Jacket Materials — PVC, LSZH, OFNR, OFNP

The fiber is the same. The outer jacket changes based on where you’re allowed to run the cable and what happens if there’s a fire.

PVC (Polyvinyl Chloride)

Standard riser-rated jacket for indoor use. Cheap, flexible, easy to strip. When it burns it releases hydrochloric acid and dense black smoke — so building codes restrict where you can run it.

Use PVC for: general in-cabinet patching where fire codes allow, non-plenum indoor spaces, lab bench setups.

LSZH (Low Smoke Zero Halogen)

Emits significantly less smoke than PVC and no halogen-based acids when it burns. The default choice for occupied indoor spaces, especially in the EU where halogen restrictions are enforced tightly.

Use LSZH for: offices, classrooms, hospitals, trains, tunnels, telecom rooms, anywhere people will be evacuating past the cable in a fire.

OFNR — Optical Fiber, Nonconductive, Riser

UL-rated for vertical runs between floors of a building (risers). More fire-resistant than general-purpose PVC. Required by NFPA 70 (National Electrical Code) for anything going up a riser shaft.

Use OFNR for: vertical building runs, floor-to-floor riser cable trays in North America.

OFNP — Optical Fiber, Nonconductive, Plenum

The highest fire rating. Required for cables installed in plenum air-handling spaces — the space above drop ceilings and below raised floors where the HVAC system pulls air through. Fluoropolymer jacket, low flame spread, minimal smoke.

Use OFNP for: anything running through a plenum air return, and anywhere else your local code requires plenum-rated cable.

Quick reference

Where you’re running it	Jacket to specify
Inside a rack, temporary	PVC
Occupied space, code-sensitive	LSZH
Vertical between floors (US)	OFNR
Plenum air-return space (US)	OFNP
Outdoor / direct-bury	Armored + gel-filled (specialty)

When in doubt, spec up, not down. OFNP is legal everywhere OFNR is; OFNR is legal everywhere PVC is; LSZH is generally accepted in EU-code jurisdictions. Overspec costs a few percent; underspec means you tear it out and reinstall.