Arizona Low Voltage Practice key terms

The relationship stating that voltage equals current multiplied by resistance (E = I × R). It lets a technician predict how much current a circuit will draw at a given voltage and resistance, and it underlies every load calculation on a low voltage job.

The rule that electrical power in watts equals voltage multiplied by current (P = E × I). It is used to size power supplies, confirm that a device load stays within a circuit's capacity, and convert between amps and watts.

The loss of voltage along a conductor caused by its resistance, so the device at the far end receives less than the source supplies. Long, thin runs suffer most, which is why low voltage circuits specify maximum conductor length and minimum wire gauge.

The standard numbering system for conductor size in North America, where smaller numbers indicate larger conductors. Common low voltage sizes include 22, 18, 16, and 14 AWG, chosen based on current, distance, and voltage drop.

The maximum continuous current a conductor can carry safely without overheating, determined by its material, gauge, insulation rating, and installation conditions. Overloading a conductor beyond its ampacity creates fire and failure risk.

A circuit with only one path for current, so the same current flows through every component and the total resistance is the sum of the individual resistances. A break anywhere in the loop stops current to all devices.

A circuit with multiple current paths in which each branch receives the full source voltage and branches share the total current. Most low voltage device wiring is parallel so one failed device does not disable the others.

Electrical current that periodically reverses direction, typically 60 hertz in North American building power. AC powers equipment supplies and transformers, while many low voltage signaling and data circuits use direct current.

Current that flows in one direction at a steady polarity, supplied by batteries, rectifiers, and most low voltage power supplies. Access control, cameras, and alarm panels commonly operate on DC.

A listed power source that limits output voltage and current to levels considered safe for limited-energy circuits, allowing less restrictive wiring methods. Its label rating must match the load and must not be exceeded by added devices.

A fuse or circuit breaker that opens the circuit when current exceeds its rating, protecting conductors and equipment from damage or fire. Low voltage installers must not bypass, upsize, or substitute these devices without proper evaluation.

The conductor that connects the non-current-carrying metal parts of equipment to the grounding system, providing a low impedance path for fault current. It helps ensure a breaker trips rather than leaving metal enclosures energized.

The intentional permanent joining of metal parts to form an electrically conductive path that ensures electrical continuity. Proper bonding keeps all metal surfaces at the same potential, preventing shock and arcing between separated systems.

An unwanted current path created when equipment connects to ground at more than one point with differing potential. It causes hum, video interference, and data errors, and is corrected by bonding or isolation rather than by lifting safety grounds.

An unintended current path from an energized conductor to ground through a person, equipment, or moisture. It can cause shock or fire, and it is detected by equipment like ground fault circuit interrupters or monitored alarm circuits.

A device that trips when it senses a small imbalance between the outgoing and returning current, indicating current is leaking to ground. It protects people from shock and is required in many wet or outdoor locations.

A component that diverts brief high voltage spikes to ground before they reach sensitive electronics. It is commonly installed at service panels or at the head end to protect cameras, panels, and network gear from lightning and switching transients.

Cable with jacketing and insulation tested to limit flame spread and smoke production when installed in air-handling spaces. Code requires it above suspended ceilings used as return air paths, and substituting non-plenum cable there is a violation.

Cable designed to prevent flame from traveling vertically between floors in a shaft. It is used in vertical runs through floors where plenum-rated cable is not required, and it is marked accordingly on the jacket.

The method of securing cables at required intervals and within a specified distance of boxes and terminations. Proper support prevents strain on terminations, keeps cables orderly, and satisfies inspection requirements for exposed and concealed runs.

A rigid metal or nonmetallic raceway system that supports and routes cables, often overhead. It must be grounded where metal, and cables secured within it must follow fill, support, and separation requirements.

A hook-shaped hanger used to support bundles of low voltage cable from ceilings or structure without crushing or kinking them. Hooks are spaced per manufacturer and code limits and are preferred over staples for data and coaxial bundles.

The practice of keeping low voltage and line voltage conductors physically apart, or using barriers, to limit electromagnetic interference and shock risk. Required clearances vary by circuit class and must be maintained in raceways and boxes.

