Electrical Inspector Interview Questions Answers
Note: This description is used for the next twelve questions:
A 120 VAC, 60 HZ, single-phase, indoor convenience receptacle branch-circuit is installed using 12 AWG (4 mm2) stranded copper THHN/THWN. (PVC & nylon) insulated conductors in ¾ inch EMT raceway and supplies power from a panel board to a total of eight NEMA 5-20R duplex receptacles. Following Figure shows NEMA 5-20R duplex receptacle
1. [A] What NEMA standard thermal-magnetic panelboard circuit breaker rating should be utilized for this branch-circuit?
A. 30 Amp C/B
B. 25 Amp C/B
e. 20 AmpC/B
f. 15 Amp C/B
e. Ampacity rating as designed and shown on the panelboard schedule drawing
2. · [A] What will be the quantity of #12 AWG (4 mm2 ) wires installed from the panelboard to the first receptacle?
A. Four wires
B. Three wires
C. Two wires
D. Two or three wires
3. [A] What color insulation is used for a grounded circuit conductor?
A. Red
B. White
C. Black
D. Green
4. [A} What color insulation is used for an equipment ground conductor? .
A. Red
B. White
C. Black
D. Green
5. [A] What color insulation is used for the ungrounded circuit conductor?
A. Red
B. White
C. Black
D. Black or red
6. [A] ·Which of the following ratings describes a NEMA 5-20R receptacle?
A. 20 Amps, 115 VAC
B. 20 Amps, 125 VAC
C. 25 Amps, 120 VAC
D. 15 Amps, 120 VAC
7. [A} How many additional NEMA 5-20R duplex receptacles can be added to this branch circuit and still comply with NEC loading requirements?
A. One
B. Two
C. Three
D. Four
E. Five
F. Ten
G. Twelve
8. [A] What color terminal screw (in the receptacle) is the neutral wire connected to?
A. Silver
B. Brass
E. Green
D. None of the above
9. [A] Assuming the 12 AWG (4 mm2 ) THHN/THWN wire is rated for 30 Amps at an indoor ambient temperature of 30°C (86°F), what is the Ampacity rating for 12 AWG (4 mm2 ) at an indoor ambient temperature of 50°C (122°F)?
A. 20Amps
B. 25Amps
C. 28Amps
D. 32Amps
10. [A] Which of the following design and material criteria will change the Ampacity rating of 12 AWG (4 mm2 ) THHN/THWN copper wire? Mark all answers that are applicable.
A. Quantity of current-carrying conductors in a cable or conduit
B. Wet or dry location
C. Temperature rating of the conduit
D. Type of metallic conduit used (i.e., EMT, GRSC, IMC, FMC, etc.)
E. Temperature rating of the receptacle terminals
F. Temperature rating of the circuit breaker terminals
G. Solid or stranded wire
11. [A] A single light fixture is plugged into the 120 VAC receptacle branch circuit. The light fixture uses an incandescent lamp rated for 120 V and 200 W How many Amps will flow through the circuit when the light fixture is turned on?
A. 0.60 Amps
B. 1.00 Amps
C. 1.67 Amps
D. 2.00 Amps
12. [A] A single light fixture is plugged into the 120 VAC receptacle branch circuit. The light fixture uses an incandescent lamp rated for 130 V and 200 W. How many Amps will flow through the circuit when the light fixture is turned on?
A. 0. 70 Amps
B. 1.18Amps
C. 1.42 Amps
D. 1.54 Amps
E. 2.14 Amps
13. An effective ground-fault- current return path is created when all electrically conductive material (that might be energized during a fault) are bonded together and connected to what?
A. Electrical supply (neutral)
B. Ground
C. Structural steel
D. None of the above
14. A permanently mounted three-phase, three-wire electric heater is supplied by a branch circuit breaker rated at 208/120 VAC, and 100 Amps. The branch-circuit cable includes an insulated copper equipment ground conductor. What is the minimum allowed wire size for the equipment ground conductor?
A. 10 AWG (6 mm2)
B. 8 AWG (10 mm2)
C. 4 AWG (25 mm2)
D. 2 AWG (35 mm2)
15. Branch-circuit breakers used to switch high-intensity discharge lighting circuits must be listed and must be marked as
A. HID
B. SWD
C. Either A. or B.
D. Both A. and B
16. Grounding electrode taps from a separately derived system to a common grounding electrode conductor are permitted when a building or structure has multiple-separately derived systems.
A. True Statement
B. False Statement
17. A metal underground water pipe to a building or structure shall be supplemented by an additional Electrod of type specified in article 250.52. Where the supplemental electrode is a rod; pipe; or plate electrode; that portion of the copper wire that is the sole connection to the supplemental grounding electrode is not required to be larger than
A. 2/0 AWG (70 mm2)
B. 4/0 AWG (120 mm2)
C. 4 AWG (25 mm2)
D. 6 AWG (16 mm2)
18. No tap conductor shall supply another tap conductor (except through an overcurrent protective device).
A. True Statement
B. False Statement
19. In an AC electrical system; the size of the grounding electrode conductor to a concrete-encased ground electrode is not required to be larger than ———copper wire.
