What busbar rating is required for a Busbar Trunking System (BTS)?

The required busbar rating is based on the continuous load current, ambient temperature, installation method, and permissible derating. BTS assemblies are commonly specified from 100 A up to 6300 A, but the correct selection must be validated against the assembly’s rated operational current and temperature-rise limits under IEC 61439-1 and IEC 61439-6. Engineers should also check the enclosure ventilation, grouping with other trunking runs, and any future load growth. For large facilities, it is good practice to size the busbar at least with margin for diversity and planned expansion, rather than selecting only the present operating current.

How do I coordinate busbar systems with ACBs and MCCBs in a BTS?

Coordination with upstream ACBs and downstream MCCBs is essential to maintain selectivity and protect the busbar trunking against thermal and dynamic fault stress. The BTS short-circuit withstand values, such as Icw and Ipk, must be greater than the prospective fault current at the installation point. The protective device settings or characteristics should limit let-through energy so the busbar system remains within its validated withstand capability. This is typically assessed as part of the verified design approach under IEC 61439-2 and IEC 61439-6, along with the manufacturer’s coordination tables for fuse-switches, MCCBs, and ACBs.

What is the difference between copper and aluminum busbars in BTS applications?

Copper busbars offer lower resistance, better compactness, and generally higher current density, making them well suited for space-constrained risers or high-fault-level applications. Aluminum busbars are lighter and often more cost-effective, particularly in long feeder runs or large commercial trunking systems. The choice depends on electrical performance, mechanical support, joint design, oxidation control, and total lifecycle cost. Both can be compliant with IEC 61439, but the assembly must be type-verified or design-verified for temperature rise, short-circuit withstand, and dielectric performance. Joint quality and torque control are especially important for aluminum to avoid oxidation-related heating.

Does IEC 61439-6 apply specifically to Busbar Trunking Systems?

Yes. IEC 61439-6 is the specific part of the IEC 61439 series that covers busbar trunking systems. It supplements the general requirements in IEC 61439-1 and the power assembly requirements in IEC 61439-2. For a BTS, compliance evidence should cover rated current, temperature rise, dielectric properties, mechanical strength, and short-circuit performance of the trunking run, tap-off interfaces, and joints. If the system includes additional functional modules, metering, or communication devices, those elements still need to be integrated without compromising the verified performance of the assembly.

How is short-circuit withstand rating determined for busbar systems?

Short-circuit withstand is determined by comparing the busbar system’s tested or verified Icw and Ipk values with the prospective fault current at the point of installation. The protective device upstream, such as an ACB or fused switch, must be able to limit the energy enough to keep the BTS within its verified capability. In practice, designers review the manufacturer’s coordination data, including time-current curves and fault-limiting performance, then confirm the assembly’s compliance with IEC 61439 requirements. This is a critical step for industrial plants, data centers, and utility distribution corridors where fault levels can be high.

Can busbar trunking systems support SCADA or BMS monitoring?

Yes. Many modern BTS installations support communication-ready accessories such as meters, power quality monitors, Modbus RTU/TCP gateways, and digital sensors for current, voltage, temperature, and energy data. This allows integration into SCADA or BMS platforms for load tracking, preventive maintenance, and energy reporting. The communication devices must be installed without affecting the thermal and dielectric integrity of the busbar assembly, and the overall system still has to comply with IEC 61439 verification requirements. In large buildings and industrial plants, this capability is often used for submetering and operational visibility.

What forms of separation are used in BTS-related busbar assemblies?

In BTS applications, separation may be implemented to improve safety, maintenance access, and fault containment, especially where multiple tap-off points or parallel distribution paths are used. While form-of-separation terminology is more commonly associated with cubicle assemblies, the same engineering principle applies to segregating conductive parts, joints, and tap-off interfaces within trunking enclosures. The goal is to reduce the risk of accidental contact and limit fault propagation. The exact arrangement must still satisfy IEC 61439-6 and the manufacturer’s verified configuration for the specific trunking system.

Where are busbar trunking systems with busbar systems typically used?

