What Is BS EN 61439? A Guide to Low-Voltage Control Panel Standards
If you are specifying, purchasing or upgrading an industrial control panel, you may have come across the term BS EN 61439. But what does the standard actually cover, and why should it matter to the people responsible for industrial equipment?
BS EN 61439 is a series of standards covering low-voltage switchgear and control gear assemblies. In practical terms, it establishes requirements that help ensure electrical assemblies are appropriately designed, constructed and verified for their intended application.
For manufacturers, engineers and end users, BS EN 61439 provides an important framework for demonstrating that an assembly has been considered as a complete system, rather than simply being a collection of individually compliant electrical components.
What does BS EN 61439 mean?
BS EN 61439 forms part of the IEC 61439 series of international standards for low-voltage switchgear and control gear assemblies.
The current general UK standard is BS EN IEC 61439-1:2021, which sets out the general definitions, service conditions, construction requirements, technical characteristics and verification requirements for low-voltage assemblies. It generally applies to assemblies with rated voltages not exceeding 1,000 V AC or 1,500 V DC.
However, BS EN IEC 61439-1 is not intended to be used on its own to determine conformity. It works alongside the relevant assembly-specific part of the 61439 series.
For many industrial power switchgear and control gear assemblies, BS EN IEC 61439-2 is particularly relevant because it provides the specific requirements for power switchgear and control gear assemblies.
Why was BS EN 61439 introduced?
An electrical component can comply with its individual product standard and still behave differently once installed alongside other components inside an enclosure.
Heat is a good example.
A circuit breaker, power supply, contactor, PLC, variable speed drive or other component does not operate in isolation once it has been incorporated into a control panel. Component positioning, ventilation, enclosure size, conductor sizing, loading and the heat generated by surrounding equipment can all influence operating conditions.
This is one of the reasons why simply selecting compliant components is not enough.
BS EN 61439 considers the assembly as a system and establishes requirements for its construction, performance and verification. BSI specifically notes that controlgear components can behave differently when working in close proximity, which is why verification of the complete assembly is important.
What does BS EN 61439 cover?
The standard addresses a wide range of factors affecting the safety and performance of an electrical assembly.
These include areas such as electrical clearances and creepage distances, protection against electric shock, dielectric properties, temperature rise, short-circuit withstand strength, electromagnetic compatibility (EMC), mechanical operation and the effectiveness of protective circuits.
The exact requirements and verification methods depend on the type of assembly and the relevant part of the standard.
The important point for someone purchasing an industrial control panel is that BS EN 61439 goes much further than asking whether the individual components inside the enclosure are suitable.
The way those components are combined matters too.
What is design verification?
One of the most important concepts within BS EN 61439 is design verification.
Design verification provides evidence that the design of an assembly meets the applicable requirements of the standard.
Depending on the particular characteristic being assessed, verification can involve testing, comparison with a verified reference design or assessment according to the permitted methods within the standard.
This can cover characteristics such as temperature rise, short-circuit withstand capability, dielectric properties, clearances and creepage distances and protection against electric shock.
It is therefore not accurate to think of BS EN 61439 as simply requiring a panel to pass one final electrical test.
Compliance needs to be considered throughout the design and manufacturing process.
Design verification and routine verification are not the same thing
This distinction is particularly useful when discussing a new control panel with a manufacturer.
Design verification establishes that the design of the assembly meets the relevant requirements.
Routine verification, on the other hand, is carried out on completed assemblies to identify faults in materials and manufacture and confirm that the finished assembly meets the relevant requirements.
This means a panel can undergo routine electrical testing without that testing automatically answering every question relating to the underlying design.
For plant operators and engineering teams, understanding this difference can make conversations with potential control panel manufacturers considerably more meaningful.
Instead of asking only:
“Will the panel be tested?”
it can be more useful to ask:
“How has the panel design been verified, and what routine verification will be completed before delivery?”
What parts of BS EN 61439 are relevant?
BS EN 61439 is not a single standard covering every assembly in exactly the same way. It is a multi-part series.
For example, Part 1 provides the general rules, while Part 2 covers power switchgear and control gear assemblies. Other parts address distribution boards intended to be operated by ordinary persons, assemblies for construction sites, assemblies for power distribution in public networks and busbar trunking systems.
This is important because specifying that a panel should simply “comply with BS EN 61439” does not necessarily provide all the information required to define the assembly.
The application, operating environment, electrical characteristics and intended use still need to be properly understood.
Why does BS EN 61439 matter when buying a control panel?
For the person purchasing a control panel, the standard provides a useful basis for asking better questions about what is actually being supplied.
A control panel may look perfectly acceptable from the outside. The components may also come from reputable manufacturers.
What cannot necessarily be determined by looking at the enclosure is whether issues such as thermal performance, conductor sizing, fault withstand, electrical protection and component integration have been properly considered.
This becomes particularly important where the panel is controlling production-critical equipment.
A poorly considered assembly can contribute to overheating, nuisance tripping, premature component failure, difficult maintenance and, in more serious circumstances, electrical safety risks.
For businesses where an unexpected production stoppage can cost considerably more than the control panel itself, panel design and verification should not be treated as paperwork exercises.
Does BS EN 61439 apply to bespoke control panels?
Yes, the principles of the standard are not limited to mass-produced assemblies.
BSI states that the requirements apply whether assemblies are designed, manufactured and verified on a one-off basis or manufactured in quantity.
This is particularly relevant within industrial automation because many control panels are designed for a specific machine, process or production environment.
A bespoke panel still needs an appropriate engineering approach. In fact, the individual nature of the application makes understanding operating conditions, loads, equipment and environmental factors especially important.
What information should you expect from a control panel manufacturer?
When commissioning a new industrial control panel, documentation should form part of the discussion from the beginning rather than being something requested after the panel has already been manufactured.
Depending on the project, this may include electrical schematics, component schedules, panel layouts, cable and terminal information, test documentation, verification records and operating or maintenance information.
Where PLCs, HMIs, drives or other programmable devices are involved, maintaining the correct software backups and revision information can be just as important for the long-term maintainability of the system.
Good documentation becomes particularly valuable several years later when a component fails, a production line needs modifying or an obsolete device needs replacing.
BS EN 61439 and the wider control system
BS EN 61439 is important, but it should not be considered in isolation.
Industrial control panels can sit within a much larger regulatory and standards environment.
Depending on the application, additional requirements relating to machinery, electrical equipment, functional safety, EMC or hazardous environments may also need to be considered. BSI itself notes that some applications can require compliance with other standards or legislation in addition to the IEC 61439 series.
The objective should therefore not simply be to produce a panel carrying the right reference to a standard.
It should be to design and manufacture an electrical control system that is safe, suitable for its environment, maintainable and capable of supporting the equipment it controls throughout its working life.
Planning a new control panel or reviewing an existing system?
Understanding BS EN 61439 is particularly useful when specifying a new control panel, replacing an ageing panel or reviewing equipment that has been modified repeatedly over many years.
At Stratos Control Systems, we design and manufacture industrial control panels around the requirements of the application, considering not only the immediate control requirements but also documentation, maintainability, system integration and the future operation of the equipment.
Whether you are planning a new panel, replacing obsolete equipment or need to understand the condition of an existing control system, involving an experienced control panel manufacturer early in the project can help identify requirements before they become expensive problems during manufacture, installation or commissioning.
Speak to Stratos Control Systems about industrial control panel design, manufacture, upgrades and automation support.
