IEC/SC 121B - Low-voltage switchgear and controlgear assemblies

IEC 61439-3:2024 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. This second edition cancels and replaces the first edition published in 2012. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) alignment with the structure of IEC 61439-1:2020; b) inclusion in the scope of more examples of the type of protection and control devices; c) deletion of type A and Type B DBOs; d) addition of a new Annex BB related to DBOs used in a prosumer’s electrical installation (PEI); e) addition of a new Annex CC related to rated current of a DBO with additional source of supply in parallel/simultaneously with another source that is connected to the DBO e.g. PV.

IEC 61439-5:2023 is available as IEC 61439-5:2023 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61439-5:2023 defines the specific requirements for public electricity network distribution assemblies (PENDAs). PENDAs have the following criteria: - used for the distribution of electrical energy in three phase systems for which the rated voltage does not exceed 1 000 V AC (see Figure 101 for a typical distribution network) and DC systems not exceeding 1 500 V DC; - stationary; - open type assemblies are not covered by this document; - suitable for installation in places where only skilled persons have access for their use, however, outdoor types can be installed in situations that are accessible to ordinary persons - intended for use in energy distribution in public power grids; - indoor use: assemblies for installation inside of electric power substations; - outdoor use: assemblies containing an enclosure suitable for open air installation. This third edition cancels and replaces the second edition published in 2014. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) omission of the requirement to conduct mechanical tests at -25 °C when enclosures are made of a metallic material; b) addition of assumed loading factors generation supplies and electric vehicle charging applications; c) additional dielectric tests when a PENDA is used in a distribution substation with separate HV and LV earths; d) further clarification of representative samples for design verification.

Clause 1 of IEC 61439-1:2020 is applicable except as follows. Replacement: This part of IEC 61439 defines the specific requirements for Assemblies for the following applications: marinas, camping sites, market squares and electric vehicle charging stations as follows: - Assemblies for which the rated voltage does not exceed 1 000 V AC or 1 500 V DC; - Assemblies intended for use in connection with the generation, transmission, distribution and conversion of electric energy, and for the control of electric energy consuming equipment; - Assemblies operated by ordinary persons (e.g. to plug and unplug of electrical equipment); - Assemblies intended to be installed and used in market squares, marinas, camping sites and other similar sites accessible to the public including temporary installations; - Assemblies intended for charging stations for electric vehicles (AEVCS) for Mode 3 and Mode 4. They are designed to integrate the functionality and additional requirements for electric vehicle conductive charging systems according to IEC 61851-1:2017. NOTE 1 Throughout this document, the terms AMHS (see 3.1.701), ACCS (see 3.1.702), AMPS (see 3.1.703), AEVCS (see 3.1.704) are used for low-voltage switchgear and controlgear assemblies intended for use respectively in marinas and similar locations (AMHS), camping sites and similar locations (ACCS), market squares and other similar external public sites (AMPS) and charging stations (AEVCS). The term assemblies is used for indicating all these boards. This standard is not applicable to assemblies intended to be installed on board of ships, houseboats, pleasure crafts and similar vessels. For the correct selection of the switching devices and components, the following standards apply: - IEC 60364-7-709 (AMHS) or - IEC 60364-7-708 (ACCS) or - IEC 60364-7-740 (AMPS) or - IEC 60364-7-722 (AEVCS). This document applies to all assemblies whether they are designed, manufactured and verified on a one-off basis or fully standardised and manufactured in quantity. The manufacturing and/or assembling may be carried out other than by the original manufacturer (see 3.10.1 of IEC 61439-1:2020). This document does not apply to individual devices and self-contained components such as circuit breakers, fuse switches, electronic equipment, which comply with their relevant product standards. NOTE 2 Where electrical equipment is directly connected to public low-189 voltage supply system and equipped with an energy meter for billing of the legal provider of the low-voltage supply, additional particular requirements based on national regulations apply, if any. This document does not apply to boxes and enclosures for electrical accessories for household and similar fixed electrical installations as defined in IEC 60670-24.

IEC 62208:2023 applies to empty enclosures, as provided by the enclosure manufacturer, prior to the incorporation of switchgear and controlgear components by the assembly manufacturer. This document specifies general definitions, classifications, characteristics and test requirements of enclosures to be used as part of switchgear and controlgear assemblies (e.g. in accordance with the product standard in the IEC 61439 series), the rated voltage of which does not exceed 1 000 V AC or 1 500 V DC, and suitable for general use for either indoor or outdoor applications. This third edition cancels and replaces the second edition published in 2011. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) consideration of the modifications introduced in IEC 61439-1:2020; b) alignment of test procedures with the newest relevant standards.

