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Question 1. Which NEC article defines the term “grounded conductor”? A) Article 100 B) Article 250 C) Article 210 D) Article 310 Answer: A Explanation: Article 100 provides definitions for terms used throughout the NEC, including “grounded conductor”. Question 2. Ohm’s Law states that voltage equals: A) Current divided by resistance B) Current multiplied by resistance C) Resistance divided by current D) Power divided by current Answer: B Explanation: V = I × R, where V is voltage, I is current, and R is resistance. Question 3. In a series circuit supplying a sign, the total resistance is: A) The sum of individual resistances B) The product of individual resistances C) The reciprocal of the sum of reciprocals D) Equal to the largest individual resistance Answer: A Explanation: Series resistances add directly: R_total = R1 + R2 + ….
Question 4. Which symbol on a sign plan indicates a neon transformer? A) A circle with “T” inside B) A square with “N” inside C) A rectangle with “TR” D) A triangle with “NE” Answer: C Explanation: NEC sign plans commonly use a rectangle labeled “TR” to denote a transformer, and neon transformers are identified by context. Question 5. The minimum size for a service entrance conductor for a 200 A residential service is: A) 4/0 AWG copper B) 2/0 AWG aluminum C) 3/0 AWG copper D) 1/0 AWG aluminum Answer: A Explanation: Per Table 310.15(B)(16), 4/0 AWG copper is rated for 230 A at 75 °C, meeting the 200 A requirement. Question 6. Grounding electrode conductors must be installed: A) Only at the service disconnect B) From the equipment grounding conductor to the earth C) From the grounded conductor to a grounding electrode D) Only for separate buildings Answer: C
C) 40 A
D) 45 A
Answer: C Explanation: Continuous loads must be protected at 125 % of the load: 30 A × 1.25 = 37.5 A, rounded up to the next standard size, 40 A. Question 10. When applying temperature correction factors, a conductor installed in a location with an ambient temperature of 40 °C (104 °F) uses a factor of: A) 0. B) 0. C) 0. D) 0. Answer: B Explanation: Table 310.15(B)(2)(a) lists a correction factor of 0.91 for 40 °C ambient temperature for 75 °C conductors. Question 11. The ampacity of a 12 AWG copper conductor with 90 °C insulation, after applying a 0.88 temperature correction factor, is: A) 25 A B) 30 A C) 35 A D) 20 A Answer: B Explanation: 12 AWG copper at 90 °C is rated 30 A; applying 0.88 yields 26.4 A, rounded to the next lower standard rating, 25 A, but the NEC requires the unadjusted ampacity for OCPD selection, so 30 A is used before correction for voltage drop calculations.
Question 12. Which conduit type is permitted for direct burial of sign feeder conductors? A) EMT B) Rigid metal conduit (RMC) C) PVC conduit schedule 40 D) Flexible metal conduit (FMC) Answer: C Explanation: PVC conduit schedule 40 is rated for direct burial per NEC 352.10. Question 13. The maximum number of 14 AWG conductors allowed in a single 1‑in. EMT conduit is: A) 12 B) 10 C) 8 D) 6 Answer: B Explanation: Table 1 in Chapter 9 gives a fill limit of 40 % for more than two conductors; 1‑in. EMT can hold 10 conductors of 14 AWG. Question 14. In a wet location, conductors must be: A) Insulated with THHN only B) Rated for wet conditions, such as THWN or XHHW C) Covered with a moisture‑resistant tape D) Placed in metal conduit only Answer: B
B) Exactly the transformer’s full‑load current C) Not more than 80 % of the transformer’s full‑load current D) The next standard size above the full‑load current Answer: D Explanation: Per NEC 240.21(B), the OCPD shall be the next standard size above the calculated load. Question 18. When installing a sign in a hazardous (Class I) location, the wiring method must be: A) Rigid metal conduit only B) Listed as suitable for the specific hazard class, such as MC‑H C) Any conduit as long as it is grounded D) PVC conduit with a metal cover Answer: B Explanation: NEC 500 requires wiring methods to be listed for the specific hazardous classification, such as MC‑H for Class I. Question 19. An exit sign powered by a battery‑back‑up system must be capable of operating for at least: A) 30 minutes B) 60 minutes C) 90 minutes D) 120 minutes Answer: B Explanation: NEC 700.12 requires emergency lighting, including exit signs, to operate for a minimum of 90 minutes; however, for battery‑back‑up signs the typical requirement is 60 minutes of illumination at full brightness. The correct answer is B.
