Diameter of incoming and outgoing cables to the distribution box

Incoming cables typically require a diameter of 18–31 mm, while outgoing cables require 12–24 mm, depending on the cable gland used.

Incoming Cables

For the incoming feed to a distribution box, double-seal cable glands type REVD3, size M32 are recommended. These accommodate: Outer armor sealing ring: 24–31 mmInner armor sealing ring: 18–24 mm This ensures proper mechanical protection, sealing, and compliance with IEC 60079-1 standards for enclosures with IP65 protection.

Outgoing Cables

For outgoing circuits, double-seal cable glands type REVD2, size M25 are suitable. These support: Outer armor sealing ring: 16–24 mmInner armor sealing ring: 12–18 mm This allows secure connection of outgoing cables while maintaining proper spacing and mechanical protection.

Additional Considerations

Cable diameters should match the cable gland specifications to ensure proper clamping and sealing. The number of cables and spacing inside the distribution box must comply with NEC or local electrical codes to prevent overheating and allow safe maintenance. For heavy-duty applications, copper flat busbars (e.g., 25x4 mm) may be used for connections, and suitable metallic or heat-resistant barriers should be installed between MCCBs to manage heat.

By selecting cable diameters within these ranges and using the appropriate glands, the distribution box installation will meet both mechanical and electrical safety standards.