Browse 31 essential 24 hour electrician terms and definitions used by professionals in San Bernardino.
Term Index
Open any term below for a dedicated definition page.
Air Terminal is a metal component of a lightning protection system that intercepts lightning strikes and provides a controlled path to earth. Also called a lightning rod or lightning conductor. An air terminal connects to down conductors and grounding electrodes. The system helps protect structures by directing lightning current away from building materials and electrical equipment.
Arc-Fault Circuit Interrupter is a protective device that detects dangerous electrical arcing in branch-circuit wiring and disconnects power before the arc can start a fire. An AFCI monitors the current waveform for patterns linked to damaged conductors, loose connections, or crushed wires. AFCIs are installed as circuit breakers or receptacles.
Backdraft Damper is a one-way ventilation device that allows air to move through a duct in one direction and blocks reverse airflow. The damper uses gravity, spring tension, or air pressure to open during exhaust operation. It helps limit drafts, outdoor air entry, odors, pests, and conditioned-air loss when a fan is off.
Ballast is an electrical device that limits current and controls voltage in certain light fixtures. Traditional fluorescent and high-intensity discharge lamps need a ballast to start and operate safely. Electronic ballasts may improve efficiency and reduce flicker, while older magnetic ballasts can hum, overheat, or contain hazardous materials.
Branch Circuit is the portion of an electrical system that carries power from the final overcurrent device, such as a circuit breaker, to connected outlets, switches, and equipment. A branch circuit includes the conductors and equipment grounding conductor that serve a specific load area, appliance, room, or group of electrical devices.
CFM is a unit of airflow that means cubic feet per minute. The measurement shows how much air a fan, blower, duct, or ventilation system moves in one minute. Designers use CFM to size equipment, compare airflow speed, and assess ventilation needs in homes, buildings, workshops, and other enclosed spaces.
Circuit is a complete path that carries electric current from a power source through connected equipment and back to the source. A circuit normally includes conductors, overcurrent protection, switches, and loads such as lights or receptacles. The circuit must remain continuous for current to flow. While a break or fault changes its operation.
Conduit is a protective raceway that contains and routes electrical conductors. Conduit may be made from metal, PVC, or other approved materials. It shields wires from physical damage, moisture, sunlight, and chemicals while organizing wiring between panels, boxes, fixtures, and equipment. Electrical codes specify conduit type, size, support, fittings, and installation methods.
Dimmer Switch is an electrical control that adjusts the amount of power delivered to a light fixture, changing the fixture’s brightness. Unlike a standard on-off switch, a dimmer can create different light levels for tasks, comfort, or energy management. The device must match the lamp type, electrical load, wiring method, and installation location.
Electrical Code is a set of enforceable safety rules for designing, installing, inspecting, and maintaining electrical systems. The rules address wiring, equipment, grounding, overcurrent protection, clearances, and safe work practices. In the United States, the National Electrical Code provides the main technical model, while local authorities adopt and enforce a specific edition.
Electrical Panel is the main enclosure that receives electricity from a utility service and distributes it through separate circuits in a building. It contains circuit breakers or fuses, bus bars, and grounding connections. Each breaker protects conductors from excessive current by opening the circuit during an overload or short circuit.
Ground-Fault Circuit Interrupter is a protective device that monitors current flowing through a circuit and quickly disconnects power when some current takes a unintended path to ground. A GFCI helps reduce shock risk near water by comparing outgoing and returning current. Then opening the circuit when the difference reaches its trip level.
Grounding Electrode is a conductive object that connects an electrical system to the earth. Common examples include metal underground water pipe, a concrete-encased electrode, and a ground rod. The electrode connects to the grounding electrode conductor, which provides a path for lightning, surges, and other unwanted electrical energy.
Junction Box is an enclosed electrical container that protects wire connections where two or more cables meet, branch, or change direction. The box prevents accidental contact with energized conductors, limits damage from impact, and provides a serviceable location for inspection and repair. Covers must remain accessible and properly secured after installation.
LED is a semiconductor device that produces light when electric current passes through it. In lighting, a LED converts electrical energy into visible light with less heat and lower energy use than incandescent lamps.
