Benefits of Using IEC 61439 Standard in Electrical Busbar Systems


In the Electrical manufacturing industry, ‘Standards’ which define clear rules are extremely necessary for safety, proper functioning & to ensure quality at all levels. All the rules and recommendation under standards have been derived through extensive real world testing which assures correct or proper functioning of an electrical installation.

Following or not adhering to the standard would be difference between grave electrical hazard affecting the end user and safe operation of all electrical installation saving lives.


The IEC/EN 61439 is the result of the work of technical committees and subcommittees composed of representatives of the full member national electro technical committees in Europe, each dealing with a particular subject in the entire range of Electrical products and assemblies.

IEC standard 61439 covers low voltage switchgear and control gear assemblies. It is a replacement for the earlier IEC standard 60439 and is now the industry standard requirement for all low voltage switchgear and control gear panel assemblies. The new standard gives details on the requirements of products through testing and other verification methods such as design and routine verification.

Why was the new standard created?

In the earlier IEC standard 60439, ‘Design verification’ was excluded, and therefore the respective roles of equipment manufacturers and panel builders were not clearly defined, so responsibility for ensuring compliance was equally difficult to pinpoint. .

How does this new standard add value to the OEM, consultant, designer and panel builder?

The designer, be it from the consultant, OEM or the Panel builder identifies the needs and constraints for design, installation, operation and up-gradation of the complete system right at the design stage.

He chooses the correct switchgear, cables, connectors, busbar products and other components as per the specifications that he intends to use in his final assembly. Before he takes it up for manufacturing, at the design stage itself he needs to be sure that his choice of components are proper and that when the components are fitted in the control panel or Distribution panel that they follow the IEC 61439 standard.

To ensure this the designer carries out the design that ensures proper functioning of the electrical installation is carried out by following process.

1) The verification of the design by actual testing himself or by third party labs & by the calculation via prescribed tools supplied by the product manufacturer.

2) Proper documentation of this design verification (e.g. test documentation, calculations) is then made by the prescribed tools provided by the manufacturer.

The panel builder thus is not only responsible for the completed assembly but also responsible for:

– The rating of the switchgear assembly according to the customer requirements.

– The compliance with the design verification of the original manufacturer.

– The declaration of conformity to the customer (Declaration of Conformity)

– The marking and documentation of the assembly

– The performance of the design verification and documentation

General information about IEC – 61439

In IEC 61439 three verification methods are recommended

– First by test

– Second by comparisons

– Third with reference to design & by assessment.

This covers Assemblies integrated for Generation, Transmission & Distribution of Electrical Energy and assemblies designed for Electrical equipment; all in the voltage range not exceeding 1000V AC or 1500V DC.

Wöhner Busbar System and IEC 61439 standards

Wöhner has been synonymous with top performance and innovation in technology for over 88 years. With over 100 registered patents, the Wöhner group is well established worldwide as a competent and reliable partner for energy distribution, control technology and renewable energies.

Wöhner has made easier for electrical designer to adopt the new standard through following methods , this can be used for saving costs needed for additional testing and safe, proper functioning of the electrical installation, and all not dependent on type of enclosure being used.

Ø Short circuit strength: Pre calculated & tested by third party (avoids own testing requirements)*

Ø Temperature rise test: Pre calculated & tested by third party (avoids own testing requirements)

Ø current insulation: Creep-age distance and isolation voltage pre-tested according to standards

Ø Dielectric strength: By specification in product data sheet (Flexible Busbar)

*If short circuit values are not taken in to consideration, during electrical fault there would be a serious fire hazard, harmful to everyone.

Wöhner provides the current carrying capacity of the busbar and short circuit withstand capability of the system by calculation method with special tools on the website.

Tools for achieving IEC 61439

Wöhner provides following free online tools, which can be used by designer/planners, verify their own design and confer to all the standards under IEC 61439

1) Software for own design verification making the installation IEC complaint

2) Configurator tool to design and achieve the required Short circuit withstanding capability

3) Short circuit carrying capacity of a Busbar & busbar holder

4) Current carrying capacity of a Busbar

1) Software for own design verification making the installation IEC complaint:

Wöhner provides special software, which can be accessed under tools designer can fill up the Verification by comparison with a reference construction using the checklist under this tool. And documentation can be made for final submission to end user conferring to IEC requirements.


