Over the past few decades, there have been several high-profile fire accidents worldwide involving plastics exposed to fire, particularly those used for cables. It’s not just the flames that pose a danger during such incidents but also the toxic fumes they create. One notable case wherein these vapours led to a loss of life was during the 1980 King’s Cross fire in a London underground subway.
This disaster, along with many others like it, highlighted the need for greater fire resistance and non-toxic materials in jacketing materials, which eventually led to the invention of low-smoke zero-halogen (LSZH) cabling. As its name suggests, LSZH produces less dense smoke and virtually zero toxic gasses called halogens compared to other traditional materials like fluorinated ethylene propylene and polyvinyl chloride.
It may seem logical to use these safer cables for every application on paper, but their proper application is not always straightforward. Therefore, it is essential to fully understand LSZH cables, which use cases they are suited for, and how to implement them correctly before sourcing them from a trusted cable supplier in Singapore.
A Deeper Look Into LSZH Cables
The main selling point of LSZH cable insulation and jacketing is their absence of chlorine, fluorine, iodine, bromine, or astatine compounds in their makeup, which ensures they only emit minimal smoke and do not create corrosive or toxic fumes when fire is present. Additionally, it boasts other key benefits, such as flame-retardant properties and non-propagation of fire and flame features, which allow escaping from a fire more easily in the worst-case scenario.
These advantages come at a price, however, but thankfully their relative cost continues to decline over time. Beyond the more premium price tag, LSZH cables also suffer from lower flexibility compared to neoprene and PVC and are thus more susceptible to jacket cracking. To avoid such damage during installation, it is often necessary to cover them with some type of special lubrication, especially if they are to be used in cold environments.
Why LSZH Cables Are Not for Every Application
It is important to note that while cables made using halogenated compounds like FEP and PVC certainly pose a significant hazard during a fire, LSZH cables were not explicitly designed to be the universal solution that can take their place. For starters, FEP and PVC-based cables have unique advantages that are far too important to dismiss, and there are plenty of environments where they are the better choice over LSZH cables, such as open areas where gasses and smoke can dissipate quickly and those with little to no human presence.
Electrical cables are also hardly the only source of plastics that can fuel a fire when it breaks out. And with many modern FEP and PVC-based cables now getting treated with additives to enhance their fire resistance, they contribute far less to fan the flames than they used to. Last but not least, they deliver several tried-and-true benefits that are invaluable for many projects, such as:
- Great electrical performance
- Inexpensive cost
- Good wet and dry electrical characteristics
- High flexibility
- Long service life
- Ruggedness
- Adequate resistance to chemicals and temperature extremes.
In essence, LSZH cables shine in scenarios where the risks that traditional cables pose far outweigh their benefits, hence why they should not be seen as a replacement for the latter in every application.
Where LSZH Make Sense
It is often difficult to determine whether opting for LSZH cabling is the right choice, especially for those whose diligence prompts the need to dive deep into various standards and documents that address the issue. Thankfully, it is often obvious when LSZH cables and the protection they provide are a must. In general, they should be a consideration in confined spaces with lots of cables installed near each other as well as in work environments with poor ventilation, limited evacuation routes, and high voltage presence.
A few good examples of these include the applications where LSZH cables were first used, namely as marine and offshore power cable in submarines and surface ships. These places make escaping from fire either impossible or difficult, and the dense smoke and corrosive, toxic gas emitted by the flames are nothing short of catastrophic. More recent applications of LSZH commonly include theatres, tunnels, commercial aircraft, nightclubs, certain sections of airports, mass transit, data centres, and military and nuclear facilities.
Conclusion
When undertaking projects in public and high-traffic spaces, it is crucial to plan for the ‘worst-case scenario’ by ensuring all parties involved understand the appropriate use of PVC, LSZH, and fire-resistant cables. Making informed decisions relies on knowing the key differences between these cable types and considering project-specific needs. Last but not least, while LSZH cables were once seen as inferior to their traditional counterparts, advancements in manufacturing have significantly improved their performance. Today, LSZH cables offer fire retardant properties without compromising flexibility, durability in cold temperatures, or electrical efficiency, making them a reliable and safe choice for modern projects.
Have a project that could benefit from LSZH cables? Look no further than Cable Source. We are the leading cable supplier in Singapore you can rely on for high-performance cables featuring greater fire protection and performance at cost-effective prices. Explore our extensive instrumentation cable catalogue today and browse our other offerings.
