Users or specifiers of low voltage assemblies in the market today should understand that it is the responsibility of the assembly manufacturer to prove compliance and take full responsibility for the completed assembly. However, the user or specifier is required to have a basic understanding of the standard, the concepts, the parameters and the verification methods to ensure that the proof of compliance presented by the assembly manufacturer is acceptable.
Some of the main considerations:
• Identifying and understanding the applicable standards.
• Understanding the responsibility and the differences between the original manufacturer and the assembly manufacturer.
• Categories of assemblies available on the South African market.
Applicable standards
Firstly, it should be clearly stated that there is a difference between standards currently applicable on the international market and those applicable on the South African market. Internationally, the IEC 60439 series of standards was officially withdrawn in October 2015, after running its mandatory five year transit period, and replaced with the IEC 61439 series of standards.
The IEC 61439 series of standards is divided into various section and are all linked with IEC 61439-1 General Rules that are applicable to all the relevant sections:
• IEC/TR 61439-0:2013 – Guidance to specifying assemblies
• IEC 61439-1:2011 – General Rules
• IEC 61439-2:2011 – Power switchgear and controlgear assemblies
• IEC 61439-3:2012 – Distribution boards
• IEC 61439-4:2012 – Assemblies for construction sites
• IEC 61439-5:2014 – Assemblies for power distribution
• IEC 61439-6:2012 – Busbar trunking systems
• IEC 61439-7:2011 – Assemblies for specific applications such as Marinas, camping sites, market squares and vehicle charging stations
In South Africa, the complete IEC 60439 and IEC 61439 series of documents have been issued as SANS documents and both series of documents are still available. However, in South Africa additional standards have been issued and are referred to in the Wiring Code SANS 10142-1:2017 Edition 2 Table 4.1.:
• SANS 1973-1:2017 – Type tested assemblies with stated deviations and a rated short circuit withstand strength above 10 kA.
• SANS 1973-3:2017 – Safety of assemblies with a prospective short circuit current of up to and including 10 kA.
• SANS 1973-8:2017 – Safety of minimally tested assemblies(MTA) with a rated short circuit current above 10 Ka and a rated busbar current of up to and including 1600 A ac and dc.
• SANS 1973-1 is a document based on IEC 60439-1 (not IEC 61439 series) with additional national deviations applicable to South Africa only – an assembly tested to IEC 60439 and/or
IEC 61439 series does not comply with SANS 1973-1 unless these additional deviations have been addressed.
• SANS 1973-3 is a stand-alone document that has no relationship with any IEC standard and is applicable to South Africa only.
• SANS 1973-8 is a document based on the concepts of IEC 60439 (not IEC 61439 series) and its very limited testing requirements are not related to IEC 60439-1 and are applicable to South Africa only – an assembly complying with this standard complies with no IEC standard.
Original manufacturer and assembly manufacturer
These definitions were introduced in the first edition of the IEC 61439 series of documents and have been included in the SANS 1973 series of documents since 2008.
Original manufacturer:
The organisation that has carried out the original design and the associated verification of an assembly in accordance with the relevant assembly standard. The following is the list of design verifications that are normally carried out by the original manufacturer:
• Strength of materials - (resistance to corrosion, properties of insulation materials, resistance to UV, lifting, mechanical impact and marking).
• Degree of protection of enclosures (IP).
• Creepage and clearance distances.
• Protection against electric shock (continuity test and short circuit test on protective circuit).
• Incorporation of switching devices.
• Internal electrical circuits and connections.
• Terminals for external conductors.
• Dielectric properties.
• Temperature rise limits (assembly, main and vertical distribution busbars as well as all functional units).
• Short circuit withstand strength (main and vertical distribution busbar as well as conditional short circuit testing on all functional units).
• Electromagnetic compatibility (EMC).
• Mechanical operation.
Assembly manufacturer:
It should be noted that the original manufacturer and the assembly manufacturer could be or will most likely be different organisations or maybe different departments within an organisation. It is the responsibility of the assembly manufacturer to establish whether the new assembly being offered contains any deviations from the verified design and associated testing performed by the original manufacturer. In other words, the assembly manufacturer is required to establish any deviations on every new assembly and in the process prove compliance to the relevant standard. The assembly manufacturer then becomes the original manufacturer for those deviations and is required to prove compliance.
Categories of assemblies
In view of the responsibility of the assembly manufacturer, it is very important to identify the categories of assemblies being sold on the South African market as this will affect some or all the design veri fications initially performed by the original manufacturer. The categories listed below assume that the selection of switchgear, the installation, and the wiring of the switchgear is completed in South Africa. The main assembly categories can be summarised as:
• Assembly system that is designed, verified, manufactured and fully assembled in South Africa.
• Assembly system that is designed, verified and manufactured, in a foreign country and fully imported as loose parts and re-assembled locally but without any testing in South Africa.
• Assembly designed, verified but partly manufactured in South Africa and in a foreign country and re-assembled locally but without any testing in South Africa.
• Assembly designed, verified and manufactured in a foreign country and fully imported as loose parts and re-assembled locally but tested in South Africa.
• Assembly designed, verified and partly manufactured in South Africa and in a foreign country and re-assembled locally but tested in South Africa.
Conclusion
The above summary provides users and specifiers an overview of the current applicable standards on low voltage assemblies, defining the responsibility of the original manufacturer as well as some main consideration in reviewing proof of compliance. Other considerations will be:
• Understanding the parameters within each standard.
• Implementation of the applicable standard.
• Interpretations of test report.
• Understanding and implementation of associated standards such as:
1. IEC/TR 61641: 2014: Guide for testing under conditions of arcing due to internal fault.
2. IEC/TR 60890:2014: A method of temperature rise verification of low voltage switchgear and controlgear assemblies by calculation.
3. IEC 60865-1:2011: Short circuit currents – Definitions and calculation methods.
4. IEC/TR 80865-2:2015: Short circuit currents – Examples of calculations.
SABELCO Electrical designs and manufactures a full range of fully customisable, low voltage assembly solutions. These are supplied pre-assembled and pretested and comply with all local and international standards.
Enquiries: info@sabelco.co.za
