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North Carolina Low Voltage Practice practice questions

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Question 1Low Voltage Cabling Systems and Wiring Methods

When installing Cat 6 unshielded twisted pair cable in a commercial building, what is the maximum recommended horizontal cable length from the telecommunications outlet to the patch panel in the telecommunications room?

  1. 120 meters (394 feet)
  2. 150 meters (492 feet)
  3. 90 meters (295 feet) Correct answer.
  4. 45 meters (148 feet)

Explanation

The horizontal cabling channel is limited to a 90 m (295 ft) permanent link, with up to 10 m of combined patch cords for a 100 m total channel. This 90 m allowance covers the cable run from the work area outlet to the horizontal cross-connect in the telecommunications room.

Question 2Low Voltage Cabling Systems and Wiring Methods

Which cabling subsystem connects the main cross-connect in the equipment room to the horizontal cross-connects in the telecommunications rooms on each floor?

  1. Horizontal cabling
  2. Equipment cordage
  3. Backbone cabling Correct answer.
  4. Work area cabling

Explanation

Backbone cabling provides the interconnection between the main cross-connect, intermediate cross-connects, and horizontal cross-connects. It carries traffic between floors and buildings, distinct from the horizontal run that reaches individual outlets.

Question 3Low Voltage Cabling Systems and Wiring Methods

A technician is pulling Cat 6A cable through a conduit and must respect the cable's minimum bend radius. Which practice best protects the cable's electrical performance?

  1. Keep bends no tighter than the manufacturer's specified multiple of the cable diameter Correct answer.
  2. Bend the cable as tightly as needed as long as it does not kink
  3. Coil excess cable into a tight loop inside the conduit body
  4. Stretch the cable taut around corners to reduce slack

Explanation

Manufacturers specify a minimum bend radius, often expressed as a multiple of the cable's outside diameter, and exceeding it can distort the pair geometry and degrade return loss. Following the manufacturer's value preserves the cable's rated performance.

Question 4Low Voltage Cabling Systems and Wiring Methods

What is the primary purpose of the rip cord found inside a typical twisted pair cable jacket?

  1. To allow the jacket to be slit and removed without nicking the conductors Correct answer.
  2. To provide strain relief at the termination point
  3. To measure the cable length during installation
  4. To serve as a ground conductor for shielded systems

Explanation

The rip cord runs longitudinally under the jacket so an installer can slit the sheath and strip it back cleanly. This reduces the risk of damaging the insulation on the twisted pairs during termination.

Question 5Low Voltage Cabling Systems and Wiring Methods

When terminating an RJ-45 plug on a Cat 6 patch cord using the T568B wiring scheme, which conductor color occupies pin 1?

  1. White/orange Correct answer.
  2. White/green
  3. White/brown
  4. Blue

Explanation

In the T568B pinout, pin 1 is the white/orange conductor and pin 2 is orange, with green and blue pairs following the standard sequence. Consistency at both ends is essential for a working straight-through cord.

Question 6Low Voltage Cabling Systems and Wiring Methods

Which wiring method is generally required when low voltage communications cable is installed in a plenum ceiling space that serves as a return air path?

  1. Cable listed for plenum use Correct answer.
  2. Standard PVC-jacketed cable
  3. Any riser-rated cable
  4. Cable with no special listing

Explanation

Plenum spaces circulate return air throughout a building, so cables there must be listed for plenum use to limit smoke and flame spread. Standard PVC jackets are not acceptable in plenum air-handling spaces.

Question 7Low Voltage Cabling Systems and Wiring Methods

A crew is installing cable trays to support several bundles of low voltage cable above a suspended ceiling. What is the main benefit of using a cable tray rather than individual J-hooks in this location?

  1. It distributes cable weight and supports multiple bundles along a defined route Correct answer.
  2. It allows cable to be pulled without regard to bend radius
  3. It eliminates the need to bond the cable pathway
  4. It converts the cable into a plenum-rated assembly

Explanation

Cable trays provide continuous support for multiple cables and keep them on an organized route, reducing strain and sag. They also help maintain required bend radii and separation from other systems.

