Classification of Fire-Resistant Cable Tray Grades

Fire-resistant cable trays are classified by their ability to maintain circuit integrity and insulation under fire, commonly expressed as EI or E ratings such as EI60, EI90, EI120, or E30, E60, E90.

EI Ratings

EI ratings indicate the duration (in minutes) that a cable tray system can maintain Integrity (E) and Insulation (I) under standardized fire conditions. Common grades include:

• EI60: Maintains circuit integrity and insulation for 60 minutes. Suitable for projects requiring short-term emergency operation or safe shutdown .
• EI90: Maintains performance for 90 minutes, often used in critical systems like emergency lighting, alarms, or fire suppression circuits .
• EI120: Provides 120 minutes of protection, typically for high-risk or high-occupancy areas where extended fire resistance is required . These ratings are determined through fire tests on the complete assembly, including trays, cables, and accessories. The test ensures that cables remain functional and heat transfer is limited to prevent accelerated failure .

DIN 4102-12 and E Ratings

The DIN 4102-12 standard classifies cable trays using E ratings, which focus on circuit integrity:

• E30: Functional for 30 minutes under fire conditions.
• E60: Functional for 60 minutes.
• E90: Functional for 90 minutes, tested at temperatures up to 1000°C . These tests simulate real fire scenarios to ensure that essential systems like alarms, emergency lighting, and sprinklers continue to operate during a fire . Approval is granted only if the tested assembly, including cables and trays, remains operational.

AS/NZS 3013 Standard

In Australia and New Zealand, AS/NZS 3013 provides a similar classification system for cable systems, verifying fire and mechanical resistance. Type tests are conducted to confirm the level of protection for the entire connection system, ensuring compliance with local safety requirements .

Practical Considerations

• Higher EI or E ratings generally require thicker insulation, stricter seam and joint controls, or higher dry film thickness for coatings, which increases cost and installation complexity .
• Selection should match project risk: Over-specification can raise costs unnecessarily, while under-specification may compromise safety .
• “Like-for-like” evidence is critical: Only assemblies tested under the same configuration and with the same cables can be considered compliant for a given rating .

Summary

Fire-resistant cable trays are classified primarily by duration of circuit integrity and insulation under fire, expressed as EI or E ratings. Common grades include EI60/E60, EI90/E90, and EI120, with higher ratings providing longer protection. Compliance with standards like DIN 4102-12 or AS/NZS 3013 ensures that critical systems remain operational during fire events, and proper specification is essential to balance safety, cost, and installation feasibility .