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                                  IEC 61439 FAQs

                                   
                                   

                                  IEC 61439 FAQs 

                                  These are the questions that are answered on the page below. Click a question to be taken to the answer, or browse down the page to read all FAQs. Further help can be gained from the customer support team using the Customer Care Form.

                                  Questions (click for answer)


                                   

                                  Q. Why change?

                                  A. There are several reasons for change;

                                  • Designs and market needs for assemblies have evolved over the years, such that IEC 60439-1 no longer encompasses many commonly used arrangements. For example, modular systems are not effectively covered with respect to temperature rise performance.
                                  • It is not practical to fully type test every conceivable configuration of assembly produced. Where type testing is not feasible, there have to be alternative ways of ensuring an assembly meets the minimum required safety and performance criteria.
                                  • The methods for proving the design of a 'partially type tested assembly' in accordance with IEC 60439-1 are weak and rely entirely on the capability and integrity of assembly designer.
                                  • There is no standard for assemblies that do not fit within the categories of type tested or partially type tested assemblies.

                                  IEC 60439-1 and the British Standard equivalent, BS EN 60439-1 are safety standards. Compliance with BS EN 60439-1 is the easiest route to 'presumption of compliance' with the Low-voltage Directive and the application of the CE mark. It is therefore essential that the Standard remains aligned with safety requirements and that confirmation of safety performance is rigorous, consistent and equally applied to all assemblies.

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                                  Q. So what has changed between the old standards and IEC 61439?

                                  A. The most obvious change is the structure of the standard. Each generic type of assembly has a product-specific Part within the series of standards. This references applicable clauses within the General Rules and details any specific requirements about the particular generic type of assembly. Any clause in the General Rules that is not called up in the product-specific Part does not apply.

                                  The initial standards to be published are:

                                  • IEC 61430 Part 1 - General Rules – covering common requirements to two our more generic types of assembly.
                                  • IEC 61439 Part 2 - Power switchgear and control gear assemblies and any assembly not covered by any other product specific Part.

                                  NOTE! All assemblies should be specified as being in accordance with the product specific Part of the series of standards – assemblies cannot comply with the General Rules.

                                  The second major change covers the fitness for purpose.

                                  The capability of each assembly will be verified, effectively in two stages:

                                  • Design verification, to prove the design performance of the assembly in accordance with IEC 61439-2;
                                  • Routine verification, to confirm the materials and workmanship are in accordance with the design specification.

                                  At the manufactures discretion, design verification may be carried out by means of test and/or strictly controlled and defined equivalent means that include appropriate margins.

                                  The time proven engineering approach is used. Where it is not proven by test, a safety margin is added.

                                  The third change is the recognition of testing.

                                  For example:

                                  • Designs are portable. For example: a type test certificate obtained in France for a design carried out in the UK, is valid for an assembly manufactured in Australia.
                                  • Two manufacturers. Between concept and delivery of the assembly two manufactures may be involved:

                                  a) Original manufacturer responsible for the basic design and its verification and possibly the provision of the assembly in a kit form;

                                  b) Assembly manufacturer that completes and routine tests the final assembly.

                                  With appropriate instructions and quality assurance provided, kit systems produced in volume and completed by a local assembly manufacturer are an effective solution.

                                  The fourth major change covers clarification.

                                  A number of the grey areas have been clarified:

                                  • Diversity factor assumes outgoing circuits are partially loaded.
                                  • Unless otherwise stated neutral conductors will have a current rating equal to 50% of the associated phase.
                                  • A moulded case circuit breaker's (mccb) case provides adequate separation.

                                  In addition, the substitution of a device with an equivalent, for example an mccb, in a verified assembly (without new verification) is very tightly controlled. Where the devices are from the same manufacture IEC 61439 require assurances from the device manufacturer and, if the alternative device is from another manufacturer, it is unlikely to meet the standard.

                                  Compliant assemblies will provide consistent performance and safety to a high standard.

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                                  Q Who is responsible for what?

