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Question 1. Which NEC article specifically governs the installation of electric signs and outline lighting? A) Article 300 B) Article 400 C) Article 600 D) Article 800 Answer: C Explanation: NEC Article 600 is dedicated to “Electric Signs and Outline Lighting,” covering definitions, wiring methods, and equipment requirements. Question 2. In Vermont, the most recent NEC edition adopted for sign work is: A) NEC 2014 B) NEC 2017 C) NEC 2020 D) NEC 2023 Answer: C Explanation: Vermont officially adopted the 2020 NEC edition with state‑specific amendments for sign installations. Question 3. Ohm’s Law for a DC circuit states that: A) V = I × R B) P = V / I C) I = V² / R D) R = V × I Answer: A
Explanation: Ohm’s Law defines voltage as the product of current and resistance (V = I·R). Question 4. A sign requires 120 V at 5 A. What is the power consumption? A) 600 W B) 24 W C) 6000 W D) 25 W Answer: A Explanation: Power P = V × I = 120 V × 5 A = 600 W. Question 5. When sizing a feeder for a 300 W LED sign on a 240 V circuit, the minimum conductor ampacity must be at least: A) 1.25 A B) 5 A C) 10 A D) 15 A Answer: B Explanation: Load current I = P/V = 300 W / 240 V = 1.25 A. NEC requires a 125 % safety factor for continuous loads, giving 1.56 A; the next standard conductor size is 5 A. Question 6. Which conductor material is prohibited for use in sign wiring that exceeds 600 V? A) Copper B) Aluminum C) Tinned copper D) Silver‑plated copper
C) 4 A
D) 20 A
Answer: A Explanation: Power is conserved (ignoring losses): P = V₁I₁ = 120 V×0.5 A = 60 W. Secondary current I₂ = P/V₂ = 60 W/4000 V = 0.015 A. Question 10. Which raceway is permitted for outdoor sign wiring in a wet location? A) EMT B) Rigid Metal Conduit (RMC) C) Flexible Metal Conduit (FMC) D) Non‑metallic Sheathed Cable (NM) Answer: B Explanation: RMC is rated for wet locations; EMT is only for dry locations unless listed for wet use, and NM is prohibited outdoors. Question 11. The maximum number of conductors allowed in a 1‑in. EMT conduit for 14‑AWG THHN is: A) 12 B) 14 C) 16 D) 20 Answer: C Explanation: According to NEC Chapter 9 Table 1, a 1‑in. EMT can hold up to 16 conductors of 14‑AWG THHN. Question 12. A sign’s disconnecting means must be located:
A) Within 10 ft of the sign B) At the service panel only C) Not more than 30 ft from the sign and readily accessible D) Inside the sign enclosure Answer: C Explanation: NEC 600.7 requires the disconnect to be readily accessible and not more than 30 ft from the sign. Question 13. Which of the following is considered a “high‑voltage secondary conductor” for sign work? A) 120 V AC flexible cord B) 4 kV neon secondary lead C) 12 V LED driver output D) 24 V AC transformer primary Answer: B Explanation: High‑voltage secondary conductors are those exceeding 600 V, such as neon transformer secondaries. Question 14. For a sign installed in a Class I, Division 2 hazardous location, the wiring must be: A) Standard NM cable B) Explosion‑proof conduit and fittings C) Any conduit as long as it is metal D) PVC conduit only Answer: B Explanation: Hazardous locations require equipment rated for explosion protection; standard NM is prohibited.
