A lighting truss is a steel or aluminum tubular frame used to fasten and position lighting fixtures and associated cables. Trusses can be suspended from portable lighting stands, permanently mounted to the building, or suspended by wire rigging, and are commonly used for stage performances, trade shows, and nightclubs. The type of metal used in the lighting truss varies depending on the installation. Steel is commonly used in fixed installations because of its durability and the fact that weight is not an issue. Portable trusses for both small and large applications are typically made of aluminum alloy and have manufacturer-specified weight capacities.
Trusses are divided into three types, each of which is made up of parallel poles with welded cross-members for stability and strength. Trusses come in a variety of lengths, both standard and custom-cut, and can be joined together to form longer lengths. The simplest design is an I-beam lighting truss, which consists of two poles. Box trusses use four poles in a square configuration, while triangular trusses use three poles in a triangular configuration. The number of fixtures and the method of installation determine the type of truss used.
Special arc-shaped trusses are typically available in I-beam, triangular, and box constructions and are used for specialty lighting design applications. Lighting trusses in the shape of an arc are also modular and come in fixed or custom lengths. Circles, arches, and other radius shapes can be formed by joining them together.
A lighting truss’ modular design allows portability and ease of set-up for traveling and storage, in addition to convenient and safe mounting of lighting fixtures and wiring. During a move, lighting fixtures and wiring are typically not removed from the truss, reducing set-up and break-down times significantly. Each section of a large or complex lighting truss assembly can be assigned a number or code, allowing the lighting technician to duplicate the original design.
Motorized trusses are frequently used in large music concert settings. A series of motors and pulleys connected to the rigging allow the lighting technician to raise and lower the entire truss assembly for set-up and break-down, which is suspended by wire rigging attached to the venue ceiling. Some motorized lighting truss systems allow for movement of the assembly during the show, resulting in unique lighting effects.
Individual trade show booths, traveling disc jockeys, and small music groups commonly use compact trusses. The lighting truss is suspended on top of adjustable floor stands, using the same types of truss construction but with smaller pole diameters and section lengths. These highly portable truss systems offer all of the benefits of larger systems while being more suitable for smaller venues.