IEC 61439-1:2020 is available as IEC 61439-1:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61439-1:2020 lays down the general definitions and service conditions, construction requirements, technical characteristics and verification requirements for low-voltage switchgear and controlgear assemblies. NOTE Throughout this document, the term assembly(s) (see 3.1.1) is used for a low-voltage switchgear and controlgear assembly(s). For the purpose of determining assembly conformity, the requirements of the relevant part of the IEC 61439 series, Part 2 onwards, apply together with the cited requirements of this document. For assemblies not covered by Part 3 onward, Part 2 applies. This third edition cancels and replaces the second edition published in 2011. It constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) clarification that power electric converter systems, switch mode power supplies, uninterruptable power supplies and adjustable speed power drive systems are tested to their particular products standard, but when they are incorporated in assemblies the incorporation is in accordance with the IEC 61439 series of standards; b) introduction of a group rated current for circuits within a loaded assembly and the refocusing of temperature-rise verification on this new characteristic; c) addition of requirements in respect of DC; d) introduction of the concept of class I and class II assemblies regarding protection against electric shock.

IEC 61439-2:2020(E) defines the specific requirements for the power switchgear and controlgear assembly (abbreviated ‘PSC-assembly’ throughout this document see 3.1.101) as follows:  
assemblies for which the rated voltage does not exceed 1 000 V AC or 1 500 V DC;
assemblies designed for a nominal frequency of the incoming supply or supplies not exceeding 1 000 Hz;  NOTE 1 Frequencies above 1 kHz are considered as high frequencies, see also IEC 60664-1:2007, 5.3.3.2.5 to take into account additional constraints to insulation coordination.  
assemblies intended for indoor and outdoor applications;
stationary or movable assemblies with or without enclosures;
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;
assemblies designed for use under special service conditions, for example in ships and in rail vehicles, provided that the other relevant specific requirements are complied with;  NOTE 2 Supplementary requirements for assemblies in ships are covered by IEC 60092-302-2. This third edition cancels and replaces the second edition published in 2011. It constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
addition of Annexes DD, EE and FF for assemblies for use in photovoltaic installation;
clarification of the requirements for forms of internal separation and the addition of the requirement, when the form of separation is higher than 1, all parts within the functional unit compartment that remain live when the functional unit is switched off shall be protected to at least IPXXB;
alignment with the structure of IEC 61439-1:2020;
addition of temperature-rise verification for; (i) temperature-rise verification of assemblies with natural cooling and circuits rated above 1 600 A by a combination of comparison with a reference design and calculation, and; (ii) temperature-rise verification of assemblies with active cooling and rated currents up to 1 600 A.
consideration of IP with active cooling.

Clause 1 of IEC 61439-1:2011 is applicable except as follows. Replacement: NOTE 1 Throughout this document, the terms AMHS (see 3.1.701), ACCS (see 3.1.702), AMPS (see 3.1.703), AEVCS (see 3.1.7704) are used for low-voltage switchgear and controlgear assemblies intended for use respectively in marinas and similar locations (AMHS), campsites and similar locations (ACCS), market squares and other similar external public sites (AMPS) and charging stations (AEVCS). The term ASSEMBLIES is used for indicating all these boards. This Part of IEC 61439 defines the specific requirements of ASSEMBLIES as follows: - ASSEMBLIES for which the rated voltage does not exceed 1 000 V in the case of AC or 1 500 V in the case of DC; - ASSEMBLIES intended for use in connection with the generation, transmission, distribution and conversion of electric energy, and for the control of electric energy consuming equipment; - ASSEMBLIES operated by ordinary persons (e.g. plug and unplug of electrical equipment); - ASSEMBLIES intended to be installed and used in market squares, marinas, campsites and other similar outdoor public sites; - ASSEMBLIES intended for charging stations for electric vehicles (AEVCS) for Mode 3 and Mode 4. They are designed to integrate the functionality and additional requirements for electric vehicle conductive charging systems according to IEC 61851-1:2017. For the correct SELECTION of the switching devices and components, the following standards apply: - IEC 60364-7-709 (AMHS) OR - IEC 60364-7-708 (ACCS) OR - IEC 60364-7-740 (AMPS) OR - IEC 60364-7-722 (AEVCS). This document applies to all ASSEMBLIES whether they are designed, manufactured and verified on a one-off basis or fully standardised and manufactured in quantity. The manufacture and/or assembly may be carried out other than by the original manufacturer (see 3.10.1 of IEC 61439-1:2011). This document does not apply to individual devices and self-contained components such as circuit breakers, fuse switches, electronic equipment, which comply with their relevant product standards. NOTE 2 Where electrical equipment is directly connected to public low voltage supply system and equipped with a meter for billing of the legal provider of the low voltage supply, additional particular requirements based on national regulations apply, if any. This document does not apply to boxes and enclosures for electrical accessories for household and similar fixed electrical installations as defined in IEC 60670-24.

