A jacket decision that has very little to do with electrical performance and everything to do with what happens in a fire.
Quick answer: PVC and LSZH jackets perform identically in normal operation. The difference appears in a fire: PVC produces dense black smoke and hydrogen chloride gas, while LSZH produces far less smoke and no halogen gas. LSZH is specified where people evacuate through enclosed spaces — hospitals, schools, hotels, tunnels, data centres. LSZH is not the same thing as fire resistant.
Jacket material rarely appears in a client conversation until someone reads the specification document and asks why one quotation costs more. The answer is worth understanding properly, because the difference is real, the cost is real, and specifying the wrong one on a project with a fire strategy is a serious problem.
PVC contains chlorine. When it burns it produces dense black smoke and releases hydrogen chloride gas, which forms hydrochloric acid on contact with moisture — including the moisture in eyes, throat and lungs.
LSZH compounds are halogen free, typically based on polyolefins with mineral flame retardant fillers. They produce substantially less smoke and no halogen acid gas.
The distinction matters for a reason that is not obvious. In building fires, smoke inhalation is the dominant cause of death rather than burns. Dense smoke also removes visibility, and people who cannot see the exit do not reach it. A ceiling void filled with hundreds of metres of bundled data cable represents a significant quantity of jacket material directly above the escape route.
Hydrogen chloride released from burning PVC deposits as hydrochloric acid on every surface it reaches, including surfaces well away from the fire that the smoke travelled to.
The consequence is that equipment which survived the fire intact begins failing weeks afterwards as acid attacks circuit boards and connectors. In a data centre or a hospital's equipment rooms, the collateral damage from acid gas can exceed the direct fire damage. This is a substantial part of why LSZH is standard in those environments regardless of what the life safety code strictly requires.
This is the most common and most consequential misunderstanding in the field, so it is worth stating plainly.
LSZH does not mean fire resistant. It describes emissions while burning, not resistance to burning. An LSZH cable will burn.
LSZH does not mean circuit integrity. Cables that must keep working during a fire — fire alarm circuits, emergency lighting, smoke extraction control — need a specific fire resistant rating that guarantees function for a defined period at a defined temperature. That is an entirely separate specification, and an LSZH data cable does not satisfy it.
Confusing these on a project can mean a life safety system that fails in the event it exists for. If a specification calls for fire resistant cable, LSZH is not a substitute.
The governing question is: if this space fills with smoke, how quickly can people get out, and where does the smoke go?
Specify LSZH in: hospitals and nursing homes, where occupants may be immobile; schools and hostels; hotels, where occupants may be asleep and unfamiliar with the layout; airports, metro stations and tunnels, where escape routes are long and enclosed; high rise buildings, where evacuation takes time; data centres and equipment rooms, for the corrosion reason; and any project where the specification, the fire consultant or the local authority requires it.
Standard PVC is normally adequate in: open industrial sheds with rapid egress; small single storey commercial units; outdoor and underground runs, where the relevant jacket properties are UV resistance and water blocking rather than smoke behaviour; and projects where no fire strategy requirement applies.
The decision belongs at design stage. Retrofitting a jacket specification means replacing installed cable, which means the full labour cost again.
LSZH behaves differently on site, and installers used to PVC should know what to expect.
The high mineral filler loading that gives LSZH its fire behaviour also makes the jacket stiffer and somewhat more abrasion sensitive. It is less forgiving of tight bends and rough pulls through congested containment. Some LSZH compounds also absorb moisture more readily than PVC, so long term storage in humid conditions needs more care.
None of this makes LSZH difficult to install. It does mean respecting bend radius and pulling tension more carefully than a crew accustomed to PVC might be in the habit of doing — which, as it happens, is good practice with any Cat6 cable.
LSZH costs more than PVC. The compound itself is more expensive, and it is harder to extrude to a consistent quality, which raises the manufacturing cost further.
In project terms, though, the increment is modest. Cable is a small share of a structured cabling budget, and the jacket is a fraction of the cable cost. Against the total project, moving from PVC to LSZH is usually a small single-digit percentage.
When comparing quotations, make sure you are comparing the same jacket. An LSZH quotation and a PVC quotation are not competing offers for the same product, and the cheaper one is cheaper because it is a different specification. This is one of several reasons why Cat6 quotations vary so widely in India.
LSZH stands for Low Smoke Zero Halogen. It describes a cable jacket compound that produces significantly less smoke than PVC when burning and contains no halogens, so it does not release hydrogen chloride gas in a fire. The related term LSOH means the same thing.
No, and this is a common misunderstanding. LSZH describes what the jacket emits while burning, not whether it resists burning or keeps working during a fire. Fire resistance and circuit integrity are separate properties requiring separate ratings. LSZH is about protecting people evacuating, not about the cable surviving.
LSZH is typically specified in enclosed spaces where people evacuate slowly or where escape routes are limited: hospitals, schools, hotels, airports, metro stations, tunnels, high rise buildings and data centres. In open industrial sheds or where the project specification does not call for it, standard PVC is normally adequate.
Nakoda manufactures wires and cables in India across electrical, network, CCTV and telephone ranges. Our Cat6 UTP LAN cable specification, including jacket options, is on the product page.
If your project has a fire strategy requirement, tell us what the specification calls for and we will confirm what we can supply. Send a project enquiry to start the conversation.
