Plain definitions of 37 terms we use on the job in Riverside.
Term Index
Open any term below for a dedicated definition page.
An Arc-Fault Circuit Interrupter is a protective device that detects electrical arcing and opens a circuit before the arc can continue. An arc may develop when wiring becomes damaged, loose, or overheated. The device helps protect branch circuits from fires caused by unwanted arcing, while a standard breaker mainly responds to overloads or short circuits.
Also called: AFCI
An Arc Flash is a sudden electrical discharge that travels through air between energized conductors or from a conductor to ground. The discharge creates intense heat, bright light, sound, and pressure. Arc flashes often begin when a fault, damaged insulation, loose connection, or conductive object creates an unintended path for current.
A ballast is an electrical component that controls current in certain fluorescent and high-intensity discharge lamps. The ballast helps start the lamp and limits electrical flow during operation. Without the correct ballast, a compatible lamp may flicker, fail to start, produce uneven light, or place stress on the lighting circuit.
Battery Backup is a stored-energy system that supplies electricity when the main power source fails. The system charges from the electrical service or another approved source, then sends power to selected circuits through an inverter and control equipment. Supporting system upgrades support essential equipment, such as refrigeration, communication devices, lighting, or medical equipment, during an outage.
Also called: Home Battery
Bidirectional Charger is an electric vehicle charging device that can send electricity into a vehicle battery and receive electricity back from that battery. The equipment supports controlled energy flow in both directions. Depending on the system design, stored vehicle energy can serve selected building circuits during a power outage.
Bonding is the intentional electrical connection of conductive parts, such as metal enclosures, equipment grounding conductors, and metal piping, to keep them at a similar electrical potential. The connection creates a continuous path for fault current to return toward the source, helping protective devices respond when an unintended energized condition occurs.
A busbar is a solid metal conductor inside electrical equipment that distributes current to multiple circuits. In a service panel, the busbar connects branch circuit breakers to incoming power. Its design supports organized connections and helps keep panel wiring clear. A busbar may carry ungrounded or grounded conductors depending on its location and function.
Also called: Bus Bar
A capacitor is an electrical component that stores and releases energy in a circuit. In ceiling fans, the capacitor helps create the phase shift needed for the motor to start and run. Its capacitance and voltage rating must suit the motor and circuit. A failing capacitor can cause weak airflow, humming, or startup problems.
Conduit is a protective pathway that encloses and routes electrical conductors. Conduit may be made from metal or nonmetallic material, depending on the installation and environmental conditions. It helps protect wiring from physical damage, supports an organized installation, and provides a defined route through walls, ceilings, crawl spaces, and exposed areas.
Critical Loads are the selected electrical circuits that receive priority power during an outage. These circuits connect to a backup power system through dedicated equipment, such as a critical-load panel. The selection usually covers essential functions, while larger or nonessential loads remain outside the backup supply to protect available power.
Also called: Essential Loads
A disconnect switch is a manually operated device that separates electrical equipment from its power source. The switch creates a clear point for shutting off power during service, inspection, or emergency response. Disconnect switches commonly serve air conditioners, motors, panels, and other equipment that needs local electrical isolation.
Also called: Safety Disconnect
Electrical load is the amount of power that connected devices and equipment draw from an electrical system at a given time. The load changes as equipment starts, stops, or changes output. Electricians assess load to determine whether circuits, panels, feeders, and service equipment can support connected demands safely and reliably.
Also called: Load
An electrical meter is a measuring device that shows electrical values in a circuit or service. Depending on its design, it may measure voltage, current, resistance, continuity, or energy use. Electricians use meter readings to assess circuit conditions, locate faults, and confirm whether equipment receives the expected electrical supply.
Also called: Power Meter
Electrical Neutral is the current-carrying path that returns electricity from a load to the electrical source. It connects to the neutral bar in a panel and normally remains near ground potential. The neutral supports circuit operation, while the grounding conductor provides a separate path for fault current and equipment bonding.
Also called: Neutral Point
Electrical Service is the conductors, equipment, and connection that deliver utility power to a building’s electrical system. It includes the service entrance, meter connection, main disconnect, and related panel equipment. In panel upgrade work, electrical service capacity and condition help determine whether the existing system can support updated circuits and equipment.
Also called: Service Power
GFCI is a ground-fault circuit interrupter that helps protect people from electric shock. The device monitors current flowing through a circuit and disconnects power when some current takes an unintended path, such as through a person or wet surface. GFCI protection commonly serves receptacles in damp or outdoor locations.
Also called: GFI, Ground-Fault Circuit Interrupter
A ground fault is an unintended electrical connection between an energized conductor and a grounded surface, equipment enclosure, or grounding path. The fault diverts current away from its planned circuit route. This condition can create shock and fire hazards, so protective devices such as GFCI devices detect the imbalance and interrupt power.
Also called: Earth Fault
Heat Pump Water Heater is an electric water-heating appliance that moves heat from surrounding air into a storage tank. The process uses a heat pump and backup heating elements to warm household water. Unlike a standard electric water heater, the heat pump transfers available heat instead of creating all heat directly.
Also called: Hybrid Water Heater
An induction range is an electric cooking appliance that uses magnetic fields to heat compatible cookware directly on its glass surface. The range combines induction cooktop elements with an electric oven in one unit. Unlike a conventional electric range, the cooking surface transfers energy through the cookware instead of heating a separate exposed element.