Question 20. The minimum height for a sign’s mounting bracket on a building façade is: A) 5 ft above grade B) 6 ft above grade C) 7 ft above grade D) No minimum height, only clearance from the ground Answer: D Explanation: NEC 600 does not prescribe a minimum mounting height; local ordinances may, but the code only requires clearances from combustible material. Question 21. Which of the following is a permitted method for grounding a metal sign support structure? A) Connecting a #12 AWG copper wire to the nearest water pipe B) Using a grounding electrode conductor to a ground rod C) Bonding the support directly to the service neutral D) No grounding required for metal supports Answer: B Explanation: Metal sign supports must be grounded via a grounding electrode conductor to an approved grounding electrode, per NEC 250.118. Question 22. The maximum voltage drop allowed for a feeder supplying a sign is: A) 2 % B) 3 % C) 5 % D) 10 %
A) #10 AWG copper B) #12 AWG copper C) #8 AWG copper D) #14 AWG copper Answer: B Explanation: Table 250.122 specifies a #12 AWG copper bonding jumper for OCPD ratings up to 60 A. Question 26. A sign’s power supply is listed for “Class II” circuits. This means the supply is: A) Limited to 30 V and 100 VA B) Limited to 60 V and 100 VA C) Limited to 30 V and 150 VA D) Limited to 60 V and 150 VA Answer: A Explanation: Class II circuits are limited to 30 V and 100 VA per NEC 725.3. Question 27. For a sign installed outdoors in a damp location, the enclosure must be rated at least: A) NEMA 1 B) NEMA 3R C) NEMA 4 D) NEMA 4X Answer: B Explanation: NEMA 3R enclosures are required for outdoor damp locations (rain, sleet, snow).
Question 28. The minimum conductor size for a 20 A branch circuit feeding a sign in a commercial building is: A) #14 AWG copper B) #12 AWG copper C) #10 AWG copper D) #8 AWG copper Answer: B Explanation: Per NEC 210.19(A)(1), a 20 A circuit requires at least #12 AWG copper. Question 29. When a sign is supplied by a transformer with a primary voltage of 480 V and a secondary of 120 V, the transformer must be installed: A) Within 6 ft of the sign body B) In a dedicated enclosure rated for the primary voltage C) Directly on the sign structure D) In any location as long as it is grounded Answer: B Explanation: NEC 600.4(C) requires the transformer to be installed in a location suitable for the primary voltage, typically a dedicated enclosure. Question 30. Which of the following is NOT a permitted method for securing a sign’s conduit run? A) Straps spaced no more than 3 ft apart B) Staples every 4 ft C) Cable ties every 6 ft D) Rigid clamps at each box Answer: C
Answer: B Explanation: Table 250.122 indicates #6 AWG copper for a 100 A service. Question 34. In a sign system, the term “secondary conductor” refers to: A) The feeder from the service panel to the sign transformer B) The conductors that run from the transformer to the sign lamps C) The grounding conductor for the sign D) The control wiring for sign animation Answer: B Explanation: Secondary conductors carry power from the low‑voltage side of the transformer to the sign’s lighting elements. Question 35. For a sign located in a Class II hazardous area, the wiring method must be: A) Rigid metal conduit only B) Listed for Class II, such as MC‑H C) PVC conduit with a metal cover D) Any conduit as long as it is grounded Answer: B Explanation: NEC 500.6 requires wiring methods to be listed for the specific hazardous class; MC‑H is approved for Class II. Question 36. The required ampacity of a feeder supplying a 3 kW LED sign at 240 V, assuming a 125 % continuous load factor, is: A) 12.5 A B) 15.6 A
C) 18.8 A
D) 20.8 A
Answer: C Explanation: Load current = 3000 W / 240 V = 12.5 A. Multiply by 1.25 = 15.63 A. The next standard OCPD is 20 A, but ampacity must be at least 15.63 A; the feeder conductor must be sized for 15.63 A, which typically means #12 AWG copper (20 A rating). However the calculated ampacity is 15.63 A, which matches answer C (18.8 A is incorrect). Correction: The correct answer is B, 15.6 A. Question 37. When a sign’s wiring is installed in a metal raceway that is part of a grounding system, the raceway must be: A) Isolated from the grounding electrode system B) Bonded at each end and at each junction box C) Only bonded at the service panel D) Not bonded at all Answer: B Explanation: Metal raceways serving as grounding paths must be bonded at each termination per NEC 250.118. Question 38. A sign that uses a transformer with a primary voltage of 120 V and a secondary of 12 V must have the secondary conductors protected by an OCPD rated at: A) 15 A B) 20 A C) 30 A D) 40 A Answer: A Explanation: The secondary current is limited by the transformer’s rating; a 12 V, 60 W transformer draws 5 A, so a 15 A breaker (next standard size) is appropriate.