A. 2/0 AWG (70 mm2)
B. 4/0 AWG (120 mm2)
C. 4 AWG (25 mm2)
D. 6AWG (16mm2)
20. Circuit breakers shall be marked with their in a manner that will be durable and visible after installation .
A. trip mechanism type
B. Ampere rating
C. Voltage rating
D. All of the above
21. Circuit breaker handles; and similar parts that may move suddenly shall be —
A. guarded
B. isolated
C. Either guarded or isolated.
D. both guarded and isolated.
22. A NEMA 1 galvanized sheet-steel pull box (with no oversized, concentric, or eccentric knockouts) is installed. For circuits over 250 Volts to ground (e.g., 480Y/277 VAC); electrical continuity can be maintained between the box and metal conduit by
A. Using conduit connector fittings with a shoulder that seats firmly against the box and a locknut on the inside
B. Using conduit hubs listed for the purpose
C. Using double locknuts on threaded conduit (one inside and one outside the box)
D. Any of the above
23. A NEMA 1 galvanized sheet steel pull box is needed to make a horizontal 90° angle turn for two 4-inch EMT conduits and three 2-inch EMT conduits (all circuits are below 600 VAC) .. The depth of the pull box is 10 inches (254 mm) with a single square cover.: What is the minimum.size pull box allowed? ·
A. 14 inches (356 mm) square box
B. 16 inches (406 mm) square box
C. 24 inches (610 mm) square box
D. 30 inches (762 mm) square box
E. 34 inches (834 mm) square box
F. 36 inches (915 mm) square box
24. A metal elbow that is installed in an underground installation of rigid nonmetallic conduit and is isolated from possible contact by a minimum cover of __ in. (mm) to any part of the elbow shall not be required to be grounded.
A. ‘According to Table 300.5
B. 18 inches (458 mm)
C. 12 inches (305 mm) rro. 6 inches (153 mm)
25. If installed on a building, lightning protection system down conductors and ground electrodes __ be used as the NEC required ground electrodes and ground electrode conductor for the electrical power distribution system and equipment.
A. shall
B can
C. shall not
26. A grounding electrode is required if a building or structure is supplied by a feeder; or by more than one branch circuit.
A. True Statement
B. False Statement
27. Service-entrance conductors can be spliced or tapped by clamped or bolted connections as long as ___________
A. No splice is made in a raceway.
B. The free ends of conductors are covered with an insulation that is equivalent to that of the conductors or with an insulating device identified for the purpose.
C. Wire connectors or other splicing means installed on conductors that are buried in the earth shall be listed for direct burial.
D. All of the above
28. Supplementary electrodes for electrical equipment are not required to be bonded to the grounding electrode system. The 25 Ohm resistance requirement of Art. 250.56 does not apply.
A. True Statement
B. False Statement
29. A ground fault is a (an) __ electrical connection between an ungrounded (hot) conductor and metallic enclosures; metallic raceways; metallic equipment; or earth.
A. designed
B. unintentional
B. intentional
C. deliberate
30. A grounding connection shall not be made to any grounded circuit conductor on the __ side of the building service disconnecting means except as permitted for separately-derived systems, separate buildings or specific exceptions.
A. supply
B. power
C. load
D. line
31. Transformer secondary conductors can be run up to 25 ft without overcurrent protection if installed in accordance with the following: (1) The secondary conductors have an ampacity that (when multiplied by the ratio of the secondary-to-primary voltage) is at least ____________ percent of the rating of the overcurrent device protecting the primary of transformer. (2)The secondary conductors terminate in a single circuit breaker or set of fuses that have a rating not greater then the conductor ampacity. (3) The secondary conductors are protected from physical
damage.
A. 50%
B. 33113%
C. 100%
D. 25%
32. Service raceways threaded into metal service equipment such as bosses (hubs) are considered to be effectively __ to the service metal enclosure.
A. attached
B. bonded
C. grounded
D. None of the above
33. Abare 4 AWG copper conductor installed near the bottom of a concrete foundation or footing that is in direct contact with the earth may be used as a grounding electrode when the conductor is at least __ ft in length.
A. 25 feet
B. 10 feet
C. 15 feet
D. 20 feet
34 . Industrial transformer secondary conductors can have a total length of no longer than _________________ ft (m) before having overcurrent protection. The tap conductors must have an ampacity not less than the ampacity of the overcurrent protection’abd must terminate in a single circuit breaker; or set of fuses having a rating not greater than the secondary conductor ampacity.
