Plain definitions of 35 terms we use on the job in Indianapolis.
Term Index
Open any term below for a dedicated definition page.
An arc-fault circuit interrupter is a protective device that monitors electrical current for patterns linked to arcing. An arc can occur when electricity jumps across a damaged, loose, or deteriorated connection. The device can interrupt power when it detects that pattern, helping reduce the risk of wiring-related fire in supported circuits.
Also called: AFCI
An arc flash is a sudden electrical discharge that travels through an unintended path, often through air, between energized conductors or between a conductor and ground. The discharge releases intense heat, light, pressure, and sound. Arc flashes can damage equipment and create serious hazards for people near an energized electrical system.
An Automatic Transfer Switch is a power-transfer device that moves selected electrical loads between a utility source and a standby generator. The switch monitors the normal source, signals the generator when needed, and connects the generator after stable power is available. It also returns the load to utility power when normal service is restored.
Also called: ATS
A backstab connection is a wiring method that holds a solid conductor in a spring-loaded opening on the back of an electrical receptacle or switch. The conductor enters a small port instead of wrapping around a terminal screw. Movement, heat, or repeated electrical load can affect the connection and cause intermittent operation.
Also called: Backstab Wiring
Battery Backup is a power storage system that supplies electricity when the utility source fails. The system stores electrical energy, then sends power through an inverter to selected circuits or equipment during an outage. Supporting system upgrades may support lighting, communications, medical equipment, or controls, depending on their capacity and installation design.
Also called: Backup Battery
A bonding jumper is a conductive connection that joins metal electrical parts so they share a continuous path for fault current. The connection may link enclosures, raceways, service equipment, or other conductive components. This path helps protective devices respond when a fault energizes metal that should remain at the same electrical potential.
Also called: Bonding Wire
A branch circuit is the portion of an electrical system that carries power from a panelboard overcurrent device to outlets, lighting, or fixed equipment. Conductors, connections, and the circuit breaker work together as one path. A branch circuit supplies a defined area or load and returns current through the circuit neutral or grounding path as designed.
A circuit breaker is a resettable overcurrent protection device that opens an electrical circuit when current exceeds a safe operating level. The device contains switching contacts and a trip mechanism. After the fault is addressed, the breaker may be reset to restore power, provided the panel and circuit remain in suitable condition.
A conduit is a protective pathway that encloses and routes electrical wires or cables. Conduit may be made from metal or nonmetallic material, depending on the installation. It helps shield wiring from physical damage, moisture, and environmental exposure while keeping conductors organized through walls, ceilings, floors, and outdoor areas.
Also called: Electrical Conduit
A dimmer switch is a wall control that adjusts the electrical power delivered to a compatible light, allowing you to change brightness without replacing the fixture. Unlike a standard switch, which provides simple on or off control, a dimmer manages the light level through an electronic control or adjustable mechanism.
Also called: Dimmer
Electrical Grounding is a wiring method that connects electrical systems and exposed metal parts to the earth or a conductive grounding path. The connection helps carry fault current away from people and equipment, supports overcurrent device operation, and limits unwanted voltage on metal enclosures. Grounding works with bonding and circuit protection.
Also called: Grounding
Electrical Load Calculation is a structured assessment of the electrical demand a property places on its service and distribution equipment. The calculation considers fixed loads, equipment ratings, and expected usage to determine whether existing capacity can support the planned installation. Electricians use the result when evaluating service upgrades, panel changes, and new major appliances.
Also called: Load Calculation
An EV connector is the plug and matching vehicle inlet that transfer electrical power between electric vehicle supply equipment and an electric vehicle. The connector carries charging current through designated contacts and may also support communication between the vehicle and charging equipment. Connector design varies by charging system, vehicle, and region.
Also called: Electric Vehicle Connector
A Fire Alarm Panel is the central control unit that receives signals from initiating devices, monitors connected circuits, and directs notification appliances during a fire alarm condition. It also displays system status, records trouble conditions, and supports testing or silencing functions. The panel connects field devices into one supervised fire detection system.
Also called: FACP, Fire Alarm Control Panel
Generator Inlet is a listed connection point that lets a portable generator send power into a building through an approved inlet box and transfer arrangement. The inlet connects to wiring that serves selected circuits or a panel. It keeps the generator connection outside the building and supports a controlled method of backup power connection.
Also called: Generator Inlet Box
A generator interlock is a panel-mounted device that coordinates the utility main breaker and a standby generator breaker. The interlock allows only one power source to feed selected circuits at a time. This arrangement directs generator power through the home’s electrical panel while preventing simultaneous utility and generator connection.
Also called: Interlock Kit
A ground fault is an unintended electrical connection between an energized conductor and a grounded surface, conductor, or equipment enclosure. The fault can redirect current away from its intended circuit path. Ground faults may cause shock hazards, equipment damage, or protective-device operation when a breaker or ground-fault protection device detects abnormal current.
Also called: Ground Fault Condition
A grounding electrode is a conductive connection between an electrical system and the earth. Common electrodes include metal water piping, concrete-encased metal, and ground rods. The electrode connects to the grounding electrode conductor, which links the electrical service to the grounding system and helps direct unwanted electrical energy into the earth.