IEC 61439-5:2014 defines the specific requirements for public electricity network distribution assemblies (PENDAs). PENDAs have the following criteria: - used for the distribution of electrical energy in three phase systems for which the rated voltage does not exceed 1 000 V a.c. (see Figure 101 for a typical distribution network); - open ASSEMBLIES are not covered by this standard; - suitable for installation in places where only skilled persons have access for their use, however, outdoor types may be installed in situations that are accessible to ordinary persons; - for indoor or outdoor use. This second edition cancels and replaces the first edition published in 2010. It constitutes a technical revision. This edition includes the following significant technical changes with respect to the latest edition: - confirmation that tests carried out on the most onerous PENDA are deemed to verify the performance of similar and less onerous assemblies of the same general construction and rating; - more precise timing/conditions for impact force withstand tests for PENDAs designed for operation in an arctic climate; - correction of the direction of the applied force in the static load test.

IEC 61439-4:2012 defines the specific requirements of ACS as follows: - ASSEMBLIES for which the rated voltage does not exceed 1 000 V in case of a.c. or 1 500 V in case of d.c.; - ASSEMBLIES where the nominal primary voltage and the nominal secondary voltage of transformers incorporated in ACS are within the limits specified above; - ASSEMBLIES intended for use on construction sites, both indoors and outdoors, i.e. temporary places of work to which the public do not generally have access and where building construction, installation, repairs, alteration or demolition of property (buildings) or civil engineering (public works) or excavation or any other similar operations are carried out; - transportable (semi-fixed) or mobile ASSEMBLIES with enclosure. The manufacture and/or assembly may be carried out other than by the original manufacturer. This first edition of IEC 61439-4 cancels and replaces the second edition of IEC 60439-4 (2004), and constitutes a technical revision. This edition includes the following significant technical changes with respect to the last edition of IEC 60439-4: - modification of the title as 'Part 4: Particular requirements for assemblies for construction sites (ACS)'; - alignment on IEC 61439-1 regarding the structure and technical content, as applicable; - to allow comparison with tested ACS.

IEC 61439-6:2012 lays down the definitions and states the service conditions, construction requirements, technical characteristics and verification requirements for low voltage BTS (see 3.101) as follows: - BTS for which the rated voltage does not exceed 1 000 V in case of a.c. or 1 500 V in case of d.c.; - BTS intended for use in connection with the generation, transmission, distribution and conversion of electric energy, and for the control of electric energy consuming equipment; - BTS designed for use under special service conditions, for example in ships, in rail vehicles, and for domestic applications (operated by unskilled persons), provided that the relevant specific requirements are complied with; - BTS designed for electrical equipment of machines. Supplementary requirements for BTS forming part of a machine are covered by the IEC 60204 series. This first edition of IEC 61439-6 cancels and replaces the third edition of IEC 60439-2 (2000) and its Amendment 1 (2005), and constitutes a technical revision. This edition of IEC 61439-6 includes the following significant technical changes with respect to the latest edition of IEC 60439-2: - alignment on the second edition of IEC 61439-1 (2011) regarding the structure and technical content, as applicable; - introduction of new verifications, accordingly; - correction of inconsistencies in resistance, reactance and impedance measurements and calculations; - numerous editorial improvements.

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 (Inc) of the outgoing circuits does not exceed 125 A and the rated current (InA) 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 IEC 61439-1:2011.

IEC 62208:2011 applies to empty enclosures, prior to the incorporation of switchgear and controlgear components by the user, as supplied by the enclosure manufacturer. This standard specifies general definitions, classifications, characteristics and test requirements of enclosures to be used as part of switchgear and controlgear assemblies (e.g. in accordance with the IEC 61439 series), the rated voltage of which does not exceed 1 000 V a.c. or 1 500 V d.c., and suitable for general use for either indoor or outdoor applications. This second edition cancels and replaces the first edition published in 2002. This edition constitutes a technical revision and includes the following significant technical changes with respect to the last edition: - consideration of the restructured series of standards IEC 61439; - alignment of test procedures with the newest relevant standards.

