BS EN 61439 Guide for Industrial Control Panels
Understanding BS EN IEC 61439 for Low-Voltage Control Panel Assemblies
BS EN IEC 61439 is the series of standards covering low-voltage switchgear and controlgear assemblies.
For control panel designers, manufacturers, engineering teams and end users, understanding the standard is important because compliance is not simply about selecting individual components carrying the appropriate markings.
The complete assembly needs to be considered.
Components that individually comply with their respective product standards can behave differently once installed together inside an enclosure, where factors such as temperature, electrical loading, conductor arrangement, short-circuit conditions and protection need to be considered. This is one of the reasons the standard addresses the assembly as a complete system.
This guide provides a practical overview of BS EN IEC 61439 and explains some of the considerations involved when designing, manufacturing and verifying industrial control panel assemblies.
What Is BS EN IEC 61439?
BS EN IEC 61439 is a series of standards covering low-voltage switchgear and controlgear assemblies.
Part 1 establishes the general rules, including definitions, service conditions, construction requirements, technical characteristics and verification requirements. It applies to assemblies within its scope up to 1,000 V AC or 1,500 V DC.
However, Part 1 is not intended to be used by itself to determine conformity.
The appropriate assembly-specific part of the 61439 series must also be applied.
For many industrial power switchgear and controlgear assemblies, BS EN IEC 61439-2 is particularly relevant.
BS EN IEC 61439-1 and 61439-2
Understanding the relationship between Parts 1 and 2 is important.
BS EN IEC 61439-1 contains the general rules applicable across the relevant low-voltage assembly categories.
These cover areas such as:
Construction requirements.
Service conditions.
Technical characteristics.
Protection.
Temperature rise.
Dielectric properties.
Clearances and creepage distances.
Verification.
Marking and documentation.
BS EN IEC 61439-2 provides the specific requirements for power switchgear and controlgear assemblies.
The two therefore work together rather than representing alternative standards. BSI describes Part 2 as applying to power switchgear and controlgear assemblies within its defined scope.
Why BS EN IEC 61439 Matters for Control Panels
A control panel is more than a collection of individually approved electrical components.
Once devices are installed within an enclosure, they form an assembly in which the performance of one component can influence the conditions experienced by another.
Considerations can include:
Electrical loading.
Heat generation.
Component arrangement.
Conductor sizing.
Protection.
Short-circuit conditions.
Insulation.
Enclosure characteristics.
Environmental conditions.
The purpose of the 61439 framework is therefore to establish requirements and verification for the completed assembly rather than relying solely on the compliance of its individual components.
This distinction is particularly important when specifying or procuring industrial control panels.
What Is Design Verification?
Design verification demonstrates that the design of the assembly satisfies the applicable requirements of the standard.
It addresses characteristics of the assembly design rather than simply checking whether the finished panel has been wired correctly.
Depending on the applicable requirement, verification can involve recognised methods permitted by the standard.
The underlying principle is that the panel manufacturer needs appropriate evidence demonstrating that the assembly design meets its required characteristics.
This is different from routine verification, which applies to individual completed assemblies.
Areas Covered by Design Verification
Design verification considers multiple characteristics of the assembly.
Depending on the assembly and applicable requirements, these can include areas relating to:
Strength of materials and parts.
Degree of protection.
Clearances.
Creepage distances.
Protection against electric shock.
Protective circuit integrity.
Incorporation of switching devices and components.
Internal electrical circuits.
External conductor terminals.
Dielectric properties.
Temperature rise.
Short-circuit withstand.
Electromagnetic compatibility.
Mechanical operation.
The exact verification approach depends upon the particular characteristic and assembly design.
For an industrial control panel manufacturer, verification therefore needs to form part of the engineering process rather than being treated simply as a final inspection exercise.
Temperature Rise in Control Panels
Temperature is an important consideration in control panel design.
Electrical equipment generates heat during operation, and placing multiple components within an enclosure can increase the internal temperature.
Potential heat-producing equipment may include:
Variable Speed Drives.
Power supplies.
Contactors.
Transformers.
PLC power components.
Protective devices.
Conductors.
Motor control equipment.
The designer needs to consider whether the assembly can operate within the required thermal conditions.
Factors such as enclosure dimensions, component arrangement, electrical loading, ventilation and component characteristics can all influence temperature rise.
The current edition of Part 1 also introduced changes relating to group rated current and refocused aspects of temperature-rise verification around this characteristic.
Short-Circuit Withstand and Protection
Industrial control panels need to be designed for the electrical system into which they will be installed.
Prospective short-circuit conditions can place significant electrical and mechanical stress on an assembly.
The design therefore needs to consider areas such as:
Available fault current.
Protective devices.
Busbars.
Conductors.
Component ratings.
Protective coordination.
Assembly characteristics.
It is not sufficient to select components simply because their normal operating current is appropriate.
The conditions that could occur during an electrical fault also need to be considered as part of the assembly design and its required verification.
Clearances, Creepage and Electrical Protection
The physical arrangement of components and conductors within the assembly is another important consideration.
Clearance broadly concerns the shortest distance through air between conductive parts.
Creepage distance concerns the shortest distance along the surface of insulating material between conductive parts.
