1. Early cable support methods (19th century - early 20th century)

Wooden and metal raceways: In the early days of power systems, cables were often laid directly underground or inside walls, or protected with simple wooden or metal raceways.

Open steel brackets: as the industrial revolution advanced, factories and large buildings began to use steel brackets (similar to ladders) to carry cables, but lacked a standardised design.

2. The beginnings of the modern bridge (1920s-1950s)

Rise of the steel cable tray: As power systems became more complex, engineers began to design more systematic cable support solutions, and steel trays (e.g., ladder and channel) were gradually used in factories, power plants, and large buildings.

The need for standardisation: The National Electrical Manufacturers Association (NEMA) began to develop bridge standards in the mid-20th century, such as NEMA VE 1 (Standard for Metal Cable Bridges).

3. Diversification of Bridges (1960s-1990s)

Material improvement: In addition to the traditional steel bridge, materials such as aluminium alloy and glass fiber reinforced plastic (FRP) began to be applied to adapt to different environments (e.g., corrosive places such as chemical, marine, etc.).

Structural innovation:

Ladder Cable Tray: Open structure, suitable for large diameter cables.

Trough Cable Tray: closed design for better cable protection.

Wire Mesh Cable Tray: lightweight and well ventilated, suitable for data centres.

International standard promotion: IEC, BS (British Standard), GB (Chinese National Standard) and so on have introduced bridge specification one after another.

4. Modern bridge technology (21st century to present)

Intelligent and modular: Modern bridge design pays more attention to flexibility, such as modular bridge that can be quickly disassembled to adapt to the needs of data centres, 5G base stations, etc.

Fire prevention and safety standards: With the improvement of building safety requirements, fire-retardant and fire-resistant bridges (e.g. fire-coated steel bridges) have become mainstream.

Environmental protection and lightweight: aluminium alloy and composite material bridge is widely used in green building due to its light weight, corrosion resistance and recyclability.

Main types of bridge (classified by structure)

Type Characteristics Typical application

Ladder bridge Open type, good ventilation and heat dissipation Power cable, industrial plant 

Channel bridge Closed type, dustproof and anti-interference Data centre, office building 

Grid-type bridge Lightweight and flexible, quick installation Data centre, communication room 

Tray type bridge Between ladder type and trough type Comprehensive wiring, factory power distribution 

Future trends

Intelligent monitoring: integrated sensors, real-time monitoring of cable temperature, load and other data.

Higher fire rating: adapting to special environments such as high-rise buildings and nuclear power.

3D printed bridges: customised production and reduced installation time.

The development of bridges reflects advances in power, building and industrial technologies, from simple cable support to intelligent management systems, which will continue to be optimised to meet new demands in the future.