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Idaho Low Voltage Practice practice questions

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Question 1National Electrical Code (NEC) general requirements and definitions

Under NEC Article 100, which conductor is defined as a conductor that normally carries current but is not a grounded conductor or a grounding conductor?

  1. A bonding jumper
  2. An equipment grounding conductor
  3. An ungrounded conductor Correct answer.
  4. A grounding electrode conductor

Explanation

Article 100 defines an ungrounded conductor as a current-carrying conductor that is not intentionally connected to ground. Grounded conductors and grounding conductors are excluded from that definition. The term is central to identifying hot legs in low-voltage circuits.

Question 2National Electrical Code (NEC) general requirements and definitions

NEC Article 100 defines an approved product as one that is acceptable to the authority having jurisdiction. Which statement best describes how acceptability is normally established?

  1. Acceptance requires a written waiver from the utility
  2. The installer's field testing alone establishes acceptability
  3. The AHJ may accept listed equipment or evaluate unlisted equipment by other means Correct answer.
  4. Only equipment built to a manufacturer's internal standard is acceptable

Explanation

Article 100 states that acceptable equipment may be listed by a qualified testing laboratory or may be judged acceptable by the AHJ through other means. Listing is one path, not the only path. Field testing by the installer is never the basis of approval.

Question 3National Electrical Code (NEC) general requirements and definitions

A low-voltage contractor is installing Class 2 cabling in a commercial building. Which NEC chapter contains the general requirements for wiring methods that apply across the code?

  1. Chapter 1 Correct answer.
  2. Chapter 3
  3. Chapter 7
  4. Chapter 5

Explanation

Chapter 1 contains definitions, general requirements, and the fundamental rules that govern all installations. Chapter 3 covers wiring methods and materials, Chapter 5 covers special occupancies, and Chapter 7 covers special conditions. General requirements therefore sit in Chapter 1.

Question 4National Electrical Code (NEC) general requirements and definitions

When the NEC uses the word "shall," what does that term indicate about a requirement?

  1. It is an informational note only
  2. It is a permission granted to the AHJ
  3. It is a mandatory requirement Correct answer.
  4. It is a recommendation the installer may follow

Explanation

The NEC uses "shall" for mandatory requirements and "may" for permissive provisions. Informational notes are non-mandatory explanatory material. Recognizing this distinction is essential when reading any article.

Question 5National Electrical Code (NEC) general requirements and definitions

A low-voltage circuit is described as a branch circuit. Under Article 100, which characteristic distinguishes a branch circuit from a feeder?

  1. It extends from the final overcurrent device to the outlets served Correct answer.
  2. It connects the service point to the utility transformer
  3. It carries current only during emergencies
  4. It is always a grounded conductor

Explanation

A branch circuit runs from the final overcurrent protective device protecting the circuit to the outlet or outlets it serves. A feeder instead supplies a panelboard or similar distribution point downstream of the service. This boundary determines which rules apply.

Question 6National Electrical Code (NEC) general requirements and definitions

An installer runs a low-voltage cable through a bored hole in a floor joist. Which NEC concept most directly governs whether the wiring method is permitted in that location?

  1. The color of the conductor insulation
  2. The ampacity of the utility service
  3. The size of the building's service disconnect
  4. The listing and suitability of the wiring method for the environment Correct answer.

Explanation

NEC general requirements emphasize that equipment and wiring methods must be listed and suitable for the conditions of use. Location factors such as dampness, physical protection, and exposure determine suitability. Conductor color and service size do not decide whether a wiring method may be used in a given location.

Question 7National Electrical Code (NEC) general requirements and definitions

Per NEC general requirements, what is the primary purpose of identifying grounded conductors in a low-voltage system?

  1. To distinguish them from ungrounded and grounding conductors Correct answer.
  2. To eliminate the need for equipment bonding
  3. To reduce the number of overcurrent devices needed
  4. To increase the circuit voltage

Explanation

The NEC requires grounded conductors to be identifiable so they can be distinguished from ungrounded and grounding conductors throughout the system. Identification supports safe terminations and maintenance. It does not change voltage or remove bonding obligations.

Question 8National Electrical Code (NEC) general requirements and definitions

A designer is evaluating a low-voltage installation and must confirm the equipment is listed. What does the term "listed" mean under Article 100?

