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GER Licensed Electrical Inspector practice questions

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Question 1Electrical Theory and Fundamentals

A branch in a DC circuit carries 8 A and has a resistance of 15 Ω. What is the voltage drop across the branch?

  1. 120 V Correct answer.
  2. 23 V
  3. 0.53 V
  4. 1.9 V

Explanation

Ohm's law states that voltage equals current multiplied by resistance, so 8 A × 15 Ω = 120 V. The other values come from adding, dividing, or inverting the quantities instead of multiplying them.

Question 2Electrical Theory and Fundamentals

In a purely resistive AC circuit, how do the voltage and current waveforms relate to each other?

  1. Voltage and current are exactly in phase. Correct answer.
  2. Voltage leads current by 90 degrees.
  3. Current lags voltage by 45 degrees.
  4. Current leads voltage by 90 degrees.

Explanation

Resistance dissipates energy without storing it, so the current rises and falls in step with the applied voltage. Phase shifts of 90 degrees occur with pure reactance, while a 45-degree shift requires equal resistance and reactance.

Question 3Electrical Theory and Fundamentals

What is the effective resistance of three 12 Ω resistors connected in parallel?

  1. 6 Ω
  2. 36 Ω
  3. 4 Ω Correct answer.
  4. 12 Ω

Explanation

For equal resistors in parallel, the equivalent resistance is one resistor value divided by the number of branches, giving 12 Ω ÷ 3 = 4 Ω. Adding resistances applies to series connection, and the parallel result must always be smaller than the smallest branch.

Question 4Electrical Theory and Fundamentals

Which quantity is defined as the rate at which electrical energy is transferred, expressed in watts?

  1. Magnetic flux density
  2. Electric charge
  3. Electric power Correct answer.
  4. Capacitance

Explanation

Electric power is the time rate of energy transfer and equals voltage multiplied by current in a DC circuit. Charge is measured in coulombs, capacitance in farads, and flux density in teslas, so none of those describe energy per unit time.

Question 5Electrical Theory and Fundamentals

Which material class has a resistivity that decreases as temperature rises within normal operating ranges?

  1. Silver contacts
  2. Carbon compounds Correct answer.
  3. Aluminum busbars
  4. Copper conductors

Explanation

Materials with a negative temperature coefficient, such as carbon and certain semiconductors, show falling resistivity as temperature increases. Metals including copper, silver, and aluminum have positive temperature coefficients, so their resistance rises with heat.

Question 6Electrical Theory and Fundamentals

Which statement correctly describes the relationship among voltage, current, and resistance in a closed circuit?

  1. Current is directly proportional to resistance at constant voltage.
  2. Voltage is inversely proportional to current at constant resistance.
  3. Resistance is directly proportional to current at constant voltage.
  4. Current is directly proportional to voltage and inversely proportional to resistance. Correct answer.

Explanation

Ohm's law expresses current as voltage divided by resistance, so current rises with voltage and falls as resistance increases. The other statements invert these proportionalities and contradict the law.

Question 7Electrical Theory and Fundamentals

A 240 V single-phase load draws 10 A at unity power factor. What real power does it consume?

  1. 24 W
  2. 240 W
  3. 2400 W Correct answer.
  4. 1200 W

Explanation

Real power equals voltage multiplied by current multiplied by power factor, giving 240 V × 10 A × 1.0 = 2400 W. Dividing voltage by current or omitting the current multiplication produces the smaller distractors.

Question 8Electrical Theory and Fundamentals

An inductor of 0.2 H carries a current changing at 50 A per second. What magnitude of voltage is induced across it?

  1. 0.004 V
  2. 10 V Correct answer.
  3. 100 V
  4. 250 V

Explanation

The induced voltage equals inductance multiplied by the rate of change of current, so 0.2 H × 50 A/s = 10 V. Dividing the quantities instead of multiplying yields the small distractor values.

Question 9Electrical Theory and Fundamentals

A capacitor of 50 µF is connected across 400 V DC. How much charge does it store?