Unwanted electrical noise from motors, dimmers, power lines, or radio sources that degrades signals on low voltage conductors. It is reduced by shielding, twisting, distance from power wiring, and proper grounding practices.

Cable in which twisted conductor pairs are wrapped in a conductive foil or braid that drains interference to ground. The shield must be terminated correctly at one or both ends per design, or it can worsen noise and create ground loops.

Cable with twisted pairs but no conductive shield, relying on twisting and balance to reject noise. It is the standard medium for Ethernet and many voice and low voltage signal applications in commercial buildings.

Twisted pair cable graded by performance, such as Cat5e, Cat6, or Cat6A, for bandwidth and crosstalk. The category must match the application and be installed without sharp bends or over-tightening to preserve rated performance.

A certification test of the installed cabling run, excluding patch cords, measuring parameters such as insertion loss, crosstalk, and return loss. Passing results document that the link supports its rated category and are often required for acceptance.

Two standardized pin assignments for terminating eight-position modular jacks and plugs. Both work electrically, but a single project must use one consistently, and mixing them on the same cable creates a crossover failure.

A planned hierarchical cabling system with defined subsystems, media, and administration that supports voice, data, and other low voltage services. It separates cabling from equipment and makes moves, adds, and changes predictable and testable.

A dedicated space housing cross-connects, network equipment, and cable terminations for a floor or area. It requires controlled access, adequate power and cooling, and separation from electrical equipment and water hazards.

An alarm circuit that continuously monitors wiring integrity and reports opens, shorts, or ground faults to the control panel. Supervision ensures a damaged conductor produces a trouble signal instead of silently disabling protection.

The fire alarm circuit connecting detectors and manual pull stations to the control panel. It may be conventional or addressable, and its wiring class, style, and supervision determine how faults and alarms are reported.

The fire alarm circuit that powers horns, strobes, and speakers to warn occupants. It must be designed within voltage drop and synchronization limits so every appliance operates at its listed output.

A fire alarm architecture in which each device has a unique address, letting the panel identify the exact device in alarm or trouble. It reduces wiring runs and speeds troubleshooting compared with conventional zone circuits.

The card, fob, keypad code, or biometric identifier a person presents to request entry. Credential technology and encryption level determine how easily it can be cloned or spoofed, so selection is a security decision.

A lock that releases when power is removed, allowing free egress during fire or power loss. It is typically required on egress doors, in contrast to fail-secure locks that stay locked without power.

A lock that remains locked when power is removed, protecting the opening during outages. Because it can trap occupants, it is limited to doors where code permits and is usually paired with mechanical egress hardware.

A motion or push-button device that releases the electric lock from inside so occupants can leave without a credential. It supports free egress and must be installed so it reliably detects persons approaching the door.

A passive device that adapts an unbalanced signal, such as coaxial video, to balanced twisted pair and back again. It allows cameras or displays to use existing category cable instead of coax over moderate distances.

A technology that delivers both data and DC power over Ethernet cabling to devices such as cameras, phones, and access points. Power budget, cable length, and standards class must be verified so devices receive adequate wattage.

The state agency that licenses contractors, administers examinations, and enforces contracting rules and workmanship standards in Arizona. It investigates complaints and can discipline licensees, so knowing its requirements is part of lawful practice.

An Arizona contractor classification authorizing the holder to contract for specified low voltage work within defined scope limits. Performing or offering that work without the proper license can lead to citations, fines, and loss of payment rights.

A narrow statutory exception allowing certain work, such as some minor or owner-performed tasks, without a contractor license. Exemptions are interpreted strictly, and assuming one applies when it does not is a common violation.

A safety procedure that isolates energy sources and applies locks and tags so equipment cannot be re-energized during work. It protects technicians servicing panels, motors, and circuits from unexpected startup or release of stored energy.

Worn gear such as safety glasses, gloves, hard hats, and arc-rated clothing that reduces injury from electrical, fall, and physical hazards. Selection must match the task's identified hazards and the voltage involved.

Correct selection, setup, and use of ladders, including the four-to-one angle for extension ladders and three-point contact while climbing. Many low voltage injuries come from falls, so inspection and placement rules are exam-relevant safety content.