  1. The equipment is included in a list published by a qualified testing laboratory Correct answer.
  2. The equipment has been field-modified by the installer
  3. The equipment has passed the utility's interconnection study
  4. The equipment meets a local building department's design preference

Explanation

Article 100 defines listed as equipment included in a list published by an organization acceptable to the AHJ that maintains periodic inspection of production. Listing involves third-party evaluation, not field modification. Local design preferences and utility studies are separate matters.

Question 9National Electrical Code (NEC) general requirements and definitions

Which NEC chapter would an installer consult for rules on special conditions such as emergency and standby power systems that may affect low-voltage work?

  1. Chapter 6
  2. Chapter 7 Correct answer.
  3. Chapter 2
  4. Chapter 4

Explanation

Chapter 7 addresses special conditions, including emergency systems, legally required standby systems, and optional standby systems. Chapter 2 covers wiring and protection, Chapter 4 covers equipment for general use, and Chapter 6 covers special equipment.

Question 10National Electrical Code (NEC) general requirements and definitions

A technician is asked to verify that a low-voltage power supply is suitable for the environment. Which NEC general requirement is most relevant to that determination?

  1. Equipment must use only aluminum conductors
  2. Equipment must be installed in accordance with its listing and labeling Correct answer.
  3. Equipment must be painted to match the building interior
  4. Equipment must be supplied by the utility at medium voltage

Explanation

The NEC requires equipment to be installed and used in accordance with any instructions included in its listing or labeling. That includes environmental ratings such as damp or wet location suitability. Cosmetic, voltage, and conductor-material conditions are not general requirements.

Question 11National Electrical Code (NEC) general requirements and definitions

Under Article 100, what is an "outlet" in a low-voltage wiring system?

  1. The service disconnect enclosure
  2. The grounding electrode itself
  3. A point on the wiring system where current is taken to supply utilization equipment Correct answer.
  4. Only a receptacle where a plug is inserted

Explanation

An outlet is any point on the wiring system at which current is taken to supply utilization equipment. It is broader than a receptacle and includes luminaires, appliances, and hard-wired equipment connections. Service equipment and grounding electrodes are separate concepts.

Question 12National Electrical Code (NEC) general requirements and definitions

A low-voltage installer is selecting a raceway for a damp location. Which NEC general principle best guides the choice?

  1. The raceway must be the largest size available
  2. The raceway must be listed and suitable for the location Correct answer.
  3. The raceway must be metallic in all cases
  4. Any raceway may be used if it is painted

Explanation

General requirements direct that wiring methods and equipment be listed and suitable for the environment in which they are installed. Damp locations call for methods rated for that condition. Size and metal content do not by themselves establish suitability.

Question 13National Electrical Code (NEC) general requirements and definitions

What does the NEC term "grounded" mean when applied to a conductor?

  1. The conductor is intentionally connected to earth Correct answer.
  2. The conductor is uninsulated
  3. The conductor carries no current at any time
  4. The conductor is always the largest in the raceway

Explanation

A grounded conductor is one that is intentionally connected to earth, typically the neutral of a grounded system. It is distinct from the equipment grounding conductor and normally carries current. Insulation status and conductor size are unrelated to the definition.

Question 14National Electrical Code (NEC) general requirements and definitions

An inspector cites a low-voltage installation for using equipment that is not approved. Which party ultimately makes the acceptability determination under Article 100?

  1. The authority having jurisdiction Correct answer.
  2. The general contractor
  3. The electrical worker's union
  4. The manufacturer's sales representative

Explanation

Article 100 defines approved as acceptable to the authority having jurisdiction. The AHJ is the entity that determines acceptability, whether through listing or other means. Manufacturers, contractors, and unions do not hold that authority.

Question 15National Electrical Code (NEC) general requirements and definitions

A designer needs to know which article of the NEC contains general requirements for overcurrent protection that apply to low-voltage circuits. Which chapter houses those general protection rules?

  1. Chapter 8
  2. Chapter 2 Correct answer.
  3. Chapter 9
  4. Chapter 5

Explanation

Chapter 2 contains Article 240 on overcurrent protection along with general wiring and protection rules. Chapter 5 covers special occupancies, Chapter 8 covers communications systems, and Chapter 9 contains tables. General overcurrent rules therefore fall in Chapter 2.

Question 16National Electrical Code (NEC) general requirements and definitions

Under Article 100, which term describes a conductor that connects normally non-current-carrying metal parts of equipment to the system grounding conductor?

