North Carolina Electrical Contractor - Electric Sign (SP-ES)

North Carolina Electrical Contractor – Electric Sign (SP-ES) · 5 questions, 12% of exam

Key Concepts

Sign-specific grounding (Article 600, Part I) - Metal equipment of signs, outline lighting, and skeleton tubing systems shall be grounded by connection to the equipment grounding conductor (EGC) of the supply branch circuit(s) or feeder, using the EGC types specified in 250.118 — 600.7(A)(1). EGC size is per 250.122 — 600.7(A)(2); connections are made per 250.130 and by a method in 250.8 — 600.7(A)(3). - Auxiliary grounding electrode(s) are permitted for signs and outline lighting and must meet 250.54 — 600.7(A)(4). - Metal parts of a building shall not be used as a secondary return conductor or an EGC — 600.7(A)(5) and 600.32(A)(5) — and shall not be used as a means for bonding metal parts and equipment of signs together or to the transformer/power-supply EGC — 600.7(B)(3).

Key Concepts

Scope of Article 240 — Parts I through VII cover overcurrent protection not more than 1000 volts, nominal; Part VIII covers supervised industrial installations not more than 1000 volts, nominal; Part IX covers overcurrent protection over 1000 volts, nominal (240.1).

Circuit breaker operation and marking - Circuit breakers shall be trip free and capable of being closed and opened by manual operation; normal operation by other than manual means (electrical, pneumatic) is permitted if means for manual operation are also provided (240.80). - Breakers shall clearly indicate open "off" or closed "on"; where handles operate vertically, "up" is the "on" position (240.81). - Ampere rating shall be durable and visible after installation (240.83(A)). Breakers rated 100 amperes or less and 1000 volts or less shall have the ampere rating molded, stamped, etched, or similarly marked into handles or escutcheon areas (240.83(B)). - Every circuit breaker having an interrupting rating other than 5000 amperes shall have its interrupting rating shown on the breaker; not required on breakers used for supplementary protection (240.83(C)). -…

Key Concepts

Conductor characteristics (Article 310) - Minimum conductor size for voltage ratings up to and including 2000 volts: 14 AWG copper or 12 AWG aluminum/copper-clad aluminum, except as permitted elsewhere in the Code — 310.3(A). - Where installed in raceways, conductors 8 AWG and larger shall be stranded, unless specifically permitted or required to be solid — 310.3(C). - Conductors may be connected in parallel only in sizes 1/0 AWG and larger — 310.10(G)(1). - A grounding or bonding conductor shall not be counted when applying 310.15(C)(1) — 310.15(F). - Raceways/cables in direct sunlight on or above rooftops, less than 23 mm (7/8 in.) above the roof: add 33°C (60°F) to the outdoor temperature — 310.15(B)(2).

Cable types — permitted and not permitted uses - Type AC: permitted for feeders and branch circuits, exposed or concealed, in cable trays, and in dry locations — 320.10. Not permitted where subject to physical damage, in damp or wet locations, in exposed masonry air voids, where exposed to corrosive conditions — 320.12. - Type MI: permitted…

Key Concepts

Scope and box type restrictions - Article 314 covers outlet, device, junction and pull boxes, conduit bodies, fittings used to join raceways/cables to boxes, and handhole enclosures. Cast metal, sheet metal, nonmetallic and other boxes such as FS, FD and larger boxes are not classified as conduit bodies (NEC 2020, 314.1). - Round boxes shall not be used where conduits or connectors requiring locknuts or bushings are connected to the side of the box (314.2). - Nonmetallic boxes are permitted only with open wiring on insulators, concealed knob-and-tube, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways. Exception No. 1: where internal bonding means are provided between all entries, nonmetallic boxes are permitted with metal raceways or metal-armored cables (314.3). Exception No. 2 covers integral bonding means between all threaded entries in nonmetallic boxes listed for the purpose. - Metal boxes shall be grounded and bonded per Parts I, IV, V, VI, VII and X of Article 250, except as permitted in 250.112(I) (314.4). A means for connecting an…

Subtopics: conductor ampacity requirements, overcurrent protective device sizing

Key Concepts

Sign branch circuits are continuous loads. Branch circuits that supply signs shall be rated in accordance with 600.5(C)(1) or (C)(2) and shall be considered to be continuous loads for the purposes of calculations — NEC 2020, 600.5(C).

Two different rating ceilings, by sign type: - Neon tubing installations: branch circuits shall not be rated in excess of 30 amperes — 600.5(C)(1). - All other signs and outline lighting systems: branch circuits shall be rated not to exceed 20 amperes — 600.5(C)(2).

Required sign outlet circuit. Each commercial building and each commercial occupancy accessible to pedestrians shall have at least one outlet in an accessible location at each entrance to each tenant space for sign or outline lighting system use. The outlet(s) shall be supplied by a branch circuit rated at least 20 amperes that supplies no other load — 600.5(A). Note the direction: 600.5(A) is a minimum rating; 600.5(C)(1) and (C)(2) are maximums.

Appliances, Equipment, and Lighting

Key Concepts

Dry-type transformers installed indoors

• Dry-type transformers rated 112½ kVA or less installed indoors shall have a separation of at least 300 mm (12 in.) from combustible material unless separated by a fire-resistant, heat-insulated barrier. This does not apply to transformers rated 1000 volts, nominal, or less that are completely enclosed except for ventilating openings. — 450.21(A)
• Individual dry-type transformers of more than 112½ kVA shall be installed in a transformer room of fire-resistant construction having a minimum fire rating of 1 hour. — 450.21(B)
• Exception No. 1: Transformers with Class 155 or higher insulation systems separated from combustible material by a fire-resistant, heat-insulating barrier or by not less than 1.83 m (6 ft) horizontally and 3.7 m (12 ft) vertically.
• Exception No. 2: Transformers with Class 155 or higher insulation systems and completely enclosed except for ventilating openings.
• Dry-type transformers rated over 35,000 volts shall be installed in a vault complying with Part III. — 450.21(C)

Transformer vaults (Part III)

Key Concepts

Code arrangement and rule types (Article 90) - Chapters 1–4 apply generally; Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions and may supplement or modify Chapters 1 through 7. Chapter 8 covers communications systems and is not subject to the requirements of Chapters 1 through 7 except where specifically referenced in Chapter 8 (NEC 2020, 90.3). - Mandatory rules are characterized by the terms shall or shall not (90.5(A)). Permissive rules use shall be permitted or shall not be required (90.5(B)). Explanatory material, such as informational notes, is informational only and is not enforceable (90.5(C)). - The Code does not cover installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles (90.2(B)(1)).

Key Concepts

Business structures (Chapter 2) - Sole proprietorship: owner bears unlimited personal liability; formed with a DBA filing; entity not taxed (Summary of Business Legal Structures table). - Partnerships: general partners have personal and unlimited liability; limited partners have no personal liability and are liable only for the previously agreed-upon contribution to or investment in the business (Chapter 2 — Partnerships, Liability). Partners file federal returns on IRS Form 1065. A limited partnership is formed with a Limited Partnership Certificate and Limited Partnership Agreement (Summary table). - C corporation: unlimited number of shareholders, generally no personal liability, taxed at the corporate level with a further tax on dividends ("double taxation"); formed with Articles of Incorporation and Bylaws (Summary table). - S corporation requirements: domestic corporation with one class of stock; no more than 100 shareholders who are U.S. citizens or legal residents; all shareholders consent; permitted tax year; filing of IRS Form 2553 (Chapter 2 — S Corporations). - LLC: not taxed at the entity level. **One owner = taxed as a sole…