Busbar trunking systems are widely used in high-rise building risers, commercial campuses, hospitals, airports, data centers, manufacturing plants, and utility distribution corridors. They are preferred where fast installation, modular expansion, and reliable high-current distribution are needed. Compared with cable runs, BTS offers cleaner routing, easier tap-off additions, and improved maintenance accessibility. For EPC contractors and facility managers, the key engineering advantages are predictable performance, verified IEC 61439 compliance, and simpler lifecycle expansion. In critical facilities, BTS is often combined with ACB- or MCCB-based distribution boards and central monitoring systems.

Panel + Component

Busbar Systems in Busbar Trunking System (BTS)

Busbar Systems selection, integration, and best practices for Busbar Trunking System (BTS) assemblies compliant with IEC 61439.

Overview

Busbar systems are the core power-conducting element in a Busbar Trunking System (BTS), where the assembly must deliver continuous current transfer with low impedance, controlled temperature rise, and verified short-circuit withstand performance. In BTS applications, the busbar set typically consists of copper or aluminum conductors, insulation barriers, support insulators, joint packs, tap-off interfaces, and enclosure sections designed as a coordinated IEC 61439 assembly. Selection starts with the required rated operational current, commonly from 100 A for compact feeders up to 6300 A for heavy industrial risers and main distribution runs, with specific attention to ambient temperature, installation method, and derating due to grouping or enclosure heat dissipation. For engineered systems, the busbar arrangement must be matched to the application architecture: plug-in trunking for modular branch take-offs, sandwich busbar arrangements for high short-circuit robustness, or feeder trunking for point-to-point distribution. Upstream and downstream protective devices such as ACBs, MCCBs, fuse-switch disconnectors, and protection relays must be coordinated to achieve selectivity and acceptable let-through energy. In practice, this means verifying the BTS rated short-time withstand current (Icw), peak withstand current (Ipk), and fault level coordination against the prospective fault current at the installation point. For critical plants, these values are often assessed together with arc containment requirements and, where applicable, IEC 61641 considerations for internal arcing in low-voltage switchgear assemblies. IEC 61439-1 defines the general rules, while IEC 61439-2 applies to power switchgear and controlgear assemblies, and IEC 61439-6 specifically addresses busbar trunking systems. A compliant design must demonstrate verified performance for temperature rise, dielectric properties, short-circuit strength, creepage and clearance, and mechanical integrity. Busbar systems within BTS assemblies also need careful attention to forms of separation, especially in multi-circuit risers or tap-off sections where segregation improves maintainability and fault containment. Although BTS is not a conventional cubicle board, the same engineering discipline applies when integrating metering, SCADA gateways, Modbus TCP/RTU communication modules, or BMS interfaces for energy monitoring. Material choice influences both performance and cost. Copper busbars offer lower resistance and better compactness, while aluminum systems reduce weight and can be economical in long-run distribution. Joint technology, plating, torque control, and expansion joints are critical to prevent hot spots and mechanical stress. In corrosive or humid environments, enclosure protection and material compatibility become essential, especially for industrial facilities, data centers, hospitals, airports, and commercial risers. Where hazardous locations are involved, surrounding installation constraints may also require consideration of IEC 60079 principles, even if the BTS itself is installed outside the classified zone. A well-selected busbar system in BTS improves installation speed compared with cable-based distribution, simplifies expansion through tap-off units, and enhances lifecycle maintainability. Typical applications include vertical risers in high-rise buildings, feeder distribution in manufacturing plants, utility substations, and large commercial campuses. The best designs document rated current, short-circuit rating, degree of protection, temperature-rise data, and protection coordination as part of the final assembly dossier, ensuring the BTS can be accepted by EPC contractors, inspectors, and facility maintenance teams with confidence.

Key Features

Busbar Systems rated for Busbar Trunking System (BTS) operating conditions
IEC 61439 compliant integration and coordination
Thermal management within panel enclosure limits
Communication-ready for SCADA/BMS integration
Coordination with upstream and downstream protection devices

Specifications

Panel Type	Busbar Trunking System (BTS)
Component	Busbar Systems
Standard	IEC 61439-2
Integration	Type-tested coordination

Back to Hubs

Busbar Trunking System (BTS)

Busbar Systems

Frequently Asked Questions

Need a Custom Panel Built to Spec?

Patrion's engineering team designs and manufactures IEC 61439 compliant panels. Get a design review or quote.

Contact Patrion Call +90 232 332 22 78