  1. 8 µC
  2. 20 C
  3. 0.02 C Correct answer.
  4. 0.125 C

Explanation

Charge equals capacitance multiplied by voltage, so 50 × 10⁻⁶ F × 400 V = 0.02 C. The distractors come from dividing instead of multiplying or from misplacing the micro prefix.

Question 10Electrical Theory and Fundamentals

Two parallel conductors carrying current in opposite directions will experience what mechanical force?

  1. A twisting torque only
  2. A force pushing them apart Correct answer.
  3. A force pulling them together
  4. No force at all

Explanation

Each conductor lies in the magnetic field produced by the other, and opposite current directions produce fields that repel, forcing the conductors apart. Conductors carrying current in the same direction attract instead.

Question 11Electrical Theory and Fundamentals

A coil of 200 turns links a flux that changes by 0.05 Wb in 0.4 s. What average EMF is induced?

  1. 40 V
  2. 4 V
  3. 10 V
  4. 25 V Correct answer.

Explanation

Faraday's law gives EMF as turns multiplied by flux change divided by time: 200 × 0.05 ÷ 0.4 = 25 V. Omitting the turns or inverting the ratio produces the other values.

Question 12Electrical Theory and Fundamentals

A three-phase balanced load draws 20 A per phase at 480 V line-to-line with a power factor of 0.8. What is the real power?

  1. 23.1 kW
  2. 13.3 kW Correct answer.
  3. 7.68 kW
  4. 16.6 kW

Explanation

For a balanced three-phase load, power equals √3 times line voltage times line current times power factor: 1.732 × 480 × 20 × 0.8 ≈ 13.3 kW. Using the single-phase formula or omitting the power factor gives the other results.

Question 13Electrical Theory and Fundamentals

A sinusoidal supply has a frequency of 60 Hz. What is its angular frequency in radians per second?

  1. 120 rad/s
  2. 377 rad/s Correct answer.
  3. 60 rad/s
  4. 94 rad/s

Explanation

Angular frequency equals 2π times the frequency in hertz, so 2π × 60 ≈ 377 rad/s. The other values confuse frequency in hertz with angular measure or drop the 2π factor.

Question 14Electrical Theory and Fundamentals

In a series RLC circuit at resonance, which condition applies?

  1. Total impedance equals the resistance only. Correct answer.
  2. Capacitive reactance exceeds inductive reactance.
  3. Inductive reactance exceeds capacitive reactance.
  4. Total impedance is zero regardless of resistance.

Explanation

At resonance the inductive and capacitive reactances are equal and cancel, leaving only resistance as the impedance. The circuit current reaches its maximum and is in phase with the voltage at that point.

Question 15Electrical Theory and Fundamentals

A 120 V source delivers 6 A to a load. What is the apparent power and, at a power factor of 0.75, the real power?

  1. 20 VA and 15 W
  2. 540 VA and 720 W
  3. 720 VA and 540 W Correct answer.
  4. 720 VA and 960 W

Explanation

Apparent power equals voltage times current, 120 × 6 = 720 VA, and real power equals apparent power times power factor, 720 × 0.75 = 540 W. Real power can never exceed apparent power.

Question 16Electrical Theory and Fundamentals

What happens to the total resistance of a series circuit when an additional resistor is connected in series?

  1. It remains unchanged.
  2. It decreases in proportion to the new resistor.
  3. It increases by the value of the added resistor. Correct answer.
  4. It becomes equal to the largest resistor.

Explanation

In a series circuit the same current passes through every element, so resistances add directly and the total rises by the value of the added resistor. The total is always greater than any individual resistor in the series string.

Question 17Electrical Theory and Fundamentals

A conductor of resistivity 1.7 × 10⁻⁸ Ω·m has a length of 100 m and a cross-sectional area of 2 × 10⁻⁶ m². What is its resistance?

  1. 8.5 Ω
  2. 0.85 Ω Correct answer.
  3. 0.085 Ω
  4. 0.0085 Ω

Explanation

Resistance equals resistivity times length divided by area: (1.7 × 10⁻⁸ × 100) ÷ (2 × 10⁻⁶) = 0.85 Ω. Misplacing a decimal power in the area term produces the tenfold errors.

