Electrical, in plain English.

The lingo.

AFCI

Arc-fault circuit interrupter, a breaker that detects the sparking of a damaged wire or loose connection and shuts the circuit off. Required on most living-area circuits in new work.

Aluminum wiring

Branch wiring used in some homes built from about 1965 to 1973. It loosens and overheats at connections; fixes include approved connectors or rewiring, and insurers ask about it.

Amp, volt, watt

Amps are current, volts are pressure, watts are power (volts times amps). A 20 amp, 120 volt circuit can carry about 2,400 watts, and code allows a continuous load of 80 percent of that.

Breaker

The switch that trips to cut a circuit when it draws too much current. A breaker that trips repeatedly is protecting you from something; do not replace it with a bigger one.

Conduit

Metal or plastic pipe that protects wires, used outdoors, in garages and wherever cable would be exposed to damage.

Dedicated circuit

A circuit serving one appliance only: range, dryer, microwave, dishwasher, EV charger, HVAC. Sharing them is how breakers trip and wires overheat.

EV charger (Level 2)

A 240 volt charger that adds 20 to 40 miles of range per hour. Needs a dedicated 40 to 60 amp circuit; a load calculation decides whether the panel can handle it.

GFCI

Ground-fault circuit interrupter, the outlet or breaker with test and reset buttons. Required near water: kitchens, baths, garages, outdoors. It cuts power in milliseconds when current leaks to ground.

Grounding and bonding

Connecting the electrical system to the earth and tying metal parts together so a fault trips a breaker instead of energizing a pipe or a chassis.

Knob and tube

Ungrounded wiring from before the 1940s, with ceramic knobs and tubes. Often still live in old houses; it cannot be buried in insulation and many insurers will not cover it.

Load calculation

The math an electrician does to confirm the service and panel can carry everything in the house plus what you are adding. Required for panel upgrades and large new loads.

Permit and inspection

Most electrical work beyond replacing a fixture requires a permit and a municipal inspection. It protects you when you sell and when you file an insurance claim.

Romex (NM cable)

The plastic-sheathed cable used for most residential circuits. 14 gauge for 15 amp circuits, 12 gauge for 20 amp.

Service panel

The breaker box where power enters and is divided into circuits. Older 60 and 100 amp panels are often upgraded to 200 amps for EV chargers, heat pumps and modern kitchens.

Subpanel

A second breaker panel fed from the main, often in a garage, shop or addition. Grounds and neutrals are kept separate there.

Surge protector (whole-house)

A device at the panel that clamps voltage spikes from lightning and utility switching before they reach electronics and appliances.

Transfer switch

The switch that isolates the house from the grid so a generator can power it safely. Plugging a generator into a wall outlet can kill a line worker.

From the Pros.

Written by the people who do this work every day, in your area.

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