NOTE Throughout this standard, the abbreviation ACS (ASSEMBLY for construction site, see 3.1.101) is used for a low-voltage switchgear and controlgear assembly intended for use on construction and similar sites. This part of 61439 defines the specific requirements of ACS as follows: - ASSEMBLIES for which the rated voltage does not exceed 1 000 V in case of AC or 1 500 V in case of DC; - ASSEMBLIES where the nominal primary voltage and the nominal secondary voltage of transformers incorporated in ACS are within the limits specified above; - ASSEMBLIES intended for use on construction sites, both indoors and outdoors, i.e. temporary places of work to which the public do not generally have access and where building construction, installation, repairs, alteration or demolition of property (buildings) or civil engineering (public works) or excavation or any other similar operations are carried out; - transportable (semi-fixed) or mobile ASSEMBLIES with enclosure. The manufacture and/or assembly may be carried out other than by the original manufacturer. This standard does not apply to individual devices and self-contained components, such as motor starters, fuse switches, electronic equipment, etc. which will comply with the relevant product standards. This standard does not apply to ASSEMBLIES for use in the administrative centres of construction sites (offices, cloakrooms, ASSEMBLY rooms, canteens, restaurants, dormitories, toilets, etc.). Requirements for electrical protection provided by equipment manufactured according to this International Standard are given in IEC 60364-7-704.

IEC 61439-1:2011 lays down the definitions and states the service conditions, construction requirements, technical characteristics and verification requirements for low-voltage switchgear and controlgear assemblies. This standard cannot be used alone to specify an ASSEMBLY or used for a purpose of determining conformity. ASSEMBLIES shall comply with the relevant part of the IEC 61439 series; Parts 2 onwards. This standard applies to low-voltage switchgear and controlgear assemblies (ASSEMBLIES) only when required by the relevant ASSEMBLY standard as follows: - ASSEMBLIES for which the rated voltage does not exceed 1 000 V in case of a.c. or 1 500 V in case of d.c.; - stationary or movable ASSEMBLIES with or without enclosure; - ASSEMBLIES intended for use in connection with the generation, transmission, distribution and conversion of electric energy, and for the control of electric energy consuming equipment; - ASSEMBLIES designed for use under special service conditions, for example in ships and in rail vehicles provided that the other relevant specific requirements are complied with; - ASSEMBLIES designed for electrical equipment of machines provided that the other relevant specific requirements are complied with. This second edition cancels and replaces the first edition published in 2009. It constitutes a technical revision. This second edition includes the following significant technical changes with respect to the last edition of IEC 61439-1: - revision of service conditions in Clause 7; - numerous changes regarding verification methods in Clause 10; - modification of routine verification in respect of clearances and creepage distances (see 11.3); - adaption of the tables in Annex C and Annex D to the revised requirements and verification methods; - revision of the EMC requirements in Annex J; - shifting of tables from Annex H to new Annex N; - new Annex O with guidance on temperature rise verification; - new Annex P with a verification method for short-circuit withstand strength (integration of the content of IEC/TR 61117); - update of normative references; - general editorial review.

IEC 61439-2:2011 defines the specific requirements of power switchgear and controlgear assemblies (PSC-ASSEMBLIES) as follows: - ASSEMBLIES for which the rated voltage does not exceed 1 000 V in case of a.c. or 1 500 V in case of d.c.; - stationary or movable ASSEMBLIES with or without enclosure; - ASSEMBLIES intended for use in connection with the generation, transmission, distribution and conversion of electric energy, and for the control of electric energy consuming equipment; - ASSEMBLIES designed for use under special service conditions, for example in ships and in rail vehicles provided that the other relevant specific requirements are complied with; - ASSEMBLIES designed for electrical equipment of machines. Supplementary requirements for ASSEMBLIES forming part of a machine are covered by the IEC 60204 series. This second edition cancels and replaces the first edition published in 2009. It constitutes a technical revision. This second edition includes the following significant technical changes with respect to the last edition of IEC 61439-2: - clarification of the scope; - revision of requirements for withdrawable and removable parts; - revision of mechanical impact test (10.2.6); - extension of Table 101; - review of Table BB.1 to reflect modified requirements and verifications; - general editorial review. This publication is to be read in conjunction with IEC 61439-1:2009.