  1. Service conductor
  2. Equipment grounding conductor Correct answer.
  3. Ungrounded conductor
  4. Grounded conductor

Explanation

The equipment grounding conductor provides a path from normally non-current-carrying metal parts back to the grounding system. It normally carries no current except during a fault. Ungrounded and grounded conductors are circuit conductors, and service conductors supply the premises.

Question 17National Electrical Code (NEC) general requirements and definitions

A low-voltage job requires a junction box in a location subject to physical damage. Which NEC general requirement most directly applies?

  1. The box must be listed and protected from damage as required for the location Correct answer.
  2. The box must be transparent
  3. The box must be installed above eye level
  4. The box must contain only copper conductors

Explanation

General requirements call for listed equipment suitable for the environment and protected where subject to physical damage. The NEC does not require transparency, copper-only conductors, or a specific mounting height for junction boxes.

Question 18National Electrical Code (NEC) general requirements and definitions

Which statement correctly describes how the NEC treats informational notes?

  1. They apply only to utility-owned equipment
  2. They override the article text they accompany
  3. They are explanatory and not enforceable as code requirements Correct answer.
  4. They are mandatory rules enforceable by the AHJ

Explanation

Informational notes are explanatory material intended to help the user understand the code text. They are not mandatory requirements and cannot override the article they accompany. Enforcement rests on the mandatory text, not the notes.

Question 19National Electrical Code (NEC) general requirements and definitions

An installer is working with a low-voltage system and must identify the "service point" under Article 100. What does the service point mark?

  1. The point where the serving utility's conductors connect to the premises wiring Correct answer.
  2. The point where a junction box is installed
  3. The point where a receptacle is mounted
  4. The point where the grounding electrode is buried

Explanation

The service point is the point of connection between the serving utility and the premises wiring. It establishes where utility responsibility ends and premises wiring begins. Receptacles, electrodes, and junction boxes are not service points.

Question 20National Electrical Code (NEC) general requirements and definitions

A low-voltage contractor proposes to use a wiring method in a wet location that is listed only for dry locations. What is the correct NEC position?

  1. The method may be used if the run is short
  2. The method is not suitable because it is not listed for the conditions of use Correct answer.
  3. The method may be used if the AHJ does not inspect the job
  4. The method may be used if the voltage is below 30 volts

Explanation

General requirements require equipment to be suitable for the environment, and listing for dry locations does not extend to wet locations. Low voltage or short runs do not waive suitability. Avoiding inspection is never a code-compliant basis for installation.

Question 21National Electrical Code (NEC) general requirements and definitions

Which NEC chapter contains the rules for communications circuits, which often involve low-voltage cabling in buildings?

  1. Chapter 9
  2. Chapter 8 Correct answer.
  3. Chapter 3
  4. Chapter 5

Explanation

Chapter 8 covers communications systems, including the low-voltage cabling used for voice, data, and similar signals. Chapter 3 covers general wiring methods, Chapter 5 covers special occupancies, and Chapter 9 contains tables. Communications cabling rules thus fall in Chapter 8.

Question 22National Electrical Code (NEC) general requirements and definitions

Under Article 100, what distinguishes a "feeder" from a "service conductor"?

  1. A feeder carries current only during faults
  2. A feeder supplies a panelboard or similar point downstream of the service equipment Correct answer.
  3. A feeder is always installed underground
  4. A feeder is limited to Class 2 circuits

Explanation

A feeder is the circuit conductor between the service equipment or source and the final branch-circuit overcurrent device. Service conductors instead run from the service point to the service equipment. Fault-only operation, underground installation, and Class 2 limits are not distinguishing traits.

Question 23National Electrical Code (NEC) general requirements and definitions

A low-voltage installer must mark conductors so their function is clear at terminations. Which NEC general principle supports this practice?

  1. Grounded and grounding conductors must be identifiable Correct answer.
  2. Conductors must be color-coded by the manufacturer's preference
  3. Conductors must be labeled with the utility's account number
  4. Conductors must be marked with the building address

Explanation

The NEC requires grounded and grounding conductors to be identifiable so their function is clear at terminations and throughout the system. Manufacturer preference, utility account numbers, and building addresses are not the basis for conductor identification.

Question 24National Electrical Code (NEC) general requirements and definitions

An installer is unsure whether a low-voltage product must be listed to be installed. Which statement reflects the NEC general requirement?

