How many amperes is the secondary distribution box in the factory

The amperage of a secondary distribution box in a factory typically ranges from 100 A to 400 A per phase, depending on the load and design of the facility.Voltage and Phase ConfigurationSecondary distribution boxes in factories usually operate at low-voltage levels, commonly 400/230 V, 3-phase, 4-wire systems in many countries, including India and Europe . Single-phase loads are connected between a phase and neutral (230 V), while three-phase motor loads are connected across the three-phase lines (400 V), . The exact voltage and phase configuration influence the current rating of the distribution box.Factors Affecting AmperageThe current rating of a secondary distribution box depends on several factors:Total connected load: The sum of all machinery, lighting, and auxiliary equipment supplied by the box .Number of phases: Three-phase systems distribute the load across three lines, reducing the per-phase current for the same power .Design and safety margin: Industrial panels are designed with a margin to handle peak loads and future expansion .Cable and breaker ratings: The busbars, cables, and protective devices inside the box determine the maximum safe current .Typical Amperage RangesSmall to medium factories: Secondary distribution boxes often have ratings of 100–200 A per phase.Large factories or heavy industrial loads: Ratings can go up to 400 A or more per phase, sometimes with multiple parallel feeders or sub-panels to distribute the load .Design ConsiderationsSecondary distribution boxes are usually located close to the load centers to minimize cable lengths and voltage drops . They may include busbars, circuit breakers, and metering devices to ensure safe and reliable operation. In some designs, the load is split across two electrically independent buses with a tie breaker to improve service continuity .Key TakeawayWhile there is no single standard amperage for all factory secondary distribution boxes, 100–400 A per phase is typical, with the exact value determined by the factory's total load, voltage, and safety requirements . For precise specification, a detailed load analysis and consultation with an electrical engineer are recommended.