NEC Article 314 and local electrical codes specify minimum requirements for box sizing, mounting, grounding, and labeling. Using listed enclosures from manufacturers meeting UL and NEMA standards ensures inspection approval and liability protection. You'll learn what they are, why they're required, the difference. It takes the incoming power and safely distributes it to different circuits throughout your building. 15, a junction box is required whenever: You cannot: Common Misunderstanding If a cable passes through without splicing or terminating, you may not need to install a junction box — but you must still protect the conductors according to the wiring method rules. A junction box must be. Work Space Requirements Maintain work space requirements as indicated on all new installations. Exercise judgement on existing installations where encroachment has occurred. Clear. Below is a comprehensive guide to NEC rules for outdoor receptacles, lighting, conduit, boxes, pool zones, and more. Exception: Some snow-melting or deicing. The National Electrical Code (NEC) provides detailed rules and regulations for properly installing electrical wiring systems in the United States.