Plain definitions of 35 terms we use on the job in Cincinnati.
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, it opens the circuit to stop power flow. AFCI protection helps address fire risks caused by damaged wiring, loose connections, or faulty electrical equipment.
Also called: AFCI
Battery Backup is a stored-energy system that supplies electrical power when normal utility power stops. The system charges from an electrical source, then sends power to selected equipment through an inverter or control unit. In emergency lighting, battery backup keeps designated fixtures operating during an outage so people can see marked paths and exits.
Also called: Backup Battery
A branch circuit is a wiring path that carries electricity from a panelboard to outlets, lights, appliances, or other connected loads. The circuit includes conductors and overcurrent protection that serve a specific part of an electrical system. A branch circuit may supply one load or several loads designed to operate together.
Busbar is a rigid conductive bar inside an electrical panel that distributes power to connected circuit breakers or other equipment. The bar provides a common connection point for incoming electrical current. Separate busbars may serve energized conductors, neutral conductors, or grounding conductors, depending on the panel design and installation.
Also called: Bus Bar
A carbon monoxide alarm is a safety device that detects carbon monoxide gas in indoor air and sounds an alert when the gas reaches a dangerous level. Carbon monoxide has no reliable color or odor warning. The alarm helps occupants recognize a possible fuel-burning appliance, venting, or combustion problem before exposure becomes severe.
Also called: CO Alarm
Ceiling Fan Downrod is a rigid metal rod that connects a ceiling fan motor housing to its mounting bracket. The rod lowers the fan from the ceiling, supports the fan assembly, and carries wiring between the ceiling connection and motor. Downrods suit rooms with taller ceilings or sloped ceiling surfaces.
Also called: Fan Downrod
Conduit is a protective pathway that encloses and routes electrical conductors. It may be made from metal or nonmetallic material and can run through walls, along surfaces, or underground. Conduit protects wiring from physical damage, moisture, soil contact, and other conditions that could affect an electrical installation.
Also called: Electrical Conduit
A Continuity Test is an electrical check that determines whether a complete conductive path exists between two points. A meter sends a small test signal through the circuit and indicates a continuous path with a reading or tone. An open path produces a different result, helping identify breaks, loose connections, or disconnected conductors.
Also called: Continuity Check
Dusk-to-Dawn Sensor is a photoelectric control that detects surrounding light and switches an outdoor lighting circuit on after dark and off in daylight. The sensor helps landscape lights operate automatically without a manual switch or timer. Proper placement keeps nearby fixtures, windows, and reflected light from affecting its readings.
Also called: Photocell
Electrical Bonding is the connection of metal parts, electrical equipment, and conductive pathways so they share a dependable electrical path. This connection helps keep exposed metal at a similar electrical potential during normal operation or a fault. Bonding works with grounding and protective devices as part of a complete electrical system.
Also called: Bonding
Electrical Load is the amount of power that connected equipment draws from an electrical system at a given time. The load includes appliances, lighting, heating equipment, motors, and electronic devices. Electricians assess the combined demand to determine whether a panel, feeder, circuit, or service can support the equipment safely.
Also called: Load
A Generator Interlock is a mechanical device fitted to an electrical panel that prevents the utility main breaker and a generator breaker from being on at the same time. The interlock guides power through the panel while blocking conflicting breaker positions. This arrangement supports controlled generator connection without transferring power through an unintended path.
Also called: Interlock Kit
A Ground-Fault Circuit Interrupter is a protective device that monitors electrical current flowing through a circuit and quickly disconnects power when current takes an unintended path. The device helps reduce shock risk near water or grounded surfaces. It commonly appears as a receptacle with test and reset buttons or as a circuit breaker.
Also called: GFCI
A grounding electrode is a conductive object, such as a metal rod, plate, or building steel, that connects an electrical system to the earth. The electrode provides a path for unwanted electrical energy and supports the grounding system during faults, surges, or lightning-related events. Its performance depends on its material, placement, and connections.
Also called: Ground Rod
A Junction Box is an enclosure that houses electrical wire connections, splices, and branch points. The box protects the connections from physical damage and keeps them contained within the wiring system. Junction boxes may be made from metal or plastic and are installed where conductors join, separate, or change direction.
Also called: Electrical Box
An LED driver is an electronic power-control device that supplies light-emitting diodes with the voltage or current they need to operate safely. The driver converts incoming electrical power into a form the LED fixture can use. It may be built into the fixture or installed as a separate component.
Also called: LED Power Supply
A Load Center is an electrical enclosure that houses circuit breakers and distributes power from the service conductors to branch circuits throughout a building. The enclosure also provides a place for overcurrent protection and circuit connections. In residential work, people often use load center and electrical panel to describe the same equipment.
Also called: Breaker Panel
A motion sensor is an electronic device that detects movement within a monitored area and sends a signal to control equipment. Security lighting systems use that signal to switch a light on when someone approaches. The sensor may detect changes in infrared energy, sound waves, or another selected field.
