Minnesota Low Voltage Practice key terms

A circuit supplied by a listed power source that limits energy to levels safe for fire and electric shock, as defined by Article 725. It typically powers signaling, control, or communication equipment and has voltage and power limits set by its class designation.

A circuit supplied by a listed power source with energy limits higher than Class 2 but still restricted, per Article 725. Class 3 wiring methods and separation rules apply, and it is commonly used for control and signaling where more power is needed.

A circuit whose power source and wiring are listed and restricted so that fire and shock risk stay low, covered by Articles 725, 760, and 800 series. The power source listing, not the load, establishes the circuit classification.

The National Electrical Code article governing Class 1, Class 2, and Class 3 remote-control, signaling, and power-limited circuits. It sets power source listings, wiring methods, and separation requirements from power conductors.

The National Electrical Code article covering general requirements for communications circuits, including outside plant, grounding, and protection of communications cables. It addresses entrance, bonding, and separation from power conductors.

The National Electrical Code article for fire alarm systems, covering power-limited and non-power-limited fire alarm circuits, their wiring methods, and survivability requirements. It distinguishes NPLFA and PLFA circuits and governs pathway protection.

Non-power-limited fire alarm circuit, as defined in Article 760. It carries higher energy and requires specific wiring methods such as raceways or fire-rated cable, with stricter separation and survivability rules than power-limited fire alarm circuits.

Power-limited fire alarm circuit under Article 760, supplied by a listed power source with restricted energy. It permits listed fire alarm cable and has its own separation, support, and marking requirements.

The ability of a fire alarm circuit or pathway to continue functioning during a fire, achieved through circuit integrity methods such as listed fire-rated cable or raceways. Article 760 specifies where survivability is required, such as for notification and voice evacuation.

A listed device that limits surge energy on communications or signaling conductors entering a building, protecting personnel and equipment. It is installed at or near the point of entry and bonded to the grounding electrode system.

A listed device that provides a common point for bonding communications, CATV, and satellite system grounding conductors to the building grounding electrode system. It is required by Article 250 and simplifies intersystem bonding.

The conductor that connects the grounding electrode system to the service equipment or separately derived system grounded conductor. Article 250 sets its sizing based on the service or feeder conductor size and material.

The set of grounding electrodes and their bonding connections that establish a reference to earth, described in Article 250. It includes rods, pipes, plates, concrete-encased electrodes, and the metal water piping system, all bonded together.

The conductor that provides a low-impedance path from metal enclosures and equipment to the system grounding point, enabling overcurrent devices to clear ground faults. Its sizing and identification are governed by Article 250.

A conductor that ensures electrical continuity between metal parts that must be electrically connected, such as service equipment enclosures or grounding electrodes. Article 250 specifies sizes for main, equipment, and supply-side bonding jumpers.

A device such as a fuse or circuit breaker that automatically opens a circuit when current exceeds a set value, protecting conductors and equipment. Article 240 governs its rating, location, and application.

The maximum current a conductor can carry continuously under stated conditions without exceeding its temperature rating. It depends on conductor material, size, insulation, ambient temperature, and the number of current-carrying conductors in a raceway.

The process of reducing a conductor's ampacity to account for conditions such as elevated ambient temperature or multiple current-carrying conductors bundled in a raceway. Adjustment and correction factors are applied per Article 310 tables.

The reduction in voltage along a circuit caused by conductor resistance and reactance, which can impair equipment performance. It is calculated from current, conductor length, and resistance, and is limited by informational notes and design practice.

The relationship stating that voltage equals current multiplied by resistance, expressed as V = I × R. It underpins circuit calculations for loads, voltage drop, and fault current, and is applied throughout electrical design and troubleshooting.

A circuit in which current has only one path through all components, so the same current flows through each and total resistance is the sum of individual resistances. Voltage divides across the loads in proportion to resistance.

A circuit in which components are connected across the same two nodes, so each sees the same voltage while current divides among branches. Total resistance is less than the smallest branch resistance.

An enclosed channel designed to hold and protect conductors, such as conduit, tubing, or wireway. Article 300 and Chapter 3 articles set installation, support, fill, and bend requirements for each raceway type.

The percentage of a raceway's internal cross-sectional area occupied by conductors, limited by Chapter 9 tables to allow heat dissipation and pulling. It is determined from conductor dimensions and raceway trade size.