A. 35 feet (10.7 m)
B. 25 feet (7.6 m)
C. 8 feet (2.4 m)
D. 75 feet (22.9 m)
35. A __ shall be considered equivalent to an overcurrent trip unit.
A. current transformer
B. overcurrent relay
C. Either A. or B.
D. Both A. and B.
36. Non-current-carrying conductive materials enclosing electrical conductors or equipment; or forming part of such equipment; shall be connected to earth to limit voltage to ground on these materials~ ··
A. True Statement
B. False Statement
37. Service-entrance conductors entering or on the exterior of buildings or other structures shall be insulated.
A. True Statement
B. False Statement
38. A building or structure that is supplied by a feeder must have the interior metal water-piping system bonded with a conductor sized from
A. – Table 310.16
B. Table 250.66 ·
C. Table 250.122
D. None of the above
39. What type of electrical test instrument is used to assess 600 VAC wire insulation integrity?
A. Volt-Ohm-Amp multi-meter
B. Grounding meter
C. Clamp-on Amp meter
D. Meg-Ohm meter
40. Which of the following raceway inspection and test procedures are applicable to Electrical Metallic Tubing (EMT) conduit and fittings?
(Mark all that apply)
A. Field-cut threads are tapered and at correct pitch
B. All set screws are tightened to manufacturers recommended torque.
C. Conduit not damaged by bending tool, and bend radius exceeds minimum allowed.
D. Conduit ends are reamed out with no burrs or sharp edges present.
E. Union fittings or Myers type conduit hubs are provided for future removal and maintenance of equipment.
F. Conduit is fully seated in compression connector
G. Listed or labeled conduit and fittings were installed.
H. 3 inch and larger conduit is supported every 20 feet
41. Which of the following raceway inspection and test procedures are applicable to Galvanized Rigid steel (GRS) conduit and fittings. (Mark all that apply)
A. Field-cut threads are tap~red and:at correct pitch.
B. All set-screws are tightened to manufacturers recommended torque:
C- Conduit not damaged by bending tool, and bend radius exceeds minimum allowed.
D. Conduit ends are reamed out with no burrs or sharp edges present.
E. Union fittings or Myers type conduit hubs are provided for future removal and maintenance of equipment.
F. Conduit is fully seated in compression connector
E. Listed or labeled conduit and fittings were installed.
F. 3 inch and larger conduit is supported every 20 feet
42. What is the maximum number of 90° bends allowed in a conduit run between cable pulling points (e.g., pull boxes)?
A. One
B. Two
C. Three
D. Four
E. Five
F. Six
43. Which of the following rigid nonmetallic conduit types can be used below grade, directly buried in earth? Mark all that apply.
A. NEMA TC-8 Type DB PVC conduit
B. NEMA TC-8 Type EB PVC conduit
C. Schedule 40 PVC conduit
D. Schedule 80 PVC conduit
E. Schedule 40 HOPE conduit
44. Which of the following rigid nonmetallic conduit types can be used below grade, embedded in concrete? Mark all that apply.
A. NEMA TC-8 Type DB P.VC conduit
B . NEMA TC-8 Type EB PVC conduit
C. Schedule 40 PVC conduit
D. Schedule 80 PVC conduit
E. Schedule 40 HOPE conduit
47. Which of the following cable types can be used in cable tray? Mark all that apply.
A. Type TC cable
B. Type CT cable
C. Type AC cable
D. Type MC cable
E. Type NM cable
F. Type Ml cable
G. Type XHHW cable
H. Type THHN cable
I. Type PUTC cable
J. Type MV cable
K. Type SE cable
48. A 150 kV A transformer has a three-phase, three-wire primary winding and a three-phase, four-wire secondary winding. A Volt meter __ __ __ measures 277 VAC between phase A and ground on the primary side and 208 VAC between phase B and phase C on the secondary side. What is the secondary single-phase voltage rating?
A. 480 VAC
B. 277 VAC
C. 240 VAC
D. 208 VAc
E. 120 VAC
F. 69 VAC
49. A 150 kVA transformer has a three phase, three-wire primary winding and a three-phase, four-wire secondary winding. A Volt meter measures 277 VAC between phase A and ground on the primary side and 208 VAC between phase conductors on the secondary side. What is the primary full load line current?
A. 541.5 Amps
B. 313 Amps
C. 0.721 Amps
D. 721 Amps
E. 180.4 Amps
F. 416.4 Amps
50. A 150 kVA transformer has a three-phase, three-wire primary winding and a three-phase, four-wire secondary winding. A Volt meter measures 277 VAC between phase A and ground on the primary side and 208 VAC between phase conductors on the secondary side. What is the secondary full load line current?
A. 541.5 Amps
B. 313 Amps
C. 0.721 Amps
D. 721 Amps
E. 180.4 Amps
F. 416.4 Amps
Answers:
- B
- D
- D
- B
- B
- D
- B
- D
- A,B,E,F
- C
- D
- B
- A
- A
- A
- D
- A
- A
- D
- D
- B
- C
- D
- C
- A
- D
- B
- B
- A
- D
- B
- B
- B
- B
- A
- A
- C
- D
- A,B,D,F,G,H
- A,C,D,E,G,H
- C
- A,C,D,E
- A,B
- A,B,D
- A,B,D
- A,C,D,E,F,G,H,J
- E
- B
- F
Electrical construction (Infrastructure)Engineer interview questions
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