3 Fiber Optic Cable Fire Rating – OFNP, OFNR And OFN

November 16, 2021

The fire rating of fiber optic cable can be specificed into 3 types, which are OFNP, OFNR and OFN. Before we can talk about the flame retardant grade, we can first understand what is LSZH (Low Smoke Zero Halogen).

What Is LSZH

As early as the mid-1980s, halogen-containing (especially brominated) flame retardant polymer systems were widely used in the cable industry due to their outstanding flame retardant effects.

Among them, polyvinyl chloride (PVC) is a good example, but PVC has a disadvantage that it releases a large amount of smoke when burned, and it produces severe corrosive and toxic gases. Therefore, fiber cables within buildings now mainly use low-smoke and halogen-free materials.

LSZH (low smoke and halogen free) material has some obvious advantages that are low smoke, low toxicity, low corrosion, and high flame retardancy.

Fiber Optic Cable Fire Rating

According to the UL standard, the types of optical fiber cable are specified into the following 4 categories.


OFNP (Optical FIber Non-conductive Plenum) is the highest flame retardant grade of fiber optic cable. When a fan is used on the fiber optic cable to force the flame to blow, the fiber cable will extinguish itself within 5 meters of the flame spread. At the same time, the cable will not emit toxic smoke or steam.

OFCP (Optical Fiber Conductive Plenium) is a conductive plenum grade fiber cable. Conductive fiber optic cable means it has a metal part inside the fiber cable, such as steel wire, steel or aluminum tape for armoring protection. And non-conductive fiber cable has no metal materials or conductivity.

Plenum grade is usually installed in a ventilation duct, pipes, plenums or the air return booster system used by air handling equipment in communication network applications.


OFNR (Optical Fiber Non-conductive Riser) is the second-ranked flame retardant fiber optic cable. Under the condition that the fan is forced to blow, the fiber optic cable must be extinguished by itself within 5 meters of flame spread. OFNR-grade optical cables are allowed to be used in vertical backbones


OFN or OFNG stands for optical fiber non-conductive cables for general purpose. It can be used in general cabling environments. And the OFC or OFCG is optical fiber conductive for general purpose. Which is the same as OFN or OFNG, only the fiber optic cable has conductive metal materials.


Communication cables such as optical cables are an important part of modern intelligent buildings,the choice of optical communication cable has become an element that cannot be ignored.

In addition to considering performance when choosing fiber optic cables, fire protection and environmental protection should also be considered to improve the safety index of the commercial or residential building.

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Tony Lau is technical manager and co-founder at HOC. He loves writing about content optical fiber communications, specializes in fiber optic cables, FTTH turnkey solutions, ADSS cable, and ODN networks.

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