Busbar Systems and IEC 61439 Standards

Busbars systems, or busbar supports are essentially heavy conductors, typically made of copper, which carry and distribute powerful electric currents to components that consume electrical power throughout an assembly.

Busbars are not only easy to install (certainly compared to cabling), they also play a major role in the design and safe operation of a switchgear and controlgear assembly. 

The recent introduction of the IEC 61439 switchgear and control standards has significant implications for the design and performance of the copper busbar system.  It’s an area which engineers need to appreciate, not least because the new testing regime and the requirement for compliance has changed the way we think about the selection of the busbar system. 


One of the most important requirements of any switchgear power distribution system is to carry fault currents (short circuits) safely until a protection device, namely the fuse or the moulded case circuit breaker, interrupts the fault.

This capability, and the product specification, is the subject of testing which is covered by the IEC 61439 standard and which provides vital information for building a safe assembly.

Busbar testing, in fact, was revolutionised following the introduction of the standard which came into force in November 2014.  It continued a determination across the sector to harmonise the low voltage industry through the creation of one standard which provided protection for both personnel and switchgear.

IEC 61439 requires busbar systems to be tested – by their manufacturers – within enclosures rather than (as previously happened) as a standalone arrangement.  This is a step forward for the industry, providing access for system engineers to data delivered in situ which offered both a more realistic assessment and more accurate and reliable data than before.

Further information at www.rittal.co.uk and www.friedhelm-loh-group.com or on twitter @rittal_ltd.

How to Design and Size a Busbar

The introduction of the IEC 61439 switchgear and control standards has had significant implications for the design and performance of the copper busbar system. 

It’s an area which design engineers need to appreciate, not least because the new testing regime and the requirement for compliance has changed the way we think about the selection of the busbar system. 


There are a number of key factors relating to the design/layout stage of an assembly:

Where to put the busbar

The decision as to where to put the busbar depends on the location of the incoming cables and the position of the incoming protection device.

The form rating helps determine the layout of the assembly, the position of devices such as the circuit breaker, terminals and the busbar system, as well as whether the busbar requires a cover.

Ultimately, the size of the enclosure will be dependent upon both the form rating and the busbar system fitted.

Current rating

The total load has to be pre-calculated as this impacts on the size of the busbar.  Consideration must also be given to the IEC 61439 standards because under certain circumstances it requires a rating of 125% of the full load current.

Knowing the current loadings means that watt loss can be calculated which will in turn have a direct impact on temperature rises within the enclosure. Again, this is a key element of the standard, along with the maximum temperature ratings.


Connecting conductors to the busbar can cause problems for contractors as any oversized cables may be too large to terminate on the busbar system.

Design engineers need to consider this possibility and compensate with different busbar adaptors or terminals.  But, remember that any additional copper connections may invalidate the busbar warranty as they could be considered to be extending its capability beyond the tested system.

Under the standard, all copper connections above 1600A have to be tested for impact of heat rise on the air circuit breaker.  In addition, the connections from and to the main busbar system have to be physically tested by the original equipment manufacturer of the switchgear system.  Essentially, the panel builder cannot make their own.

Fault ratings

High-fault currents (short-circuits) can obviously be highly destructive.  The initial electro-mechanical force generated in fault conditions can be huge – tens of thousands amps. As a consequence, the busbar system must be robust enough to carry the current until the short-circuit protection device (such as a fuse or MCCB) trips.

Design engineers have to be aware of the fault rating from the outset, a level that is determined by several factors: the size of the supply transformer; the impedance of cables from the transformer; and current limiting effects of the protection device.  The fault rating can be given as either a RMS kA – which typically has a time withstand value of one second – or a peak value measured in kA.

Instructions around how to install the busbar support are the responsibility of the original manufacturer of the switchgear system and issues such as the spacing of the busbar supports are determined by the manufacturer’s testing. These distances are governed by the fault level and the size of the copper bar.  They and their spacing (ie. how far they are apart) have a major bearing on the strength of the system; if the supports are fitted too close to each or too widely distant, then the system’s performance under fault conditions could be badly affected.

Further information at www.rittal.co.uk and www.friedhelm-loh-group.com or on twitter @rittal_ltd.


Rittal Showcasing Enclosures at Railtex 2017

Rittal Showcasing Enclosures at Railtex 2017

Rittal will be showcasing its PADS and LU approved enclosures at Railtex 2017.

The company will be exhibiting a range of Network Rail and London Underground approved enclosure systems used extensively within the rail network, rail telecoms and throughout the underground network.  The company’s range of approvals includes PADS for track side and the S-1085 for the underground.