Question 18Electrical Theory and Fundamentals

Why is the neutral conductor of a balanced three-phase, four-wire system often smaller than the phase conductors?

  1. The neutral carries the full sum of the three phase currents at all times.
  2. The neutral carries no current under any load condition.
  3. The neutral is sized for the highest harmonic current only.
  4. The neutral carries only the unbalanced current, which is near zero when balanced. Correct answer.

Explanation

In a balanced system the three phase currents sum to zero at the neutral point, so only imbalance current returns through the neutral. The neutral is not current-free in practice because loads are rarely perfectly balanced.

Question 19Electrical Theory and Fundamentals

A transformer has 500 primary turns and 50 secondary turns. With 240 V applied to the primary, what is the secondary voltage?

  1. 24 V Correct answer.
  2. 2.4 V
  3. 48 V
  4. 2400 V

Explanation

The voltage ratio equals the turns ratio, so the secondary voltage is 240 V × (50 ÷ 500) = 24 V. A step-down turns ratio produces a proportionally lower secondary voltage.

Question 20Electrical Theory and Fundamentals

A 10 Ω resistor dissipates 250 W. What current flows through it?

  1. 50 A
  2. 2.5 A
  3. 25 A
  4. 5 A Correct answer.

Explanation

Power equals current squared times resistance, so current equals the square root of power divided by resistance: √(250 ÷ 10) = 5 A. The distractors come from dividing power by resistance without taking the square root.

Question 21Electrical Theory and Fundamentals

In an AC circuit, what does the term impedance describe?

  1. The opposition due only to capacitance
  2. The phase angle between voltage and current
  3. The total opposition to current flow, combining resistance and reactance Correct answer.
  4. The energy stored in a magnetic field

Explanation

Impedance is the vector combination of resistance and reactance and represents total opposition to alternating current. Reactance alone covers only the reactive part, while the phase angle is a separate derived quantity.

Question 22Electrical Theory and Fundamentals

A series circuit has a 30 Ω resistor and a capacitive reactance of 40 Ω. What is the magnitude of the total impedance?

  1. 70 Ω
  2. 35 Ω
  3. 10 Ω
  4. 50 Ω Correct answer.

Explanation

Resistance and reactance combine vectorially at right angles, so impedance equals the square root of (30² + 40²) = 50 Ω. Simple addition of the two values ignores their 90-degree phase relationship.

Question 23Electrical Theory and Fundamentals

A 60 Hz supply feeds a 100 µF capacitor. What is its capacitive reactance?

  1. 0.0377 Ω
  2. 2.65 Ω
  3. 26.5 Ω Correct answer.
  4. 265 Ω

Explanation

Capacitive reactance equals 1 divided by 2π times frequency times capacitance: 1 ÷ (2π × 60 × 100 × 10⁻⁶) ≈ 26.5 Ω. Omitting the 2π factor or misplacing the micro prefix creates the other values.

Question 24Electrical Theory and Fundamentals

A load draws 15 A at 0.6 power factor from a 480 V single-phase supply. What is the reactive power?

  1. 5.76 kvar Correct answer.
  2. 2.88 kvar
  3. 7.2 kvar
  4. 4.32 kvar

Explanation

Apparent power is 480 × 15 = 7200 VA, and reactive power equals apparent power times the sine of the phase angle: 7200 × 0.8 = 5.76 kvar. Using the power factor instead of the sine gives real power, not reactive power.

Question 25Wiring Methods and Materials

A branch circuit feeding a 3-phase, 480 V, 30 A continuous load in a commercial building is to be wired with THHN copper conductors in EMT. Which minimum conductor size does the ampacity table require before any adjustment factors are applied?

  1. 8 AWG Correct answer.
  2. 4 AWG
  3. 6 AWG
  4. 10 AWG

Explanation

A continuous load must be served at 125 percent of its rating, so the circuit ampacity basis is 30 A times 1.25, or 37.5 A. THHN copper in the 75 C column carries 50 A at 8 AWG, which is the smallest size that equals or exceeds 37.5 A. The 10 AWG and 12 AWG sizes fall below the required ampacity.

