What is LSZH Cable? Low Smoke Zero Halogen Explained
Short answer: LSZH (Low Smoke Zero Halogen) cable uses a special jacket compound that produces minimal smoke and zero toxic halogen gases when burned. In Australia, LSZH is the practical standard for any commercial or public building install where fire safety regulations apply, including hospitals, schools, airports, data centres and government facilities.
Low Smoke Zero Halogen (LSZH) refers to cable jacketing materials that emit minimal smoke and no toxic halogen gases (like chlorine or fluorine) when exposed to high heat. This makes them a critically important component for safety in many installations.
Why LSZH Matters: The Fire Safety Problem with PVC
Standard PVC cable is cheap and flexible, but it has a major problem in a fire. When PVC burns, it releases:
- Dense black smoke that reduces visibility and hinders evacuation
- Hydrogen chloride gas (HCl) which is toxic and corrosive
- Other halogen compounds that damage lungs and electronics
In a building fire, this isn't just a theoretical risk. The London King's Cross fire in 1987, which killed 31 people, was made significantly worse by the toxic smoke from PVC cable burning in the underground tunnels. That tragedy is what drove the development and adoption of LSZH cable globally.
Key Safety Features of LSZH Cable
- Low Smoke Emission: LSZH cables produce significantly less smoke than standard PVC, improving visibility for safe evacuation during a fire.
- Zero Halogen Toxicity: They do not release harmful halogen gases (chlorine, fluorine, bromine), reducing the risk of injury from inhaling toxic fumes.
- Non-Corrosive: The lack of acidic gases during combustion protects sensitive electronic equipment from damage. After a fire, areas with LSZH cabling typically see less long-term corrosion damage to nearby equipment than areas with PVC.
- Flame Retardant: LSZH is self-extinguishing and slows fire spread, giving more time for evacuation and fire response.
When is LSZH Cable Required in Australia?
Australia doesn't have a single blanket law mandating LSZH, but the National Construction Code (NCC) imposes fire safety requirements on commercial and public buildings that effectively make LSZH the default choice. Key Australian standards include:
- AS/NZS 3000 (Wiring Rules) covers electrical installation safety and references the need for appropriate cable selection in fire-rated spaces.
- AS/NZS 1660 covers cable test methods including smoke and gas emission for fire performance.
- AS/NZS IEC 60332 specifies flame propagation tests for cables.
- AS/CA S009 covers installation requirements for telecommunications cabling.
In practical terms, LSZH is the right specification for:
- Hospitals, aged care, medical centres
- Schools, universities, childcare facilities
- Airports, train stations, tunnels
- Government buildings, courts, libraries
- Data centres, server rooms, comms rooms
- Multi-storey commercial buildings
- Apartment buildings and high-density residential
- Any enclosed space with limited ventilation
For standard single-storey homes and small offices, PVC is usually acceptable, but most installers now default to LSZH for everything because the cost difference is minimal and the safety upgrade is significant.
LSZH vs PVC vs Plenum: The Comparison
| Property | PVC | LSZH | Plenum (CMP) |
|---|---|---|---|
| Smoke Emission | High, dense black | Low, light | Very low |
| Toxic Halogen Gas | Yes (HCl, dioxins) | None | Minimal |
| Flame Spread | Moderate | Slow, self-extinguishing | Very slow |
| Australian Standard | Basic compliance | AS/NZS 1660, IEC 60332 | US NFPA 70 (rare here) |
| Flexibility | High | Moderate | Lower |
| Cost Premium | Baseline | +15-25% | +50-80% |
| Common in Australia | Residential only | Standard for commercial | Rare, US imports only |
For more detail on jacket types, see our guide to Ethernet cable jacket types.
Common Applications for LSZH
- Poorly Ventilated Areas: Ideal for confined spaces such as aircraft, rail carriages, ships, and submarines where smoke evacuation is difficult.
- Public Infrastructure: Widely used in tunnels, train stations, and other public transport systems where evacuation routes need clear visibility.
- High-Risk Facilities: Essential in data centres, hospitals, and nuclear facilities to protect both people and expensive equipment from toxic gases and corrosion.
- Multi-Storey Buildings: Apartment blocks, office towers, and mixed-use developments where fire could spread between floors via cable trays and risers.
- Education Facilities: Schools, universities, and childcare centres where vulnerable populations need maximum evacuation time.
How to Identify LSZH Cable
Compliant LSZH cable will have several identifying features:
- "LSZH" or "LSOH" printed on the jacket along with the cable category (Cat6, Cat6A, etc.)
- Reference to AS/NZS 1660 or IEC 60332 test compliance
- The RCM mark indicating Australian regulatory compliance
- Jacket feel: LSZH typically feels slightly stiffer than PVC due to the different polymer base, though modern LSZH is much more flexible than older formulations
If a cable doesn't have these markings, treat it with suspicion. Always source from a reputable supplier who can verify compliance, especially given that CCA (Copper Clad Aluminium) cable is illegal in Australia and often comes with misleading jacket claims.
Frequently Asked Questions
What does LSZH stand for?
LSZH stands for Low Smoke Zero Halogen. It refers to cable jacketing that produces minimal smoke and no toxic halogen gases (chlorine, fluorine, bromine) when burned. You'll also see it written as LSOH (Low Smoke Zero Halogen), or LS0H, all the same thing.
What's the difference between LSZH and PVC cable?
PVC produces dense black smoke and toxic halogen gases when burned. LSZH produces light smoke and no halogens. PVC is cheaper but unsafe in confined spaces and prohibited by fire codes in most commercial buildings. See our jacket types guide for more comparisons.
Is LSZH cable mandatory in Australia?
Not by a single blanket law, but the National Construction Code (NCC) requires appropriate fire-safe cabling in most commercial and public buildings, which effectively makes LSZH the practical standard. Check your specific building's BCA classification to confirm requirements.
Is LSZH the same as plenum cable?
No. Both prioritise fire safety but differently. LSZH focuses on reducing smoke and toxic gas output (people-safe). Plenum (CMP) focuses on minimising flame spread in air-handling spaces (US standard, rare in Australia). LSZH is the Australian equivalent.
Is LSZH more expensive than PVC?
Yes, LSZH typically costs 15-25% more than PVC. However, it's still significantly cheaper than plenum-rated cable and is the cost-effective choice for meeting Australian fire safety requirements.
Can I use LSZH cable outdoors?
Standard LSZH isn't UV-resistant and will degrade in direct sunlight. For outdoor installs, use UV-rated outdoor cable or gel-filled cable for buried runs. See our jacket types guide for outdoor options.
Does LSZH cable perform differently to PVC for data?
No. Jacket material doesn't affect data performance. Both PVC and LSZH Cat6 cables, for example, deliver identical network speeds. LSZH only changes what happens to the cable in a fire, not how it carries signals.
Can I mix LSZH and PVC cable in the same install?
Technically yes, but it defeats the purpose. In a fire, the weakest link determines the outcome. One PVC cable in an otherwise LSZH install will still release toxic smoke. For fire-rated installations, all cable in the protected area should be LSZH.
Shop LSZH Cables
Access Communications offers a comprehensive range of LSZH cables suitable for high-spec networking. Explore our Cat6a LSZH Bulk Cable or our pre-terminated Cat6a LSZH Patch Leads. All our LSZH cable uses 100% solid copper conductors and is backed by our limited lifetime warranty.
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