Order of household electrical distribution boxes in apartment buildings

In apartment buildings, electrical distribution follows a hierarchical order: main building supply → apartment meters → apartment distribution boards → individual circuits for lighting, sockets, and high-power appliances.

Building-Level Distribution

At the building level, electricity from the utility enters through a house connection device and is routed to a main distribution box in the house connection room. This box divides the supply among individual apartments via lines with three outer conductors, typically rated for at least 63 A, and each apartment has its own electricity meter ( ). The main distribution box contains bus bars, main circuit breakers, and protection devices to ensure safety and prevent overloads ( ).

Apartment-Level Distribution

Inside each apartment, a central small distribution board (also called a circuit distributor or breaker panel) is usually installed in a hallway or accessible area. The recommended configuration includes ( ):

1. Main Switch: Controls the entire apartment's electrical system, allowing complete shutdown for maintenance or emergencies.
2. Room Socket Circuits: Each room has its own circuit to isolate electrical issues and prevent them from affecting the whole apartment.
3. High-Power Appliance Circuits: Dedicated circuits for appliances like stoves, air conditioners, and water heaters to prevent overloading.
4. Lighting Circuits: Separate circuits for lighting to ensure stable operation independent of other loads.

Safety and Standards

• Overcurrent and Residual Current Protection: Each circuit should have appropriate breakers or RCDs to prevent short circuits and overloads ( ).
• Circuit Sizing: Distribution boards must be dimensioned according to the number of rooms, appliances, and future expansion needs, following standards such as DIN 18015-2 ( ).
• Placement: Boards should be installed in dry, accessible areas with proper ventilation, typically around 1.5 meters above the floor ( ).
• Labeling: Each circuit should be clearly labeled for easy identification and maintenance ( ).

Summary

The hierarchical order ensures safety, efficiency, and ease of maintenance:

1. Main building supply → 2. Apartment electricity meter → 3. Apartment distribution board → 4. Individual circuits (lighting, sockets, high-power appliances). This structure allows for modular upgrades, isolation of faults, and compliance with electrical safety standards, ensuring reliable power distribution throughout the building.