Equipotential bonding of cable tray

Equipotential bonding ensures all conductive parts of a cable tray system are electrically connected to maintain safety and prevent potential differences.

Purpose of Equipotential Bonding

Equipotential bonding in cable tray systems is designed to connect all conductive parts and electrical equipment to a common potential, reducing the risk of electric shock and protecting both personnel and equipment. This is particularly important in hazardous areas (Ex zones), where even small potential differences can create safety hazards . By integrating conductive system parts, motors, sensors, and power units into a bonded network, the system ensures consistent and permanent electrical continuity .

Components and Installation

A typical equipotential bonding system for cable trays includes:

• Equipotential bonding plates and clamps: These attach to the cable tray and provide secure connection points for conductive parts .
• Closed ring equipotential bonding conductors: These form a continuous loop around the system, ensuring all parts are at the same potential .
• Special pipe clamps and bonding bars: Used to integrate additional equipment or structural conductive parts into the bonding network . The system can be mounted on mesh or solid cable trays, and it is designed to remain effective even during structural modifications, preventing accidental isolation of conductive parts .

Regulatory and Safety Considerations

Equipotential bonding aligns with standards such as the National Electrical Code (NEC) and BS 7671, which require that conductive materials enclosing electrical conductors be grounded and bonded to limit voltage to ground and facilitate protective device operation . Key requirements include:

• Permanent and electrically continuous connections.
• Capacity to safely conduct fault currents.
• Low impedance to ensure proper operation of over-current protection devices . In Ex zones, equipotential bonding is critical to prevent sparks or potential differences that could ignite flammable atmospheres .

Benefits

• Enhanced safety: Reduces risk of electric shock and equipment damage.
• System reliability: Maintains consistent electrical potential across all conductive parts.
• Compliance: Meets regulatory requirements for grounding and bonding in industrial and hazardous environments.
• Ease of integration: Allows effortless connection of new equipment or modifications without compromising safety . Equipotential bonding is therefore a fundamental practice in cable tray installations, ensuring both operational safety and regulatory compliance.