Question 26Wiring Methods and Materials

Which wiring method is permitted to be installed in a concrete slab on grade where the slab is in direct contact with the earth?

  1. Armored cable
  2. Rigid polyvinyl chloride conduit Correct answer.
  3. Electrical nonmetallic tubing
  4. Surface metal raceway

Explanation

Rigid PVC conduit is recognized for direct burial and for embedment in concrete in contact with the earth, provided the fittings and joints are suited to the location. ENT and surface metal raceway are limited to specific dry or protected applications and are not permitted in poured concrete in contact with earth. Armored cable is likewise restricted to interior and protected uses.

Question 27Wiring Methods and Materials

A 1-inch trade size rigid metal conduit carries three 4/0 AWG THWN copper conductors and one bare 6 AWG equipment grounding conductor. Which statement about the fill is correct?

  1. The fill is permitted because the grounding conductor is not counted
  2. The fill must be recalculated because the bare conductor is counted at its actual area Correct answer.
  3. The fill is permitted because conduit fill is based on conductor count only
  4. The fill is prohibited because four large conductors exceed 40 percent

Explanation

Conduit fill is computed from the total cross-sectional area of all conductors, including bare equipment grounding conductors, compared with the usable area of the raceway. The bare conductor occupies space and must be counted at its tabulated area. Fill is not determined by conductor count alone, and a bare conductor is not excluded from the calculation.

Question 28Wiring Methods and Materials

In a rigid metal conduit system, what is the primary purpose of bonding the conduit at each end and using listed bonding jumpers around expansion fittings?

  1. To provide a low-impedance fault current path Correct answer.
  2. To prevent galvanic corrosion at the joints
  3. To reduce inductive heating of the conductors
  4. To limit voltage drop on long runs

Explanation

Metallic raceways are part of the equipment grounding conductor path, and bonding ensures a low-impedance return path so overcurrent devices operate promptly during a ground fault. Bonding jumpers around expansion fittings and at terminations maintain electrical continuity of that path. Voltage drop, corrosion control, and inductive heating are separate design concerns.

Question 29Wiring Methods and Materials

A 20 A branch circuit supplies a single receptacle in a garage. Which receptacle configuration is required?

  1. A 15 A receptacle on a 20 A circuit
  2. A 20 A receptacle on a 20 A circuit Correct answer.
  3. A 30 A receptacle on a 20 A circuit
  4. A 15 A receptacle protected by a 20 A breaker

Explanation

A single receptacle on an individual branch circuit must have an ampere rating not less than the branch circuit rating. On a 20 A circuit, the single receptacle must therefore be rated 20 A. A 15 A receptacle is permitted only where the circuit supplies two or more receptacles.

Question 30Wiring Methods and Materials

A feeder supplies a panelboard through a 2-inch conduit. The calculated load requires conductors with an ampacity of 200 A. Which factor most directly determines the minimum conductor size selected from the ampacity table?

  1. The length of the feeder run
  2. The number of bends in the conduit
  3. The ambient temperature of the panelboard room
  4. The terminal temperature rating of the equipment Correct answer.

Explanation

Conductor ampacity must be coordinated with the temperature rating of the terminations, so the 60 C, 75 C, or 90 C column used depends on the equipment terminal ratings. Ambient temperature and conduit fill then adjust the ampacity, but the terminal rating establishes the base column. Conduit bends affect pulling, not ampacity.

Question 31Wiring Methods and Materials

A 3-phase, 4-wire feeder is installed in a single raceway. Which conductor arrangement is required to limit inductive heating of the raceway?

  1. All conductors of the circuit in the same raceway Correct answer.
  2. Each phase conductor in its own raceway
  3. The neutral run in a separate metallic raceway
  4. All phase conductors in one raceway and the neutral in a separate raceway

Explanation

All conductors of a circuit, including the neutral and equipment grounding conductor, must be grouped in the same raceway to cancel the magnetic fields produced by the phase currents. Splitting conductors among separate ferrous raceways causes inductive heating and voltage rise. Grouping is required for parallel runs as well.