LED Driver is an electronic power supply that converts incoming electrical power into the controlled voltage or current a LED needs to operate safely. The driver regulates output, limits current, and may support dimming, switching, or communication controls. Drivers appear inside many LED lamps and fixtures, or in separate enclosures.
Light Fixture is a complete lighting assembly that holds a lamp or LED, directs light, connects to an electrical circuit, and provides mechanical and electrical protection. A light fixture may include a housing, socket, lens, reflector, mounting hardware, switch, or integrated driver. Common types include ceiling lights, wall sconces, recessed lights, and outdoor luminaires.
Load Calculation is the process of estimating the electrical demand a building, circuit, or service will place on an electrical system. The calculation adds expected loads from lighting, receptacles, appliances, heating, cooling, motors, and other equipment. The result helps determine suitable service capacity, feeder size, circuit ratings, and overcurrent protection.
Lumen is the SI unit that measures the total amount of visible light emitted by a source. A lamp rated.800 lumens produces twice the visible light of a 400-lumen lamp under stated test conditions. Lumens describe light output, while watts describe electrical power consumption and don't directly measure brightness.
National Electrical Code is a safety standard published by the National Fire Protection Association that sets minimum requirements for electrical wiring, equipment, installation, and inspection. The code covers homes, commercial buildings, industrial sites, and special locations. Local governments adopt and enforce editions of the code through laws, permits, and inspections.
Photocell is a light-sensitive electrical control that detects surrounding brightness and switches a connected lighting circuit on or off. A photocell commonly turns outdoor lights on at dusk and off at dawn. The device uses a photoelectric sensor, control contacts, and a rated voltage and load capacity for safe operation.
Receptacle is a wiring device that accepts a plug and provides electrical power to connected equipment. A receptacle may have one or more outlets and can include grounding, tamper resistance, weather resistance, or ground-fault protection. Common household receptacles are rated for specific voltage, current, wire, and installation conditions.
Short Circuit is a unintended low-resistance path between electrical conductors that allows excessive current to flow. The fault may connect a hot conductor to neutral, ground, or another hot conductor. Excess current can overheat wiring, trip a circuit breaker, damage equipment, create arcing, and start a fire if protective devices fail.
Surge Protector is a device that limits short increases in electrical voltage and diverts excess energy away from connected equipment. Common types include plug-in power strips, receptacle-based protectors, and service-panel devices. Surge protectors help reduce damage from switching events and nearby lightning, but they can't prevent every power disturbance or replace proper grounding.
Three-Way Switch is a wall switch system that controls one light or electrical load from two separate locations. The system uses two three-way switches and traveler wires between them. Either switch can change the load's state, so the light can turn on or off from either end of a hallway, stairway, or room.
Transformer is an electrical device that transfers energy between circuits and changes alternating-current voltage. A transformer can raise voltage for efficient transmission or lower voltage for safer use in buildings and equipment. The device uses electromagnetic induction through coils wound around a magnetic core. Without changing the electrical supply frequency.
Underwriters Laboratories is an independent safety science organization that tests products, components, and systems against published safety requirements. Its evaluation may lead to an UL Certification Mark, which shows that a specific product met stated test conditions. The mark doesn't mean every product from a manufacturer is approved or suitable for every installation.
Voltage is the electrical potential difference that pushes electric charge through a circuit. Measured in volts, voltage determines how much energy each unit of charge can transfer. Common systems include 120-volt household circuits and 240-volt circuits for larger equipment. Voltage exists between two points, not as a standalone property at one point.
Watt is the SI unit of power that measures how quickly electrical energy is used or produced. One watt equals one joule of energy per second. Electrical devices list watt ratings to show power demand, while utilities measure household energy use in kilowatt-hours, which combines power with operating time.
Wire Gauge is a numbering system that identifies the diameter and current-carrying capacity of electrical wire. In the American Wire Gauge system, a smaller gauge number means a larger conductor, while a larger number means a smaller conductor.
Wiring Diagram is a visual plan that shows how electrical wires, devices, terminals, and power sources connect in a circuit or system. It uses lines, symbols, labels, and reference numbers to explain current paths and connection points. Electricians use wiring diagrams to install, test, troubleshoot, modify, and document electrical equipment safely.