Design Verification According to IEC-EN-61439-1-2

2) Configurator tool to design and achieve the required Short circuit withstanding capability


Benefits of Using IEC 61439 Standard in Electrical Busbar Systems

A snap shot of configurator tool to achieve desired level of short circuit rating;

Wöhner configurator tool can be used to construct the power distribution and to achieve and maintain the desired short circuit withstanding capability of the system

3) To measure the Short circuit carrying capacity of a Bus bar system

We can check short circuit strength of a Busbar system by the design tools provided by Wöhner by the following simple steps:

The short circuit strength mainly depends on few parameters like size of the busbar, number of supports and distance between the busbar supports.


Using the “design” tools by Wöhner we select the busbar support in the 60 Classic 3P range (01500 Wöhner part number) busbar size of 20 mm x 10mm, Decide that we will be using two numbers of busbar supports and that the distance between number of supports will be 300 mm by giving these inputs in the “design” tools we receive the short circuit strength of 53 KA. (Refer screen shot 1)

Screen shot 1


01500 Messung Wöhner Part Number


Benefits of Using IEC 61439 Standard in Electrical Busbar Systems


Short Circuit Carrying Capacity of a Bus bar System

If we now change the distance between busbar support from 300 mm to 450 mm by maintaining all other parameters same we receive short circuit strength as 43 KA. (Refer screen shot 2).

Screen shot 2


Benefits of Using IEC 61439 Standard in Electrical Busbar Systems


Busbar Systems

1) Current carrying capacity of Busbar systems by “design” tools

We can check the “Current carrying capacity” of the Busbar systems by the “design” tools provided by Wöhner by the following simple steps.

The current carrying capacity of Busbar depends upon the Air temperature allowable inside the electrical cabinet and Busbar temperature that the end User has prescribed as Safe to use.

On the Wöhner website, we need to select the size of the busbar, temperature of air permissible in the electrical panel based upon the user specifications and allowable temperature of busbar as desired by the designer and allowed by the end user. By giving these inputs, we can get the current carrying capacity of the Busbar.

For example,

if we select busbar to be of the size 20mm x10mm, with a length of 2.4m – (Wöhner item code -01624), and if we select air temperature of 35°C and busbar temperature of 85°C, we will get the current carrying capacity 652A. (Refer screen shot 3)

Screen shot 3


Temperature of Air and Busbar

Now if we keep the size of the busbar and busbar temperature as constant and change the allowable air temperature from 35°C to 55°C. We will then receive the calculation of the current carrying capacity of the Busbar to be 508 A. (refer screen shot 4)

Screen shot 4


Benefits of Using IEC 61439 Standard in Electrical Busbar Systems

With Wöhner products, Usage verification can be done right at the stage of design akun demo slot, thus by using the IEC 61439 standard and with the examples mentioned above the Designer and the OEM manufacturer and the Electrical panel builder can design very good quality products. The End User is then provided a system, which he can trust and be ensured about the Safety and reliability,

An actual application photo of the control panels using Wöhner products.


Benefits of Using IEC 61439 Standard in Electrical Busbar Systems

Other features of Wöhner’’s unique Busbar solutions:

Innovative design by Wöhner allows mounting of electrical switchgear directly on busbars saving expensive real estate in the electrical panel. Wohner products guaranty safety & ease of assembly to our customers making the Assembly time reduce to 1/3rd of the conventional assembly time.

Copper Busbars are connected to cables & LV switchgear (100A-1000A) without drilling the Busbars. Well-designed mounting adapters & cable clamps provide a systematic & compact power distribution panel along with all features like safety, ease of assembly, ease of maintenance, etc.”


Electrical wiring & design are the most critical part of any electrical installation. Woehner Busbar system solution are uniquely designed as per IEC 61439 standard, and provides for free risk free compliance to standard with best safety, quality & cost saving

Farook Merchant – MD Messung Group (Mega Distributor for Wöhner Products in India.)

Working with world class standards brings International Quality to control panels manufactured by our customers. We are able to specify, test & guarantee to our customer; Critical specifications like Short circuit currents, temperature rise & di-electric strength as per IEC 61439 standard. This new standard gives details on the requirements of Wohner products through testing and other verification methods. It is intended to make up for some of IEC 60439’s shortcomings.”

Shrikanth Venkateshappa – International Key Account Manager, Woehner.