A recent upgrade to the Royal Opera House included customized plastic cable management to support modern LED lighting.
Live theater performances depend on engineering, including those at London’s Royal Ballet and Opera. For example, behind each performance is a technical ecosystem designed to move heavy overhead lighting trusses safely and silently. Following 25 years of reliable service since its original implementation, however, the theater underwent a critical upgrade, needing a new energy supply system that could handle the heavier weight of modern LED technology.
Before its modernization, the Royal Ballet and Opera (ROH) overstage machinery consisted of five vertically moving rows of beams equipped with halogen spotlights. In 2000, motion-plastics manufacturer igus supplied the zigzag energy chain system that safely guided the many cables during the vertical movement. For 25 years, this system operated reliably and trouble-free.
But in 2025, the ROH swapped halogen spotlights for LEDs. Although this modern solution significantly reduced energy consumption, it exceeded the load-bearing capacity of the existing suspension points. That necessitated a new support structure and energy-supply solution to manage the high volume of cables.
The new lighting hoists now consist of five 21-meter-long rows of aluminum trusses that can be moved at 250-millimeter speeds to heights more than 25 meters. Each row consists of three closely spaced units that can be individually moved. Each unit features a two-truss design with a lower section for the lighting fixtures and a main load-bearing section.
The new energy supply system had to integrate directly into this main structural truss for space savings and stability. It also had to reliably operate under load — supporting the ROH’s hundreds of annual performances and rehearsals while remaining quiet and visually unobtrusive.
The igus team was again tasked to supply an appropriate cable system. The engineers initially considered alternative solutions such as a motorized cable reel. However, due to the high volume of cabling (including motor, bus, data, fiber-optic and control lines) the zigzag system again emerged as the top option.
Zigzag systems work by folding the energy chain neatly into a basket. As the platform rises, the chain unfolds smoothly and quietly, delivering a space-saving solution for dynamic platforms without placing tensile strain on the cables. These systems also make adding or replacing individual cables a fast and easy process.
Zigzag systems, which fold and unfold vertically, naturally generate a slight pendulum effect due to their geometry. At the ROH, the massive cable load amplified this effect, with initial tests revealing 1-meter lateral deflections during operation. In a stage environment where trusses are close each other, such wide sway is a safety hazard. So, to counteract this effect, engineers arranged the zigzag in an opposed pattern. By installing two e-chain energy chains per unit that move in opposition, the lateral forces cancel each other out. Using high-precision laser measurements, engineers confirmed this configuration reduced lateral sway from 1 meter to just 20 millimeters.
For the center truss units, the engineers also implemented two guide boxes with one chain each. On the shorter side units, where space was tighter, they designed two chains to fold compactly into a single box.
The original design for the guide boxes consisted of 2.5-mm-thick steel baskets, for a system weight of roughly 200 kilograms per unit, exceeding the load capacity of the hoisting machinery. Engineers had to reduce the guide box weight to less than 150 kilograms to avoid compromising structural integrity.
The team addressed this challenge by:
- Replacing the 2.5-millimeter steel baskets with aluminum counterparts.
- Performing a structural and stress analysis to identify areas of low stress where that could be safely removed.
- This approach successfully brought the individual system weight down to 112 kilograms, excluding the cables.
In addition to the zigzag system, the igus cable management solution included its E4.56 series e-chain, specifically designed for high loads and long travel, all while maintaining a low-noise profile. Inside these chains, igus installed a suite of chainflex cables, which unlike standard cables, are engineered for continuous motion. These cables also feature electromagnetic compatibility to prevent interference with other stage equipment, as well as an ability to withstand vertical travel and the folding stresses of the zigzag system over millions of cycles.
To meet the ROH’s tight four-week maintenance window, igus delivered 15 complete zigzag systems, including boxes, chains and cables, as ready-to-install units.
The ROH project has resulted in stage infrastructure that is quieter, lighter, and more durable than what came before it, and it’s expected to outlast the 25-year record of its predecessor. Today, the lighting trusses and its cabling system (though invisible to audience members) is key to the success of every performance.
igus | www.igus.com
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