Firestop Guide

How to Firestop a Cable Tray

A cable tray is one of the harder penetrations to firestop: lots of cables, a large opening, and — the real catch — it keeps changing as circuits are added and removed. The trick is a system that seals fully but can be opened and resealed without demolition.

The re-enterable problem

IT, security and electrical trades pull new cables through a tray for the life of a building. If you firestop it with a solid plug of sealant, every cable change means cutting it out and rebuilding the system — and inspectors know it usually doesn't happen. So for trays, the goal is a re-enterable system.

Firestop pillows: the standard for trays

Firestop pillows are the go-to: UL Classified bags that stack in and around the tray and between cable bundles to seal the opening — then pull out and re-stack whenever cables change. No caulk to cut, no system to rebuild. See firestop pillows & large-opening systems.

Sealant and cable coating

For smaller trays or the annular space around a sleeve, an intumescent firestop sealant may be listed. And to stop a fire from running along the cables themselves, C70 cable coating forms an intumescent jacket over grouped cables — standard in industrial plants, utilities and data centers. See C70 cable coating & accessories.

Frequently asked questions

What is the best way to firestop a cable tray?

Through a rated wall, firestop pillows are the standard — UL Classified, stacked around and between the cables, and fully re-enterable when circuits are added or removed. For permanent floor penetrations, mortar or composite-sheet systems apply. We match the UL system to your tray size and cable fill.

Pillows or sealant for a cable tray?

Pillows are preferred for trays because they are re-enterable — you can pull and re-stack them as cables change. Sealant is used for smaller trays or annular spaces where a listed system allows it, but it is not re-enterable once cured.

What does cable tray fire coating do?

C70 cable coating forms an intumescent, fire-retardant jacket over grouped cables so a cable fire cannot propagate along the tray. It is spray- or brush-applied and water-based — separate from firestopping the wall penetration itself, and often used together with it.

Need it matched and priced?

Send your penetration schedule and we'll pull the UL system and quote it — distributor pricing, same-day shipping, free submittal support.

Browse catalog & pricing →Email sales@firestop-usa.com