Three-level distribution box with one machine and one switch

In a standard three-level distribution system, each switch in the tertiary distribution box should control only one machine; using a single switch for multiple machines is not recommended for safety and compliance.Understanding Three-Level DistributionA three-level distribution system consists of:Primary Distribution Box: Connects directly to the transformer and distributes power to secondary boxes. It handles high-voltage three-phase power and typically includes isolating switches, circuit breakers, and residual current devices (RCDs) for protection .Secondary Distribution Box: Acts as an intermediate panel, routing power to specific zones, buildings, or floors. It also includes protection devices and ensures safe distribution to tertiary boxes .Tertiary Distribution Box (Switch Box): The final distribution point that connects directly to electrical equipment. Each tertiary box is designed to follow the principle of “one machine, one switch, one protection, one box, one lock”, ensuring that each machine has its own dedicated switch and protection device .Why One Switch per Machine is RequiredSafety: Connecting multiple machines to a single switch can bypass the hierarchical protection system, increasing the risk of overloads, short circuits, or electrical hazards .Protection Compliance: Tertiary boxes are equipped with residual current devices (RCDs) or leakage protection switches. Sharing a switch among multiple machines compromises individual protection and violates construction and electrical standards .Maintenance and Control: Individual switches allow for easier isolation of a single machine for maintenance without affecting other equipment .Practical ConsiderationsBranching: While primary and secondary distribution boxes can branch power to multiple downstream boxes, tertiary boxes must not branch to multiple machines .Distance: Keep the distance between distribution boards and switch boxes under 30 meters, and between switch boxes and machines under 3 meters to minimize voltage drop and ensure safety .Three-Phase Systems: For factories or high-power applications, three-phase distribution boxes are used to balance loads and protect equipment. Each machine should still have its own circuit breaker and switch .ConclusionUsing a single switch to control multiple machines in a three-level distribution system is not recommended. Each machine should have its own dedicated tertiary switch and protection device to comply with safety standards, ensure proper protection, and maintain the integrity of the hierarchical distribution system . For multi-machine setups, consider installing additional tertiary boxes or switches to meet these requirements.