The required internal volume of an outlet, device, or junction box based on the number and size of conductors, devices, and fittings it contains. Article 314 provides volume allowances and tables used to calculate compliance.

An enclosure where conductors are spliced or connected to devices or raceways, providing protection and accessibility. It must remain accessible and be sized per Article 314 fill requirements.

The unobstructed space required in front of electrical equipment to permit safe examination and servicing, specified in Article 110. It includes depth, width, and height dimensions based on voltage and equipment conditions.

Acceptable to the authority having jurisdiction, as defined in Article 100. The term means the AHJ has determined that equipment or a method meets applicable standards, often through listing or field evaluation.

Equipment or materials included in a list published by a qualified testing organization that maintains periodic inspection and states the item meets designated standards. Listing is a key acceptance basis under Article 100 and Article 110.

Equipment or materials to which a qualified testing organization has attached a label indicating compliance with designated standards. Article 100 distinguishes labeling from listing, though listed items are typically also labeled.

A power source evaluated and marked by a testing organization for use with a specific class of circuit, such as Class 2 or PLFA. Its listing establishes the circuit classification and permitted wiring methods.

The organization, office, or individual responsible for enforcing the code and approving equipment, materials, and installations. In Minnesota, local building officials and the state electrical authority exercise this role.

The state board that licenses electricians, adopts electrical rules, and administers enforcement under Minnesota Statutes chapter 326B. It sets licensing categories, continuing education, and inspection authority for electrical work in the state.

A license issued to an individual electrician, such as a journeyman or master, authorizing that person to perform or supervise electrical work. Minnesota law distinguishes personal licenses from contractor and registration requirements.

Required credit hours a licensee must complete during each renewal cycle to maintain an active Minnesota electrical license. Hours must include specified code and safety topics and be documented with approved providers.

Written authorization from the enforcing authority to install or alter electrical work, required before work begins in most cases. It triggers inspection and must match the scope of the project and approved plans.

The distance from energized equipment within which a person could receive a second-degree burn from an arc flash. It is calculated from incident energy and defines where arc-rated PPE is required under NFPA 70E.

The amount of thermal energy per unit area that reaches a surface during an arc flash, expressed in calories per square centimeter. It determines PPE selection and the arc flash boundary under NFPA 70E.

Clothing made from materials that resist ignition and self-extinguish, with an arc rating sufficient for the calculated incident energy. NFPA 70E requires it for tasks where an arc flash hazard exists.

A document required by NFPA 70E before work on or near energized conductors outside the limits of approach, describing hazards, shock and arc flash risk, PPE, and justification for energized work.

A procedure for isolating energy sources and applying locks and tags so equipment cannot be re-energized during servicing. NFPA 70E and OSHA require it as part of establishing an electrically safe work condition.

The process of checking construction drawings and specifications against code and project requirements before construction. It identifies conflicts, missing information, and code issues early, and supports permit issuance.

A drawing revised after construction to record actual installed conditions, including routing, equipment locations, and changes. It supports closeout documentation, future maintenance, and record of deviations from design.

The process of quantifying materials, devices, and labor from drawings and specifications to prepare a bid or estimate. Accuracy depends on reading plans, schedules, and notes and accounting for waste and code-required items.

A list of incomplete or deficient work identified during inspection near project completion that must be corrected before final acceptance. It documents outstanding items and supports final payment and closeout.

Cable used for telephone, data, and similar signaling, classified by Article 800 by location and use, such as riser, plenum, or general purpose. Its marking and installation depend on the pathway and environmental rating.

Cable with a jacket and insulation rated for installation in air-handling spaces, meeting low smoke and flame spread requirements. It is marked CMP for communications or equivalent and may be used in plenums without conduit.

A vertical pathway between floors, such as a shaft or conduit run, where cable must meet flame propagation requirements for vertical installation. Riser-rated cable, marked CMR, is used in these locations.

A device that de-energizes a circuit when it detects a small current imbalance between conductors, protecting people from shock. Article 210 specifies locations and Article 406 covers receptacles with this protection.

Capable of being reached quickly for operation or inspection without climbing over obstacles or removing permanent parts, as defined in Article 100. It applies to equipment such as disconnects and overcurrent devices.

The enforcing authority's on-site verification that installed work complies with code, approved plans, and permit conditions. Minnesota requires inspections at stages such as rough-in and final, and work must be accessible for examination.