Outside of North America (the U.S., Canada, and Mexico), foreign markets commonly adopt low-voltage switchgear that complies with IEC standards or their equivalents. These typically adhere to the IEC 61439-1/2 standards, which are largely consistent with China’s GB7251 standards, though there are some differences in specific parameters and usage habits.

Foreign markets place higher demands on insulation materials for low-voltage switchgear, with many manufacturers using custom-cut insulation boards as supports. Unlike in China, where various types of pre-fabricated busbar clamps are used for different configurations and designs, foreign manufacturers prefer to use insulated structural profiles as busbar supports, which are simpler and more flexible.

Rear Horizontal Busbars: Compared to top-mounted busbars, rear horizontal busbars offer better heat dissipation and higher current-carrying capacity. Vertical busbars are split into two sections to reduce the use of copper. However, the downside of rear-mounted horizontal busbars is that they are inconvenient for rear wiring, such as in drawer-type switchgear, where front-side or side wiring is often required.

The rear section of the cabinet provides more space, allowing for more flexible busbar layouts and shorter copper lengths for solutions like bus tie connections, making installation easier. The front section also offers more room for functional units, enabling the installation of additional drawers or outgoing circuits.

Busbar Overlap: In most cases, busbars are partially overlapped without perforations. For example, the overlap area may be five times the busbar thickness, which is scientifically sound. The resistance at the busbar connection depends on the contact pressure, and increasing the overlap area excessively offers no benefits and only wastes copper.

In IEC markets, the main busbars are typically connected via joining bars. The main busbar is pre-installed at the factory, and connections on-site are made using fish-shaped bars or perforation-free overlaps. This differs from the practice in China, where main busbars are often installed on-site as a continuous bar across multiple cabinets, connecting with the branch busbars in each cabinet. While this reduces the number of connections, the installation quality may be compromised due to factors like floor conditions, affecting the torque on the screws and potentially placing extra stress on the copper bars.

Cabinet Structure: Low-voltage switchgear cabinets in foreign markets are not uniformly assembled from C-profiles. Instead, designs vary, and customers place significant importance on the strength of the cabinet. The strength of the cabinet is crucial for withstanding short-circuit currents, environmental impacts, and seismic activity, so the structural integrity of the cabinet is a high priority.

Drawer Units: The focus is on motor control units, with more use of fixed outgoing units, high installation density, and buttons and indicator lights fixed in place without needing to mount them on the door panel. This facilitates easier replacement and maintenance of functional units.

Drawer units are designed as tray-type extraction units, which are simple and convenient. They feature fewer external connections and are easier to maintain as an integrated unit. Earlier low-voltage switchgear imported into China also had this structure, but over time, due to factors like the inability to lower the IP protection rating in test positions, as well as the spread of screw operation mechanisms, drawers became standardized.

Fit for Purpose: The best designs are those that suit their intended purpose. Some designs that we might consider advantageous may not necessarily be so. Certain features may be marketing gimmicks. The core of any product lies in its safety, reliability, and ease of operation. Special designs, such as enhanced protection ratings or corrosion resistance, are necessary for specific applications. However, for general use, it’s important to avoid over-engineering for marketing purposes, as simpler products are often more reliable. Many unnecessary features can become burdensome over time, taking up space and complicating operations. Therefore, in foreign projects, low-voltage switchgear design should prioritize safety and practicality, ensuring high-quality components such as copper busbars, insulation materials with adequate CTI and flame-retardant ratings, and reliable devices. These factors are key to ensuring quality.