400x400 Spigot Truss: A Practical Buying Guide for Event and Stage Builders

August 20, 2026

When you're planning a stage, exhibition booth, or event structure, the truss you choose determines both safety and ease of assembly. Among the many options, the 400x400 spigot truss is a popular choice for medium-span applications because it balances strength, weight, and quick connection. This guide explains what 400x400 spigot truss means, how to read load data, and which of our factory's models fit your project.

What Is a 400x400 Spigot Truss?

A 400x400 spigot truss is a square truss with a cross-section of 400 mm by 400 mm. The "spigot" refers to the conical connector that slides into the mating socket on the next section, allowing fast assembly without loose bolts. Spigot trusses are common in event staging because they reduce setup time and labor.

At our factory, 400x400 spigot trusses are available in several series, each with different tube dimensions and load capacities. All are made from 6082/6061-T6 aluminum, a high-strength alloy that offers good corrosion resistance and weldability.

Key Models and Specifications

We produce several 400x400 square truss models. Here are the main ones with their tube specs:

WRS-29 Square Truss: Main tube 50x3mm, sub tube 25x2mm, brace tube 20x2mm.
WRS-30 Square Truss: Main tube 50x3mm, sub tube 25x2mm, brace tube 20x2mm.
WRS-40 Square Truss: Main tube 50x3mm, sub tube 30x2mm, brace tube 25x2mm.
WRS-4060 Square Truss: Main tube 50x3mm, sub tube 50x2mm, brace tube 30x2mm.

Note: WRS-29 and WRS-30 have identical tube dimensions. The difference may lie in other design details, so check the product pages for full specifications.

All models come in standard lengths: 50 cm, 100 cm, 150 cm, 200 cm, 250 cm, 300 cm, 350 cm, and 400 cm (except WRS-29, which goes up to 300 cm). This modularity allows you to build spans from 1 meter to over 10 meters by combining sections.

Reading Load Tables: Distributed vs. Point Load

Every truss model has a load table that lists safe loads for different spans. Two numbers are given for each span:

Distributed load (kg/m): the maximum uniform load per meter across the entire span.
Point load (kg): the maximum concentrated load applied at the center (or worst point) of the span.

For example, the WRS-29 at a 3-meter span can carry 658 kg/m distributed or 1766 kg as a point load. At a 6-meter span, those numbers drop to 317 kg/m and 948 kg. Always use the load table for your exact span and loading condition.

Comparing 400x400 Models by Load Capacity

Here's a quick comparison of the maximum spans and loads for each model (based on the provided data):

WRS-29 / WRS-30

Span range: 1 to 6 meters
Distributed load at 1m: 1942 kg/m; at 6m: 317 kg/m
Point load at 1m: 1942 kg; at 6m: 948 kg

These are lighter-duty models, ideal for smaller stages, truss arches, or lighting grids where spans are moderate.

WRS-40

Span range: 3 to 8 meters
Distributed load at 3m: 936 kg/m; at 8m: 176 kg/m
Point load at 3m: 718 kg; at 8m: 560 kg

WRS-40 offers higher capacity than WRS-29/30, especially at mid-spans, making it suitable for larger stages and heavier rigging.

WRS-4060

Span range: 4 to 9 meters
Distributed load at 4m: 805 kg/m; at 9m: 210 kg/m
Point load at 4m: 1610 kg; at 9m: 945 kg

With a larger sub tube (50x2mm), WRS-4060 provides excellent point load capacity, making it a good choice for roof systems and ground support towers.

Choosing the Right 400x400 Spigot Truss

When selecting a truss, consider the following:

Span: How far will the truss span without intermediate support? Longer spans require heavier trusses.
Load: What weight will it carry? Include lighting, speakers, banners, and rigging. Use the point load if you have concentrated loads, distributed load for uniform loads.
Deflection: All trusses flex under load. Our load tables are based on safe structural limits, but you may need to limit deflection for aesthetic or functional reasons. Consult an engineer for critical applications.
Connection type: Spigot trusses are quick to assemble but require proper pinning. Ensure you have the correct pins and clamps.
Accessories: Consider truss dollies, corner blocks, and base plates for ground support.

Sourcing Tips for Buyers

When buying 400x400 spigot trusses, always ask for:

Material certificate: Confirm 6082/6061-T6 aluminum.
Load test reports: Our load tables are TÜV-tested, but verify that your supplier provides similar documentation.
Welding quality: Check for smooth, consistent welds.
Finish: Powder coating or anodizing affects durability.

Our factory is ISO 9001:2015 certified, and our trusses are TÜV Rheinland tested, ensuring consistent quality. As a factory-direct supplier, we can offer competitive pricing, but we never compromise on safety.

Frequently Asked Questions

What is the difference between 400x400 spigot truss and other square trusses?

The 400x400 refers to the cross-section dimensions. Other sizes like 290x290 or 520x520 have different load capacities. 400x400 is a middle ground, suitable for many event applications.

Can I use a 400x400 spigot truss for a roof system?

Yes, but you must calculate the loads carefully. For large roofs, consider using WRS-4060 or larger models like WRS-52 (520x520) for additional strength.

How do I connect spigot truss sections?

Each section has a spigot on one end that fits into the socket of the next. Slide them together and secure with a pin and clip. Always follow the manufacturer's instructions.

What is the maximum span for a 400x400 spigot truss?

Based on our data, the maximum span for WRS-29/30 is 6 meters, for WRS-40 is 8 meters, and for WRS-4060 is 9 meters. However, the safe span also depends on the load and deflection limits.

For detailed specifications and load tables, visit our product pages:

By understanding the specs and load data, you can confidently choose the right 400x400 spigot truss for your next project.