Electrical Glossary
Plain-English definitions of common electrical terms you will hear from an Orange County electrician, from AFCI and GFCI to load calculations and transfer switches.
- AFCI
- Arc-fault circuit interrupter. A breaker or outlet that shuts off power when it detects dangerous arcing.
- Amp (ampere)
- The unit of electrical current. Home services are rated in amps, such as 100A or 200A.
- Branch circuit
- A circuit that runs from the panel to outlets, lights or appliances.
- Breaker
- A switch in the panel that trips to cut power when a circuit is overloaded or shorted.
- C-10 license
- The California Contractors State License Board classification for electrical contractors.
- Dedicated circuit
- A circuit that serves only one appliance, such as a microwave, dryer or EV charger.
- GFCI
- Ground-fault circuit interrupter. Cuts power when current leaks to ground, preventing shocks near water.
- Grounding
- A path that carries fault current safely to earth and helps breakers trip.
- Bonding
- Connecting metal parts so they are at the same voltage, critical for pools and gas and water lines.
- Knob and tube
- Ungrounded wiring with ceramic knobs and tubes, used in homes built before about 1940.
- Aluminum branch wiring
- Aluminum wiring used in some homes built around 1965 to 1973. It needs approved connectors to prevent overheating.
- Load calculation
- A code-based calculation of how much power a home needs, used to size services and panels.
- Load management
- A device that limits or shares power, such as for an EV charger, so a panel upgrade may not be needed.
- Main panel
- The service panel where utility power enters the home's wiring and is divided into circuits.
- Sub panel
- A secondary panel fed from the main panel, used for garages, ADUs or additions.
- Service upgrade
- Increasing the size of the utility service, for example from 100A to 200A.
- Meter base
- The housing that holds the utility meter. It often has to be replaced during a service upgrade.
- NEMA 14-50
- A 240V, 50A outlet commonly used for EV chargers and ranges.
- Level 2 charger
- A 240V EV charger that adds roughly 20 to 40 miles of range per hour.
- Surge protective device (SPD)
- A device at the panel that limits voltage spikes. It is required with new or upgraded services.
- Transfer switch
- A switch that safely connects a generator to home circuits and isolates them from the utility.
- PSPS
- Public Safety Power Shutoff. A planned outage by the utility during high fire-risk weather.
- Title 24
- California's building energy code, which includes lighting efficiency and control rules.
- Volt
- The unit of electrical pressure. US homes use 120V and 240V.
- Watt
- The unit of power: volts times amps.
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