Cable tray angle iron grounding

Metallic cable trays, including angle iron trays, must be properly grounded and bonded to ensure safety, provide a low-impedance path for fault currents, and comply with NEC standards.

Grounding Principles

Cable trays made from angle iron or other metals can serve as an Equipment Grounding Conductor (EGC) if they meet minimum cross-sectional area requirements and are installed in qualifying facilities . Grounding ensures that fault currents are safely directed to the facility's grounding system, protecting personnel and equipment from electric shock, fire hazards, and overvoltage conditions .

Bonding and Continuity

• Electrical Continuity: All sections of the cable tray must be electrically continuous. This is achieved by bolting, using splice plates, clamps, or bonding jumpers across gaps in the tray system .
• Side Rails: Both side rails of the tray should be bonded together to the next section to maintain a continuous grounding path .
• Connection to Power Source: The tray system must be bonded back to the main power source, either directly or via an EGC in the cables .

Equipment Grounding Conductor (EGC) Options

1. Tray as EGC: The metallic tray itself can act as the EGC if it meets NEC requirements for cross-sectional area and material suitability .
2. EGC in Cable: Individual cables with their own EGCs can be installed in the tray, with bonding clamps connecting the EGC to the tray sections for mechanical stability and electrical continuity .
3. Separate EGC: A dedicated insulated conductor can be run along the tray, bonded to each tray section and to equipment enclosures, especially when using aluminum trays to prevent electrolytic corrosion .

Material Considerations

• Steel Trays: Suitable for most grounding applications but should not be used as the sole EGC for circuits with ground-fault protection above 600 amperes .
• Aluminum Trays: Can be used as EGCs for circuits with ground-fault protection up to 2000 amperes, but bare copper conductors should be avoided to prevent corrosion; insulated conductors with tin or zinc-plated connectors are recommended .

Best Practices

• Use bonding clamps at each or alternate tray sections to secure EGCs and maintain mechanical stability under fault conditions .
• Ensure electrical and mechanical continuity across all tray sections, including bends, tees, and drop-outs .
• For telecommunications or low-energy circuits, grounding may focus on lightning protection and EMI mitigation rather than power fault currents, following TIA/EIA 607 standards . Proper grounding of angle iron cable trays enhances safety, system reliability, and EMI control, while ensuring compliance with NEC Article 392 and other applicable standards .