Idaho Low Voltage Practice key terms

All circuit conductors between the service equipment, source of power, or separately derived system and the final branch-circuit overcurrent device. Feeders carry power to panelboards or subpanels rather than directly to outlets.

The circuit conductors between the final overcurrent device protecting the circuit and the outlet or outlets it serves. Low-voltage and communications work often runs as branch circuits from a panel or power supply.

The conductors from the service point to the service disconnecting means. They are the utility-supplied lines feeding a building's service equipment and differ from feeders and branch-circuit conductors.

The necessary equipment, usually a switchboard or panelboard with disconnects and overcurrent devices, connected to the load end of service conductors. It is the main control and cutoff point for a building's supply.

A device such as a fuse or circuit breaker that opens a circuit when current exceeds a safe value. It protects conductors and equipment from overheating caused by overloads, short circuits, or ground faults.

The maximum current, in amperes, a conductor can carry continuously under stated conditions without exceeding its temperature rating. Ampacity depends on conductor size, insulation type, and ambient temperature.

The required reduction of a conductor's base ampacity when several current-carrying conductors share a raceway or cable, or when ambient temperature is high. It prevents overheating where heat cannot dissipate freely.

The loss of voltage along conductors caused by their resistance and reactance as current flows. Excessive drop reduces equipment performance and is limited by good design practice, not by a mandatory Code maximum.

The relationship stating that voltage equals current multiplied by resistance (E = I x R). It is the basis for calculating current, voltage, and resistance in circuits and for sizing conductors and loads.

The relationship for electrical power in a resistive circuit: watts equal volts times amperes (P = E x I). In alternating-current circuits, power factor relates true power to apparent volt-amperes.

A intentional connection to earth or to a conductive body that serves as a reference. Grounding limits voltage from lightning, line surges, or faults and stabilizes system voltage to earth.

The permanent joining of metal parts to form an electrically conductive path that ensures electrical continuity. Bonding equalizes potential so fault current can return and trip the overcurrent device.

The conductive path installed to connect normally non-current-carrying metal parts of equipment to the system grounded conductor or grounding electrode. It carries fault current and facilitates overcurrent device operation.

A conductive object such as a rod, pipe, plate, or building steel that is in direct contact with the earth. It provides the earth connection for a grounding electrode system.

The conductor that connects the grounding electrode system to the grounded conductor or equipment grounding conductor at the service or source. It provides the path between the system and earth.

A reliable conductor that ensures electrical conductivity between metal parts required to be electrically connected. It may be a supply-side, main, equipment, or system bonding jumper depending on its location.

A device that de-energizes a circuit within a set time when current to ground exceeds a threshold well below the level needed to trip a standard breaker. It protects people from electric shock.

A device that recognizes characteristic arcing in a circuit and opens it to prevent fire. It is required in many dwelling-unit branch circuits, such as bedrooms and living areas, under the Code.

An enclosed channel designed for holding wires, cables, or busbars, such as conduit, tubing, or wireway. Raceways support and protect conductors and must be installed as a complete system.

The percentage of a raceway's interior cross-sectional area occupied by conductors. The Code limits fill so conductors can be pulled without damage and heat can dissipate.

An enclosure providing space for conductors, splices, devices, and fittings at outlets and junctions. Boxes must be sized for the number and size of conductors and for the devices they contain.

The calculation of required box volume based on the number of conductors, devices, fittings, and equipment grounding conductors present. Each item is assigned a volume allowance to ensure adequate space.

A surrounding case or housing that protects equipment from accidental contact and environmental exposure. Enclosures are rated for indoor or outdoor use and for specific conditions such as moisture or dust.

A circuit with limited power and voltage, typically used for low-voltage control, signaling, or communications. Its power limitation reduces fire and shock hazards, allowing less restrictive wiring methods.

A circuit with higher voltage or power limits than a Class 2 circuit but still restricted to reduce hazard. It is used for signaling and control where greater energy is needed than Class 2 permits.

A circuit that carries signals such as voice, data, video, or alarm information rather than power. Communications circuits have their own wiring-method rules and separation requirements from power circuits.

The requirement to keep power conductors and low-voltage or communications conductors physically apart, or to use barriers or approved cable, to prevent voltage from being imposed on the low-voltage system.

A device or group of devices that can disconnect a circuit or equipment from its source of supply. It allows safe servicing and is required at service equipment and for many individual pieces of equipment.

The clear area in front of electrical equipment that must be kept free for safe operation and maintenance. Its depth and width depend on voltage and equipment, and it may not be used for storage.

A safety procedure in which energy sources are physically locked and tagged to prevent accidental energization during servicing. It protects workers from shock and unexpected startup of equipment.

Clothing and gear such as insulated gloves, eye protection, and arc-rated clothing worn to reduce injury from electrical, thermal, and physical hazards. It is selected based on the task and hazard level.

A sudden release of energy caused by an electric arc between conductors or from a conductor to ground. It can produce intense heat, light, and pressure, causing severe burns and equipment damage.

A location with unique conditions requiring modified Code rules, such as garages, places of assembly, hazardous areas, or health-care facilities. Requirements may change wiring methods, materials, or protection.

Equipment with distinct construction or operation that requires specific Code articles, such as motors, generators, signs, or elevators. Its installation rules supplement or modify the general requirements.

An area where fire or explosion hazards may exist because of flammable gases, vapors, dusts, or fibers. Equipment and wiring must be approved for the class, division, or zone classification of the area.

A license issued by the state that authorizes a business to engage in electrical contracting in Idaho. It is separate from an individual electrician's license and requires a qualifying party and registration.

An individual who meets experience and examination requirements and is designated by a licensed contractor to supervise its electrical work. The qualifying party must be actively involved in the business.

A person learning the electrical trade under supervision while accumulating the hours needed for a journeyman license. Apprentices may perform only work permitted by law and under required supervision.