Question 8Low Voltage Cabling Systems and Wiring Methods

Which tool is specifically designed to terminate conductors onto the insulation displacement connectors of a keystone jack?

  1. Punch-down tool Correct answer.
  2. Crimping tool
  3. Tone generator
  4. Cable stripper

Explanation

A punch-down tool seats each conductor into the insulation displacement contact, cutting through the insulation to make the connection. It also trims the excess conductor in a single motion.

Question 9Low Voltage Cabling Systems and Wiring Methods

During a certification test, a permanent link measures a return loss value that fails the limit while insertion loss passes. Which condition most directly causes poor return loss?

  1. Excessive overall cable length
  2. High ambient temperature at the patch panel
  3. Impedance mismatches along the link Correct answer.
  4. Undersized conduit fill

Explanation

Return loss measures reflected signal energy caused by impedance discontinuities, such as poor terminations, kinks, or mismatched components. Length and temperature primarily affect insertion loss rather than reflection.

Question 10Low Voltage Cabling Systems and Wiring Methods

A technician must separate a run of unshielded twisted pair cable from a parallel run of 480 V motor feeders in a ceiling space. What is the most appropriate action?

  1. Wrap the low voltage cable in electrical tape and run it parallel to the feeders
  2. Bundle the low voltage cable directly against the feeders to save space
  3. Run the low voltage cable inside the same conduit as the feeders
  4. Maintain separation and cross the power feeders at right angles where crossing is unavoidable Correct answer.

Explanation

Keeping low voltage cable separated from power feeders reduces electromagnetic interference, and crossing at right angles minimizes coupling when paths must intersect. Bundling or sharing conduit with power conductors increases noise and may violate code.

Question 11Low Voltage Cabling Systems and Wiring Methods

An installer is choosing between solid and stranded twisted pair cable. Which application is stranded conductor cable best suited for?

  1. Permanent horizontal runs inside walls
  2. Patch cords that are flexed repeatedly Correct answer.
  3. Backbone runs between buildings
  4. Cable installed in concrete floor ducts

Explanation

Stranded conductors tolerate repeated flexing and movement, making them well suited for patch cords and equipment cords. Solid conductors offer lower attenuation and are preferred for permanent horizontal and backbone cabling.

Question 12Low Voltage Cabling Systems and Wiring Methods

A 25-pair copper cable must be terminated on a 110-type wiring block in a telecommunications room. What is the standard function of this block in a cross-connect?

  1. It converts optical signals to electrical signals
  2. It supplies power to active network equipment
  3. It provides a termination point for cross-connect jumper wires between cables Correct answer.
  4. It acts as a surge protector for outside plant cable

Explanation

A 110-type block terminates conductors and provides a field for cross-connect jumpers that interconnect cables or equipment. It is a passive connecting hardware component, not a signal converter or power source.

Question 13Low Voltage Cabling Systems and Wiring Methods

When installing fiber optic cable in an indoor riser, why must the cable's minimum bend radius be observed more strictly than with copper cable?

  1. Fiber jackets melt at room temperature
  2. Tight bends can cause light to escape the core and increase attenuation Correct answer.
  3. Fiber cable cannot be supported by J-hooks
  4. Fiber cable carries electrical current that must be contained

Explanation

Bending fiber beyond its minimum radius causes light to leak from the core, raising attenuation and possibly causing permanent damage. Copper relies on conductor geometry, while fiber performance is directly tied to the optical path.

Question 14Low Voltage Cabling Systems and Wiring Methods

A designer is specifying connectivity for a new horizontal run and wants to confirm the channel will support 10GBASE-T over the planned distance. Which cabling category is the minimum generally recognized for 10GBASE-T at 100 meters?

  1. Cat 5e
  2. Cat 3
  3. Cat 6
  4. Cat 6A Correct answer.

Explanation

Cat 6A is specified to support 10GBASE-T across the full 100 m channel, while Cat 6 is limited to shorter distances for that application. Cat 5e and Cat 3 do not meet 10GBASE-T requirements over the standard channel.

