Plain definitions of 35 terms we use on the job in Indianapolis.
Term Index
Open any term below for a dedicated definition page.
Aluminum Wire is an electrical conductor made from aluminum and used to carry current through building circuits. Aluminum conducts electricity while weighing less than copper, but its connections need compatible terminals and careful installation. Changes in temperature can affect aluminum connections, so damaged or improperly terminated wiring may require repair or replacement.
Also called: Aluminum Wiring
An Arc-Fault Circuit Interrupter is a protective electrical device that detects unsafe arcing in a circuit and disconnects power. Arcing can occur when electricity jumps across a damaged, loose, or deteriorated connection. The device helps reduce fire risk from hidden wiring faults that a standard circuit breaker may not detect.
Also called: AFCI
Arc flash is a sudden electrical explosion that occurs when current leaves its intended path and travels through air between conductors or from a conductor to ground. The event releases intense heat, bright light, pressure, and molten metal. Arc flash can damage equipment and injure people near energized electrical parts.
An automatic transfer switch is an electrical device that moves selected circuits between a utility supply and a standby generator. It monitors the normal power source, detects an outage, and signals the generator to provide backup power. When utility power returns, the switch transfers the circuits back after the system confirms stable supply.
Also called: ATS
Ballast is an electrical component used with certain fluorescent and discharge lamps. A ballast controls the current flowing through the lamp and helps provide the starting conditions needed for operation. Magnetic and electronic ballasts serve this purpose in different ways. Ballasts may be installed inside fluorescent fixtures or mounted as separate lighting components.
Battery Management System is an electronic control system that monitors and manages rechargeable battery cells. It tracks voltage, temperature, charge level, and current flow to keep the battery within safe operating limits. In a home battery backup, the system helps coordinate charging, discharging, fault detection, and communication with the inverter.
Also called: BMS
A bidirectional inverter is a power conversion device that moves electrical energy between direct current and alternating current in either direction. It can convert battery power into usable building power and convert alternating-current power back into direct current for battery storage. This two-way function supports electric vehicle charging, vehicle-to-home systems, and battery backup equipment.
A Bollard Light is a short outdoor lighting fixture with a vertical post and a light source near its top. Landscape designers and electricians use bollard lights to guide movement and spread low-level illumination along walkways, driveways, garden edges, and other outdoor areas. The fixture may use integrated LEDs or replaceable lamps.
Also called: Bollard
Busbar is a rigid metal conductor inside an electrical panel that distributes power to circuit breakers or other connected equipment. The busbar receives electricity from the main breaker and provides contact points for branch circuits. Its design supports organized power distribution while keeping panel connections compact and accessible for inspection.
Also called: Bus Bar
A charge port is the physical connection point on an electric vehicle where charging equipment transfers electrical energy to the vehicle battery. The port contains contacts that match the charging connector and communicates with the vehicle during charging. A charge port may support alternating-current charging, direct-current charging, or both.
Also called: Charging Port
A circuit directory is a labeled guide inside or beside an electrical panel that identifies which rooms, outlets, appliances, or equipment each circuit breaker controls. The directory helps an electrician trace power sources, isolate a circuit during panel repair, and identify mislabeled or undocumented circuits before testing or making changes.
Also called: Panel Schedule
A conduit is a protective tube or channel that routes electrical wires and shields them from physical damage, moisture, and other site conditions. Conduit may be made from metal or plastic, and it can run through walls, across ceilings, underground, or along exposed surfaces. Its size and path must suit the wiring inside.
A continuity test is an electrical check that determines whether a complete path exists between two points in a circuit. A meter sends a small test current through the path and measures the result. A continuous path usually indicates low resistance. An open path suggests a break, loose connection, failed component, or disconnected conductor.
Also called: Continuity Check
Electrical Grounding is the intentional connection of electrical equipment and systems to the earth through a conductive path. The path helps direct unwanted electrical current away from people and equipment during a fault. Grounding also establishes a stable reference point for voltage and supports the operation of protective devices.
Also called: Earthing
A Fan Capacitor is an electrical component that stores and releases energy to help a ceiling fan motor start, run, or change speed. The capacitor creates a phase shift in the motor circuit, which supports rotating magnetic fields. A failed capacitor may leave a fan humming, running slowly, or unable to start.
Also called: Ceiling Fan Capacitor
Fire Alarm Pull Station is a manually operated fire alarm initiating device that lets a person signal an emergency by pulling or activating a visible handle. The station sends an alarm signal to the fire alarm control panel, which processes the signal and starts connected notification devices or other programmed responses.
Also called: Manual Pull Station
A fuse is a protective electrical device that contains a metal link designed to melt when current exceeds its safe limit. The melted link opens the circuit and stops power from reaching connected wiring. Fuses protect against excessive current, but they must be replaced after they operate because they cannot be reset.
Ground Fault Protection is a protective function that detects when electrical current leaves its intended path and responds by interrupting power. This protection helps reduce shock risk from current flowing through a person, grounded equipment, or another unintended route. Ground Fault Circuit Interrupters, commonly called GFCI devices, provide this protection at outlets and circuits.
