Plain definitions of 35 terms we use on the job in Toledo.
Term Index
Open any term below for a dedicated definition page.
An AFCI is an arc-fault circuit interrupter that monitors electrical current for patterns linked to unintended arcing. When the device detects a dangerous arc pattern, it opens the circuit to stop power flow. AFCI protection helps address arcing conditions that ordinary overcurrent protection may not detect quickly.
Also called: Arc-Fault Circuit Interrupter
Arc Flash is a sudden electrical discharge through air between energized conductors or between a conductor and ground. The discharge creates intense heat, bright light, pressure, and molten metal that can damage equipment and injure people nearby. Arc flash usually results from an unintended path caused by equipment failure, contamination, or accidental contact.
Ballast is an electrical device that regulates current in certain lighting systems, especially fluorescent lamps. The ballast helps the lamp start and keeps its electrical output stable during operation. Without a compatible ballast, a fluorescent fixture may flicker, fail to start, produce uneven light, or damage the lamp and related components.
Bonding is the intentional connection of conductive metal parts so they share a continuous electrical path. The connection may include electrical enclosures, metal water piping, equipment grounding paths, and other accessible metal components. Bonding helps keep connected parts at a similar electrical potential and gives fault current a controlled path back to the source.
Busbar is a conductive metal strip or bar inside an electrical panel that distributes power to connected circuits. A busbar provides a shared electrical path and connects with circuit breakers, neutral terminals, or grounding terminals, depending on its purpose. Its design supports organized current distribution without relying on separate conductors for every connection.
A capacitor is an electrical component that stores and releases charge to control voltage or support motor operation. In a ceiling fan, the capacitor helps create the phase shift needed for the motor to start and run at selected speeds. Its capacitance and voltage rating must match the equipment design.
Circuit is a complete electrical path that carries current from a source through conductors and connected equipment, then back to the source. A circuit may include a breaker, switches, receptacles, lighting, or appliances. Its conductors and protective devices must match the connected electrical load and the wiring system’s design.
Conduit is a tube or channel that routes and protects electrical conductors. Electricians install conduit along walls, ceilings, underground paths, and other locations where wiring needs physical support or protection. Conduit may be metal or nonmetallic, and its fittings connect sections while helping create an orderly wiring path.
Copper Wire is a conductive electrical material used to carry current through circuits. Copper’s low electrical resistance allows power to move efficiently between panels, switches, outlets, fixtures, and equipment. Insulation surrounds the metal in most building wire, helping prevent contact with other conductors and nearby materials during normal operation.
Current is the flow of electric charge through a conductor, such as a wire or a circuit path. Electrical current moves when a voltage difference creates an electric field that pushes charged particles. The amount of current depends on the circuit’s voltage and resistance, and it is measured in amperes.
Also called: Amperage
A dimmer switch is a control device that adjusts the electrical power supplied to a compatible light fixture, allowing you to raise or lower light output. Unlike a standard switch, it provides a range of brightness settings. Proper operation depends on fixture compatibility, wiring configuration, and the type of lamp installed.
A disconnect switch is a device that opens an electrical circuit and separates equipment from its power source. The switch provides a clear way to stop power from reaching connected conductors during service work, equipment replacement, or an electrical system change. Disconnect switches may serve a panel, appliance, motor, or complete building service.
Also called: Safety Disconnect
Electrical load is the amount of electrical power that connected devices draw from a circuit or electrical system. The load changes as equipment starts, stops, or operates at different levels. Electricians assess load when planning wiring, selecting circuit protection, and deciding whether a dedicated circuit can serve equipment safely and reliably.
Also called: Load
An Electrical Meter is a device that measures the electrical energy supplied to a property. The meter records consumption for utility billing and helps identify the service capacity available to the building. It connects to the incoming electrical service and works with the service panel to distribute power safely throughout the property.
Also called: Electric Meter
A ground fault is an unintended electrical connection between an energized conductor and a grounded surface, equipment enclosure, or grounding path. This condition allows current to leave its planned circuit route. A ground fault can create shock and fire hazards, so protective devices such as GFCI receptacles help detect the imbalance and interrupt power.
Grounding is a connection between an electrical system and the earth or another conductive reference point that helps direct unwanted current away from people and equipment. The connection supports stable voltage, gives fault current a controlled path, and helps protective devices respond when insulation fails or energized parts contact metal.
Also called: Earthing
A Junction Box is an enclosed electrical container that protects and organizes wire connections where conductors join, split, or change direction. The box provides a secure space for splices and helps keep connections accessible for inspection and repair. Junction boxes may be metal or nonmetallic and must suit the wiring method and installation location.
Also called: Electrical Box
Line Voltage is the electrical potential supplied directly by a building’s branch circuit or service conductors. It powers equipment such as recessed lighting, receptacles, and appliances. The term distinguishes source power from low-voltage control or communication signals. Its actual value depends on the electrical system and the circuit supplying the connected load.
