Hawaii Low Voltage Practice key terms

A wiring system operating at a nominal voltage low enough to fall outside the scope of standard power-circuit rules, commonly signaling, communications, control, and alarm circuits rated up to about 50 volts.

A circuit supplied by a listed power source with voltage and power output limited so that any fire risk is reduced and electric shock hazard is minimal under normal conditions, typically used for signaling and control.

A circuit supplied by a listed source whose voltage and current limits are higher than Class 2 but still power-limited, allowing more energy for control and signaling loads while keeping fire and shock risk controlled.

A circuit whose source is rated or listed to limit available power to a defined maximum, so that conductors and equipment may be installed under reduced requirements compared with general-purpose power wiring.

An approved power source, marked with its class and ratings, that has been tested by a recognized laboratory to confirm its output stays within the voltage and current limits for the circuit class it feeds.

A listed cable assembly rated for use on Class 2 circuits, marked with its class rating and suitable for installation in walls and other permitted locations per its listing and the applicable code article.

A listed cable assembly rated for Class 3 circuits, generally carrying a higher voltage or current rating than CL2 cable and permitted in similar pathways where its listing and code rules allow.

Cable with a jacket and insulation rated for installation in air-handling spaces, marked CMP or equivalent, so that smoke and flame spread characteristics meet the stricter requirements for ducts and plenums.

Cable rated for vertical runs between floors in a shaft, marked CMR or equivalent, with flame-propagation characteristics suited to riser applications but not necessarily approved for plenum spaces.

The printed legend on a cable jacket identifying its class, temperature rating, flame rating, and listing, which the installer uses to verify the cable is suitable for the intended location and circuit.

A nationally recognized testing laboratory, such as UL or ETL, that evaluates products against published safety standards and lists them, giving the authority having jurisdiction a basis for accepting the equipment.

The authority having jurisdiction, meaning the organization or official responsible for approving equipment, installations, and enforcement of the electrical code in a given area, often a county or city electrical inspector.

A formal authorization issued by the local building or electrical department allowing specified low-voltage work to proceed, usually requiring a scope description, fees, and inspection before the work is closed up.

The official review of installed low-voltage work by the authority having jurisdiction to confirm code compliance, often performed in stages such as rough-in before concealment and final after completion.

The stage of installation where boxes, raceways, and cable are placed inside walls and ceilings before finishes are applied, allowing inspection and later termination of devices and panels.

The percentage of a raceway's internal cross-section occupied by conductors or cable, kept below code limits so that cables can be pulled without damage and heat can dissipate properly.

An accessible enclosure placed in a raceway run to allow conductors to be pulled, spliced, or redirected, sized so that bends and pulling tension stay within acceptable limits for the cable type.

The minimum curve radius a cable or raceway may be bent without damaging conductors, insulation, or shielding, usually expressed as a multiple of the cable's outside diameter by the manufacturer.

The method and spacing of fasteners, straps, or hangers that hold cable in place, preventing sag, strain on terminations, and abrasion while meeting code and manufacturer requirements for the cable type.

A curved metal hanger used to carry bundles of low-voltage cable overhead, chosen in a size that keeps the bundle from sagging and avoids pinching or exceeding the cable's bend radius.

A rigid metal or nonmetallic raceway system of side rails and rungs that supports and routes cables, requiring proper bonding, fill limits, and support spacing according to its listing and code rules.

The intentional electrical connection of metal parts to establish a low-impedance path, ensuring exposed metal in a low-voltage system stays at the same potential and does not carry stray current.

A connection, direct or through a conductor, between an electrical system or equipment and the earth or a conductive body that serves as the reference, used to limit voltage and provide a fault path.

A conductive object such as a rod, plate, or pipe in direct contact with the earth that provides the connection point for a grounding conductor and helps dissipate fault or surge current.

A device installed on low-voltage circuits to divert transient overvoltages from lightning or switching to ground, protecting sensitive electronics and communications equipment from damage.

The required physical spacing or barrier between low-voltage cables and power conductors so that electrical noise, heat, or fault energy from power wiring does not couple into or damage the low-voltage system.

Electromagnetic interference, unwanted electrical noise radiated or conducted from power wiring, motors, or radio sources that can corrupt low-voltage signals unless cables are shielded, twisted, or separated.

Two insulated conductors twisted together so that induced noise cancels, commonly used for communications and signaling because it improves immunity to interference and reduces emissions.

Cable with a metallic foil or braid around the conductors that intercepts interference, requiring proper termination of the shield at one or both ends to be effective without creating ground loops.

An unwanted current path created when equipment is connected to ground at more than one point at different potentials, producing noise or hum in low-voltage signal and audio systems.

A twisted-pair cable rated by performance category, such as Cat 5e, Cat 6, or Cat 6A, specifying bandwidth and crosstalk limits for data and communications cabling installations.

A rack-mounted assembly of ports where horizontal cabling is terminated and cross-connected to network equipment, providing a manageable and labeled point for moves, adds, and changes.

A terminal block with slotted contacts into which solid conductors are pressed with a tool, used to terminate and cross-connect communications cabling in telecom rooms and distribution frames.

A standardized layout of cabling subsystems, including entrance, backbone, horizontal, and work-area segments, designed to support multiple low-voltage services with consistent components and administration.

A drawing revised after installation to show the actual routing, device locations, and terminations of the low-voltage system, used for future maintenance, testing, and inspection records.

A low-voltage circuit connecting initiating devices, notification appliances, or control equipment in a fire alarm system, subject to additional code and listing requirements beyond general signaling rules.

Monitoring of a low-voltage circuit or device by the control panel so that an open, short, or fault condition is detected and annunciated, rather than silently disabling the system.

A device such as a horn, strobe, or speaker that produces audible or visible alarm signals, connected on a low-voltage circuit designed and supervised to operate reliably during an emergency.