Question 15Low Voltage Cabling Systems and Wiring Methods

What is the purpose of a firestop system where a communications cable penetrates a rated fire wall?

  1. To restore the fire resistance rating of the penetrated assembly Correct answer.
  2. To increase the cable's data throughput
  3. To bond the cable shield to the building steel
  4. To provide a pathway for grounding the cable tray

Explanation

Firestopping seals the annular space around penetrating cables so the fire-resistance rating of the wall or floor assembly is maintained. It is a life-safety requirement and is separate from bonding or performance concerns.

Question 16Low Voltage Cabling Systems and Wiring Methods

An installer is dressing cables in a telecommunications rack and must route them from the patch panel to a switch. Which practice best supports proper cable management?

  1. Zip-tie bundles as tightly as possible for a neat appearance
  2. Coil slack into a tight bundle behind the switch
  3. Route cables diagonally across the rack to shorten the run
  4. Use hook-and-loop straps and maintain bend radius at the rack entry Correct answer.

Explanation

Hook-and-loop fasteners and attention to bend radius prevent deformation and allow future moves, adds, and changes. Over-tightening with zip ties can compress the pairs and degrade performance.

Question 17Low Voltage Cabling Systems and Wiring Methods

A technician is asked to identify which cable in a bundle carries a specific circuit. Which test instrument injects a signal on a conductor so it can be traced along its path?

  1. Megohmmeter
  2. Tone generator and probe Correct answer.
  3. Optical time domain reflectometer
  4. Cable certifier

Explanation

A tone generator applies an audible signal to a conductor and a probe detects it along the cable path, allowing identification within a bundle. This is a tracing function distinct from certification testing.

Question 18Low Voltage Cabling Systems and Wiring Methods

A technician must choose a pathway for a horizontal cable run through an area with no ceiling access and exposed structural steel. Which method is most appropriate for protecting the cable in this exposed location?

  1. Suspend the cable from a single wire across the span
  2. Drape the cable over ductwork
  3. Lay the cable directly on the steel beams
  4. Route the cable in a raceway or cable tray secured to the structure Correct answer.

Explanation

In exposed areas, a raceway or cable tray provides mechanical protection and organized support along the structure. Direct contact with steel, single-wire suspension, or draping over ducts does not provide adequate support or protection.

Question 19Low Voltage Cabling Systems and Wiring Methods

In a balanced twisted pair cable, what is the primary purpose of the twist in each pair?

  1. To provide a return path for DC power
  2. To reduce crosstalk and electromagnetic interference Correct answer.
  3. To make the cable easier to strip
  4. To increase the cable's tensile strength

Explanation

Twisting the two conductors of a pair causes induced noise and crosstalk to cancel, improving signal integrity. Different twist rates among pairs further reduce coupling between pairs within the same cable.

Question 20Low Voltage Cabling Systems and Wiring Methods

A shielded twisted pair cable is installed in an electrically noisy industrial area. What is required to make the shield effective?

  1. The shield must be bonded to ground at one or both ends per the system design Correct answer.
  2. The shield must be cut back entirely at the patch panel
  3. The shield must be connected to a phase conductor
  4. The shield must be left floating at both ends

Explanation

A shield only attenuates interference when it is properly bonded to ground according to the system design, providing a low-impedance path for induced currents. Leaving it floating or disconnecting it eliminates its effectiveness.

Question 21Low Voltage Cabling Systems and Wiring Methods

A certification report shows a horizontal link passing insertion loss but failing near-end crosstalk at the far end of the run. Which condition is the most likely cause?

  1. A crushed cable jacket near the middle of the run
  2. Excessive overall cable length
  3. High temperature along the cable path
  4. A poor termination or untwisted conductors at the far connector Correct answer.

Explanation

Near-end crosstalk failures often trace to terminations where too much pair untwist or poor contact allows signal to couple between pairs. Length, crushing, and temperature primarily affect attenuation rather than crosstalk at the connector.

Question 22Low Voltage Cabling Systems and Wiring Methods

An installer is pulling cable through a conduit that already contains several other cables and is approaching the maximum fill. What is the primary risk of exceeding the allowable fill?

