Standard indoor distribution boxes use modular slots typically 18 mm wide per MCB module, with DIN rail spacing and enclosure dimensions designed for flexible installation.

Slot and Module Dimensions

Most indoor distribution boards, such as ABB Styler or Legrand Atlantic units, follow modular DIN rail standards:

• Module width: Each MCB or RCD module occupies 18 mm (1 module, 1M) on the DIN rail .
• Multi-module units: Common consumer units come in 7, 10, 15, or 20 modules, allowing flexible configuration .
• DIN rail spacing: Standard DIN rails are 35 mm wide, with slots arranged to allow easy mounting and removal of devices without obstructing adjacent modules .
• Slot height: Typically accommodates standard MCBs or RCDs, around 80–90 mm tall, depending on the device type .

Enclosure Dimensions

Indoor distribution boxes vary by module count and manufacturer:

• Small wall-mounted units: 200×200×120 mm up to 800×600×300 mm .
• Larger units: For extensive setups, enclosures can reach 1000×800×400 mm or more, providing ample wiring space and room for future expansion .
• Depth considerations: Depth ranges from 160 mm to 400 mm, ensuring sufficient space for wiring, cable bends, and device clearance .

Layout Considerations

• Front cover: Transparent or opaque, with screws behind the door for safety .
• Cable entry: Knock-outs on top, bottom, and rear for flexible conduit or cable entry .
• Internal layout: Includes neutral and earth bars, with clear separation of high and low voltage circuits .
• Expansion: Some enclosures allow top/bottom extension boxes for additional modules .

Diagram Reference

A typical slot layout diagram for a 12-module consumer unit:

CodeCopy+---------------------------+| MCB MCB MCB MCB | <- Top row (6 modules)| MCB MCB MCB MCB | <- Bottom row (6 modules)+---------------------------+DIN rail runs horizontally behind modulesNeutral and Earth bars at bottomCable entry knock-outs at top/bottom

• Each MCB occupies 18 mm width; spacing ensures safe installation and heat dissipation.
• Larger units stack multiple DIN rails vertically to accommodate more modules.

Practical Tips

• Always verify manufacturer-specific technical drawings before installation, as slot spacing and internal layout may vary slightly .
• Ensure adequate depth for wire bending radius and future expansion.
• Use DIN rail-mounted accessories for modularity and easy maintenance. By following these standards, indoor distribution boxes can safely house multiple protection devices while maintaining compliance with electrical codes and providing flexibility for future upgrades.