Plain definitions of 35 terms we use on the job in Pittsburgh.
Term Index
Open any term below for a dedicated definition page.
AFCI is an arc-fault circuit interrupter that monitors electrical current for patterns linked to unintended arcing. When the device detects a potentially damaging arc, AFCI protection opens the circuit and stops power flow. AFCI devices may be installed as circuit breakers or receptacles, depending on the circuit design and panel arrangement.
Also called: Arc-fault circuit interrupter
A ballast is an electrical control device that regulates current through fluorescent and some older discharge lamps. It helps a lamp start and keeps electrical flow within its operating range. Ballasts may be magnetic or electronic, and their design must match the lamp type, fixture, voltage, and intended retrofit method.
Bonding is the intentional connection of conductive metal parts so they remain at the same electrical potential. This connection creates a controlled path for fault current and helps protective devices respond when energized wiring contacts metal equipment, enclosures, piping, or other conductive parts. Bonding works with grounding but serves a different purpose.
Also called: Equipotential bonding
Busbar is a conductive metal bar or strip that distributes electrical power among circuits inside equipment such as a panelboard. A busbar connects incoming power with circuit breakers or other connections through a solid path. Its size, material, insulation, and connection points determine how the assembly carries and routes current.
Cable is an assembly of one or more insulated conductors enclosed within a shared jacket or protective covering. Cable carries electrical power or signals between equipment, devices, and connection points. Its construction may include a grounding conductor, shielding, or layers designed for indoor, outdoor, buried, or exposed installation conditions.
A capacitor is an electrical component that stores and releases energy within a circuit. In a ceiling fan, the capacitor helps create the phase shift needed for the motor to start, run, and change speed. Its capacitance is measured in farads, while its voltage rating shows the electrical stress it can withstand.
Conduit is a protective pathway that houses and routes electrical conductors through walls, ceilings, floors, and exposed spaces. Conduit may be made from metal or nonmetallic material. It helps shield wires from impact, moisture, heat, and abrasion while keeping wiring organized and accessible for inspection, repair, or future changes.
Copper-Clad Aluminum is an electrical conductor with an aluminum core covered by a layer of copper. The copper exterior supports electrical connections, while the aluminum center reduces material weight and can lower material cost. Its performance depends on correct wire sizing, compatible terminals, and sound connections throughout the circuit.
Also called: CCA wire
A dimmer switch is a control device that adjusts the electrical power delivered to a compatible light fixture, allowing you to change brightness. Unlike a standard switch, which provides simple on-or-off control, a dimmer regulates light output through electronic components designed for the connected lamp type and circuit.
Electrical Grounding is a protective connection between an electrical system and the earth or another conductive path. The connection gives unwanted electrical current a controlled route away from people and equipment. Grounding supports protective devices, helps limit dangerous voltage on metal parts, and forms part of a properly installed electrical system.
Also called: Grounding
A fan-rated box is an electrical ceiling box designed to support the weight and movement of a ceiling fan. The box attaches securely to framing and provides a protected point for wire connections. Unlike a standard light-fixture box, a fan-rated box is built for the mechanical load created while the fan operates.
Also called: Ceiling fan box
A generator interlock is a mechanical device installed on an electrical panel that prevents the main utility breaker and a generator breaker from being on at the same time. The interlock guides safe source selection during an outage, so a portable generator can supply selected household circuits through the panel without energizing the utility lines.
Also called: Interlock kit
A GFCI is a protective electrical device that monitors current leaving and returning through a circuit. When the device detects an imbalance, it quickly interrupts power to reduce the risk of electric shock. GFCI protection commonly appears at receptacles serving damp areas, outdoor locations, kitchens, bathrooms, garages, and unfinished spaces.
Also called: Ground-fault circuit interrupter
A Hot Tub Disconnect is a dedicated switching device that separates a hot tub’s electrical supply from the equipment. The disconnect provides a clear way to shut off power near the tub during servicing or an emergency. It connects the branch circuit to the spa equipment while allowing the circuit to be opened locally.
Also called: Spa disconnect
Junction Box is an electrical enclosure that protects and contains wire connections where circuit conductors meet, split, or change direction. The box keeps splices accessible for inspection and repair while shielding connections from physical damage. Covers, cable fittings, and approved connectors help keep the enclosure secure and organized.
Also called: Electrical junction box
A landscape transformer is a device that changes standard electrical power into lower-voltage power for outdoor lighting. The transformer connects to a home circuit and supplies controlled power through landscape lighting cable. Many models include timers, photocells, or manual controls that manage when connected lights operate.
Also called: Low-voltage lighting transformer
LED Color Temperature is a lighting characteristic that describes the apparent warmth or coolness of white light. The scale relates light appearance to the color of heated material, with lower values appearing warmer and higher values appearing cooler. Color temperature helps you select LED lamps that suit a room’s purpose, finishes, and existing lighting.
