Why Cable Trays Are Installed and Grounded

Grounding has always been a controversial issue. However, with the proliferation of digital high-frequency equipment, the difficulties have become increasingly complex. Grounding refers to connecting to the earth or connecting to a conductor that works in place of the earth. Grounding is also called earthing in some international standards. Bonding is connecting metal pieces to create electrical continuity. Grounding is used for fire protection, electric shock prevention, electrical system ground fault prevention, lightning protection for buildings and electrical systems, electrical noise protection, and voltage stabilization.

Cable tray grounding, the purpose of power grounding is to reduce damage caused by ground faults in wires or equipment. Ground fault current passes through the cable tray system. Where there are gaps in the cable tray system, use bolts, connections, splice plates, clamps and bonding jumpers to connect the cable tray system. The cable tray system must be electrically continuous, not mechanically continuous. Cable trays are sometimes attached to conduits, cable channels or other wiring terminals. They must also be connected to the power source.

When the cable tray system only contains signal and communication circuits operating at low energy levels, power grounding is not acceptable, but cable tray grounding is required for lightning protection, noise and electromagnetic interference. The hazards are voltage interference, lightning-induced voltage and radiation. If the cable tray is located on the top of a building, in an externally exposed area, or in a lightning current path, lightning protection is a concern. Protection systems can be installed, such as overhead cable systems. Overview of building lightning protection parameters, installation standards for lightning protection systems.

Tray-type cable trays can be completely enclosed, and gaskets and covers are designed and tested to standards to protect sensitive circuits of cable trays from external electric and magnetic fields. Cable trays with solid bottoms as well as cable tray covers provide some shielding. Steel shielding is effective at frequencies up to around 100 kHz, but at higher frequencies, in the megahertz range, aluminum or copper shielding is more effective. The sensitivity of signal systems is determined by a variety of complex parameters. Involving electronic circuits, isolation or grounding, filtering, signal type and logic, signal cable type (non-twisted pair, twisted pair, shielded twisted pair, coaxial cable double-shielded coaxial cable), and circuit and cable characteristic impedance. Some equipment is quite resistant to external noise.