Fireproof putty such as Firebreak 55, 3M Fire Barrier Moldable Putty Stix MP+, and Hilti CP 619 T can be used to protect photovoltaic cable trays by maintaining fire resistance and smoke containment.

Key Fireproof Putty Options

1. Firebreak 55 Putty Firebreak 55 is a silicone-based ablative polymer with fire-resistant additives, designed to maintain the fire resistance of walls and penetrations where electrical cabling passes through small openings. Under fire conditions, it forms a dense char that restricts fire and smoke spread. Its non-setting nature allows easy removal or addition of cables while reusing the putty to reinstate the fire seal, making it suitable for PV cable trays that may require future modifications . 2. 3M Fire Barrier Moldable Putty Stix MP+ This intumescent, re-enterable putty provides up to 4 hours of fire protection and forms a seal against smoke and drafts. It is pliable and moldable by hand, adheres well to most construction substrates, and is safe for synthetic cable jackets, making it ideal for bundled photovoltaic cables. It has been tested according to ASTM E 814 (UL 1479) and ASTM E 119 (UL 263), ensuring compliance with fire-rated assembly standards . 3. Hilti CP 619 T Firestop Putty Roll Hilti CP 619 T is a moldable firestop putty suitable for sealing cable penetrations. It is designed for easy installation and re-entry, allowing PV cable trays to be modified without compromising fire protection. Hilti provides product demonstrations and technical support for proper application . 4. CharCoat Fireproofing Solutions CharCoat offers passive fire protection coatings for cables and cable trays, including RTV hydrophobic silicon coatings and firestop systems. These solutions are suitable for critical infrastructure and high-risk environments, providing protection against fire, smoke, and heat while maintaining circuit integrity .

Considerations for Photovoltaic Cable Trays

• Fire Rating: Ensure the putty or coating meets the required fire resistance for the installation, typically 2–4 hours for commercial PV systems.
• Re-entry Capability: Non-setting or re-enterable putties allow future cable additions or replacements without compromising fire safety.
• Compatibility: Verify that the putty is safe for synthetic cable jackets and adheres to the tray material.
• Smoke and Draft Sealing: Effective putty should also prevent smoke migration, which is critical in enclosed PV installations.
• Standards Compliance: Look for products tested to UL 1479, UL 263, or ASTM E 814/E 119 to ensure regulatory compliance. Using these fireproof putties or coatings on photovoltaic cable trays helps maintain fire compartmentation, protect cables from heat damage, and ensure safety compliance in solar installations.