BS EN IEC 61439-3:2024

Low-voltage switchgear and controlgear assemblies. Distribution boards intended to be operated by ordinary persons (DBO) | Status: Current

1 Scope This part of IEC 61439 defines the specific requirements for distribution boards intended to be operated by ordinary persons (abbreviated DBO throughout this document, see 3.1.101) as follows:

• — assemblies intended to be operated by ordinary persons (e.g. switching operations and replacing fuse-links), e.g. in domestic (household) applications;
• — assemblies containing outgoing circuits with protective devices intended to be operated by ordinary persons, complying e.g. with IEC 60898‑1, the IEC 61008 series, the IEC 61009 series, IEC 62606, IEC 62423 and IEC 60269‑3;
• — assemblies for applications where the nominal voltage to earth does not exceed 300 V AC (see Table G.1 of IEC 61439‑1:2020);

  NOTE The voltage limits for DC applications are under consideration.

• — assemblies with a rated current (Inc) of the outgoing circuits not exceeding 125 A and a rated current (InA) not exceeding 250 A;
• — assemblies intended for use in connection with the generation, transmission, distribution and conversion of electrical energy, and for the control of equipment consuming electrical energy and for associated data processing;
• — enclosed, stationary assemblies;
• — assemblies for indoor or outdoor use.

DBOs can contain protection devices, control devices, signalling devices alone or a combination of devices e.g. circuit-breakers, load shedding relay, energy management, communication devices, lighting control. This document does not apply to an empty enclosure nor to individual devices and self-contained components, such as circuit-breakers, fuse-switches, electronic equipment. which comply with the relevant product standards, it describes the integration of devices, or self-contained components, or both, into a DBO or into an empty enclosure forming a DBO. This document applies to DBOs designed, manufactured, and verified on a one-off basis or fully standardized and manufactured in quantity. This document does not apply to the specific types of assemblies covered by other parts of the IEC 61439 series.

NOTE Enclosures for electrical accessories for household and similar fixed electrical installations are covered in IEC 60670‑24.