UL 1685: Cable Smoke Release Fire Testing Services
Accredited UL 1685 cable smoke release fire testing from Infinita Lab, performed to the exact standard requirements - accurate, reproducible results with full documentation for compliance, R&D, and quality control programs.
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- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
What Is UL 1685 Cable Smoke Release Fire?
UL 1685, Vertical-Tray Fire-Propagation and Smoke-Release Test for Electrical and Optical-Fiber Cables, is the standard fire-performance test used to evaluate how electrical power, control, communication, and optical-fibre cables behave when exposed to open flame in a vertical cable tray. The test was developed to answer a practical, life-safety question: if a fire starts near a bundle of cables running through a tray, riser, or open vertical shaft, how far will the flame travel up the cable run, and how much smoke will it release into the surrounding space?
At a high level, the method mounts cable specimens vertically on a steel ladder-type tray inside an enclosed test chamber and exposes the lower section of the bundle to a controlled propane-fed burner flame for a fixed exposure period. During and after exposure, technicians measure how far up the tray the char damage extends and use a photometric smoke-measurement system to record the total and peak smoke released by the burning cable jacket and insulation materials. Cables that keep flame damage below a defined height and stay under specified smoke-release limits qualify for a “limited smoke” designation.
This testing matters because cables are frequently routed in bundles through trays, plenums, risers, and open shafts where a localised ignition source could otherwise propagate fire and generate dense smoke that impairs evacuation and firefighting. UL 1685 gives manufacturers, specifiers, code officials, and building owners a standardised, repeatable way to compare cable products, support product listings, and satisfy fire-code and life-safety requirements tied to cable installations in commercial, industrial, data centre, and telecommunications environments.
Applications and Benefits of UL 1685 Cable Smoke Release Fire Testing
Scope
- UL 1685 measures vertical flame propagation and smoke release from electrical and optical-fibre cables burned in a simulated cable-tray fire scenario.
- The test configuration mounts cable specimens vertically on a steel ladder-type cable tray inside an enclosed fire-test chamber.
- A calibrated burner applies a direct flame to the lower portion of the mounted cable specimens for a specified, fixed exposure duration.
- Pass/fail evaluation is based on the maximum vertical char or damage height reached on the cable bundle and on the total and peak smoke release measured by a photometric smoke-detection system.
- The method applies to electrical power, control, and instrumentation cables as well as optical-fibre and communication cables intended for tray, riser, plenum, or open vertical-shaft installations.
- UL 1685 results support product listings, code compliance submissions, and specification decisions for cable products marketed with a “limited smoke” or low flame-propagation designation.
- The standard is closely related to other vertical-tray flame-test methods, including IEEE 1202 and CSA FT4, which use similar vertical-tray mounting principles but apply their own burner geometry, exposure conditions, and acceptance criteria.
- Testing is widely used to support installations in data centres, commercial high-rise buildings, industrial facilities, and telecommunications infrastructure where cables run through common pathways shared by multiple building systems.
- The scope of UL 1685 is limited to flame propagation and smoke-release performance; it does not evaluate combustion product toxicity, electrical performance, or general cable construction requirements.
- Results are used by cable manufacturers, engineering firms, and facility owners to document that a cable product meets recognised fire-performance benchmarks before installation in fire-sensitive building pathways.
Applications
- Data centre cable tray and raised-floor infrastructure where dense cable bundling increases fire and smoke exposure risk.
- Commercial high-rise buildings routing power and communication cables through vertical shafts and riser systems.
- Industrial facilities using open cable tray networks to distribute power, control, and instrumentation cabling.
- Telecommunications and network infrastructure providers qualifying fibre-optic and copper cable products for tray installation.
- Cable manufacturers seeking UL listing or a “limited smoke” designation to support product marketing and code compliance.
- Building owners and fire-protection engineers evaluating cable products as part of a broader life-safety and fire-code compliance strategy.
- Specification engineers comparing competing cable products on flame-propagation and smoke-release performance before project approval.
Benefits
- Provides a standardised, repeatable benchmark for comparing flame propagation and smoke output across different cable products.
- Supports UL listing and “limited smoke” marking claims used in product documentation and marketing.