Also called: Color temperature
Load Calculation is a method for estimating the electrical demand a property places on its service and distribution equipment. The method accounts for existing circuits, fixed appliances, heating and cooling equipment, and planned additions. The result helps determine whether an electrical panel has suitable capacity for safe, reliable operation and future connected loads.
Also called: Electrical load calculation
Motion Sensor is a device that detects movement within a defined area and sends a signal to control lighting or another connected system. The device may sense changes in infrared energy, microwave reflection, or both. In security lighting, detection can turn a light on when a person, vehicle, or animal enters its coverage area.
Also called: Occupancy sensor
Neutral Wire is the circuit conductor that carries electrical current back toward the source after current passes through a load. It normally connects to the neutral bus in an electrical panel and completes the circuit with a hot wire. Neutral wires are commonly identified by white or gray insulation, although identification must be verified.
Also called: Neutral conductor
A photocell is a light-sensitive electrical control that switches outdoor lighting on or off according to surrounding brightness. The device responds to daylight and darkness, allowing fixtures to operate without a manual switch or scheduled timer. Photocells are common in security lighting, exterior wall packs, post lights, and other applications that need automatic dusk-to-dawn operation.
Also called: Photoelectric sensor
Pool Bonding is an electrical connection between conductive parts of a pool system that helps keep those parts at a similar voltage. The bonding network may connect metal equipment, structural components, piping, and other conductive surfaces. Pool bonding differs from grounding because bonding equalizes voltage between connected parts, while grounding provides a path for fault current.
Also called: Equipotential bonding grid
Raceway is a protective pathway that contains and routes electrical conductors, cables, or other wiring. A raceway may be rigid or flexible and may be made from metal or insulating material. It can protect wiring from physical damage, organize circuits, and support cleaner installations in commercial buildings, equipment areas, and service spaces.
Recessed Housing is the enclosure installed inside a ceiling to hold a recessed light, its lamp or LED module, and related electrical parts. The housing supports the fixture, protects connections, and provides the mounting structure above the finished ceiling. Housing type must match the ceiling, light source, and installation conditions.
Also called: Can light housing
Recessed Light Trim is the visible finishing part installed around a recessed light opening. It covers the edge of the ceiling cutout and shapes how the fixture looks from below. Trim may also control glare, direct light, or seal the opening, depending on its design and compatibility with the recessed housing.
Also called: Can light trim
A service drop is the overhead electrical connection that carries utility power from a pole or other utility support to a building’s service point. It includes the conductors and supporting components that cross the space between the utility system and the premises. The utility typically owns the service drop, while the property owner maintains connected equipment.
Also called: Overhead service drop
A standby generator is a permanently installed backup power system that supplies electricity when utility service fails. The unit connects to selected building circuits through a transfer switch. It starts automatically after detecting an outage, then stops when utility power returns. Standby generators commonly support essential loads such as heating equipment, refrigeration, lighting, and communication devices.
Also called: Whole-house generator
A Surge Protector is a device that limits short voltage spikes and directs excess electrical energy away from connected equipment. A surge protector may be installed at an outlet for one appliance or at an electrical panel for broader protection. It helps reduce damage from switching events and disturbances on the power system.
Also called: Surge suppressor
A Tamper-Resistant Receptacle is an electrical outlet with internal shutters that block access to the energized contact openings unless a matching plug applies pressure to both openings at once. The design helps prevent objects from entering one opening alone. These receptacles are commonly selected for areas where children may be present.
Also called: TR receptacle
A three-way switch is a control device that lets you operate one light or fixture from two separate wall locations. The switch does not work alone. It connects with another three-way switch through traveler wires, allowing either location to change the circuit’s state without requiring a separate switch for each fixture.
Transfer Switch is a device that moves selected electrical loads between a utility supply and a generator supply. The device prevents both sources from feeding the same circuits at once. A transfer switch may operate automatically when utility power fails or manually when a person moves the switch to the generator position.
Underground Conduit is a protective raceway installed below ground to carry and shield electrical conductors. The conduit may be rigid or flexible, metallic or nonmetallic, depending on the installation. It creates a defined path between electrical equipment and structures while helping protect wiring from soil, moisture, impact, and future excavation.
Also called: Buried conduit
Voltage Drop is the reduction in electrical pressure that occurs as current travels through a conductor, connection, or device. The reduction becomes greater when a circuit carries more load or has excessive resistance. Voltage drop can leave equipment receiving less voltage than its design requires, causing weak operation, flickering, heat, or nuisance shutdowns.
A Wire Nut is a twist-on connector that joins compatible electrical conductors inside an enclosure. Its threaded interior grips the stripped wire ends as the connector turns, creating a compact mechanical and electrical connection. Wire nuts come in different sizes and materials, so the connector must match the conductors and the connection's application.
Also called: Wire connector
Wire Size is the classification of a conductor’s diameter and current-carrying capacity. The selected size depends on the circuit’s load, conductor material, installation conditions, and allowable voltage drop. Correct sizing helps the wiring carry electrical current without excessive heating and supports reliable operation of connected equipment.
Also called: Conductor size