  1. Listing is required only for utility-owned equipment
  2. Listing is required only where the code specifically requires it or the AHJ accepts it as the means of approval Correct answer.
  3. All low-voltage products must be listed without exception
  4. No low-voltage product may be listed

Explanation

The NEC requires listing where a specific article mandates it, and the AHJ may accept listed equipment as evidence of approval. A blanket listing requirement for all low-voltage products does not exist. Listing is not limited to utility-owned equipment.

Question 25Wiring methods and materials

In a low-voltage installation, what is the minimum permitted trade size of electrical metallic tubing (EMT)?

  1. 1/2 inch Correct answer.
  2. 1 inch
  3. 3/4 inch
  4. 3/8 inch

Explanation

The National Electrical Code permits EMT in trade sizes 1/2 through 4. The smallest standard trade size recognized for EMT is 1/2 inch, which is the practical minimum for a low-voltage raceway installation.

Question 26Wiring methods and materials

Which wiring method is generally required for low-voltage cabling installed in an exposed location subject to physical damage?

  1. Laying the cable in an open ceiling plenum
  2. Listed raceway or listed tubing protection Correct answer.
  3. Suspending the cable with cable ties
  4. Direct stapling to the building surface

Explanation

Cables that are exposed to physical damage must be protected, typically with a listed raceway, tubing, or other approved means. Staples, ties, or open plenum runs do not provide the mechanical protection the code requires where damage is likely.

Question 27Wiring methods and materials

What is the primary purpose of a listed plenum-rated cable in a low-voltage system?

  1. To limit smoke and flame spread in air-handling spaces Correct answer.
  2. To provide a direct burial rating for underground runs
  3. To serve as a grounding conductor for the equipment
  4. To increase the current-carrying capacity of the cable

Explanation

Plenum-rated cable is listed for installation in air-handling spaces because its jacket limits smoke generation and flame spread. It does not change ampacity, burial suitability, or grounding function.

Question 28Wiring methods and materials

A low-voltage cable is installed in a raceway that contains conductors of a Class 2 circuit and conductors of a power circuit. Which condition must be met?

  1. The Class 2 conductors may share the raceway if the cable is plenum rated
  2. The power conductors may share the raceway if the voltage is under 300 volts
  3. The Class 2 conductors must be separated by a barrier or installed in a separate raceway Correct answer.
  4. The power conductors may share the raceway if the total fill is under 40 percent

Explanation

Class 2 circuit conductors generally must be separated from power conductors by a barrier or run in a separate raceway to prevent inadvertent contact and voltage exposure. Voltage level, plenum rating, and conduit fill do not substitute for the required separation.

Question 29Wiring methods and materials

Which of the following is an acceptable method for supporting low-voltage cable in a finished ceiling?

  1. Looping the cable over ductwork
  2. Resting the cable on ceiling tile
  3. Listed cable supports or straps secured to the structure Correct answer.
  4. Taping the cable to a sprinkler pipe

Explanation

Low-voltage cable must be supported by listed straps, staples, or supports attached to the building structure. Ceiling tile, sprinkler pipe, and ductwork are not approved support surfaces because they are not structural and may be disturbed.

Question 30Wiring methods and materials

What type of raceway is commonly used for low-voltage wiring in concrete slabs where flexibility is not needed?

  1. Flexible cord
  2. Rigid metal conduit Correct answer.
  3. Liquidtight flexible metal conduit
  4. Electrical nonmetallic tubing

Explanation

Rigid metal conduit is a durable raceway often embedded in concrete for low-voltage wiring where a rigid path is desired. Flexible raceways and cords are not intended for direct burial in concrete pours.

Question 31Wiring methods and materials

A low-voltage cable passes through a metal stud. What protection is required?

  1. Nothing, because low-voltage cable is exempt
  2. A fire-rated sealant at the penetration
  3. A listed bushing or grommet to protect the cable from abrasion Correct answer.
  4. A grounding clip bonded to the stud

Explanation

Where cable passes through metal framing members, a listed bushing, grommet, or equivalent protection is required to prevent the sharp metal from abrading the jacket. Low-voltage cable is not exempt from physical protection at penetrations.

Question 32Wiring methods and materials

What is the minimum burial depth generally required for direct-buried low-voltage cable not under a driveway?

  1. 12 inches
  2. 6 inches Correct answer.
  3. 24 inches
  4. 18 inches

Explanation

Direct-buried low-voltage cable typically requires a minimum cover of 6 inches where it is not beneath a driveway or roadway. Deeper cover is required under driveways and streets.

