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 unintended arcing. When the device detects a dangerous arc signature, the AFCI opens the circuit to reduce fire risk from damaged, loose, or deteriorated wiring. AFCIs may be installed as breakers or receptacles.
Also called: AFCI
Backfeed is the unintended flow of electrical power from a generator, solar system, battery, or another source into wiring that utility power normally supplies. The condition can energize circuits believed to be de-energized and create dangerous voltage at equipment or utility lines. A properly installed transfer switch prevents this unwanted connection.
A ballast is an electrical component that regulates current in certain lighting systems. It helps fluorescent lamps start and keeps their electrical output stable during operation. Traditional magnetic ballasts use coils, while electronic ballasts use electronic circuits. The correct ballast must match the lamp type, fixture design, and supply voltage.
A Bidirectional Inverter is a power conversion device that sends direct-current energy to an alternating-current system and converts alternating-current power back to direct current. This two-way operation supports energy exchange between equipment such as an electric vehicle, battery, solar system, and building electrical service while managing voltage, current, and operating mode.
Bonding is the intentional connection of metal parts and electrical conductors so they share the same electrical potential and provide a dependable path for fault current. Bonding may connect equipment, enclosures, raceways, and other conductive parts. The connection helps protective devices respond when unwanted current reaches exposed metal.
A busbar is a conductive metal strip or bar that distributes electrical power among connected circuits inside equipment such as a panelboard. Busbars provide a common connection point for breakers or other conductors. Their size, material, insulation, and mounting arrangement must suit the panel design and the electrical load.
A Circuit Breaker is a resettable electrical switching device that opens a circuit when current exceeds a safe operating level. The device interrupts power to protect conductors and connected equipment from overcurrent. After the cause is corrected, the breaker can be reset. Unlike a fuse, a breaker does not require replacement after operation.
Conduit is a protective raceway that encloses electrical wires and cables. It may be made from metal or nonmetallic material and can run through walls, ceilings, floors, or exposed areas. Conduit helps protect wiring from impact, moisture, abrasion, and other physical damage while supporting an organized electrical installation.
A continuity test is an electrical check that determines whether a circuit path is complete from one point to another. A meter sends a small test signal through the path and indicates whether current can pass. The result helps identify open wires, loose connections, damaged conductors, or broken components during electrical troubleshooting.
A dimmer switch is a control device that adjusts the electrical power delivered to a compatible light source. The adjustment changes the light's brightness without requiring a different lamp. Dimmer switches replace many standard wall switches, but the switch and light source must support the same dimming method for smooth operation.
Electrical Load Calculation is a structured estimate of the electrical demand created by a building’s circuits, appliances, heating equipment, and other connected loads. The calculation helps determine whether an existing service can support planned equipment and whether an electrical service upgrade may need larger service conductors, equipment, or distribution capacity.
Also called: Load Calculation
An equipment grounding conductor is a wire that connects exposed metal parts of electrical equipment to the grounding system. It provides a low-resistance path for fault current, helping protective devices disconnect power when energized metal contacts the equipment enclosure. It normally carries no current during proper operation.
Also called: Grounding Wire
EVSE is equipment that supplies electrical power to an electric vehicle and manages the connection between the vehicle and the building’s electrical system. An EVSE assembly typically includes a charging cable, connector, control circuitry, and protective functions. The term covers the charging equipment, not the vehicle’s onboard battery charger.
Also called: Electric Vehicle Supply Equipment
A grounding electrode is a conductive connection between an electrical system and the earth. It may be a metal component in contact with soil, such as a grounding electrode system component. The connection helps establish a stable reference to earth and supports the electrical system during lightning, surges, and other abnormal conditions.
Also called: Ground Rod
A Heat Detector is a fire alarm initiating device that responds to unusually high heat or a rapid rise in temperature. It sends a signal to an alarm control panel when its sensing element reaches a set condition. Heat detectors suit areas where smoke, dust, fumes, or steam could cause unwanted alarms.
An inverter is an electrical device that changes direct current into alternating current for equipment designed to run on household-style power. In generator systems, the inverter helps produce a controlled output from stored or generated energy. Its design can support stable power for sensitive electronics, depending on the generator and system configuration.
Islanding is a condition in which a distributed energy system continues supplying power to a section of an electrical grid that has been separated from the utility source. The isolated section may include an inverter, battery, vehicle, or local loads. Islanding can be intentional during backup operation or unintended during a grid interruption.
A Junction Box is an enclosed electrical box that contains wire splices, connections, or branch points. The enclosure protects conductors from physical damage and helps keep connections accessible for inspection and repair. Junction boxes may be metal or nonmetallic and can serve lighting circuits, receptacles, appliances, or other wiring sections.
