Learn what the NEC requires for junction boxes, from box fill calculations and grounding to outdoor use and fire-rated wall installations. The National Electrical Code (NEC), published as NFPA 70, sets minimum safety standards for electrical junction boxes in residential and. NEC 314. NEC Article 314 establishes requirements for the installation and use of electrical boxes, conduit bodies, fittings, and handhole enclosures. A conduit body is a removable-cover section of a conduit system that provides access at junctions or termination points. Article 314 applies to: These. An electrical box encloses wire connections at every switch, outlet, and fixture point, and correct sizing per NEC code is required to pass inspection.