A 3-phase distribution board handles three active conductors — L1, L2, and L3 — plus a neutral and earth (in a four-wire system). It's designed for three-phase power systems, which are the standard for industrial, commercial, and high-demand installations across. The Unified Facilities Criteria (UFC) system is prescribed by MIL-STD 3007 and provides planning, design, construction, sustainment, restoration, and modernization criteria, and applies to the Military Departments, the Defense Agencies, and the DoD Field Activities in accordance with USD (AT&L). Power distribution boards and lighting distribution boards should preferably be installed separately. When power and lighting are combined in the same distribution board, they must be distributed via separate branch circuits. Unlike single-phase. 1) Generally, the incoming line of power distribution box adopts five wire system, that is, a, B and C three-way phase line (the general color is yellow, green and red), one way zero line (the color is light blue) and one way ground line (the color is yellow with green stripes). Outgoing line. Practice good wiring: secure grounding, neat cable management, proper insulation, and correct wire gauge and breaker size. Include protection devices like breakers, fuses, and surge protectors—each circuit should have its own protection. Comply with standards: Follow NEC, IEC, or local codes.