Questions and Answers
Where type NM cables pass through cut or drilled slots or holes in metal members, the cable shall be protected by ___ which are installed in the opening prior to the installation of the cable and which securely cover all metal edges.
For locations not specifically identified in Table 300.5, a lesser cover depth than required in Column 5 shall be permitted where specified in the installation instructions of a(n) ____ low-voltage lighting system.
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Backfill used for underground wiring shall not damage, ___ or prevent adequate compaction of fill or contribute to corrosion.
Conduits or raceways through which moisture may contact live part shall be ___ at either or both ends.
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All conductors of the same circuit shall be ___, unless otherwise specifically permitted in the Code.
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Aluminum raceways, cable trays, and other components shall be provided with supplementary corrosion protection if they are:
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Short sections of raceways used for ___ shall not be required to be installed complete between outlet, junction, or splicing points.
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___ is a nonferrous, nonmagnetic metal that has no heating due to hysteresis heating.
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Wiring methods and cabling systems listed for use in other spaces used for environmental air (plenums) shall be permitted to be installed in ducts specifically fabricated for environmental air-handling purposes.
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Parallel conductors shall have the same ___.
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If cables meeting the requirements in 310.15(B)(3)(4)a through C with more than 20 current-carrying conductors are installed longer than 24 in. without maintaining spacing, are stacked, or are supported on bridle rings, a ___ percent adjustment factor shall be applied.
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For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, single-phase feeder conductors consisting of ___ ungrounded conductor(s) and the neutral conductor from a 208Y/120 volt system shall be permitted to be sized in accordance with 310.15(B)(7)(1) through (3).
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True or False: The service or feeder ratings addressed by 310.15(B)(7) are based on the standard ampacity rating from 240.6(A).
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The minimum size copper conductor permitted for branch circuits under 600V is ___ AWG.
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Surface-type cabinets, cutout boxes, and meter socket enclosures in damp or wet locations shall be mounted so there is at least ___-in. airspace between the enclosure and the wall or supporting surface.
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In walls constructed of wood or other ___ material, electrical cabinets shall be flush with the finished surface or project therefrom.
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Each cable entering a cutout box ___.
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Nonmetallic boxes can be used with ___
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Outlet boxes required in 314.27 shall be permitted to support ___ locking support and mounting receptacles used in combination with compatible attachment fittings.
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Handhole enclosure covers shall require the use of tools to open, or they shall weigh over ___ lb.
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At type AC cable terminations, a(n) ___ shall be provided.
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Study Notes
Cable Protection and Installation Requirements
- NM cables passing through metal members must be protected by listed bushings or grommets to cover metal edges.
- For low-voltage lighting systems not listed in Table 300.5, shallower cover depths are allowed per installation instructions.
Backfill and Underground Wiring
- Backfill materials must not damage raceways, cables, or conductors, and should allow for proper compaction.
Conduit and Raceway Sealing
- Conduits that may contact moisture with live parts need to be sealed or plugged at either end.
Circuit Conductors
- Conductors within the same circuit must be in the same raceway or cable, or in close proximity within the same trench unless otherwise specified.
Corrosion Protection
- Aluminum equipment like raceways and fittings in contact with concrete or the earth must have additional corrosion protection.
Raceways and Physical Damage
- Short sections of raceways can be used without being installed completely between outlet points.
Aluminum Characteristics
- Aluminum is a nonferrous metal, nonmagnetic, and does not heat due to hysteresis heating.
Wiring Methods in Plenums
- Wiring systems listed for environmental air can be installed in specially designed ducts if connecting to equipment or within a length limit of 4 feet.
Parallel Conductors
- Parallel conductors must share the same length, material, and circular mil area.
Adjustment Factor for Cables
- Cables with over 20 current-carrying conductors installed longer than 24 inches without proper spacing must apply a 60% adjustment factor.
Single-Phase Feeder Conductors
- In multi-family dwellings, single-phase feeder conductors can consist of 2 ungrounded conductors and one neutral from a 208Y/120 volt system per specific sizing guidelines.
Service and Feeder Ratings
- The ratings for service or feeder address in 310.15(B)(7) are based on standard ampacity from 240.6(A).
Minimum Copper Conductor Size
- The minimum size permissible for copper conductors in branch circuits under 600V is 14 AWG.
Installation of Surface Cabinets
- Surface-type cabinets and similar installations in damp/wet areas must maintain a ¼ inch airspace from the wall.
Electrical Cabinets in Combustible Walls
- Cabinets must be either flush with finished surfaces or mounted to project from combustible material walls.
Cable Securing Requirement
- Each cable entering a cutout box must be secured to the box itself.
Nonmetallic Boxes Usage
- Nonmetallic boxes are compatible with various materials, including nonmetallic sheaths and raceways, as well as flexible cords.
Outlet Box Support
- Outlet boxes must comply with requirements allowing for secure locking support when used with compatible fittings.
Handhole Enclosure Cover Requirements
- Covers for handhole enclosures should require tools to open or weigh over 100 pounds.
AC Cable Terminations
- At AC cable terminations, fittings or boxes designed for protection must be provided.
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Description
This quiz covers important installation requirements for cable protection, backfill materials, and corrosion protection in electrical wiring. Understand the guidelines for conduit sealing, raceways, and conductor arrangements to ensure compliance with safety standards. Test your knowledge on best practices in electrical installations.