Load Management is the planned control of electrical demand across connected equipment. The system monitors available capacity and adjusts selected loads when demand approaches a set limit. In bidirectional charging systems, load management helps coordinate vehicle charging, household consumption, and power flowing from the vehicle without exceeding the electrical system’s operating capacity.
Load Shedding is a power management process that disconnects selected electrical loads to keep a generator, electrical system, or utility network within its available capacity. The process gives priority to essential equipment, such as refrigeration or medical devices, while temporarily turning off lower-priority loads, such as electric heating or water heating.
A Manual Transfer Switch is a switching device that connects selected electrical loads to an alternate power source, such as a portable generator. The switch prevents the normal utility supply and generator supply from feeding the same circuits at once. A person operates the switch to move designated loads between power sources.
A multimeter is a handheld electrical testing instrument that measures values such as voltage, current, and resistance. It combines several testing functions in one tool and displays readings on a digital screen or analog scale. Electricians use those readings to trace faults, verify circuit conditions, and compare actual performance with expected operation.
A neutral conductor is a current-carrying wire that provides the normal return path from a circuit load to the electrical source. It is commonly connected to the neutral point of a system and may be identified by white or gray insulation. The neutral conductor works with energized conductors to complete many branch circuits.
Also called: Neutral Wire
An open neutral is a break or failed connection in the neutral conductor of an electrical circuit. The neutral normally carries current back to the service panel. When that path is interrupted, connected devices may stop working, flicker, or receive unstable voltage. An open neutral can affect one circuit or several circuits.
Overcurrent Protection is a system that limits electrical current when a circuit carries more power than its wiring or equipment can safely handle. Circuit breakers and fuses provide this protection by interrupting the flow of electricity during an overload or short circuit. Proper protection helps prevent conductor damage and reduces fire risk.
A panelboard is an electrical enclosure that holds circuit breakers, busbars, and connection points for distributing power to branch circuits. The enclosure receives power from an electrical service or feeder, while each breaker protects a connected circuit from excessive current. Panelboards organize circuit wiring and provide a central point for disconnecting circuits.
Also called: Electrical Panel
A photocell is an electrical light sensor that detects surrounding brightness and controls a connected lighting circuit. Outdoor security lights commonly use photocells to switch on at dusk and switch off at dawn. The sensor helps automate lighting without a wall switch or timer, provided the fixture and wiring support photocell control.
Also called: Dusk-To-Dawn Sensor
A service entrance is the part of an electrical system that carries power from the utility connection to the building’s service equipment. It includes the service conductors and related equipment that connect the utility supply with the main disconnect or panelboard. This area forms the transition between utility power and the property’s electrical distribution system.
Also called: Electrical Service Entrance
A smoke detector is a life-safety device that senses airborne particles from combustion and produces an alert when smoke reaches its sensing chamber. A detector may operate as a standalone unit or connect to a fire alarm system. Smoke detectors help identify developing fires, while heat detectors respond to temperature changes instead of smoke.
Also called: Smoke Alarm
A standby generator is a permanently installed backup power system that supplies electricity when utility power fails. A transfer switch connects selected household or commercial circuits to the generator, then returns those circuits to utility power after service is restored. Standby generators commonly use natural gas or propane as fuel.
Also called: Backup Generator
A Surge Protective Device is an electrical protection component that limits sudden voltage increases and redirects excess energy away from connected wiring and equipment. Installed at a service panel or other suitable point, the device helps reduce damage from transient surges caused by utility switching, lightning activity, or equipment operation.
Also called: SPD, Surge Protector
A Transfer Switch is a switching device that moves electrical loads between a utility source and an alternate source, such as a standby generator. The device prevents both sources from feeding the same circuits at once. Transfer switches may operate automatically or require manual operation, depending on the generator system and installation.
Voltage Drop is the reduction in electrical voltage that occurs as current travels through a conductor, connection, or circuit component. The reduction results from the electrical resistance of the path. Excessive voltage drop can make equipment operate poorly, cause lights to dim, or prevent a load from starting correctly.
A wire nut is a twist-on connector that joins exposed electrical conductors inside an approved enclosure. The connector grips the conductors with an internal spring or threaded insert and provides an insulated outer shell. Wire nuts come in sizes suited to different conductor types and combinations, so selection must match the wiring.
Also called: Wire Connector
Wiring Diagram is a visual plan that shows how electrical devices, conductors, terminals, and protective components connect within a circuit. Standard symbols identify each part, while lines show electrical paths and connection points. Electricians use the diagram to trace circuits, verify intended connections, diagnose faults, and guide repairs or installation work.