Question 33Wiring methods and materials

Which of the following best describes the function of a raceway in a low-voltage wiring system?

  1. It provides a physical path and mechanical protection for conductors Correct answer.
  2. It replaces the need for equipment grounding
  3. It provides overcurrent protection for the circuit
  4. It boosts the signal strength of the low-voltage circuit

Explanation

A raceway encloses conductors and provides a physical path with mechanical protection. It does not amplify signals, replace grounding, or provide overcurrent protection.

Question 34Wiring methods and materials

A low-voltage cable is run parallel to a power circuit. What is the primary reason to maintain separation from the power conductors?

  1. To satisfy the plenum rating requirement
  2. To reduce electrical noise and avoid contact with higher voltage Correct answer.
  3. To increase the ampacity of the low-voltage cable
  4. To allow the use of smaller conduit

Explanation

Separating low-voltage signal cable from power conductors reduces electromagnetic interference and prevents accidental contact with higher voltage. It does not affect ampacity, plenum listing, or conduit sizing.

Question 35Wiring methods and materials

Which fitting is appropriate for connecting electrical metallic tubing in a wet location?

  1. A standard set-screw connector
  2. A plastic push-on connector
  3. A grounding bushing
  4. A listed raintight or wet-location fitting Correct answer.

Explanation

Connections in wet locations must use listed raintight or wet-location fittings to prevent water entry. Standard set-screw connectors, plastic push-on fittings, and grounding bushings are not rated for wet locations.

Question 36Wiring methods and materials

What is the maximum conduit fill, by conductor count, permitted for a single low-voltage cable in a raceway?

  1. The raceway may be filled to 100 percent
  2. There is no fill limit for low-voltage cable
  3. The fill must not exceed the percentage allowed for the conductor type and raceway Correct answer.
  4. The raceway may be filled to 80 percent

Explanation

Raceway fill must comply with the allowable percentage for the number and type of conductors, which prevents jamming and jacket damage during installation. A 100 percent or 80 percent fill is not generally permitted, and low-voltage cable is not exempt.

Question 37Wiring methods and materials

Which wiring method is suitable for low-voltage wiring in a hazardous (classified) location?

  1. Any plenum-rated cable
  2. Open wiring on insulators
  3. Flexible cord with a strain relief
  4. A wiring method listed and approved for the specific hazardous location Correct answer.

Explanation

In hazardous locations, the wiring method must be listed and approved for the specific class and division or zone. Ordinary plenum cable, flexible cord, and open wiring are not acceptable unless specifically listed for that environment.

Question 38Wiring methods and materials

What is the purpose of a firestop at a penetration where low-voltage cable passes through a fire-rated wall?

  1. To restore the fire-resistance rating of the penetrated assembly Correct answer.
  2. To increase the ampacity of the cable
  3. To bond the cable to the building ground
  4. To provide mechanical support to the cable

Explanation

A listed firestop system restores the fire-resistance rating of a wall or floor that has been penetrated. It does not provide support, bonding, or ampacity benefits.

Question 39Wiring methods and materials

A low-voltage cable is installed in an area where it will be exposed to sunlight. Which cable characteristic is required?

  1. A plenum rating
  2. A listing marked as sunlight resistant Correct answer.
  3. A coaxial construction
  4. A direct burial rating

Explanation

Cable exposed to direct sunlight must be listed and marked as sunlight resistant to prevent jacket deterioration from ultraviolet exposure. Plenum and burial ratings address different conditions, and coaxial construction is unrelated.

Question 40Wiring methods and materials

Which of the following is true about using flexible cord as a permanent wiring method for low-voltage equipment?

  1. Flexible cord is permitted only where specifically allowed for the application Correct answer.
  2. Flexible cord may be run through walls without protection
  3. Flexible cord may replace any raceway installation
  4. Flexible cord may be used as a substitute for permanent wiring in all cases

Explanation

Flexible cord is intended for pendants, appliances, and similar uses and is permitted only where the code specifically allows it. It may not replace permanent wiring methods or be run through walls without protection.

Question 41Wiring methods and materials

What is the minimum size of equipment grounding conductor generally required for a low-voltage circuit?

  1. A 22 AWG conductor
  2. The size specified by the overcurrent device and conductor sizing rules Correct answer.
  3. No grounding conductor is required for low voltage
  4. A 16 AWG conductor

Explanation

The equipment grounding conductor must be sized according to the overcurrent protection and the applicable conductor sizing rules. Arbitrary small sizes such as 22 or 16 AWG are not generally acceptable, and low-voltage circuits still require grounding where applicable.

