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Iec year 1 final exam ACCURATE
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FROM 2025 TO 2026 | ACCURATE AND
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1. Which term best describes a service lateral? A. Overhead drop B. Service ground C. Service entrance D. Underground feed ✅ Rationale: A service lateral is the underground conductors that deliver electricity from the utility to the service point. 2. How many kW does a 100-ampere residential service draw when fully loaded? A. 10 kW B. 240 kW C. 100 kW D. 24 kW ✅ Rationale: Power (kW) = Voltage × Current ÷ 1000 = 240V × 100A ÷ 1000 = 24 kW. 3. If a 95-watt lamp operates for 11 hours, the utility will bill for how many kWh? A. 8. B. 10. C. 11. D. 1.045 ✅ E. 1. Rationale: Energy = 95W × 11hr ÷ 1000 = 1.045 kWh. 4. Monthly energy cost to operate a 200W sodium lamp (12 hrs/day, 30 days, $0.11/kWh)? A. $7.92 ✅ B. $8. C. $15. D. $6. E. $ Rationale: 200W × 12h × 30 = 72,000 Wh = 72 kWh. 72 × $0.11 = $7.92.
5. To minimize damage during a fault, what should be minimized? A. Time duration of the fault ✅ B. Ampere level of the fault current C. Both A and B D. Neither A nor B Rationale: Reducing the fault duration minimizes thermal and arc energy damage. 6. Which NEC® Article covers grounding and bonding? A. 422 B. 424 C. 250 ✅ D. 240 E. 280 Rationale: NEC Article 250 specifically addresses grounding and bonding. 7. Self-tapping sheet metal screws (TEK screws) ___ permitted for equipment ground. A. Are B. Are not ✅ Rationale: NEC prohibits TEK screws due to unreliability in providing a permanent ground. 8. A metal underground water pipe meeting NEC criteria is a good ___. A. Insulator B. Service conductor C. Grounding electrode ✅ D. Neutral Rationale: Such a pipe is recognized by NEC as an effective grounding electrode. 9. Grounding electrode conductor to metal water piping must be within ___ of entry. A. 25 ft B. 10 ft C. 5 ft (1.52 m) ✅ Rationale: NEC requires connection within 5 feet of water pipe entry to ensure continuity. 10. Which NEC® Table determines grounding electrode conductor size? A. 250. B. 310.15(B)(16) C. 250.66 ✅ D. 314.16(A)
D. 250 Part VI Rationale: Fuses are covered under NEC 240, Part V.
17. Which currents can flow through a fuse? A. Overload B. Short-circuit C. Normal D. Ground-fault E. All of these ✅ Rationale: A fuse protects against all these types of currents depending on system conditions. 18. Standard size circuit breakers include? A. I & III only B. I, II & III ✅ C. II & III only D. I & II only Rationale: 20, 25, and 30 amps are all standard circuit breaker sizes. 19. Plug fuses are usable in which systems? A. I & III only B. II & III only C. I only D. I & II only ✅ E. Any of these Rationale: Plug fuses are allowed on 120/240V and 120/208V systems, not on 277/480V. 20. Best ground-fault return path with least resistance? A. 12 AWG EGC inside PVC B. ¾" EMT with 12 AWG EGC ✅ C. Both have equal resistance Rationale: EMT provides a parallel metallic path with lower impedance than PVC. 21. What is a 3/0 AWG conductor? A. 0000 B. 000 ✅ C. 0 D. 00 Rationale: 3/0 is equivalent to 000 AWG in conductor sizing. 22. Lighting load in residential service is calculated at ___. A. 1,500 watts
B. 2 VA
C. 3 VA ✅
D. 1 VA
Rationale: NEC requires 3 volt-amperes per square foot for general lighting load.