Also called: Occupancy Sensor
A neutral wire is a grounded conductor that carries current back to the electrical panel after power passes through a load. It completes many household circuits and helps maintain the intended voltage between energized conductors and connected devices. Neutral wires commonly connect receptacles, switches, lighting fixtures, and other electrical equipment to the panel.
Also called: Neutral Conductor
NM Cable is a factory-assembled electrical cable with insulated circuit conductors and a grounding conductor inside a nonmetallic jacket. Electricians route NM Cable through finished and unfinished building spaces to supply branch circuits. The cable carries power between an electrical panel, switches, receptacles, lighting fixtures, and connected equipment in dry locations.
Also called: Nonmetallic Cable, Romex
Overcurrent protection is a system that limits electrical current when a circuit carries more electricity than its conductors or equipment can safely handle. Circuit breakers and fuses provide this protection by opening the circuit during an overload or short circuit. The interruption reduces overheating and helps protect wiring from damage.
Also called: Overload Protection
A Photoelectric Smoke Alarm is a smoke-sensing device that uses a light source and sensor to detect particles suspended in the alarm chamber. Smoke changes the light reaching the sensor, which activates the alarm. This design commonly responds well to smoke from slow, smoldering fires and is used in homes and other occupied spaces.
Also called: Photoelectric Detector
A receptacle is a wiring device that provides connection points for plugs from electrical equipment. The device transfers power from a branch circuit to a cord through contact openings, while its design may include grounding, tamper resistance, or ground-fault protection. Receptacle describes the installed device, while outlet often serves as the everyday name.
Also called: Outlet
A service entrance is the point and equipment where utility power enters a building and connects to the building’s electrical system. It includes the conductors, meter connection, main disconnect, and related equipment that receive utility power. The service entrance establishes the system’s supply path before electricity reaches branch circuits, receptacles, or lighting.
Also called: Electrical Service Entrance
A short circuit is an unintended low-resistance path that lets current move outside its planned route. The path may form between conductors at different voltages or between an energized conductor and ground. The resulting current surge can heat wiring, trip overcurrent protection, damage equipment, or reveal a fault in insulation or connections.
Also called: Electrical Short
A Smoke Alarm is a safety device that detects airborne particles from combustion and produces an audible warning. Most models use photoelectric sensing, ionization sensing, or both to identify smoke. Smoke alarms may receive power from household wiring, batteries, or both. They are installed in locations where occupants need early warning of a fire.
Also called: Smoke Detector
A Tamper-Resistant Receptacle is an electrical outlet with spring-loaded shutters inside its slots. The shutters stay closed when an object presses against only one slot, which helps prevent unintended contact with energized parts. The shutters open when a matching plug applies pressure to the slots at the same time during normal use.
Also called: TR Receptacle
Thermal Imaging is a diagnostic method that displays surface temperature differences as a visual heat pattern. An infrared camera detects thermal energy from electrical equipment and converts those readings into an image. Electricians use the pattern to investigate possible overloaded connections, damaged components, or abnormal heating without relying on sight alone.
Also called: Infrared Scanning
A Transfer Switch is an electrical switching device that moves selected circuits between a utility supply and a backup generator. The switch prevents both power sources from feeding the same circuit at once. Transfer switches may operate manually or automatically, depending on the system design, generator controls, and required level of outage response.
Also called: Generator Transfer Switch
Underground Conduit is a protective pathway installed below ground for electrical conductors. The conduit shields wires from soil, moisture, impact, and other damage. It may be made from approved plastic or metal and can connect buildings, outdoor equipment, panels, and other electrical points while allowing conductors to be replaced or serviced.
Also called: Buried Conduit
Voltage Drop is the reduction in electrical pressure that occurs as current travels through a wire, cable, connection, or other circuit component. The reduction results from electrical resistance and becomes more noticeable when a circuit carries a heavier load or uses a long, undersized, or damaged conductor.
Also called: Line Drop
Wire Gauge is a standardized way to describe a conductor’s diameter and current-carrying capacity. The gauge designation helps identify whether a wire suits a circuit’s electrical load, installation method, and connection points. In common American wiring, a smaller gauge number generally indicates a thicker conductor, while a larger number indicates a thinner conductor.
Also called: AWG
Wire Nut is a twist-on connector that joins compatible electrical conductors inside an approved enclosure. The connector has an insulated outer shell and an internal spring or threaded insert that grips the prepared wire ends. Wire nuts come in sizes suited to different wire combinations and create a removable connection for wiring repairs.
Also called: Wire Connector
A Wiring Diagram is a visual plan that shows how electrical wires, devices, terminals, and protective components connect within a circuit. Standard symbols represent parts, while lines show electrical paths and connection points. Electricians use the diagram to trace circuit operation, identify conductors, and compare installed wiring with the intended design.
Also called: Circuit Diagram
A zero voltage tester is a test instrument used to check whether electrical voltage is absent from a conductor, terminal, or enclosure. The tester helps confirm a deenergized condition before inspection or repair. It may detect voltage through direct contact or by sensing an electrical field, depending on its design.
Also called: Non-Contact Voltage Tester