Explanation: NEC recommends a maximum of 3 % voltage drop for feeders to ensure proper operation of signs. Question 18. When using a cord‑and‑plug connection for a portable sign, the grounding conductor must be: A) 14‑AWG copper only B) Same size as the hot conductor C) No larger than 18 AWG D) Not required if the sign is double‑insulated Answer: B Explanation: NEC 400.7 requires the grounding conductor to be the same size as the ungrounded conductors in the cord set. Question 19. The NEC permits the use of Type MC cable for sign wiring when: A) The sign is portable B) The cable is installed in a raceway only C) The cable is listed for sign applications and the voltage does not exceed 600 V D) The cable is used outdoors without conduit Answer: C Explanation: Type MC is allowed if it is listed for sign use and the voltage rating is within the permissible limit. Question 20. Which of the following is NOT a permissible method for supporting high‑voltage secondary conductors in a neon sign? A) Metal straps with insulated clamps B) Plastic zip ties directly on the conductors
C) Rigid conduit with proper fittings D) Listed cable trays Answer: B Explanation: Plastic zip ties are not approved for supporting high‑voltage secondary conductors due to insufficient insulation and mechanical strength. Question 21. The required size of an equipment grounding conductor (EGC) for a 20‑A branch circuit using copper conductors is: A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: A Explanation: NEC Table 250.122 specifies 14 AWG copper for a 20‑A circuit. Question 22. A sign’s power supply must be installed with a minimum clearance from the roof surface of: A) 0 in. (flush) B) 2 in. C) 6 in. D) 12 in. Answer: C Explanation: NEC 600.6 requires a minimum of 6 in. clearance from combustible roof material. Question 23. When calculating load for a mixed‑sign installation (neon 150 W, LED 200 W, incandescent 250 W), the total demand factor applied per NEC 600.4 is:
Question 26. Which of the following is a required feature of a sign disconnect switch? A) Must be a lockable breaker or fused switch B) Must be a non‑locking rocker switch C) Must be located inside the sign enclosure D) Must be a dimmer control Answer: A Explanation: NEC 600.7 mandates a lockable, readily accessible disconnect. Question 27. For a sign mounted on a metal pole, the bonding jumper must be sized at least: A) 12 AWG copper B) 14 AWG copper C) 10 AWG copper D) 8 AWG copper Answer: B Explanation: NEC 250.122 requires a minimum of 14 AWG copper for bonding metal sign structures. Question 28. The maximum allowable length of a flexible cord used to power a portable sign is: A) 25 ft B) 50 ft C) 75 ft D) No specific limit, as long as voltage drop is acceptable Answer: D Explanation: NEC does not set a fixed length limit; the cord must be sized to handle the load and voltage drop.
Question 29. When installing a sign in a damp location, the enclosure must be listed for: A) Dry locations only B) Wet locations C) Outdoor use but not wet locations D) Indoor use only Answer: B Explanation: NEC 600.7 requires enclosures in damp or wet locations to be listed for those conditions. Question 30. The ampacity of a 10‑AWG aluminum conductor with 75 °C insulation in a conduit with three current‑carrying conductors is: A) 30 A B) 35 A C) 40 A D) 45 A Answer: B Explanation: NEC Table 310.15(B)(16) gives 40 A for 10‑AWG Al at 75 °C; with three conductors, apply a 0.8 derating factor → 32 A, rounded up to the next standard size 35 A. Question 31. Which of the following is NOT a permitted method for grounding a sign’s metal enclosure? A) Directly bonding to a grounding electrode system B) Using a grounding lug attached to the equipment grounding conductor C) Relying on the conduit as the sole grounding path without a bonding jumper D) Installing a grounding screw inside the enclosure connected to the EGC
C) 90 °C
D) 105 °C
Answer: C Explanation: Outdoor-rated flexible cords are typically marked 90 °C for better heat resistance. Question 35. A sign’s high‑intensity discharge (HID) ballast must be installed with a minimum clearance of: A) 1 in. from combustible material B) 2 in. from combustible material C) 4 in. from combustible material D) 6 in. from combustible material Answer: D Explanation: NEC 600.6 requires a 6 in. clearance for HID ballasts due to heat generation. Question 36. In a three‑phase sign power system, the line current for a 5 kW load at 480 V (line‑to‑line) is: A) 5.99 A B) 6.02 A C) 7.55 A D) 10.42 A Answer: B Explanation: Power per phase = 5 kW / √3 = 2.887 kW. Current I = P_phase / V_phase = 2887 W / 277 V ≈ 10.42 A. (Correction: Actually line‑to‑line voltage 480 V, line‑to‑neutral = 277 V. I = 5000 W / (√ 3 × 480 V) = 6.02 A.) Therefore answer B. Question 37. Which of the following is a required marking on a sign transformer?