- Helps demonstrate compliance with fire-code and life-safety requirements for cables installed in trays, risers, and vertical shafts.
- Gives specifiers and building owners objective data for selecting cable products suited to fire-sensitive environments.
- Identifies flame-propagation and smoke-release characteristics early in product development, reducing the risk of costly redesigns later.
- Builds a defensible, third-party test record that can support regulatory review, customer audits, and engineering decisions.
Our UL 1685 Testing Procedure
Sample Preparation
Cable specimens are installed vertically on a tray in the required arrangement for testing.
1Flame Application
A standardized ignition source is applied to the cable tray assembly for the specified duration.
2Smoke and Flame Observation
Flame spread, smoke release, and cable damage height are monitored during the exposure period.
3Data Recording & Evaluation
The measured fire and smoke performance values are recorded and evaluated according to the acceptance criteria.
4UL 1685 Test Parameters and Requirements
| Parameter | Details |
|---|---|
| Applicable Materials | Electrical and optical fiber cables |
| Test Orientation | Vertical tray configuration |
| Fire Exposure | Standardized flame source |
| Evaluation Criteria | Flame spread, smoke release, and cable damage height |
| Smoke Metrics | Peak smoke release and total smoke generation |
| Measured Outputs | Flame propagation and smoke-release performance |
- Vertical steel ladder-type cable tray – Holds mounted cable specimens in the standardized vertical test configuration inside the burn chamber.
- Propane-fed ribbon burner – Delivers a controlled, direct flame to the lower section of the cable bundle for the specified exposure period.
- Photometric smoke-density measurement system – Continuously measures light obscuration to determine optical density and calculate peak and total smoke release.
- Enclosed fire-test chamber – Contains the flame exposure and smoke generation in a controlled environment for consistent, repeatable testing.
- Char/damage height measurement tools – Used to determine the maximum vertical extent of flame damage on the cable specimen after exposure.
- Timer and data-acquisition system – Records exposure duration, smoke-density readings, and other test parameters throughout the run.
- Specimen mounting and cable-fill fixtures – Secure cable specimens to the tray in the arrangement required by the test method.
Equipment and Instrumentation Used for UL 1685 Testing
What You Receive: Test Report, Data, and Certification
- Detailed test report documenting specimen identification, cable construction, and mounting configuration on the tray.
- Recorded flame-exposure conditions, including burner setup and exposure duration.
- Measured vertical char/damage height results compared against the standard’s acceptance criteria.
- Smoke-release data, including peak optical density and total smoke-release values.
- Clear pass/fail determination supporting UL listing, “limited smoke” marking, and code-compliance documentation.
- A defensible, third-party report suitable for regulatory submissions, customer audits, and internal engineering review.
UL 1685 Cable Smoke Release Fire FAQs
UL 1685 assesses how flames spread and how much smoke electrical and optical fiber cables release. It helps determine if cable designs limit smoke production and fire spread during standard vertical tray fire tests.
Smoke-release testing helps find cables that lower visibility risks and toxic exposure during fires. UL 1685 helps select safer cables for buildings, tunnels, and industrial sites where getting people out quickly is essential.
UL 1685 is often used for electrical power cables, control cables, communication cables, and optical fiber cables that are placed in trays. This standard evaluates how well these cables perform in terms of flame spread and smoke generation.
UL 1685 testing places vertically mounted cable trays in front of a controlled flame source. It monitors how the flames spread and how much smoke is released. This setup helps evaluate how well cables perform in a fire under consistent lab conditions.
UL 1685 tests how cables spread flames and release smoke in a controlled lab setting. It may not fully reflect the complicated conditions of real fires, which can vary due to ventilation, installation differences, or the presence of various combustible materials.
Why Choose Infinita Lab for Art Material Labeling Testing
When your Cable Smoke Release Fire results have to hold up - for compliance, a customer audit, or an engineering decision - UL 1685 accuracy and an unbiased third-party report matter more than price. Infinita Lab routes your UL 1685 cable smoke release fire testing to ISO/IEC 17025-accredited U.S. partner labs with hands-on method experience, so you get defensible data, transparent reporting, and turnaround times built around your project deadline - not ours.
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