23. Allowed load for laundry circuit in residential service calculation? A. 1,500 volt-amperes ✅ B. 2,000 volt-amperes C. 1,920 watts D. 1,440 watts Rationale: NEC requires 1,500 VA for each laundry branch circuit. 24. Minimum conductor size for 125A 120/240V service using copper THHN? A. 1 B. 4 C. 3 D. 2 ✅ E. None of these Rationale: NEC Table 310.16 lists 2 AWG copper as the minimum for 125A service. 25. For noncoincident loads, service load must include ___. A. Smaller B. Larger ✅ Rationale: Only the larger of the noncoincident loads is included in service calculations. 27. In a 3-wire, 120/240V single-phase residential service, the neutral conductor carries the unbalanced current from the ___. A. Hot-to-ground loads B. Hot-to-hot loads C. 120V branch circuits ✅ D. Grounding electrode conductor Rationale: The neutral conductor carries the unbalanced load from the 120V circuits (hot-to-neutral). 28. A 15-amp circuit with 14 AWG copper conductors is allowed a maximum continuous load of how many amps? A. 12 A B. 10 A C. 15 A D. 80% of 15 A (12 A) ✅ Rationale: NEC 210.20(A) limits continuous loads on OCPDs to 80% of the rating: 15 A × 0.8 = 12 A.
A. 20 A
B. 24 A ✅
C. 30 A
D. 15 A
Rationale: I = P ÷ V = 5,760 ÷ 240 = 24 A.
35. What’s the smallest copper grounding electrode conductor required for a 100- amp residential service? A. #10 AWG B. #8 AWG ✅ C. #6 AWG D. #4 AWG Rationale: NEC Table 250.66 specifies #8 copper for 100A service. 36. Which of the following grounding electrode conductors must be connected within 5 feet of where the water pipe enters the building? A. Grounding conductor to the service panel B. Equipment grounding conductor C. Grounding electrode conductor ✅ D. Bonding jumper Rationale: NEC 250.68(C)(1) requires that the grounding electrode conductor be connected within the first 5 feet of entry for metal water pipes used as electrodes. 37. Which of the following statements is true about load centers and bolt-on breakers? A. Load centers generally do not accept bolt-on breakers. ✅ B. Load centers always require bolt-on breakers. C. Load centers must be rated for bolt-on breakers only. D. Bolt-on breakers are required for all panel types. Rationale: Residential load centers typically use plug-on breakers, not bolt-on types. 38. Plug fuses are permitted for use on which of the following systems? A. 277/480V, 3-phase, 4-wire B. 120/240V, 1-phase, 3-wire and 120/208V, 3-phase, 4-wire ✅ C. 480V, 3-phase, 3-wire D. All voltage systems Rationale: Plug fuses are suitable for lower voltage systems such as 120/240V and 120/208V, not for higher voltage systems like 277/480V. 39. For residential services, general lighting load is calculated at how many volt- amperes per square foot? A. 2 VA B. 3 VA ✅ C. 4 VA
D. 1.5 VA
Rationale: Per NEC 220.12, the general lighting load is calculated at 3 VA per square foot.
40. When calculating residential service load, what demand is assigned to a laundry circuit? A. 1,500 VA ✅ B. 2,000 VA C. 1,440 W D. 1,200 W Rationale: NEC 220.52 assigns a 1,500 VA load to a dedicated laundry circuit. 41. What is the smallest permitted conductor size for a 125A, 120/240V, 3-wire residential service (using copper THHN/THWN)? A. 3 AWG B. 4 AWG C. 2 AWG ✅ D. 1 AWG Rationale: NEC Table 310.16 shows that 2 AWG copper is rated for 115A–130A depending on insulation and installation conditions. 42. When two large noncoincident loads (like A/C and heating) exist, what load must be included in the residential service calculation? A. The larger of the two ✅ B. The sum of both C. The average of both D. The smaller of the two Rationale: NEC 220.60 allows the larger of noncoincident loads to be counted, not both. The number of conductors permitted in 80 PVC is specified in Table ___. Select one: a. 310.15(B)(16) b. 3 10. c. 3 47. d.
a. 22
b. 22
c.
