Stage Lighting
Stage Trussing Buying Guide
Trussing is the structural backbone that holds lighting fixtures, speakers and LED screens safely above a stage, and choosing the wrong type or an underrated span is a genuine safety risk, not just a performance issue. This guide covers truss types, load calculations and safe spans for events across Kenya.
Why truss type and material matter
Truss is built from aluminium or steel tubing welded into triangular or square (box) cross-sections, chosen for high strength relative to weight. Aluminium truss dominates the touring and event market because it is far lighter to rig and transport than steel, while still meeting the load ratings needed for lighting and speaker arrays.
Common truss profiles
| Truss type | Typical use | Notes |
|---|---|---|
| Triangle truss (290mm-300mm) | Small to mid stages, lighting rigs | Lighter, economical, good for spans up to about 6-8m |
| Box truss (290mm-400mm square) | Mid to large stages, moving head arrays | Higher load capacity and torsional rigidity than triangle |
| Box truss (400mm-500mm square) | Large concert stages, ground support towers | Higher spans and loads, used for major productions |
| Ladder/beam truss | Backdrop supports, banner frames | Lower load rating, not for heavy fixture loads |
Understanding load ratings
A truss's load rating depends on its span (unsupported distance between support points) and how the load is distributed along its length. A shorter span carries significantly more weight than a longer one using the identical truss section, because bending force increases sharply as span increases.
| Truss section | Span | Approx. safe uniformly distributed load |
|---|---|---|
| 290mm triangle | 4m | 300-400 kg |
| 290mm triangle | 8m | 80-150 kg |
| 390mm box | 6m | 600-900 kg |
| 390mm box | 10m | 250-400 kg |
Always request manufacturer load charts
The figures above are general guidance only. Every manufacturer publishes specific load charts for their truss sections, and these should always be consulted (or requested from your supplier) before finalising a rigging plan for any load-bearing installation.
Ground support versus flown truss
Ground support systems use truss towers with a base and hoist mechanism to lift a horizontal truss span without needing an overhead rigging point, ideal for outdoor events, tents, or venues without a rated ceiling grid. Flown truss, suspended from a venue's rigging points or motorised chain hoists, is more common in permanent venues with engineered grids.
Calculating combined loads
A common mistake is calculating truss load based only on fixture weight, forgetting cable, clamps, safety cables and any signage or drape also hung from the same truss run. A realistic rigging plan totals every suspended item's weight and applies the manufacturer's safety factor, typically requiring the rated capacity to be at least 5-10 times the actual working load for overhead rigging above people.
Corner blocks, connectors and accessories
Truss sections join using conical or box corner connectors secured with pins and safety clips. Using mismatched connectors from different manufacturers, or worn pins, is a common cause of rigging failure. Always inspect pins and clips before each use and replace any showing wear or deformation.
Base plates, towers and outriggers
Ground-supported truss towers need adequately weighted or outrigger-stabilised base plates to resist tipping, particularly for outdoor use where wind loading adds significant lateral force. Never rely on a base plate rating alone without confirming the ground surface can bear the concentrated point load, especially on grass, sand or uneven surfaces common at Kenyan outdoor event grounds.
Planning a truss rig for an event
- List every item to be hung: fixtures, cable, clamps, speakers, screens, drape
- Total the combined weight including hardware, not just fixtures
- Select truss section and span rated well above the total load with adequate safety factor
- Choose flown or ground-support configuration based on venue rigging points
- Confirm ground surface and base plate/outrigger adequacy for ground support
- Inspect all connectors, pins and safety clips before assembly
- Have rigging inspected by a qualified rigger before the event opens to the public
Renting versus buying truss
Event companies running frequent productions generally find owning a core truss inventory more economical over time than repeated rental, while venues or companies with occasional large events may find renting for peak productions more practical than owning towers used only a few times a year.
Frequently asked questions
What size truss do I need for a small stage lighting rig?+
For spans up to about 6-8 metres carrying a modest lighting rig, 290mm triangle truss is generally adequate and economical. Larger fixture loads or longer spans need box truss with a higher load rating.
How much weight can a truss safely hold?+
It depends entirely on truss section and span; a shorter span carries substantially more weight than a longer one using the same truss. Always check the manufacturer's load chart for the specific span and section being used.
Is ground support truss safe for outdoor events?+
Yes, when properly weighted or outrigger-stabilised for wind loading and set up on a surface confirmed to bear the base plate load. Ground support is actually the standard choice for outdoor events without overhead rigging points.
What safety factor should overhead truss rigging use?+
Industry practice for rigging above people typically requires the truss and rigging hardware's rated capacity to be at least 5-10 times the actual working load, accounting for dynamic forces and unexpected stress.
Should I rent or buy trussing for my events company?+
Companies running frequent events generally save money owning a core truss inventory, while businesses with only occasional large productions often find rental more cost-effective for peak needs.
How often should truss connectors be inspected?+
Truss pins, clips and connectors should be visually inspected before every assembly, and any showing wear, bending or corrosion should be replaced immediately rather than reused.