Also called: Ground Rod
A Junction Box is an enclosed electrical box that protects and contains wire splices, connections, and branch-circuit conductors. The enclosure keeps connection points accessible for inspection and repair while reducing exposure to accidental contact, movement, and physical damage. Junction boxes may be made from metal or nonmetallic materials and installed in walls, ceilings, or accessible areas.
Also called: Electrical Junction Box
Line voltage is the electrical potential supplied by a power source to a circuit, appliance, or lighting system. It is the voltage present on energized conductors before a device changes or uses that power. Electricians check line voltage during troubleshooting to confirm whether power reaches the equipment and where a fault may begin.
Also called: Mains Voltage
Load Shedding is a controlled process that reduces electrical demand by turning off, delaying, or limiting selected loads. An energy management system, transfer switch, or panel control may shed nonessential equipment when available power cannot safely support every connected circuit. The process helps maintain service for priority loads during constrained operation.
Also called: Load Management
Neutral wire is a current-carrying conductor that completes the electrical path from a load back to the electrical panel. It normally connects to the neutral bar and works with the energized line conductor to supply power to outlets, lights, and appliances. A neutral wire is not the same as an equipment grounding conductor.
Also called: Neutral Conductor
Overcurrent Protection is a system function that limits electrical current when a circuit carries more electricity than its wiring or equipment can safely handle. A circuit breaker or fuse provides this protection by opening the circuit during an overload or short circuit. The action helps prevent conductor damage and reduces fire risk.
Photocell is a light-sensitive electrical control that detects surrounding brightness and switches an outdoor lighting circuit on or off. A photocell helps fixtures operate from dusk to dawn without a manual switch. The device responds to ambient light, so its placement and connection affect how reliably landscape, security, and other exterior lights operate.
Also called: Dusk-to-Dawn Sensor, Photo Sensor
A pigtail is a short length of electrical wire used to connect one device or terminal to one or more circuit conductors. The connection usually joins wires with an approved connector inside an electrical box. Pigtails support secure splicing, simplify device replacement, and help keep conductors organized during wiring repair.
Also called: Pigtail Wire
Polarity is the arrangement of electrical connections that identifies the intended direction of current or the relationship between conductors. In alternating-current wiring, polarity distinguishes the energized line conductor from the neutral conductor. In direct-current systems, polarity identifies positive and negative connections. Correct polarity helps equipment operate as designed and supports safe testing.
Also called: Electrical Polarity
A Power Inverter is an electrical device that converts direct current from a battery or other source into alternating current for equipment that needs household-style power. In bidirectional charging systems, the inverter may also reverse that conversion, sending alternating current back into stored direct-current energy.
Also called: Inverter
A service entrance is the point where utility power enters a building and connects to the premises wiring system. The term includes the conductors, equipment, and connections that carry power from the utility supply to the main disconnect or electrical panel. A service entrance supports the building’s complete electrical distribution system.
Also called: Electrical Service Entrance
A short circuit is an unintended low-resistance path that allows electrical current to bypass part of a circuit. The sudden current increase can trip a circuit breaker, blow a fuse, damage wiring, or create heat. Short circuits often result from damaged insulation, loose conductors, faulty devices, moisture, or wiring connections that touch.
Also called: Electrical Short
A Surge Protector is an electrical protection device that limits sudden voltage increases before those surges reach connected equipment. The device redirects excess energy through a grounding path or absorbs part of the surge. Surge protectors may serve one outlet, a group of devices, or the electrical service for an entire building.
Also called: Surge Suppressor
A transformer is an electrical device that transfers energy between circuits through magnetic induction. A transformer can raise or lower alternating-current voltage while changing current in the opposite direction. Transformers support power distribution, equipment operation, and control systems by matching available voltage with the needs of connected electrical loads.
Also called: Electrical Transformer
Vehicle-to-Grid is a bidirectional energy system that lets an electric vehicle exchange power with the electrical grid. The vehicle can receive electricity for charging and send stored electricity back through compatible charging equipment. Grid controls coordinate this exchange to support power management while preserving the vehicle owner's ability to use the vehicle.
Also called: V2G
Voltage Drop is the reduction in electrical voltage that occurs as current travels through a conductor, connection, or device. Resistance in the circuit uses part of the available voltage. The amount depends on the circuit load, conductor characteristics, connection condition, and distance between the power source and the equipment.
Also called: Voltage Loss
A wire nut is an insulated twist-on connector that joins electrical conductors inside an approved enclosure. Its internal spring grips the stripped wire ends as the cap turns onto them. Wire nuts come in different sizes for different conductor combinations. A proper connection keeps the joint mechanically secure and electrically continuous.
Also called: Wire Connector
A Wiring Diagram is a visual map of an electrical circuit that shows wires, devices, connections, and power flow. Symbols identify components, while lines show how those components connect. Electricians use the diagram to trace circuits, understand control paths, verify connections, and locate possible causes during electrical troubleshooting.
Also called: Electrical Wiring Diagram