  1. Improved crosstalk performance
  2. Increased difficulty of pulling that can damage cable and reduce heat dissipation Correct answer.
  3. Elimination of the need for firestopping
  4. Automatic conversion of the cable to plenum rating

Explanation

Overfilled raceways increase pulling tension and friction, which can stretch or damage conductors, and they reduce the ability to dissipate heat. Fill limits exist to protect both installation integrity and operating conditions.

Question 23Low Voltage Cabling Systems and Wiring Methods

A designer must route a backbone cable between two buildings on a campus. Which consideration most directly affects the choice of outside plant cable and its installation method?

  1. The color of the patch panels in each building
  2. Exposure to moisture, sunlight, and physical damage along the route Correct answer.
  3. The brand of the network switches
  4. The number of work area outlets in each building

Explanation

Outside plant cable must withstand environmental exposure such as moisture, UV radiation, and mechanical stress, which drives jacket material and installation method choices like conduit or aerial support. Interior aesthetics and equipment brands do not determine the cable's environmental rating.

Question 24Low Voltage Cabling Systems and Wiring Methods

During a site survey, a technician finds that a proposed horizontal pathway crosses a high-voltage feeder at a shallow angle. Why is crossing at a right angle preferred over a shallow angle?

  1. It changes the cable's category rating
  2. It allows the cable to be run without support
  3. It eliminates the need for firestopping at the crossing
  4. It reduces the length of cable exposed to coupling and minimizes induced interference Correct answer.

Explanation

A perpendicular crossing minimizes the parallel distance over which the interfering field can couple into the signal cable. Shallow-angle crossings create a longer coupled region and increase noise pickup.

Question 25Low Voltage Cabling Systems and Wiring Methods

A technician is installing a fiber distribution panel and must manage slack for future retermination. Which practice preserves optical performance while providing service loop?

  1. Cut the slack short to avoid any coiling
  2. Fold the slack back on itself and tape it flat
  3. Coil the slack into a loop no smaller than the cable's minimum bend radius and secure it Correct answer.
  4. Wrap the slack tightly around a small spool

Explanation

Service loops should be formed at a radius at or above the cable's minimum bend radius and secured without crushing. Tight coiling or folding creates small-radius bends that increase attenuation or break fibers.

Question 26Low Voltage Cabling Systems and Wiring Methods

A low voltage installer is selecting cable for a horizontal run above a suspended ceiling that is also used as an air-handling return-air plenum. Which cable jacket rating is normally required for this location?

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

Explanation

Cable installed in an environmental air-handling space must carry a plenum listing, designated CMP for communications cable. CMP cable uses low-smoke, low-flame-spread materials so a fire in the ceiling void does not distribute smoke and flame through the building air system.

Question 27Low Voltage Cabling Systems and Wiring Methods

A technician is installing category 6A unshielded twisted pair for a horizontal run. Which practice best preserves the cable's balance and crosstalk performance during installation?

  1. Bundling the cable tightly with zip ties cinched as firmly as possible
  2. Removing the jacket several inches back so conductors can be fanned out neatly
  3. Untwisting each pair fully before punching down to reduce handling time
  4. Maintaining the pair twists up to the termination point and limiting untwisting to the minimum needed Correct answer.

Explanation

Pair twist is what gives balanced twisted pair cable its immunity to noise and its control of crosstalk, so twists must be maintained as close to the termination as the connector allows. Excessive untwisting or jacket removal degrades near-end crosstalk and return loss at the link.

Question 28Low Voltage Cabling Systems and Wiring Methods

A crew must support a bundle of category 6 cables running horizontally across a ceiling space between two points of attachment. Which support method is generally acceptable for horizontal low voltage cable?

  1. J-hooks or cable supports spaced per the cable manufacturer's recommendations Correct answer.
  2. Fastened with staples driven through the jacket
  3. Directly laid on the ceiling grid tees
  4. Suspended by the cable's own tension between the two anchors

Explanation

Horizontal cable is supported by listed supports such as J-hooks or cable trays at intervals the manufacturer specifies, which prevents sag and jacket deformation. Cable should not rest on ceiling grid or be supported by staples, since both damage the cable and violate support requirements.

