🙋 In this junction box calculator, we refer to the specifications provided by the National Fire Protection Association® (NFPA®) in the NFPA 70: National Electrical Code® 2020 (2020 NEC®) Article 314. 28 Pull and Junction Boxes and Conduit Bodies. Learn key electrical code requirements for junction boxes, including sizing, grounding, materials, and clearance to ensure safety and efficiency. Electrical safety is non-negotiable, and the National Electrical Code (NEC) sets the gold standard for safe installations in the U. Note: This article is based on the 2005 NEC. He has worked on exciting projects such as environmentally aware radar, using genetic algorithms to tune radar, and building the UK. Sizing rules You must size pull boxes, junction boxes, and conduit bodies large enough so a crew can install the conductors without damaging them.