Cable tray resistance plate

A cable tray resistance plate is used to ensure electrical continuity and grounding across cable tray sections, maintaining a resistance of less than 0.1 ohms as per IEC 61537 standards.

Function and Purpose

A resistance plate (also called a bonding or continuity plate) is installed at joints or connections between cable tray sections to maintain electrical continuity. This is critical when the cable tray serves as part of the earthing or bonding system, allowing fault currents to safely pass without overheating or causing electrical hazards . It ensures that all tray sections are electrically connected, even if the trays are coated, painted, or made of different materials.

Standards and Requirements

According to IEC 61537, cable trays used for grounding must meet specific resistance limits. The resistance across joints, including those with resistance plates, should be less than 0.1 ohms . This ensures that in the event of a fault, the tray can safely carry the current. Accessories such as earthing clamps, jumpers, and bonding plates must also comply with the same standard. Post-installation, continuity tests are recommended, especially if trays are coated or painted, to verify proper electrical contact .

Material Considerations

Resistance plates are typically made from conductive metals compatible with the tray material, such as galvanized steel, stainless steel, or aluminum . The choice of material depends on environmental conditions, including corrosion risk, temperature, and chemical exposure. For example, stainless steel plates are preferred in marine or corrosive environments due to their superior corrosion resistance .

Installation Tips

• Place the resistance plate at every joint or splice where electrical continuity is required.
• Ensure tight mechanical connections using bolts or clamps to minimize contact resistance.
• Verify continuity with a multimeter or specialized resistance tester after installation.
• Consider coating or plating compatibility to prevent galvanic corrosion and maintain long-term conductivity .

Summary

A cable tray resistance plate is essential for maintaining safe and reliable grounding in cable tray systems. It ensures low-resistance electrical continuity across joints, complies with IEC 61537 standards, and protects both personnel and equipment from electrical faults. Proper material selection, installation, and testing are key to its effectiveness .