History and Development of Bridge Tray 

Bridge Tray (Cable Tray) is an open or closed structural system used to support and protect cables and wires, which is widely used in the fields of construction, industry, electric power, and communication. Its development history is closely related to the progress of electrical engineering, building technology and material science. The following is the evolution of bridge: 

1. Early Cable Support Methods (Late 19th - Early 20th Century) 

In the early development of the power system, cables were mainly laid in the following ways: 

Wooden or Metal Wire Channel: Early cables were directly fixed in wooden or iron channels, lacking standardised design.

Conduit wiring (Conduit): At the end of the 19th century, metal conduits (e.g. galvanised steel pipes) began to be used to protect cables, but installation was complicated and costly.

Overhead open wires: Some power lines use bare wires set up on insulators, which is less safe.

Problems: The traditional wiring method is difficult to adapt to industrialisation, poor heat dissipation of cables and maintenance difficulties.

2. The prototype of bridge (1920s-40s) 

As electrification accelerated, engineers began to design more efficient cable support systems: 

1920s: American companies such as General Electric (GE) experimented with metal tray structures for factory cable laying.

1930s-40s: During World War II, the need for fast wiring in military and industrial facilities drove the initial use of open metal bridges.

Material improvements: Galvanised steel (rust-proof) and aluminium alloys (lightweight) began to be used in bridge manufacturing.

Characteristics: Simple structure, mostly ladder type (Ladder Type), easy to cable heat dissipation and maintenance.

3. Standardisation and Popularisation (1950s-1970s) 

After World War II, with the expansion of commercial buildings and industrial facilities, bridge technology matured: 

1950s: The National Electrical Manufacturers Association (NEMA) formulated bridge standards (e.g., NEMA VE1) to regulate dimensions, loads and other parameters.

1960s: 

Europe promotes the Perforated Cable Tray to improve cable fixing flexibility.

FRP (Fibreglass Reinforced Plastic) bridges are introduced for use in corrosive environments (e.g. chemical plants).

1970s: 

Enclosed Channel Cable Tray is popularised for increased electromagnetic shielding and protection.

Bridges are widely used in data centres and telecoms.

Industry movers: 

B-Line (USA): one of the early bridge manufacturers.

OBO Bettermann (Germany): Promoted the standardisation of bridges in Europe. 4.

4. Modern bridge technology (1980 to present) 

With the development of new materials, smart buildings and green energy, bridge technology continues to innovate: 

1980s-90s: 

Aluminium alloy bridge is widely adopted for its light weight and corrosion resistance.

Fire-Rated Cable Tray is used in high-rise buildings and tunnels.

2000s: 

Modular design for quick installation and expansion.

The popularity of fibre-optic cables leads to the optimisation of bridge structures (e.g. compartmentalised bridges).

2010-present: 

Intelligent bridges: integrated sensors monitor cable temperature, load (IoT technology).

Environmentally friendly materials: recyclable metals, halogen-free flame retardant coatings.

BIM (Building Information Modelling) application: digitalisation of bridge design and construction.

Representative Companies: 

USA: Cooper B-Line, Eaton, Panduit 

Europe: Legrand, Niedax 

China: Jiangsu Wanqi, Zhongtian Technology