The high stakes surrounding rail and mass transit systems have made halogen-free cables a critical component to safeguard passengers, infrastructure and operations in the event of a fire. Low smoke zero halogen (LSZH) cables are engineered to emit less toxic gas and dense smoking, therefore offering protection to the specific hazards of enclosed tunnels, stations and train carriages where evacuation is a high priority.
With more than 15 years’ experience in producing halogen-free cables for challenging industrial and transit environments, at Hulk Electric, we know how to select the right cable for fire protection, while complying with regulations and keeping systems reliable. This guide discusses the importance of these cables and how to properly select them for rail applications.
Why Fire Behaviour of Cables Matters More in Rail and Mass Transit
In the confined areas found in subway tunnels, rail carriages, or underground stations, smoke and toxic gases can quickly spread, making it difficult to evacuate and rescue. When exposed to fire, traditional PVC-sheathed wires can produce voluminous black smoke, corrosive halogen acids, block escape routes, disrupt sensitive electronic equipment and threaten lives.
Halogen-free / LSZH cables are specifically engineered to counter these risks by:
- Generating a very low smoke density that maintains visibility for occupants and fire response team.
- Removing the halogen elements to avoid the release of corrosive halogen acid gases.
- Providing flame-retarding, self-extinguishing properties that help to slow the spread of flames along cable pathways.
This blend makes halogen-free cables a critical piece of the puzzle in contemporary rail fire safety solutions.
Where Halogen-Free Cables Are Used in Rail and Mass Transit
Subway and Light Rail Tunnels
LSZH cables are frequently required in subway and light rail tunnels because of the critical requirement for low smoke in an emergency. They can be installed alongside power feeders, emergency lighting, signaling systems, communications and ventilating control devices on the side of the tunnel and on cable trays, so they can be used even in the most challenging environments.
Train, Metro and Tram Carriages
Halogen-free cables provide power to control systems, door mechanisms, HVAC, passenger information systems and CCTV in railway cars and metro cars as well as trams inside the cars. Passengers are in close proximity and there is a lack of escape routes; low-smoke & halogen-free properties greatly minimize inhalation risk and keep evacuation routes clear.
Stations, Platforms and Ancillary Rail Infrastructure
LSZH cables are used for lighting, public address systems, alarms and ventilation systems in stations, platforms, escalators, lifts and control rooms. They also help to handle underground networks for communications and power in modern urban rail systems, including for 5G integration.
Regulations and Standards Driving Halogen-Free Cable Use in Rail
Rapid Transit Fire Codes and National Requirements
In many countries, rapid transit codes require low smoke, no halogen cables for underground systems, sometimes complemented by fire resistant cables for critical ones. These are an important component of subway safety codes around the world.
NFPA 130 and EN 45545-2
NFPA 130 is focused on fire prevention and smoke control in all fixed guideway transit and passenger rail systems, including the stations, vehicles and ventilation. In the railway industry, the fire safety requirements for railway rolling stock are set in a very detailed manner by EN 45545-2, which focuses on materials that help to slow down the spread of fire and limit the generation of toxic fumes.
Halogen-free cable families comply with internationally recognized tests like IEC 60754 (halogen content) and IEC 61034 (smoke density) to help projects meet international standards.
How Halogen-Free Cables Improve Passenger Protection
Smoke Control and Evacuation Visibility
LSZH solutions significantly lower the smoke density in the system as opposed to conventional cables, allowing for improved visibility of exits, signage and escape routes, which is essential in smoke-filled tunnels and carriages to evacuate the space safely and quickly.
Reduced Toxic and Corrosive Gas Exposure
These cables do not produce the hydrogen chloride and other harmful acids that they would without the halogens, reducing the risk to passengers and staff in an incident and to their eyes and respiratory systems.
Fire Safety and Reliability of Rail Infrastructure
Protecting Signaling, Power and Communication Systems
All rail systems require continuous signaling, traction power and communications. Halogen-free cables help prevent corrosive damage of metals and electronics allowing for faster recovery and cost savings from fire events.
Integrated Fire-Safety Strategy with Halogen-Free and Fire-Resistant Cables
The general trend of best practice is to use general purpose low-smoke cable along with fire rated cable (which are sometimes also low-smoke and are often manufactured with a sheath that does not contain any halogens). This will reduce the spread of flames, spread smoke control, and provide adequate operating time for alarms, lighting and ventilation for evacuation and fire fighting.
Practical Notes for Engineers Specifying Cables in Rail Projects
On rail projects prioritize the use of halogen-free / LSZH cable wherever practicable, for:
- The tunnels and stations are underground.The tunnels and stations are below ground.
- Carriages for training and metro.
- Control rooms, ticket halls and equipment rooms
Ensure conformance to relevant standards, IEC 60754, IEC 61034, EN 45545-2, NFPA 130) and make sure the requirements are clearly outlined in specifications to avoid substitution with lower performing alternatives. A knowledgeable manufacturer can help determine the best solutions that will meet fire performance, mechanical flexibility, and durability requirements.
We at Hulk Electric (Dongguan) Co., Ltd. specialize in the production of high quality halogen-free cables designed to meet the needs of the rail and mass transit, which are backed by full certificates such as UL, CE and RoHS. We pride ourselves in our custom solutions that perform reliably under the toughest conditions and meet your project schedule.
Tell us about your rail application requirements and we’ll help you choose or engineer the most suitable rail application cable to ensure optimal safety and compliance.
