26 (D), all working spaces must have a minimum Electrical equipment headroom of 2. 0 m (6 ft 6 in), measured from the floor or platform to the ceiling or any overhead obstruction like pipes or ductwork. This ensures a worker isn't forced to crouch or work in an awkward. Per NEC 110. While. Dedicated equipment space is for the equipment so that there is ample room for installing conduits, cables, cable trays and related wiring methods. The National Electrical Code. The National Electrical Code (NEC) governs electrical junction box rules. These rules define when you must install a box, how large it must be, how you must install it, and how inspectors evaluate compliance.