Question 32Wiring Methods and Materials

Which wiring method is permitted for a 20 A branch circuit in a wet location such as an exterior wall of a car wash building?

  1. Surface metal raceway
  2. Nonmetallic sheathed cable
  3. Liquidtight flexible nonmetallic conduit Correct answer.
  4. Electrical metallic tubing with compression fittings

Explanation

Liquidtight flexible nonmetallic conduit is listed for wet locations and is commonly used where flexibility and moisture resistance are needed. EMT with compression fittings is not by itself a wet-location method unless specifically listed. Nonmetallic sheathed cable and surface metal raceway are dry-location methods.

Question 33Wiring Methods and Materials

A 60 A feeder uses 6 AWG copper THHN conductors in a raceway where the ambient temperature reaches 50 C. Using the 90 C column ampacity of 75 A and an ambient correction factor of 0.82, what is the corrected ampacity?

  1. 75.0 A
  2. 82.0 A
  3. 49.2 A
  4. 61.5 A Correct answer.

Explanation

The corrected ampacity equals the table ampacity multiplied by the ambient correction factor: 75 A times 0.82 equals 61.5 A. This corrected value is then compared with the load and the terminal rating. The 90 C column may be used for correction only if the terminations are rated for it.

Question 34Wiring Methods and Materials

A metal raceway crosses a building expansion joint. What is required to maintain the electrical continuity of the raceway and the equipment grounding path?

  1. A nonmetallic sleeve over the joint
  2. A listed expansion fitting with a bonding jumper Correct answer.
  3. A separate grounding electrode conductor
  4. A rigid coupling with thread sealant

Explanation

Expansion fittings accommodate movement, and a bonding jumper ensures the equipment grounding path remains continuous across the fitting. A rigid coupling would resist movement and could be damaged. A nonmetallic sleeve does not maintain continuity, and a grounding electrode conductor serves a different purpose.

Question 35Wiring Methods and Materials

A 3-phase, 3-wire feeder carries 100 A per phase. What is the minimum copper conductor size if THWN conductors are installed in a raceway with 75 C terminations?

  1. 6 AWG
  2. 3 AWG Correct answer.
  3. 8 AWG
  4. 1 AWG

Explanation

With 75 C terminations and a 100 A load, the conductor must carry at least 100 A in the 75 C column. Copper 3 AWG is rated 100 A at 75 C, making it the minimum size. The 6 AWG and 8 AWG sizes fall well below 100 A.

Question 36Wiring Methods and Materials

Which of the following is a recognized method of supporting 1-inch rigid metal conduit installed vertically on an exterior wall?

  1. Supporting at intervals not exceeding 10 feet and within 3 feet of each box Correct answer.
  2. Supporting only at the top and bottom of the run
  3. Supporting with wire ties at each fitting
  4. Supporting at intervals not exceeding 20 feet

Explanation

Rigid metal conduit must be securely supported at intervals not exceeding 10 feet and within 3 feet of each box, fitting, or termination. Supporting only at the ends leaves the intermediate length unsupported. Longer intervals and wire ties do not provide the required secure support.

Question 37Wiring Methods and Materials

A 100 A feeder is installed using parallel 3 AWG copper conductors in two separate raceways. Which requirement must be met for the parallel installation?

  1. The equipment grounding conductor may be run in only one raceway
  2. Each parallel conductor must be the same length, material, and size Correct answer.
  3. The neutral may be omitted in one raceway
  4. The parallel conductors may be different sizes if the total ampacity matches

Explanation

Parallel conductors must be identical in length, material, size, insulation, and termination to ensure equal current division. Mixing sizes or lengths causes unequal loading. The neutral and equipment grounding conductors must be run with their circuit conductors in each raceway, not omitted from one.

Question 38Wiring Methods and Materials

A junction box in a ceiling contains splices for 12 AWG conductors. Which requirement applies to the box fill calculation?