Question 42Wiring methods and materials

Which type of raceway is best suited for routing low-voltage cable around obstructions where bends are frequent?

  1. Rigid metal conduit
  2. Rigid PVC conduit
  3. Electrical metallic tubing
  4. Flexible metal conduit Correct answer.

Explanation

Flexible metal conduit accommodates frequent bends and routing around obstructions more easily than rigid raceways. Rigid metal, rigid PVC, and EMT require more careful bending and fitting.

Question 43Wiring methods and materials

What does the marking on a low-voltage cable jacket typically indicate?

  1. The cable type, listing, and temperature rating Correct answer.
  2. The name of the installing contractor
  3. The exact length of the cable run
  4. The building address where it is installed

Explanation

Cable jacket markings identify the cable type, the listing agency, and the temperature and voltage ratings. They do not indicate run length, building address, or installer identity.

Question 44Wiring methods and materials

A low-voltage cable is installed in a raceway that is subject to different temperatures along its length. What must be considered?

  1. The ampacity and jacket rating must be suitable for the highest ambient temperature Correct answer.
  2. Temperature has no effect on low-voltage cable
  3. Only the average temperature matters
  4. The cable may exceed its temperature rating briefly

Explanation

Cable and raceway components must be rated for the highest ambient temperature they will encounter. Average temperature and brief excursions above the rating are not acceptable bases for selection.

Question 45Wiring methods and materials

Which of the following is required when low-voltage cable is installed in a suspended ceiling used as an air-handling space?

  1. The cable must be supported by the ceiling grid
  2. The cable must be direct buried
  3. The cable must be armored
  4. The cable must be listed for plenum use Correct answer.

Explanation

A suspended ceiling used for return air is an air-handling space, so the cable must be listed for plenum use. Armor, burial rating, and support by the grid are not substitutes for the plenum listing.

Question 46Wiring methods and materials

What is the purpose of a expansion fitting in a raceway run for low-voltage cable?

  1. To increase the number of conductors allowed
  2. To seal the raceway against water entry
  3. To provide a grounding connection
  4. To accommodate thermal expansion and contraction of the raceway Correct answer.

Explanation

Expansion fittings allow a raceway to move with thermal expansion and contraction without damaging the conduit or connections. They do not affect conductor count, grounding, or water sealing.

Question 47Wiring methods and materials

Which of the following describes a listed cable tray used for low-voltage cable?

  1. A type of junction box
  2. A device that provides overcurrent protection
  3. A support system that provides mechanical support and routing for cables Correct answer.
  4. A fitting that bonds the cable to ground

Explanation

Cable tray is a support system that carries and routes cables while providing mechanical support. It does not provide overcurrent protection, bonding, or act as a junction box.

Question 48Wiring methods and materials

A low-voltage circuit is installed in a location where the cable may be exposed to oil or chemicals. What should be selected?

  1. A cable with a direct burial rating
  2. A cable with a sunlight-resistant marking
  3. Any standard plenum cable
  4. A cable with a jacket listed as resistant to the specific exposure Correct answer.

Explanation

Where oil, chemicals, or other corrosive substances are present, the cable jacket must be listed as resistant to that specific exposure. Plenum, burial, and sunlight markings address different conditions.

Question 49Low voltage and communications circuits

Which type of cable is specifically listed for use in plenum spaces because of its low smoke and flame characteristics?

  1. CMG-rated cable
  2. CMX-rated cable
  3. CMR-rated cable
  4. CMP-rated cable Correct answer.

Explanation

Plenum-rated cable carries the CMP designation and is tested for low smoke production and flame spread in air-handling spaces. CMR is for risers, CMG is general purpose, and CMX is limited to residential and outdoor use.

Question 50Low voltage and communications circuits

A low voltage contractor is installing a Class 2 circuit in a commercial building. What is the primary purpose of limiting a circuit to Class 2 power levels?

  1. To allow the circuit to be installed without any overcurrent protection
  2. To permit the circuit to share conduit with power conductors
  3. To guarantee the circuit operates without any voltage drop
  4. To reduce the fire and electric shock hazard inherent to the circuit Correct answer.

Explanation

Class 2 designation is based on limiting the energy available under normal and fault conditions so that the fire and shock risk is low. This lower hazard level is what allows more flexible wiring methods and installation rules.