Applying NEC Article 312, Part 1

Article 312 provides the requirements for cabinets, cutout boxes, and meter socket enclosures.These are all types of enclosures (see Art. 100 and also the usage in Sec. 312.2).

Part II forms the bulk of this Article, and it covers the construction specifications for these enclosures. But those requirements are for the manufacturer, rather than the installer.

Part I, however, is for the installer. Here are some key points to take note of:

• Article 312 does not apply to equipment operating at over 1,000V, except as specifically referenced elsewhere in the NEC [312.1].
• In damp or wet locations, these enclosures must be equipped (or placed) to prevent the entry and accumulation of moisture [312.2] (and meet a few additional requirements noted here).
• When installing a cabinet in a noncombustible wall, ensure the front edge isn’t set back more than 1/4 in. from the finished surface [312.3]. If the wall is combustible, mount cabinets flush with the finished surface (or ensure they project from it).
• Use an approved method to close openings through which conductors enter [312.5)(A)].
• Where cables are used, secure each one to the enclosure [312.5(C)].