Unterverteilung

Unterverteilung is a term used in electrical installations to describe a distribution board that is fed from a main distribution board (Hauptverteilung) and then distributes electrical power to individual circuits, rooms, or further sub-distribution boards. Its primary function is to organize and protect the downstream circuits, providing a clear point for switching and fault isolation.

A Unterverteilung typically contains protective devices such as circuit breakers (Leitungsschutzschalter) and, where required, residual current devices (FI‑Schutzschalter) or RCBOs. It also has neutral and protective earth bus bars, labeled circuit terminations, and an enclosure that may include a main switch or a disconnect. The design aims at safe, reliable operation, with proper segregation of live parts, clear labeling, and adequate protection against accidental contact. The configuration may include internal busbars, fuses, and mounting rails, and it is sized to match the expected load and screening requirements of the area it serves.

In residential and commercial installations, Unterverteilungen serve to distribute power to lighting, sockets, fixed appliances, and other loads. They can be located on every floor or building section and may themselves feed additional Unterverteilungen in larger installations. Proper planning considers phase balance, cable sizing, and selective tripping to ensure that a fault in one circuit does not affect the entire installation.

Standards and safety guidance for Unterverteilungen include compliance with national DIN VDE/IEC regulations, installation in accessible, labeled enclosures, and regular inspection to maintain protective functions and electrical safety.