Also called: Mains Voltage
A load center is an electrical distribution enclosure that receives power from the service and routes it through circuit breakers to branch circuits. The enclosure contains busbars, breaker positions, and neutral and grounding connections. In many homes, people call the load center the electrical panel or breaker panel.
Also called: Breaker Panel
A neutral wire is a grounded circuit conductor that carries current back to the electrical service after current powers a connected load. It normally maintains near-zero voltage to ground, but it can carry current during operation. Neutral wires commonly connect receptacles, lights, and other line-to-neutral loads to the service panel.
Also called: Neutral Conductor
Ohm is the standard unit of electrical resistance, which describes how strongly a material or component opposes current flow. One ohm relates voltage and current through Ohm’s law. A resistor, heating element, wire, or damaged connection can each present resistance that affects how an electrical circuit operates.
Also called: Ω
Photocell is a light-sensitive electrical control that detects surrounding brightness and switches a connected lighting circuit on or off. In landscape lighting, a photocell commonly turns lights on at dusk and off when daylight returns. The device helps automate outdoor lighting without requiring a person to operate a wall switch.
Also called: Photoelectric Sensor
Power Surge is a sudden increase in electrical voltage that travels through wiring and connected equipment. The event may come from utility switching, lightning activity, or a fault within an electrical system. Excess voltage can stress or damage sensitive electronics, appliances, and control boards when protective devices do not divert the energy.
Also called: Voltage Surge
A receptacle is a wiring device that provides contact points for connecting electrical equipment to a circuit. Common household receptacles accept plugs and transfer current through connected conductors. A receptacle may include features such as grounding contacts, tamper resistance, or ground-fault protection, depending on its design and intended location.
Also called: Electrical Outlet
A Service Drop is the overhead electrical connection that carries utility power from a nearby distribution line to a building’s service equipment. It includes the conductors and their support points at the structure. The service drop connects the utility system with the customer-owned wiring that supplies the building.
A short circuit is an unintended path with very low resistance that allows electrical current to bypass the normal load. The sudden current increase can heat conductors, trip a circuit breaker, damage equipment, or create arcing. Short circuits commonly result from damaged insulation, loose connections, moisture, or contact between conductors.
Single-Phase Power is an alternating-current electrical supply in which voltage rises and falls in one repeating waveform. This arrangement serves many homes and small properties because it supports ordinary lighting, receptacles, appliances, and smaller mechanical equipment. The system typically includes energized conductors, a neutral path, and an equipment grounding path.
Also called: Single-Phase Electricity
A Surge Protector is an electrical device that limits excess voltage and redirects surge energy away from connected equipment. A whole-home surge protector installs at the electrical panel and helps protect circuits throughout a property. It differs from a basic power strip because it connects to the building’s electrical system and grounding path.
Also called: Surge Suppressor
Thermal Imaging is a noncontact inspection method that detects infrared energy and displays temperature differences as colors or patterns. An electrician uses a thermal camera to find unusual heat at electrical connections, breakers, conductors, and equipment. The images help identify areas that deserve closer testing, but they do not replace electrical measurements or visual inspection.
Also called: Infrared Inspection
A Three-Way Switch is a device that controls one light or lighting load from two separate locations. Unlike a standard single-pole switch, a three-way switch works with a second three-way switch through traveler wires. Common applications include hallways, stairways, and rooms with entrances at opposite sides.
Voltage is the electrical potential difference that creates pressure for current to move through a circuit. A voltage difference exists between two points, such as a conductor and a neutral path. The difference is measured in volts and helps determine whether equipment can receive the electrical energy it needs to operate.
Also called: Electrical Potential
A watt is a unit of power that describes how quickly electrical energy is used or produced. In electrical work, wattage shows the operating demand of a lamp, appliance, motor, or other load. A higher watt rating means the device uses or produces power at a faster rate under stated operating conditions.
Also called: W
Wire Gauge is a sizing system that describes a conductor’s diameter and its ability to carry electrical current. The gauge affects resistance, heat, voltage drop, and the type of circuit where a wire may be suitable. Proper selection must match the circuit’s load, conductor material, insulation, installation method, and protective device.
Also called: Wire Size
A wire nut is an insulated twist-on connector that joins compatible electrical conductors inside an electrical box or enclosure. The connector grips the wires through internal threads or a spring insert, creating a firm electrical path. Wire nuts come in different sizes and materials to match the conductors and connection.
Also called: Wire Connector
A wiring diagram is a visual plan that shows how electrical components connect within a circuit or system. Standard symbols represent devices such as switches, receptacles, breakers, and lights. Lines identify conductors and connection paths. Electricians read the diagram to trace circuits, verify intended connections, and locate wiring faults.
Also called: Circuit Diagram