d. 220. e. 220.56 - ANSWER 220. The minimum size service disconnect for a single-family dwelling with a computed load of 10 kVA is ___ amperes. Select one: a. 6 0 b. 3 0 c. 100 d. 50 - ANSWER 100 For a 100-Amp, 120/240-V, 3W commercial service, ___ AWG copper THHN/THWN conductors are the smallest permitted for the ungrounded conductors. Select one: a. 6 b. 3 c. 2
d. 4 e. none of these - ANSWER 3 Article ___ of the NEC® is the article that gives requirements for swimming pool installations. Select one: a. 7 50 b. 6 80 c. 560 d. 860 - ANSWER 680 Generally, safety switches and wall switches must be located at least ___ from the inside edge of a swimming pool. Select one: a. 5 ' b. 3 ' c. 8 ' d. 2 0' e. 10' - ANSWER 5'
all of these - ANSWER All of these What is the minimum number of 125-volt, 15- or 20-ampere convenience receptacles that the NEC® requires to be installed near a permanently installed pool? The pool is located in your neighbor's backyard. Select one: a. two (one at each end) b. one c. four (one on each side) d. none are required - ANSWER One When receptacles that provide power for water-pump motors or for other loads directly related to the circulation and sanitation system are located at least 6 feet and 10 feet from the inside walls of the pool, these receptacles are required to meet which of the following conditions? I. They consist of single receptacles. II. They employ a locking configuration. III. They are of the grounding type. IV. They have GFCI protection. Select one: a. I & IV only b. I & II only c. III & IV only d. IV only
e. I, III & IV - ANSWER III & IV only Electrical equipment located 7 feet from the inside wall of a pool is required to be grounded. Select one: a. True b. False - ANSWER False The Standard for Electrical Safety in the Workplace requires that all electrical equipment operating at over ___ volts to ground be de-energized and locked out before anyone is permitted to work on or near the equipment. Select one: a. 8 0 b. 5 0 c. 250 d. 150 - ANSWER 50 Home automation controllers that utilize radio frequency (RF) ___. Select one: a. require the receiver to be in sight of the sender b. can send signals through walls - ANSWER can send signals through walls It is permitted to run normal power conductors and optional standby power conductors in the same raceway or enclosure.
II or III only f. none of these - ANSWER I only While installing Cat 5 cable, pulling too hard can damage the ___. Select one: a. jac ket b. ins ulation c. conductor d. all of these - ANSWER All of these When a portable generator provides power for frame-mounted receptacles only, the NEC® ___ require the frame to be connected to a grounding electrode. Select one: a. does b. does not - ANSWER Does not Transfer switches use a ___ to prevent the feedback of electricity between the generator power and the normal utility power. Select one: a. capacitor bank b. mechanical interlock
c. SPST switch d. twistlock - ANSWER Mechanical interlock Without exceptions, all metal parts of an indoor spa or hot tub must be bonded. Select one: a. True b. False – ANSWER What is the result if the neutral wire becomes open on a multiwire circuit having unequal loads? Select one: a. The load of higher resistance would overheat and probably be damaged. b. The load of lesser resistance would overheat and probably be damaged. c. No effect until one load is turned off or opens. d. No effect. - ANSWER The load of higher resistance would overheat and probably be damaged. Refer to Figure 128.202. ___ volts are applied across the water heater element. Select one: a. 1 20 b. 2 40 c. 0
a. parallel b. series - ANSWER Parallel The neutral has been broken in the circuit shown in Figure 128.418. The current through Lamp F (IF) with the neutral opened is ___ amps. Select one: a. 6 b. 1 c. 2 d. 8 e. 3 - ANSWER 1 Refer to Figure 128.523. Each battery puts out 12 volts. The voltage applied to the load is ___ volts. Select one: a. 4 8 b. 0 c. 2 4 d. 3 6 e. 12 - ANSWER 24 What is the minimum number of receptacles required in an unfinished basement? Select one:
a. 2 b. 4 c. 1 d. 0 - ANSWER 1 What part of the NEC® is a reference for calculating conduit fill where all conductors are the same size? Select one: a. Article 100 b. Table 310.15(B)(16) c. Annex C d. Table 314.16(A) - ANSWER Annex C From NEC® Table 8 in Ch 9, the overall diameter of a 1/0 bare stranded copper conductor is ___ inches. Select one: a.. 1855 b.. 074 c.. 372