These distances contribute to maintaining appropriate electrical insulation within the assembly.
The wider standard also addresses areas including dielectric properties, protection against electric shock, terminals, electrical connections and insulation-related requirements.
This is one reason good control panel design requires more than simply fitting all required components into the available enclosure space.
What Is Routine Verification?
Routine verification is performed on completed assemblies.
Where design verification establishes that the design meets applicable requirements, routine verification checks aspects of the individual manufactured assembly.
Depending on the applicable requirements, this involves inspection and testing intended to identify issues arising from manufacture, assembly or wiring.
Areas can include checks relating to:
Degree of protection.
Clearances and creepage distances.
Protection against electric shock.
Protective circuits.
Component installation.
Internal circuits and connections.
External conductor terminals.
Mechanical operation.
Dielectric properties.
Wiring and functional operation.
Routine verification should therefore form part of the manufacturing and quality process for the completed control panel.
Documentation and Control Panel Identification
Documentation is an important part of delivering a maintainable industrial control panel.
Depending on the project and assembly, useful documentation can include:
Electrical schematics.
Component schedules.
Ratings.
Design information.
Verification records.
Routine verification records.
Test documentation.
Equipment identification.
Terminal information.
Manufacturer information.
The assembly itself also requires appropriate identification and marking under the applicable requirements.
Good documentation provides benefits beyond initial conformity.
Years later, maintenance engineers may need to identify components, understand modifications, investigate faults or replace obsolete equipment.
A well-documented control panel is significantly easier to support throughout its lifecycle.
Specifying a BS EN IEC 61439 Control Panel
Customers also have an important role in ensuring that the panel manufacturer receives sufficient information about the intended application.
IEC publishes IEC TR 61439-0 specifically to help specifiers define the characteristics and application requirements needed by the manufacturer when specifying an assembly.
Information may need to cover areas such as:
Electrical supply:
What supply and system characteristics will the assembly operate with?
Loads:
What equipment will the panel control?
Operating environment:
Will the panel operate indoors, outdoors or under particular environmental conditions?
Fault conditions:
What prospective short-circuit conditions need to be considered?
Ingress protection:
What level of environmental protection is required?
Future expansion:
Does the panel require capacity for future modifications?
Operational requirements:
How will the equipment be controlled and maintained?
Project-specific requirements:
Are there other standards, specifications or application requirements that apply?
This is why specifying a control panel purely by dimensions, PLC type and number of I/O points is rarely sufficient.
Why BS EN IEC 61439 Matters When Choosing a Control Panel Manufacturer
The quality of an industrial control panel is not determined simply by whether the wiring looks tidy.
The manufacturer needs to consider the electrical characteristics, component selection, enclosure, thermal behaviour, protection, internal arrangement and verification requirements of the complete assembly.
For manufacturers and engineering teams procuring new control panels, it is therefore worth understanding how the panel builder approaches:
Design verification.
Routine verification.
Component selection.
Thermal considerations.
Electrical design.
Documentation.
Testing.
Manufacturing quality.
Stratos provides industrial control panel design and manufacture alongside PLC programming and wider automation engineering.
This allows the control panel to be considered as part of the complete automation system rather than as an isolated electrical enclosure.
Need Help with Industrial Control Panel Design?
Control panel design involves considerably more than selecting components and fitting them into an enclosure.
Electrical characteristics, component selection, thermal performance, protection, verification, documentation and the requirements of the wider automation system all need to be considered.
Stratos designs and manufactures industrial control panels alongside PLC and automation engineering, helping manufacturers develop control systems that are practical to operate, maintain and support throughout their lifecycle.
Speak to our engineers about control panel design, manufacture, refurbishment or modernisation.
For anyone using this guide for an actual compliance decision, I would also link directly to the BSI BS EN IEC 61439 series rather than presenting the resource page as a substitute for the standard itself.
Frequently Asked Questions
What is BS EN 61439?
BS EN IEC 61439 is the British-adopted series of standards for low-voltage switchgear and controlgear assemblies. Part 1 establishes general rules, while subsequent parts provide requirements for particular assembly types.
What is the difference between BS EN IEC 61439-1 and 61439-2?
Part 1 establishes the general rules for low-voltage switchgear and controlgear assemblies. Part 2 contains specific requirements for power switchgear and controlgear assemblies. The relevant requirements of Part 1 and the applicable assembly-specific part are used together.
What is the difference between design verification and routine verification?
Design verification establishes that the assembly design meets the applicable requirements. Routine verification is performed on completed assemblies to identify issues associated with manufacture and assembly. Both form important parts of the overall verification framework.
Does using compliant components make a control panel BS EN IEC 61439 compliant?
Not by itself. Individual devices may comply with their own product standards, but BS EN IEC 61439 addresses their integration into the complete low-voltage assembly. The assembly itself must satisfy the applicable requirements and verification process.
Does BS EN IEC 61439 apply to every industrial control panel?
The applicable standards depend on the type of assembly, its electrical characteristics, intended use and other relevant requirements. BS EN IEC 61439-1 cannot be used alone to determine assembly conformity; the relevant assembly-specific part must also be identified.