Also called: GFCI Protection
Junction Box is an enclosed electrical box that protects and contains connections where wires join, split, or change direction. The enclosure keeps wire connections organized and shields them from accidental contact, physical damage, and environmental exposure. Junction boxes may be metal or nonmetallic and must match the wiring method and installation location.
Also called: Electrical Junction Box
An LED Driver is an electronic power supply that converts incoming electrical power into the controlled current or voltage an LED fixture needs. The driver helps LEDs operate at a stable level and protects them from unsuitable power. Some drivers are built into fixtures, while others mount separately above a ceiling or inside an enclosure.
Also called: LED Power Supply
A load calculation is an electrical design assessment that estimates the power demand of a home or building. The assessment considers existing circuits, fixed equipment, heating and cooling systems, and planned additions. Electricians use the result to judge whether the current service can support the connected loads without overloading conductors or equipment.
Also called: Electrical Load Calculation
A Main Breaker is the primary circuit breaker in an electrical panel that controls power entering the premises. The device opens the circuit when excessive current or a short circuit threatens the service equipment. Switching it off can disconnect power to branch circuits, although some equipment may remain energized ahead of the breaker.
Also called: Main Circuit Breaker
A Motion Sensor is an electronic device that detects movement within a selected area and signals a lighting control, alarm, or other connected system. Common sensors use changes in infrared energy, microwave signals, or both to identify motion. In security lighting, the sensor activates a light when movement meets its detection settings.
Also called: Occupancy Sensor
A neutral wire is a circuit conductor that carries current back to the electrical panel from a connected load. The neutral maintains a reference point near ground potential and completes many household circuits with a hot wire. It is commonly identified by white or gray insulation, although identification must be verified before work.
Also called: Neutral Conductor
A photocell is a light-sensitive electrical control that switches outdoor lighting on when surrounding light fades and off when daylight returns. It helps automate dusk-to-dawn operation without requiring a person to operate a wall switch. Photocells commonly control porch lights, security lights, parking-area fixtures, and landscape lighting.
Also called: Photoelectric Cell
A Recessed Light Trim is the visible finishing component installed around a recessed light opening. It covers the edge of the ceiling cutout and shapes how the fixture looks and directs light. Trim styles include baffle, reflector, adjustable, and shower designs. The trim must match the recessed housing or compatible LED module.
Also called: Downlight Trim
Romex is a common trade name for nonmetallic-sheathed electrical cable used in building wiring. The cable contains insulated conductors and a grounding conductor inside a protective outer jacket. Electricians route it through approved spaces to supply outlets, switches, lighting, and other electrical devices in many residential construction projects.
Also called: NM-B Cable, Nonmetallic Cable
Service Disconnect is the main device that separates a building’s electrical system from the utility supply. The device may be a breaker, switch, or fused disconnect located near the service entrance. Opening the disconnect stops power from reaching the building’s panel, allowing qualified workers to isolate the installation during service work.
Also called: Disconnect Switch
A Short Circuit is an unintended electrical path with very low resistance between points at different voltage levels. The path allows current to rise sharply, which can trip a breaker, blow a fuse, damage wiring, or create heat. Short circuits commonly result from damaged insulation, loose conductors, moisture, or failed electrical components.
Also called: Electrical Short
A subpanel is a smaller electrical distribution panel supplied by the main panel through a feeder circuit. It provides additional circuit breaker spaces in another part of a building. The subpanel distributes power to local branch circuits while the main panel remains the primary point for service control and overall system protection.
Also called: Subpanel Panel
A Surge Protector is a device that limits short bursts of excessive voltage before those bursts reach connected electrical equipment. It redirects or absorbs extra electrical energy through protective components. A surge protector may serve one appliance at an outlet or protect multiple circuits when installed at an electrical panel.
Also called: Surge Suppressor
Thermal Imaging is a noncontact inspection method that shows surface temperature differences as an image. An infrared camera detects heat energy from electrical equipment and displays warmer and cooler areas through colors or shades. Electricians use these patterns to identify possible connection, load, or component problems that may require closer testing.
Also called: Infrared Thermography
Voltage Drop is the reduction in electrical potential that occurs as current travels through a conductor, connection, or device. Resistance in the circuit absorbs part of the available voltage, so the equipment at the far end receives less electrical pressure than the source provides. The condition may affect performance, starting, or reliable operation.
Weatherhead is a protective fitting at the top of an overhead electrical service mast. The fitting directs service entrance conductors into a building while its shaped opening and cover help keep rain away from the conductors and mast. A Weatherhead works with the service mast, conduit, and utility connection as part of the service entrance.
Also called: Service Entrance Cap
Wire Nut is a twist-on connector that joins and insulates stripped electrical wires inside an electrical box or enclosure. The connector has a threaded interior that grips the conductors as the cap turns. Wire nuts come in different sizes and colors for different wire combinations, but each connection must match the conductor type and connector rating.
Also called: Wire Connector