Question 29Low Voltage Cabling Systems and Wiring Methods

A technician is terminating a category 6 cable on a patch panel and notices the cable jacket does not reach the connector body, leaving several inches of exposed untwisted conductors. What is the most appropriate corrective action?

  1. Leave it as installed because the link will certify if insertion loss passes
  2. Add a tie wrap around the exposed pairs to hold them together
  3. Re-terminate so the jacket enters the connector body and untwisted length is minimized Correct answer.
  4. Wrap the exposed conductors with electrical tape to protect them

Explanation

Termination standards require the cable jacket to be brought into the connector body and the pair twists maintained to within the specified distance of the contacts. Exposed untwisted conductors create impedance mismatch and crosstalk that tape or ties cannot correct.

Question 30Low Voltage Cabling Systems and Wiring Methods

A designer must confirm that a new copper backbone run will support a 10GBASE-T uplink between two telecommunications rooms. Which cabling characteristic most directly limits the distance the link can achieve at that data rate?

  1. The number of spare ports in the rack
  2. The color code sequence used at the patch panel
  3. The choice of label printer for cable identification
  4. Alien crosstalk and insertion loss performance of the installed cable Correct answer.

Explanation

At 10GBASE-T, signal loss and crosstalk between adjacent cables are the limiting electrical impairments, and category 6A cabling is specified to control them. Administrative items such as color codes, spare ports, and labeling do not affect the electrical channel performance.

Question 31Low Voltage Cabling Systems and Wiring Methods

An installer must route a horizontal cable through a masonry wall that is part of a rated fire separation. Which requirement applies to the penetration?

  1. The penetration must be sealed with a listed firestop system appropriate to the wall construction Correct answer.
  2. A plastic bushing alone is sufficient to close the opening
  3. The hole may be left open if the cable is plenum rated
  4. The cable must be sleeved with PVC conduit and the annular space left open

Explanation

Penetrations of rated assemblies must be protected by a firestop system tested and listed for that construction and for the penetrating items. Cable rating and bushings address other concerns and do not restore the fire resistance of the wall.

Question 32Low Voltage Cabling Systems and Wiring Methods

A technician is pulling cable through a conduit and finds the pull tension rising sharply near the end of the run. Which action is appropriate?

  1. Stop and investigate the obstruction rather than exceeding the cable's maximum pulling tension Correct answer.
  2. Attach the pull line to a single conductor to spread the load
  3. Add lubricant and double the pulling speed to finish quickly
  4. Continue pulling with more force since the run is nearly complete

Explanation

Exceeding the manufacturer's maximum pulling tension stretches conductors and permanently alters pair geometry, causing failures that may not appear until certification. Stopping to clear an obstruction or add a pull point protects the cable.

Question 33Low Voltage Cabling Systems and Wiring Methods

A technician must bond the metallic shield of a shielded twisted pair cable in a commercial installation. Which practice supports proper shield performance?

  1. Ground the shield to the cable tray only, with no connection to the building bonding system
  2. Bond the shield to the telecommunications bonding infrastructure at the specified points Correct answer.
  3. Leave the shield floating at both ends to avoid ground loops
  4. Connect the shield only to the nearest electrical receptacle grounding pin

Explanation

The shield only rejects interference when it is bonded to the building's telecommunications bonding system as the manufacturer and standard require. An unbonded shield acts as an antenna and can worsen noise coupling.

Question 34Low Voltage Cabling Systems and Wiring Methods

A crew is installing a fiber optic backbone in an indoor pathway and must manage excess cable at a splice enclosure. Which practice protects the fiber?

  1. Hang the slack from the enclosure door hinge
  2. Fold the slack back on itself and clamp it with a tie
  3. Coil the slack tightly to save space in the enclosure
  4. Coil the slack in loops at or above the cable's minimum bend radius and secure it Correct answer.

Explanation

Fiber attenuates or breaks when bent tighter than its minimum bend radius, so slack is stored in generous loops secured without crushing. Tight coiling, sharp folds, and improvised hanging all risk microbending loss or fiber fracture.

