When metal ladder cable trays came of age, they were used to support the new armored shielded power cables that were permitted outside the conduit environment. Utilities and industrial companies initiated the use of expanded metal and solid trough-styled trays for supporting power and control cable.
Cable trays quickly proved their worth as a safe, dependable and cost-effective solution to routing and supporting cables. Installed cost savings of over 50% on project after project drove the market for metal cable trays to over 80 million dollars.
Cable Tray is NOT A WIREWAY and is viewed as a support for cables. This provides the designer and user many benefits.
- Full free air rating of cables, results in smaller conductors vs. conduit
- Greater fill volume allowed, results in less space
- Used in all locations except elevatorshafts (the only prohibition on cable tray use)
- Used as an equipment grounding conductor (classified by UL)
- Less stress on cables during installation and operation
- Increased safety, no moisture condensation problems nor transmission of corrosive or explosive gases, as with conduit
- Simplified maintenance with the flexibility of adding or changing circuits
- Simplified engineering and construction. Add, change, modify more easily
- Used with other wiring methods
- Longer support spans up to 55' (Chalfant’s standard systems to 40’)