Explanation: NEC does not require spacing between circuits in the same conduit as long as fill limits are observed. Question 42. For a sign located in a parking garage with a concrete floor, the conduit must be: A) EMT only B) Rigid PVC only C) Listed for use in concrete encasement D) Flexible metal conduit only Answer: C Explanation: Conduit in concrete must be listed for that purpose, such as PVC conduit rated for concrete encasement per NEC 352.10. Question 43. The purpose of a surge protective device (SPD) on a sign’s power supply is to: A) Limit the current to the sign to 15 A B) Reduce voltage spikes caused by lightning or switching transients C) Provide a backup power source D) Act as a ground fault circuit interrupter (GFCI) Answer: B Explanation: SPDs clamp transient overvoltages to protect sensitive sign electronics. Question 44. Which of the following is NOT a permitted method for bonding a sign’s metal frame to the grounding system? A) Using a grounding lug with a #10 AWG copper wire B) Directly attaching the frame to a water pipe C) Connecting a bonding jumper to the grounding electrode conductor
D) Using a listed grounding strap Answer: B Explanation: Direct attachment to a water pipe is not allowed unless the pipe is part of the grounding electrode system and meets specific conditions; generally a dedicated grounding lug is required. Question 45. The NEC requires that a sign’s power source be disconnected for maintenance by: A) Removing the fuse only B) Opening the service panel C) Using a listed disconnecting means within sight of the sign D) Turning off the main breaker only Answer: C Explanation: NEC 600.6 mandates a readily accessible disconnect within sight of the sign. Question 46. The minimum size of a grounding electrode conductor for a 400 A service is: A) #4 AWG copper B) #2 AWG copper C) #1/0 AWG copper D) #4/0 AWG copper Answer: C Explanation: Table 250.122 specifies #1/0 AWG copper for 400 A services. Question 47. When a sign is powered by a photovoltaic (PV) system, the PV array must be considered a: A) Separate derived system B) Part of the service entrance
B) 75 °C rated and used only outdoors C) Marked with “AL” and sized per Table 310.15(B)(16) D) Never permitted for sign circuits Answer: C Explanation: Aluminum conductors are allowed when properly marked and sized according to the NEC tables. Question 51. The required minimum height for a sign’s emergency lighting fixture above the floor is: A) 4 ft B) 5 ft C) 6 ft D) 7 ft Answer: C Explanation: NEC 700.12 requires emergency lighting to be mounted at a height not less than 6 ft above the floor. Question 52. When a sign’s power supply is located in a separate room, the room must be equipped with: A) A dedicated GFCI receptacle B) A fire‑rated door C) An accessible disconnecting means for the sign D) An automatic sprinkler system only Answer: C Explanation: NEC 600.6 requires the disconnect to be readily accessible, which can be located in a separate room.
Question 53. The NEC allows a sign’s transformer to be mounted on a metal pole without a separate grounding electrode if: A) The pole is grounded to the building’s grounding system B) The transformer is listed for pole mounting C) The pole is made of steel D) The transformer is less than 500 VA Answer: A Explanation: Grounding the pole to the building’s grounding system satisfies the grounding requirement for the transformer. Question 54. For a sign that uses a 120 V, 60 W fluorescent lamp, the minimum size of the branch‑circuit conductor is: A) #14 AWG copper B) #12 AWG copper C) #10 AWG copper D) #8 AWG copper Answer: A Explanation: The load is 0.5 A; a #14 AWG copper conductor (15 A rating) is sufficient. Question 55. The NEC requires that a sign’s wiring in a wet location be protected from corrosion by: A) Using THHN only B) Applying anti‑corrosion tape C) Using conductors with a wet‑rating such as THWN‑ 2 D) Installing a dehumidifier in the enclosure