  1. Splices do not affect box fill
  2. Only the largest conductor is counted
  3. Each conductor entering the box counts once, and each splice adds a volume allowance Correct answer.
  4. Box fill is based on the number of devices only

Explanation

Box fill is computed by counting each conductor that enters the box, adding allowances for each splice or joint, and adding allowances for devices and grounding conductors. The total volume must not exceed the box capacity. Counting only the largest conductor or ignoring splices understates the required volume.

Question 39Wiring Methods and Materials

A 480 V motor branch circuit uses liquidtight flexible metal conduit for the final connection. What is the maximum length permitted for this flexible connection where the conduit also serves as the equipment grounding conductor?

  1. 3 feet
  2. 6 feet Correct answer.
  3. 10 feet
  4. 25 feet

Explanation

Liquidtight flexible metal conduit may serve as an equipment grounding conductor only for lengths up to 6 feet, and only where the circuit conductors are protected at 20 A or less and other conditions are met. Longer lengths require a separate equipment grounding conductor. The 10-foot and 25-foot lengths exceed this limit.

Question 40Wiring Methods and Materials

A 200 A service uses 2/0 AWG copper conductors. What is the minimum size copper equipment grounding conductor required for the service raceway?

  1. 2 AWG
  2. 1/0 AWG
  3. 4 AWG Correct answer.
  4. 6 AWG

Explanation

The equipment grounding conductor for a service is sized from the service conductor rating using the equipment grounding conductor table. For 2/0 AWG copper service conductors, 4 AWG copper is the minimum. The 6 AWG and 2 AWG sizes do not match the table value for this service size.

Question 41Wiring Methods and Materials

A feeder passes through a building and is installed in a metal wireway. Which requirement applies to the wireway where it is used as an equipment grounding conductor?

  1. The wireway must be supported every 5 feet
  2. The wireway must be painted to resist corrosion
  3. The wireway may be used as a grounding conductor without listing
  4. The wireway must be listed and marked for use as an equipment grounding conductor Correct answer.

Explanation

A metal wireway used as an equipment grounding conductor must be listed and marked for that purpose. Ordinary sheet metal enclosures are not automatically acceptable grounding paths. Paint and support spacing are installation details but do not establish grounding suitability.

Question 42Wiring Methods and Materials

A branch circuit supplies a 15 A, 125 V receptacle in a dwelling unit. Which conductor size is the minimum permitted for the branch circuit conductors?

  1. 14 AWG copper Correct answer.
  2. 10 AWG copper
  3. 12 AWG copper
  4. 16 AWG copper

Explanation

A 15 A branch circuit may use 14 AWG copper conductors, which are rated 15 A at 60 C. The 12 AWG and 10 AWG sizes are larger than the minimum. A 16 AWG conductor is not a standard branch circuit size for this application.

Question 43Wiring Methods and Materials

A 3-phase, 4-wire, 208 V feeder supplies a panelboard with a calculated neutral load of 80 A. The phase conductors are 3/0 AWG copper. What is the minimum neutral conductor size permitted?

  1. The neutral may be omitted entirely
  2. The neutral may be sized for the calculated neutral load but not smaller than the required minimum Correct answer.
  3. The neutral must always equal the phase conductor size
  4. The neutral must be larger than the phase conductors

Explanation

Where the major portion of the load is linear, the neutral may be sized for the calculated neutral load, subject to the minimum size rules for the circuit. It need not always equal the phase conductors, but it cannot be omitted where a neutral is required. A neutral larger than the phase conductors is not required here.

Question 44Wiring Methods and Materials

Which of the following is required when nonmetallic sheathed cable is installed through a bored hole in a wood stud?

  1. The cable must be supported every 12 inches
  2. The cable must be armored
  3. No protection is ever required in wood studs
  4. A listed bushing or protection where the cable is within 1-1/4 inches of the stud edge Correct answer.

Explanation

Nonmetallic sheathed cable passing through a bored hole must be protected by a listed bushing or equivalent where the hole is within 1-1/4 inches of the nearest edge of the stud. This prevents damage from nails and screws. Protection is not required at greater distances from the edge.

