Third level distribution box: refers to the final junction box of each electrical appliance, which can be movable and fixed. The distribution box shall be set below the main distribution box, and the switch box shall be set below the distribution box, and the. This fact sheet explains how to apply the requirements shown in AS/NZS 3012:2019 Electrical installations – construction and demolition sites (AS/NZS 3012:2019), which is called up as a mandatory standard by section 163 of the Work Health and Safety Regulation 2025 (WHS Regulation). The standard. The National Electrical Code (NEC) provides comprehensive safety standards for electrical installations, including requirements for electrical panels (main service panels and subpanels or breaker box). It takes the incoming power and safely distributes it to different circuits throughout your building.