NEC Article 314 provides comprehensive requirements for the installation and use of boxes, conduit bodies, and other enclosures used in electrical systems. These requirements ensure that the installations are safe, reliable, and accessible. Here is a detailed overview of NEC Article 314:

314.1 Scope

This section establishes the scope of Article 314, which includes the installation and use of all boxes and conduit bodies used as outlet, device, junction, or pull boxes, depending on their use. It also covers handhole enclosures and fittings for connecting raceways and cables.

314.2 Round Boxes

Round boxes are not permitted where raceways or connectors requiring locknuts or bushings are connected to the side of the box. This ensures adequate locking and electrical continuity.

314.3 Nonmetallic Boxes

Nonmetallic boxes have specific restrictions and generally should not be mixed with metallic raceways and fittings. This maintains the integrity and safety of the installation.

314.4 Metal Boxes

Metal boxes must be grounded and bonded to ensure electrical continuity and safety. Bonding is required especially on the load side of the system.

314.5 Screws or Other Fasteners

This new section ensures that proper screws and fasteners are used when they enter the wiring compartment of an outlet box, device box, pull box, junction box, conduit bodies, fittings, and handhole enclosures. The use of improper fasteners can compromise the safety and integrity of the installation.

314.15 Damp, Wet, or Hazardous Locations

Boxes, conduit bodies, and fittings installed in damp or wet locations must be placed or equipped to prevent moisture from entering or accumulating within the enclosure. They must be listed for use in such environments to ensure safety and durability.

314.16 Number of Conductors in Outlet, Device, and Junction Boxes, and Conduit Bodies

Boxes and conduit bodies must be of sufficient size to provide free space for all enclosed conductors. This includes the volume calculations for box fill, ensuring that the box can accommodate the conductors without overcrowding, which can lead to overheating and potential fire hazards.

314.17 Conductors Entering Boxes, Conduit Bodies, or Fittings

Conductors must be protected from abrasion and must enter through properly installed and approved openings. Metal and nonmetallic boxes have specific requirements to ensure the conductors are not damaged during installation and use.

314.20 In Wall or Ceiling

Boxes must be installed such that the front edge of the box is flush with the finished surface of the wall or ceiling. This ensures that the cover plates can be properly installed and provide a finished appearance as well as protection.

314.21 Repairing Noncombustible Surfaces

Noncombustible surfaces around boxes must be repaired to prevent gaps greater than 1/4 inch. This prevents the spread of fire and maintains the integrity of the installation.

314.23 Supports

Boxes and conduit bodies must be securely and rigidly supported to prevent physical damage and ensure stability. This includes methods such as mounting on a stud or other stable surface.

314.24 Dimensions of Boxes

Boxes must have adequate depth to accommodate devices and ensure safe wiring practices. This section ensures that devices can be properly installed without crowding or damaging the conductors.

314.25 Covers and Canopies

Boxes must be equipped with covers or canopies to provide protection to the enclosed conductors and devices. These covers must be properly installed to ensure a safe and reliable installation.

314.27 Boxes at Ceiling-Suspended (Paddle) Fan Outlets

Boxes intended for use with ceiling-suspended (paddle) fans must be listed and marked for this purpose to ensure they can support the weight and motion of the fan.

314.28 Pull and Junction Boxes and Conduit Bodies for Conductors 4 AWG or Larger

This section specifies the minimum size requirements for pull and junction boxes and conduit bodies to ensure they can accommodate the conductors and provide adequate space for wiring.

314.29 Boxes, Conduit Bodies, and Handhole Enclosures to Be Accessible

All boxes, conduit bodies, and handhole enclosures must be accessible for maintenance and inspection without requiring the removal of any part of the building or structure.

314.30 Handhole Enclosures

Handhole enclosures must be designed and installed to provide easy access for personnel entry and to protect the enclosed conductors and connections from physical damage and environmental exposure.

For further details and specific requirements, referring to the NEC Handbook and additional resources provided by the NFPA is highly recommended.