Question 45Wiring Methods and Materials

A 250 V, 30 A single-phase load is located 150 feet from the panelboard. The conductors are 8 AWG copper. Which consideration most directly affects whether the conductor size should be increased?

  1. The size of the panelboard enclosure
  2. Voltage drop over the long run Correct answer.
  3. The number of receptacles on the circuit
  4. The color of the insulation

Explanation

Long runs can produce excessive voltage drop, and conductors may need to be increased in size to keep the drop within acceptable limits. Insulation color, receptacle count, and enclosure size do not affect voltage drop. Ampacity alone may not be sufficient for long feeders.

Question 46Wiring Methods and Materials

A feeder is installed in a raceway that is exposed to direct sunlight on a rooftop. Which adjustment is required for the conductor ampacity?

  1. Reduce the conductor size to offset heating
  2. Add a second raceway to share the load
  3. Apply an ambient temperature correction for the higher rooftop temperature Correct answer.
  4. Use the 90 C column without correction

Explanation

Conductors exposed to elevated rooftop temperatures must have their ampacity corrected for the higher ambient. Using the 90 C column without correction ignores the temperature rise. Reducing conductor size or adding a raceway does not substitute for the required correction.

Question 47Wiring Methods and Materials

A metal-clad cable is installed in a location subject to physical damage. Which wiring method is specifically recognized for providing a high degree of protection against physical damage?

  1. Surface metal raceway
  2. Electrical nonmetallic tubing
  3. Rigid metal conduit Correct answer.
  4. Nonmetallic sheathed cable

Explanation

Rigid metal conduit provides a high degree of physical protection and is suitable for locations subject to severe damage. ENT and nonmetallic sheathed cable offer limited protection, and surface metal raceway is intended for surface wiring in dry locations.

Question 48Wiring Methods and Materials

A 480 V, 3-phase feeder uses 500 kcmil copper conductors in a cable tray. Which installation practice is required to maintain the ampacity rating?

  1. Remove the tray covers to increase ventilation
  2. Install the conductors in a single layer only
  3. Bundle all conductors tightly together
  4. Maintain the required spacing and grouping of conductors in the tray Correct answer.

Explanation

Cable tray ampacity depends on the maintained spacing and grouping of the conductors as specified in the installation rules. Tight bundling changes the heat dissipation and may require derating. Removing covers or forcing a single layer is not the general requirement.

Question 49Wiring Methods and Materials

A grounding electrode conductor is installed from a metal water pipe to the service equipment. Which requirement applies to the connection point?

  1. The connection must be made within the first 5 feet of the pipe entering the building Correct answer.
  2. The connection must be made at the farthest point from the service
  3. The connection must be made at the water meter only
  4. The connection may be made anywhere on the water pipe

Explanation

Where a metal underground water pipe is used as a grounding electrode, the grounding electrode conductor must connect within the first 5 feet of the pipe entering the building. This ensures the connection is made ahead of removable sections such as meters. Connections at arbitrary points or at the meter only are not permitted.

Question 50Wiring Methods and Materials

A rigid metal conduit run is installed outdoors in a coastal industrial area where the conduit is exposed to corrosive salt spray and will be buried directly in soil for part of its length. Which requirement governs the protection of this conduit where it enters the ground?

  1. The conduit must be replaced with electrical metallic tubing wherever it contacts soil
  2. The conduit may be installed bare because rigid metal conduit is inherently corrosion resistant in all soil conditions
  3. The conduit must be coated with an approved corrosion-resistant material and, where buried, protected against corrosion by a listed supplementary coating or wrapping Correct answer.
  4. The conduit requires only that threaded joints be painted with ordinary exterior house paint

Explanation

Rigid metal conduit is galvanized for corrosion protection, but where it is exposed to severe corrosive influences such as salt spray or direct burial, the raceway must be protected with an approved corrosion-resistant coating or supplementary protection. Ordinary paint or bare galvanized steel is not sufficient for direct burial in corrosive soil.