In an enclosed marine space, the danger in a cable fire is rarely the flame. It is the smoke that removes visibility from an evacuation route and the acid gas that corrodes the electronics the vessel depends on. The sheath compound decides which of those two outcomes you get.
What happens when PVC burns
PVC and other halogenated sheaths release hydrogen chloride when they burn. HCl is corrosive to electronic equipment and toxic when inhaled, and it combines with moisture to form hydrochloric acid, which attacks metalwork well beyond the seat of the fire. The smoke from a halogenated sheath is dense and dark, which is precisely the condition that makes an evacuation slow.
What LSZH compounds do differently
LSZH — low smoke zero halogen — compounds are formulated to meet two measurable limits. Halogen gas emission is tested to IEC 60754-1 (quantity of halogen acid gas) and IEC 60754-2 (conductivity and pH of the gas solution). Smoke density is tested to IEC 61034-2, which measures light transmittance through a defined smoke chamber.
The result is not a cable that resists fire better than PVC. It is a cable whose combustion products are less dangerous in a confined space. That distinction matters, because LSZH is often sold as if it were a fire barrier. It is a smoke and gas specification, and it is normally specified alongside IEC 60332 flame propagation rather than instead of it.
Where LSZH is required
- Passenger ships and cruise vessels — SOLAS fire-safety requirements for accommodation and public areas
- Offshore living quarters — operator specifications for manned platforms
- Naval and government vessels — frequently specified as the default
- Tunnels and enclosed infrastructure — land-based standards that also inform marine practice
Where standard sheaths remain appropriate
For open deck, machinery spaces with a fixed fire-fighting system and other areas where SOLAS does not mandate LSZH, SHF1 and SHF2 sheathed cables remain compliant and are usually the more economical choice. SHF compounds are halogen-reduced rather than halogen-free, and they perform well where the risk is flame spread along a cable tray rather than smoke in a manned space.
The correct approach is to match the sheath to the zone requirement in the vessel’s fire-safety concept, not to apply one compound across the whole ship.
A practical selection checklist
- Which zones in the fire-safety plan are designated as accommodation or public space?
- Does the owner or operator specification add LSZH to machinery spaces?
- Is a smoke-density limit stated numerically, or only by reference to IEC 61034?
- Is a toxicity requirement added on top of the halogen limit?
- Does the LSZH route share a tray with halogenated cable, which would defeat the purpose?
Cost and processing
LSZH compounds cost more than PVC or standard SHF and process more slowly, so the cable is more expensive per metre. On a passenger vessel the LSZH specification is normally confined to the zones where it is required, which keeps the cost impact proportionate to the risk it addresses.
Our LSZH flame retardant marine cable is built to IEC 60092-353 with IEC 60754 and IEC 61034 performance, and the marine power cable range includes the SHF1 and SHF2 alternatives for the zones that do not need halogen-free construction. If you are unsure which zones apply, send the fire-safety plan and the cable schedule and we will map each route to a sheath.
The sheath decision does not change the electrical construction. The LSZH flame retardant marine cable is the halogen-free variant of the standard 0.6/1kV EPR insulated marine power cable, and the same sheath option is available on the shielded marine control cable for signal circuits in the same space.