                                  A The new standard requires that application specific assemblies, as most are, must be provided without problems. The various stake holders must focus on their responsibilities, whilst working in a team with all the other parties involved in the process.

                                  • Purchasers and specifiers should view an assembly as a ‘black box' and specify the inputs and outputs to the assembly and define the interfaces between the assembly and the outside world. To assist in this, the standard includes a check list in Annex CC <link to Annex> identifying the details that should be provided in a complete specification.
                                  • The manufacturer is responsible for the internal configuration and the performance of the assembly, relative to the external parameters as defined by the purchaser or specifier. They are also responsible for correctly incorporating the components and ensuring the design meets the specification, and is fully verified and fit for purpose.
                                  • The manufacturer, or combination of manufacturers (original manufacturer and assembly manufacturer), is regarded as the experts and they must have sufficient knowledge of assemblies to satisfy this role.
                                  • Application specific assemblies requires a partnership of stakeholders.

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                                  Q. Who is ultimately responsible?

                                  A. Ultimate responsibility is established via the contract and usually rests with the party selling the assembly to the purchaser. However, a panel builder may work in partnership with an original manufacturer and pass down some of his responsibility via a subcontract.

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                                  Q. Who polices the new standard?

                                  A. The new standard assumes the manufacturer will ensure his equipment complies with the standard. Policing the application of the CE mark is the responsibility of the Dept of Business Enterprise & Regulatory Reform (BERR) (previously DTI)

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                                  Q. When will it actually be enforced?

                                  A. Once published, a new IEC Standard becomes the current issue.However, a reasonable period of time to migrate from one IEC standard to the next is normally accepted. European and British Standard usually have a defined period during which the old and new standards are both considered current. This 'grace period' will be known once BS EN 61439-2 is published.

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                                  Q. Does it affect contractors?

                                  A. The fundamental change for contractors is to ensure they specify assemblies in accordance with IEC 61439-2. Contractors should also ensure they provide all the details specified in Annex CC of BS EN 61439-2.

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                                  Q. How should I change my approach?

                                  A. A competent and diligent assembly manufacturer/builder will not have to make significant changes in their approach to the provision of assemblies. The new standard requires a logical approach to the design and verification of an assembly that is essentially present good practice. Where previously partially type tested assemblies or assemblies outside of the scope of IEC 60439-1 have been provided, the panel builder may find it advantageous to purchase a basic design verified assembly in kit form. This will enable the panel builder to avoid the time and cost of much of the design verification process.

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                                  Q. What does it all mean?

                                  A. Compliance with the new standard is compulsory. All assemblies must be shown to meet minimum safety and performance standards by design and routine verification. Many of the alternatives to type testing rely on interpolation from a tested reference design.Once the European equivalent standard, EN 61439-2 (BS EN 61439-2) has been listed in the Official Journal of the European Union, full compliance with this standard will become the easiest route to ‘presumption of compliance’ with the EMC and Low-voltage Directives, both of which are essential before the CE mark can be applied to the majority of low-voltage assemblies. Merely ‘partially’ proven design or only routine testing of some assemblies is forbidden.

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                                  Q. If I go for the calculation route, where are the formulae?

                                  A. All the design rules and formulae are either included in the new Standard or included in documents that are referenced in the Standard.

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                                  Q. How can we help?

                                  A. Schneider Electric’s Tom Mennell has represented Beama, and in turn BSI, on the IEC committee throughout the development of the new standard. This has given us a unique insight into the background, requirements, and implications of the new standard. We are also able to provide complete assemblies that fully comply with the new standard. In addition, panel builders can avoid the time and costs associated with developing their own verified design by using our design verified kit systems. We can also support you to make the transformation and adopt a new approach to assembly performance and safety.

                                  In 2009 Schneider Electric will be running a series of Seminars and Training sessions to help all customers with the publication of IEC 61439. Also, an A4 technical guide will be available in either hard copy or in electronic format as a .pdf file. A dedicated website will be launched early Jan 2009 and will have full details relating to Schneider Electric’s support of IEC 61439.

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