Also called: Induction Cooktop
A Junction Box is an enclosure that protects and contains electrical wire connections. It provides a defined space for splices, branch circuits, and fixture wiring. The box helps shield connections from physical damage and keeps conductors organized. Junction boxes may be metal or nonmetallic, depending on the wiring method and installation conditions.
Also called: Electrical Box
Line voltage is the electrical pressure supplied by a building’s power system to operate equipment, lighting, and receptacles. The term usually describes voltage present on energized circuit conductors. Line voltage differs from low-voltage control power, which operates devices such as thermostats, doorbells, and signaling equipment.
Also called: Mains Voltage
Load Calculation is an electrical engineering process that estimates the power demand of a property, circuit, or equipment group. The calculation considers existing loads, planned equipment, and how those loads operate. Electricians use the result to assess whether electrical service, panel capacity, and conductors can support added demand without overloading the system.
Also called: Electrical Load Calculation
Load Shedding is a power-management method that temporarily reduces or pauses selected electrical loads when total demand approaches a system limit. The control system gives priority to essential circuits while delaying flexible equipment, such as an EV charger. This approach helps prevent an overloaded service, feeder, or panel from operating beyond its intended capacity.
Also called: Load Management
A Main Breaker is the primary overcurrent protection device in an electrical panel. The device controls power to the panel’s branch circuits and can shut off power to the building’s electrical system. The main breaker also opens the circuit when current exceeds its rated capacity, helping limit damage from overloads or short circuits.
Also called: Main Circuit Breaker
An overcurrent is an electrical flow that exceeds the safe capacity of a circuit, wiring system, or device. It can result from excessive connected load, a short circuit, or another fault. Protective devices such as circuit breakers detect the condition and interrupt power to limit heating and equipment damage.
Also called: Excess Current
Photocell is a light-sensitive electrical control that detects surrounding brightness and switches a connected light on or off. Outdoor lighting commonly uses a photocell to turn fixtures on at dusk and off at dawn. The device supports automatic operation without a wall switch or timer, although placement and wiring affect performance.
Also called: Photoelectric Cell
Power Surge is a brief rise in electrical voltage above the level that connected equipment is designed to handle. The event can enter through utility lines, wiring, or communication cables. A surge may damage sensitive electronics immediately or weaken components over time, even when circuit breakers do not trip.
Also called: Electrical Surge
A service entrance is the point where utility power enters a building and connects with the property’s electrical system. It includes the conductors, meter connection, service equipment, and main disconnect that receive and control incoming electricity. The service entrance links the utility supply to the electrical panel and branch circuits.
Also called: Electrical Service Entrance
A short circuit is an unintended low-resistance path between electrical points that should remain separate. The path allows current to move outside its intended circuit route. The sudden current increase can trip a circuit breaker, damage wiring, or create heat. Electrical troubleshooting identifies the fault’s location and corrects the underlying wiring or equipment problem.
Also called: Electrical Short
A Tamper-Resistant Outlet is a receptacle with internal shutters that block access to the energized contacts when a plug is absent. The shutters open when matching pressure is applied to both slots by a standard plug. This design helps reduce accidental contact with electrical parts while preserving normal power access for household devices.
Also called: TR Outlet
A Three-Way Switch is a wall switch arrangement that controls one light or lighting circuit from two separate locations. Each switch connects through traveler wires, so either location can change the light's state. This setup is common in hallways, stairways, and rooms with more than one entrance.
Also called: 3-Way Switch
A Transfer Switch is an electrical device that moves selected circuits between utility power and a backup generator. The switch helps prevent both power sources from feeding the same circuits at once. It may operate manually or automatically, depending on the generator system and the equipment installed.
Voltage Drop is the reduction in electrical pressure that occurs as current travels through a conductor, connection, or device. The reduction becomes more noticeable when a circuit carries a heavier load or has greater resistance. Excessive voltage drop can make equipment perform poorly, run hotter, or fail to receive the power it needs.
A voltage tester is a handheld electrical testing tool that checks whether electrical potential is present at a wire, terminal, outlet, or other circuit point. Depending on its design, the tester may detect voltage without contact or measure voltage through test leads. Electricians use the result to guide troubleshooting and verify circuit conditions.
Also called: Voltage Detector
Wire Gauge is a standardized system for describing a conductor’s thickness and current-carrying capacity. The gauge designation helps electricians select wire for a circuit’s load, installation method, and connection points. A suitable gauge supports reliable operation, while an unsuitable size can contribute to overheating, voltage loss, or code correction work.
Also called: Wire Size
A wire nut is an insulated twist-on connector that joins compatible electrical conductors inside a junction box, outlet box, or other approved enclosure. The connector grips the stripped wire ends through an internal spring or threaded insert. Proper selection depends on conductor material, wire size, and the number of wires being joined.
Also called: Wire Connector
Working Clearance is the accessible space kept around electrical equipment so people can inspect, operate, service, and repair it safely. The space supports clear movement at panels, disconnects, and other service points. Its needed size and arrangement depend on the equipment, surrounding surfaces, access path, and work performed.
Also called: Electrical Working Space
