The distance between a plug-in box and a distribution box is not fixed but should be minimized for safety, efficiency, and compliance with wiring standards, typically within a few meters depending on voltage, current, and installation type.

General Guidelines

1. Minimize Voltage Drop: The distance between the distribution box and the plug-in box should be as short as practical to reduce voltage drop, especially for high-current circuits. Longer distances require thicker cables to maintain efficiency and prevent overheating. 2. Safety and Accessibility: Electrical codes recommend that wiring between the distribution box and plug-in boxes be routed safely, avoiding sharp bends, heat sources, or areas prone to mechanical damage. The boxes should remain accessible for maintenance and inspection . 3. Wiring Method Considerations:

• For standard 220V circuits, a single phase line, neutral, and ground wire are used.
• For 380V three-phase circuits, all three phase lines plus neutral and ground are required.
• The wiring should be continuous, properly insulated, and securely connected to terminal blocks in both boxes . 4. Industrial or Modular Systems: In systems using plug-in modules, such as EtherCAT or EJ backplanes, the distance is often dictated by the design of the backplane and the reach of the bus connections. Typically, modules are mounted directly on the distribution board or backplane, minimizing cable length to a few centimeters to ensure signal integrity and safety . 5. Local Electrical Codes: Always follow local electrical regulations, which may specify maximum cable lengths, conduit requirements, and spacing for different types of installations. For residential setups, distances are usually within 1–5 meters, while industrial setups may allow longer runs if proper cable sizing and protection are used .

Practical Recommendation

• Residential: Keep the plug-in box within 1–3 meters of the distribution box.
• Industrial/Modular: Mount plug-in modules directly on or adjacent to the distribution board or backplane.
• Cable Sizing: Adjust wire gauge according to distance and load to prevent overheating and voltage drop.
• Grounding: Ensure all metal enclosures are properly grounded to prevent electrical hazards . By following these guidelines, you ensure safe, efficient, and code-compliant installation between the plug-in box and the distribution box.