Question 35Low Voltage Cabling Systems and Wiring Methods

A technician needs to verify that a newly installed horizontal link meets its category performance requirements before handover. Which test set result set is required for a copper link certification?

  1. Only the length measurement
  2. Only insertion loss at 100 MHz
  3. Only continuity and wire map
  4. Insertion loss, near-end crosstalk, return loss, and the other parameters specified for the link class Correct answer.

Explanation

Certification of a copper link requires the full suite of parameters defined for the link class, including insertion loss, near-end crosstalk, return loss, and others. A wire map or length check alone does not demonstrate that the link will support the intended application.

Question 36Low Voltage Cabling Systems and Wiring Methods

An installer is placing cable in a cable tray that also carries power conductors for a 480 V motor circuit. Which arrangement is generally required?

  1. Remove the tray's barrier to simplify routing
  2. Maintain the separation or barrier specified for communications cable and power conductors in the same tray Correct answer.
  3. Lay the communications cable directly against the power conductors
  4. Bundle the communications cable with the power conductors to save space

Explanation

Where communications cable shares a tray with power conductors, a barrier or the required separation must be maintained to limit electromagnetic coupling and to satisfy code separation rules. Direct contact with power conductors increases noise and is not permitted.

Question 37Low Voltage Cabling Systems and Wiring Methods

A technician is troubleshooting a link that passes insertion loss but fails near-end crosstalk. Which installation defect is the most likely cause?

  1. A cable run that is slightly longer than the design length
  2. Excessive untwisting or a poorly seated connector at the tested end Correct answer.
  3. A slack loop stored above the ceiling
  4. A missing cable label at the patch panel

Explanation

Near-end crosstalk is measured at the same end as the injected signal, so a defect at that end such as untwisted conductors or a poorly seated plug is the usual cause. Length affects insertion loss, and labeling or slack storage does not create crosstalk.

Question 38Low Voltage Cabling Systems and Wiring Methods

A large open office is being cabled with wireless access points that must serve high-density client areas. Which cabling decision best supports future access point upgrades without recabling?

  1. Install category 6A cabling to each access point location Correct answer.
  2. Install a single shared cable daisy-chained between access points
  3. Install category 3 cable to each access point location
  4. Install coaxial cable to each access point location

Explanation

Category 6A supports multi-gigabit links over the full horizontal distance and provides headroom for higher-capacity access points without replacing cable. Daisy-chaining or using older or coaxial cable limits bandwidth and flexibility.

Question 39Low Voltage Cabling Systems and Wiring Methods

A technician is installing cable through a sleeve that penetrates a rated floor assembly and must also maintain the required clearance for the cable pathway. Which combination of measures satisfies both concerns?

  1. Size the sleeve for the pathway, then seal the annular space with a listed firestop system Correct answer.
  2. Run the cable through the sleeve without any seal because the sleeve is metal
  3. Oversize the sleeve and leave the annular space open for ventilation
  4. Seal the sleeve with combustible foam and omit the listed system

Explanation

The sleeve provides the pathway, but the opening still requires a firestop system listed for the assembly and the penetrating items, installed to the system's details. A metal sleeve by itself does not restore the fire resistance of the floor.

Question 40Low Voltage Cabling Systems and Wiring Methods

A campus project requires a backbone link between two buildings, and the designer is comparing media options. Which consideration most directly favors optical fiber for this link?

  1. Lower cost of field terminations than copper
  2. Compatibility with passive copper patch panels
  3. Immunity to electromagnetic interference and support for long distances between buildings Correct answer.
  4. Ability to deliver power to remote devices over the same cable

Explanation

Optical fiber is unaffected by electromagnetic interference and supports much longer runs than copper, which makes it well suited to inter-building backbone links. Copper remains simpler to terminate, can deliver power, and uses copper patch panels, so those points do not favor fiber.

Question 41Electrical Theory, Circuits, and Calculations

A low voltage technician needs to compute the current drawn by a 120-watt load connected to a 24-volt DC power supply. Which value is correct?

