IEC 61439-3:2012 defines the specific requirements for distribution boards intended to be operated by ordinary persons (DBO). DBOs have the following criteria: - intended to be operated by ordinary persons (e.g. switching operations and replacing fuse-links), e.g. in domestic (household) applications - outgoing circuits contain protective devices, intended to be operated by ordinary persons, complying e.g. with IEC 60898-1, IEC 61008, IEC 61009, IEC 62423 and IEC 60269-3 - rated voltage to earth does not exceed 300 V a.c. - rated current (I< sub> nc< / sub> ) of the outgoing circuits does not exceed 125 A and the rated current (I< sub> nA< / sub> ) of the DBO does not exceed 250 A - intended for the distribution of electrical energy - enclosed, stationary - for indoor or outdoor use. This first edition cancels and replaces the first edition of IEC 60439-3 (1990), Amendment 1 (1993) and Amendment 2 (2001). It constitutes a technical revision. This edition includes the following significant technical changes with respect to IEC 60439-3 (including the amendments): - alignment with IEC 61439-1:2011. This publication is to be read in conjunction with < a href=' http:/ / webstore.iec.ch/ webstore/ webstore.nsf/ ArtNum_PK/ 45415' > IEC 61439-1:2011< / a> .