.

Junction Box

An enclosure where wires are joined. Every splice must be inside an accessible box.

Kilowatt-hour (kWh)

The unit your power bill is based on: 1,000 watts used for one hour.

Knob and Tube Wiring

Early wiring (roughly 1880s to 1940s) with no ground wire, run on ceramic knobs. Often a candidate for rewiring.

Load

Anything that uses electricity: lights, appliances, motors.

Load Calculation

A code-based calculation of how much power a building needs, used to size a service or confirm room for an EV charger.

Lockout/Tagout

A safety procedure that locks a circuit off while it is being worked on.

Low Voltage

Systems under 50 volts, such as landscape lighting, doorbells, thermostats and data cabling.

Lumen

A measure of how much visible light a bulb produces. Use lumens, not watts, to compare LED brightness.

Main Breaker

The large breaker that shuts off power to the whole panel.

Meter Base

The socket on the outside of a building that holds the utility meter.

MWBC (Multi-Wire Branch Circuit)

Two circuits sharing one neutral. Requires a handle-tied or two-pole breaker.

Neutral Wire

The conductor that carries current back to the source. Usually white. Many smart switches need one.

NM Cable (Romex)

Non-metallic sheathed cable, the most common residential wiring.

Ohm

The unit of electrical resistance.

Open Ground

A three-prong outlet with no ground connection, a common inspection finding.

Overload

More current than a circuit is rated for, which trips the breaker.

Permit

Official approval from the city or county to perform electrical work, followed by inspection.

Pigtail

A short wire used to connect several wires to one device terminal, or to join copper to aluminum with the right connector.

Polarity

Correct connection of hot and neutral. Reversed polarity can leave fixture shells energized.

Raceway

Any enclosed channel for wires, including conduit and surface raceway.

Receptacle

The code term for an outlet you plug into.

Recessed Light

A light installed into the ceiling so it sits flush. IC-rated fixtures can touch insulation.

Service Entrance

The conductors and equipment that bring utility power into a building.

Service Upgrade

Increasing a building's capacity, for example from 100 to 200 amps, by replacing the panel, meter base and service conductors.

Short Circuit

An unintended low-resistance connection between hot and neutral or ground, causing a large current and a tripped breaker.

Smart Panel

A panel that monitors circuits and can control them from an app.

Smoke Alarm Interconnection

Wiring smoke alarms together so when one sounds, all sound. Required in new construction.

Standby Generator

A permanently installed generator, usually natural gas or propane, that starts automatically during an outage.

Subpanel

A secondary panel fed from the main panel, often in a garage, addition or outbuilding.

Surge Protective Device (SPD)

A device that diverts voltage spikes from lightning or the grid. Whole-home SPDs mount at the panel.

Tamper-Resistant Receptacle

An outlet with shutters that block objects other than plugs. Required in homes.

Three-Way Switch

A pair of switches that control one light from two locations.

Transformer

A device that changes voltage, from utility pole transformers to low-voltage lighting transformers.

Under-Cabinet Lighting

Task lighting mounted under kitchen cabinets, usually LED strips or pucks.

Voltage

Electrical pressure. US homes use 120V for most outlets and 240V for large appliances.

Voltage Drop

Loss of voltage over long wire runs. Electricians upsize wire to keep it in check.

Watt

A unit of power. Volts x amps = watts.

Weather-Resistant Receptacle

An outdoor-rated outlet built to resist moisture and UV. Required in damp and wet locations.

Whole-House Rewire

Replacing a building's old wiring with new cable, devices and protection.

Wire Gauge (AWG)

Wire size. Smaller numbers are thicker: 14 AWG for 15A circuits, 12 AWG for 20A circuits.

Zinsco Panel

A discontinued panel brand whose breakers can fuse to the bus bar and fail to trip. Commonly replaced.

No matching terms. Have a question? Call us and we will explain it.