Visitors to Stand N41 will also be able to talk to the company’s expert team, who will be on hand throughout the show to provide advice.


Efficient Engineering

Rittal is one of the world’s leading system suppliers for housing and enclosure technologies, combining a focus on energy conservation with efficient engineering.  The company’s renowned infrastructure system offers five perfectly matched modules: rack, power, cooling, security and monitoring and remote management.

Based around Rittal’s TS 8 control cabinet and TS IT rack system platform, it offers maximum rack volumes, high levels of surface protection, stability and endless expansion possibilities.

The TS IT racks for example are simple and flexible enclosure systems which feature snap-in technology, flexible internal configuration, intelligent cable management system, vented
doors and multi-functional roofs.

Thermal performance, more than any other single element of the design, must form the base line for the design of any enclosure. Rittal Therm, design and calculation software can help users correctly identify the heat dissipation requirements within enclosures, and support their application and installation.

Safety and Security

Enclosures have a vital role to play both in ensuring the safety and security of electrical equipment and also in protecting the people who operate it.

All Rittal’s enclosure systems are compliant with LUL specifications for Fire Safety Performance of Materials. They are widely applied across global networks including enclosure technologies, electronics packaging, power distribution, UPS, climate control, IT Solutions including high density cooling, kiosks, control and monitoring solutions, fuel cells, renewable energy solutions along with the integration and service to support these technologies.

Ease of installation

For installations of outdoor free-standing enclosures, there are custom-built Rittal pre-cast concrete base/plinths which significantly reduce the time and cost of the install, as well as
preventing disruption to services by removing the need to mix concrete and remove waste from site.

Other key products in the range include wall-mounted boxes and pole-mounting kits to fasten metal and non-metal enclosures to round and square poles.

Power Distribution

Visitors to the show will also be able to find out more about the company’s popular busbar systems Ri4Power electrical power distribution system and latest Power Engineering planning software.

The software provides comprehensive support in planning and verifying standardised Ri4Power switchgear, as required by IEC 61439-1/-2 standard.

As with all Rittal’s solutions the power distribution range has been subject to the most stringent testing, demonstrating their capability to operate in the toughest and most demanding environments.

Rittal’s highly qualified team will be able to offer support across all stages of the project, from design through to installation and commissioning.

Further information at www.rittal.co.uk and www.friedhelm-loh-group.com or on twitter @rittal_ltd.

Rittal Expertise on Show at Maintec 2017

Rittal will be showcasing some of its leading technology and much of its considerable expertise at Maintec 2017 (21-23 March, at the NEC, Birmingham).

Visitors to Rittal’s Stand M169 will be able to discuss their requirements for innovative enclosure systems and find out more about how the adequate provision of the maintenance and correct specification of system can result in substantial reduction in down time, energy use and equipment failure.

Of particular note will be the presence of the multi-award winning Blue e+ climate control system which was launched in 2015 to great acclaim thanks to its outstanding energy savings and flexibility.

System Surveys, Servicing and Maintenance 

Anyone keen to improve the long-term health of their systems can talk to Rittal’s expert team on the stand. These discussions might range from possible remedial action if equipment is  overheating,  tripping or failing, to optimum service programmes for maintaining systems‘ viability throughout its working life.

For example, running manufacturing automation systems consistently at high temperatures will have a major negative impact on the system’s performance, reduce its service life and raise potential safety issues. These may lead to a loss of production, costly equipment replacement/repair and Health & Safety issues. All of these factors are preventable with the correct action.


A Rittal RiAssure3 survey will identify the likely risk of a system overheating which could lead to equipment tripping or failing.  It will then provide recommendations around remedial action – for example, changes to the system’s service and maintenance regime to help improve its efficacy or the need to invest in different climate control technology.

Blue e+ – Climate Control solutions 

The Blue e+ climate control system is a major advance for both the industrial and IT sectors and provides benefits to all users.  It addresses common problems of panel builders, systems integrators, original equipment manufacturers and end users alike.

As well as being far more energy efficient than existing cooling solutions, the Blue e+ uses state of the art technologies to deliver greater flexibility, safety and ease of handling.

Key to the efficiency of the Blue e+ is Rittal’s innovative patented hybrid system which uses a clever combination of a compressor cooling device and a heat pipe to take maximum advantage of passive cooling.

As a consequence, energy savings have been up to 75 per cent better than conventional units – a quantum leap forward for cooling systems, and a major incentive for manufacturers seeking to minimise steep rises in energy prices.

Further information at www.rittal.co.uk and www.friedhelm-loh-group.com or on twitter @rittal_ltd.