Welded structure for installation of distribution box

A welded structure for a distribution box ensures high structural integrity, long-term sealing, and reliable mounting, provided proper materials, welding techniques, and design standards are followed.

Material Selection and Steel Thickness

For a welded distribution box, the cabinet body should be made of cold-rolled steel plates with a minimum thickness of 2. 0 mm, while the back plate should be at least 3. 0 mm thick.

Doors and panel surfaces should also be no less than 2. 0 mm. For supporting lugs or brackets, flat steel of 40x4 mm is commonly used, with lengths around 10 cm for secure mounting.

High-strength steel grades such as Q345B, Q355B, or stainless steel can be selected depending on environmental exposure and load requirements.

Welding Quality and Techniques

The welding process is critical for both structural strength and sealing performance. Continuous welding along all seams is preferred over spot welding to prevent water ingress and maintain IP ratings (IP54, IP65, or higher for outdoor use). Welds should be uniform, smooth, and free of air holes, welding skin, or cracks.

Proper pre-welding preparation, including plate edge beveling and alignment with internal diaphragms or stiffeners, ensures full-penetration welds and defect-free joints. Submerged arc welding (SAW) is recommended for deep, reliable welds, with post-weld inspection to verify quality.

Structural Design and Mounting

Welded distribution boxes can be mounted on walls, floors, or poles depending on size and weight. Two lugs are typically welded at the lower left and upper right corners for non-floor-mounted boxes to facilitate secure attachment. The mounting substrate must support the box plus maximum equipment weight with a suitable safety factor.

For vibration-prone environments, isolation pads or dampers should be installed behind the box to protect internal wiring. Bolt connections should include flat and spring washers, with 2–5 threads exposed for secure fastening.

Component Layout and Maintenance

Inside the box, heavier components should be mounted lower to improve the center of gravity and reduce stress on welds. Reserved inlet and outlet holes should be equipped with sealing accessories to maintain ingress protection. Regular maintenance includes checking for rust, discoloration, and secure connections, as well as ensuring drawer-type or capacitor cabinets operate smoothly.

Advantages of Welded Structures

High structural rigidity and torsional stiffness, suitable for heavy-duty or outdoor applications. Superior sealing performance compared to spot-welded or modular designs, ensuring long-term IP compliance. Durability under transport and installation stresses, including vibration and impact.

While modular designs offer flexibility and easier assembly, welded structures remain preferred for applications requiring maximum strength, environmental protection, and long-term reliability.