Why compliance with BS EN IEC 61439 matters

Sean Smith, Chair of the Engineered Systems Product Group at BEAMA, looks at how the BS EN IEC 61439 series provides essential guidance for ensuring safety, and why compliance is not just best practice, but a critical safeguard.

Low-voltage switchgear assemblies are central to most electricity distribution networks and typically operate without issue, often because they’re rarely fully loaded or tested to their design limits. However, when failures occur, sometimes years after installation, the consequences can be severe, including fire, electric shock, service disruption and even loss of life.

Redefining the safety, performance and testing requirements for low-voltage switchgear and control gear assemblies in industrial, commercial and residential environments, the BS EN IEC 61439 series was introduced in the UK in 2009 as a replacement for EN 60439. Providing a step-by-step guide to requirements for construction, testing and verification of bespoke and standard assemblies, BS EN IEC 61439 outlines the minimum standard for designing assemblies. It offers clarity on requirements for low-voltage assemblies.

Adherence to BS EN IEC 61439 Parts 1 and 2 enables manufacturers to assure customers that every low-voltage switchgear assembly meets the latest safety requirements, demonstrates conformity and performs to a high standard. As the series also covers distribution boards, usage on construction sites, in public networks and busbar trunking, it’s a reliable guide for both manufacturers and installers. 

Clear definitions

BS 7671 defines a low-voltage switchgear and control gear assembly as a combination of one or more low-voltage switching devices with associated control, measuring, signalling, protective and regulating equipment, including all internal interconnections and structural components. Installing an assembly that does not fully conform with BS EN IEC 61439 breaches BS 7671, which could lead to significant legal and safety consequences. Failure to comply can result in fines, criminal charges, civil liability and insurance issues.

BS EN IEC 61439 Parts 1 and 2 provide clarity for those designing, manufacturing and installing low-voltage switchgear assemblies within the wider electrical system. Technical understanding is critical to ensure assemblies meet the essential safety requirements of the Electrical Equipment (Safety) Regulations 2016. Applying the relevant parts reduces the likelihood of legal and operational failures, providing a defensible framework for compliance and quality assurance.

In an evolving electrical landscape, one-size-fits-all solutions rarely suffice, and BS EN IEC 61439 Part 2 recognises that no two assemblies are identical and provides flexibility for bespoke solutions.

To ensure manufacturers and installers can provide fully conforming solutions, the standards offer a framework for all scenarios, including bespoke designs tailored to specific requirements. Applied consistently, they ensure that assemblies will protect the electrical system, whether in a small commercial premises or a large data centre.

Consistent conformity 

Failures in low-voltage switchgear assemblies are uncommon but can have catastrophic consequences if systems are poorly specified, designed or manufactured. Over time, increased load, environmental factors and material ageing can stress assemblies. Under-rated components or poor construction can lead to overheating, insulation breakdown and, in extreme cases, fires and explosion.

These risks highlight the importance of specifying, testing and ensuring assemblies fully conform to relevant standards and regulations from the outset.

One significant change in BS EN IEC 61439 Part 2 compared to its predecessor was the removal of Partially Type Tested Assemblies (PTTAs). Under the old standard, assemblies could be classified as Type Tested Assemblies (TTAs) or PTTAs, allowing flexibility but also creating loopholes and inconsistencies, especially for bespoke assemblies. The revised standard removes this classification and introduces a mandatory framework for ‘Design Verification’ and ‘Routine Verification’ of all low-voltage switchgear and control gear assemblies, whether standard, modified or custom built.

While the BS EN IEC 61439 series sets out best practice, consistent safety, reliability and conformity can only be achieved through rigorous adherence across every project.

Specifying for safety

In procurement, conformance with BS EN IEC 61439 is often assumed rather than specified. Formally requiring adherence at the specification stage is an effective way to avoid disputes over performance, safety or legal accountability.

Given the extensive verifications mandated by the standards, procurement teams or end users should confirm full conformance as part of due diligence. Compliance is central to fulfilling statutory obligations relating to electrical safety and reducing the risk of future liability.

Once an assembly is operational, the Electricity at Work Regulations 1989 may apply. Any incident involving injury or fatality could trigger an investigation by the Health and Safety Executive (HSE). If non-conformance, poor design or substandard workmanship is found to be a factor, the designer, manufacturer or installer may face significant fines or custodial sentences.

Such liability is not limited by time and, from a commercial perspective, manufacturers making unsubstantiated or misleading claims about assembly performance risk breaching consumer protection and trade laws, with issues potentially emerging years after installation. 

In summary, strict adherence to BS EN IEC 61439 Parts 1 and 2 provides manufacturers with the assurance and evidence to demonstrate that every low-voltage switchgear assembly is engineered to the latest safety requirements and capable of delivering consistent, high-level performance throughout its operational life.

beama.org.uk

This article appeared in Electrotechnical News September/October 2025 edition – read it here