A) Manufacturer’s phone number B) Input voltage, output voltage, and maximum wattage C) Color of the sign it powers D) Installation date Answer: B Explanation: NEC requires transformers to be marked with input voltage, output voltage, and maximum wattage. Question 38. For a sign located in a Class III hazardous area, the wiring must be: A) Standard NM cable B) Intrinsically safe or explosion‑proof conduit and fittings C) Rigid PVC conduit only D) Any conduit as long as it is metal Answer: B Explanation: Class III locations demand intrinsically safe or explosion‑proof equipment to prevent ignition. Question 39. The permissible voltage for a sign’s secondary wiring (high‑voltage) is: A) Up to 600 V B) Up to 1 kV C) Up to 5 kV D) Unlimited, as long as it is insulated Answer: C Explanation: NEC permits secondary voltages for signs up to 5 kV, provided they meet insulation and safety requirements.
Explanation: Portable signs are those that can be moved or relocated without permanent attachment. Question 43. The NEC permits the use of Type NM cable for sign wiring only when: A) The sign is outdoors B) The sign is located in a dry, interior space and voltage does not exceed 600 V C) The sign uses neon lighting D) The cable is protected by conduit outdoors Answer: B Explanation: NM cable is limited to dry, interior installations with voltage ≤600 V. Question 44. For a sign feeder that runs 150 ft with a 3 % voltage drop limit on a 120 V circuit, the minimum conductor size required (copper) is: A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: C Explanation: Using the voltage‑drop formula, 8 AWG copper (≈0.628 Ω/1000 ft) yields <3 % drop for typical loads over 150 ft. Question 45. The required disconnect for a sign with a 250 W neon transformer must be rated at least: A) 5 A B) 10 A C) 15 A
D) 20 A
Answer: B Explanation: The transformer draws about 2 A; a 10‑A disconnect provides adequate rating and meets the minimum 15 A breaker rule for small loads. Question 46. When a sign’s wiring includes more than three current‑carrying conductors in a conduit, the ampacity must be: A) Increased by 10 % B) Reduced according to NEC Table 310.15(B)(3)(a) C) Remains the same D) De‑rated to 50 % Answer: B Explanation: NEC requires derating of conductors when more than three are present, using Table 310.15(B)(3)(a). Question 47. Which of the following is NOT a permitted grounding electrode for a sign installation? A) Concrete‑encased electrode (Ufer) B) Ground rod C) Metal water pipe (if not isolated) D) Aluminum foil wrapping Answer: D Explanation: Aluminum foil is not an acceptable grounding electrode. Question 48. The NEC definition of “electric sign” excludes: A) Neon signs
Question 51. The NEC allows a sign to be powered from a dedicated 20‑A branch circuit if the total load does not exceed: A) 1200 W B) 1500 W C) 1800 W D) 2400 W Answer: C Explanation: 20 A × 120 V = 2400 VA; applying the 80 % continuous load rule gives 1920 W, but NEC generally caps sign loads at 1800 W for a dedicated circuit. Question 52. Which of the following is the correct method for bonding a metal sign support to the grounding system? A) Using a 6‑AWG copper strap with a listed bonding lug B) Wrapping the support with aluminum foil C) Painting the support with conductive paint D) Relying on the conduit alone Answer: A Explanation: A listed bonding lug and appropriately sized copper strap ensure a reliable ground path. Question 53. The NEC requires that sign disconnects be: A) Operable with a standard light switch B) Capable of being locked in the “off” position C) Installed inside the sign enclosure only D) Controlled remotely only Answer: B
Explanation: Disconnects must be lockable to prevent inadvertent energization. Question 54. For a sign located on a building roof, the minimum clearance from the roof surface to the bottom of the sign’s transformer is: A) 0 in. (flush) B) 2 in. C) 4 in. D) 6 in. Answer: D Explanation: NEC 600.6 mandates a 6‑in. clearance from combustible roof material. Question 55. When a sign uses a 24 V DC LED driver, the driver must be listed for: A) Use in wet locations only B) Use in dry locations only C) Use in both wet and dry locations if installed accordingly D) Only indoor use Answer: C Explanation: If the driver is listed for both wet and dry locations, it may be installed per the listing. Question 56. The NEC permits the use of flexible metal conduit (FMC) for sign wiring in a damp location only if the FMC is: A) Listed for wet locations B) Painted with waterproof paint C) Supported every 2 ft D) Used with a plastic cover
