Electricians glossary

Short, plain-English definitions of the terms you'll meet when choosing a electrician provider in Spartanburg, SC.

What is a 240-volt circuit?: A 240-volt circuit uses two hot wires (or a hot wire and a neutral) to deliver power at double the voltage of standard 120V household circuits, supplying high-power appliances like water heaters and air conditioning units.
What is a circuit breaker?: A circuit breaker is an automatic switch that interrupts electrical current when it detects an overload or fault, protecting wiring and appliances from damage or fire.
What is a dedicated circuit?: A dedicated circuit is an electrical circuit that serves only one appliance or fixture, required by code for high-power devices to prevent overload and ensure safe operation.
What is a GFCI outlet?: A GFCI (ground-fault circuit interrupter) outlet detects imbalances in electrical current and shuts off power in milliseconds to prevent shock, commonly required in wet or damp areas.
What is a journeyman electrician?: A journeyman electrician is a licensed professional who has completed a multi-year apprenticeship and passed a state exam, qualifying them to perform electrical installations, maintenance, and repairs independently under applicable codes.
What is a kilowatt-hour?: A kilowatt-hour (kWh) is the amount of electrical energy consumed when 1,000 watts of power run for one hour, and is the standard unit on which utility companies bill customers.
What is a licensed electrician in South Carolina?: A licensed electrician in South Carolina holds state certification at one of three levels (apprentice, journeyman, or master) that authorizes them to perform electrical work within their tier's scope of practice.
What is a master electrician?: A master electrician is a licensed professional who has met advanced training and examination requirements, permitting them to work independently, supervise journeymen and apprentices, and pull electrical permits in their state.
What is a service entrance?: A service entrance is the physical point where electrical power from the utility company enters a residence, consisting of the meter base, weatherhead, service conductors, and main disconnect.
What is a standby generator?: A standby generator is a fixed, permanently installed backup power system that automatically detects power loss and starts to supply electricity to a home or building.
What is a subpanel?: A subpanel is a secondary electrical distribution box that receives power from the main service panel and distributes it to circuits in a specific area of a home or property.
What is a transfer switch?: A transfer switch is a safety device that switches your home's electrical load between grid power and a backup generator without allowing both sources to feed the electrical system simultaneously.
What is a whole-house surge protector?: A whole-house surge protector is a device installed at the main electrical panel that shields all circuits and connected appliances from sudden voltage spikes caused by lightning strikes, power grid fluctuations, or switching surges.
What is aluminum wiring?: Aluminum wiring is branch circuit electrical wire used in homes built during the 1960s and 1970s as a cheaper alternative to copper, known for oxidation and connection problems that require professional evaluation.
What is amperage?: Amperage is the measure of electrical current strength flowing through a circuit, expressed in amps (A). A home's main electrical panel is rated in amperage to determine how much total electrical load it can safely deliver.
What is an AFCI breaker?: An arc-fault circuit interrupter (AFCI) is a specialized circuit breaker that detects dangerous electrical arcing conditions and cuts power to prevent fires.
What is an electrical panel?: An electrical panel is the main distribution box in a home that receives power from the utility line and routes it through circuit breakers to various rooms and appliances.
What is an electrical permit?: An electrical permit is an authorization issued by Spartanburg County or the City of Spartanburg that allows a licensed electrician to perform wiring, panel upgrades, or circuit work and subjects the installation to code inspection before it can be used.
What is grounding and bonding?: Grounding and bonding are safety systems that provide a safe path for electrical current and equalize electrical potential; grounding connects equipment to the earth, while bonding connects conductive surfaces together to prevent shock and fire hazards.
What is knob-and-tube wiring?: Knob-and-tube wiring is an early electrical distribution method that runs individual copper wires through ceramic insulators mounted on wooden frames, typically found in homes built before the 1950s. It is now considered unsafe and unreliable by modern standards.
What is load calculation?: Load calculation is the process of determining a home's total electrical demand and sizing the electrical panel and circuits to safely handle that demand according to National Electrical Code rules.
What is Romex?: Romex is a trademarked brand name for nonmetallic (NM) sheathed electrical cable commonly used in residential wiring installations. It contains individual THHN conductors wrapped in a plastic outer sheath and is available in gauges from 14 AWG to 2 AWG.
What is the NEC (National Electrical Code)?: The National Electrical Code (NEC) is the standard electrical safety code adopted by South Carolina that sets minimum requirements for the design, installation, and inspection of electrical systems in buildings and structures.
What is wire gauge (AWG)?: American Wire Gauge (AWG) is a standardized system for measuring the diameter and current-carrying capacity of electrical conductors, where smaller numbers indicate thicker wire with higher amperage ratings.