  1. 5 A Correct answer.
  2. 0.2 A
  3. 2.4 A
  4. 2880 A

Explanation

Ohm's law power relationship gives I = P / V. Dividing 120 W by 24 V yields 5 A, a typical calculation when sizing low voltage conductors and power supplies for access control or CCTV loads.

Question 42Electrical Theory, Circuits, and Calculations

In a series circuit containing three resistors, which statement about current is true?

  1. Current is greatest through the largest resistor.
  2. Current is zero in the segment after the last resistor.
  3. Current is the same through every resistor. Correct answer.
  4. Current splits among the resistors in proportion to resistance.

Explanation

A series circuit provides only one path for electron flow, so the same current passes through each element regardless of its resistance value. Voltage divides across the resistors, but current does not.

Question 43Electrical Theory, Circuits, and Calculations

Two 8-ohm resistors are connected in parallel. What is the equivalent resistance of the combination?

  1. 2 ohms
  2. 4 ohms Correct answer.
  3. 8 ohms
  4. 16 ohms

Explanation

For two equal resistors in parallel, the equivalent resistance is half of one resistor's value, so 8 ohms becomes 4 ohms. The general formula 1/RT = 1/R1 + 1/R2 confirms this result.

Question 44Electrical Theory, Circuits, and Calculations

Which unit expresses electrical resistance?

  1. Ohm Correct answer.
  2. Ampere
  3. Volt
  4. Watt

Explanation

Resistance is measured in ohms, the opposition to current flow in a circuit. The ampere measures current, the volt measures potential difference, and the watt measures power.

Question 45Electrical Theory, Circuits, and Calculations

A circuit has a 12-volt source and a total resistance of 6 ohms. What current flows?

  1. 0.5 A
  2. 72 A
  3. 2 A Correct answer.
  4. 6 A

Explanation

Ohm's law states I = V / R. Dividing 12 V by 6 ohms gives 2 A, the current that low voltage device wiring must carry without exceeding conductor ampacity.

Question 46Electrical Theory, Circuits, and Calculations

Which material is typically used as the conductor in low voltage cabling because of its high conductivity?

  1. Copper Correct answer.
  2. Rubber
  3. Fiberglass
  4. PVC

Explanation

Copper offers low resistance per unit length, making it the standard conductor metal for low voltage wiring. Rubber, PVC, and fiberglass serve as insulation or structural materials rather than conductors.

Question 47Electrical Theory, Circuits, and Calculations

A 24-volt DC circuit draws 0.5 A. What power does the load consume?

  1. 0.02 W
  2. 12 W Correct answer.
  3. 48 W
  4. 24.5 W

Explanation

Power equals voltage multiplied by current, so 24 V times 0.5 A equals 12 W. This figure helps technicians confirm that a power supply can support the connected low voltage devices.

Question 48Electrical Theory, Circuits, and Calculations

What is the primary function of a fuse in a low voltage circuit?

  1. To filter electrical noise from the signal
  2. To increase the voltage supplied to the load
  3. To convert AC to DC for the load
  4. To open the circuit when current exceeds a safe level Correct answer.

Explanation

A fuse contains a metal element that melts and opens the circuit when current exceeds its rating, protecting conductors and equipment from overheating. It does not change voltage or convert power.

Question 49Electrical Theory, Circuits, and Calculations

Three resistors of 2, 3, and 5 ohms are connected in series. What is the total resistance?

  1. 3.3 ohms
  2. 1 ohm
  3. 10 ohms Correct answer.
  4. 0.97 ohm

Explanation

In a series circuit, total resistance is the sum of the individual resistances. Adding 2, 3, and 5 ohms yields 10 ohms, which limits current in the single loop.

Question 50Electrical Theory, Circuits, and Calculations

A 100-foot run of copper conductor has a resistance of 0.5 ohms and carries 2 A. What is the voltage drop along that run?

  1. 1 V Correct answer.
  2. 100 V
  3. 0.25 V
  4. 4 V

Explanation

Voltage drop equals current times resistance, so 2 A times 0.5 ohms equals 1 V. Keeping voltage drop low matters in low voltage systems because a small loss is a large percentage of a 24 V supply.