What is the difference between LSZH and OFNR?

With the many types of fiber cables and the components that make up each one, it can be confusing to know which fiber cable is the best for your business. One of the biggest questions we at BigCatCables.com get asked is what is the difference between OFNR fiber cables and LSZH fiber cables. While they seem similar, they're two very different and very important attributes of fiber cables, and the same fiber cable can be both. To understand these attributes better, we have to understand the construction of fiber cables and the different rating levels associated with fiber optic cabling.

Optical Fiber Construction

There are several parts that make up the fiber cable.

  • The cladding, coating, strength member and the outer jacket.
  • The outer jacket is the first layer of protection and adds strength to the fiber to withstand different conditions such as fire, moisture, chemical, and stress during installations and operations.

Fiber Cable Outer Jacket Material Types

There are a variety of materials used for  fiber cable outer jackets These materials have different characteristics, the list below shows the most popular types of outer jacket materials and its uses.


Characteristics and Uses

PVC (Polyvinylchloride)

Most commonly used material for outer jacket. It is low cost, strong, flexible, fire resistant and can be used in many applications.

PE (Polyethylene)

Very good electrical properties while maintaining high insulation. PE cables may be firm and solid but are more flexible.

PVDF (Polyvinyl Difluoride)

Has more flame-resistant properties than the PE cable and primarily used for plenum areas.

PUR (Polyurethane)

PUR is very flexible and scratch resistant that is mainly used in low-temperature environments.

LSZH (Low Smoke Zero Halogen)

LSZH is less toxic than PVC. It has a flame-retardant outer cover that doesn’t produce halogen when heated. Mainly used in confined installations.

The National Electrical Code (NEC) has a classification system for fiber cables. These requirements specify how the fiber cables will behave in case of fire conditions.

What is the Plenum Area?

A plenum area is a space used to move air to workspaces for the purpose of ventilation or to form air flow for an air distribution system.

What is the Riser Area?

Examples of riser areas are floor openings, tubes, or channels that run upwards over one or more floors. Riser cable is planned for use in upright shafts that run between floors.

What is the General-Purpose Area?

A general-purpose area is all other areas that are not plenum or riser on the same space or floor.

Fire Rating Levels

There are four levels of fire resistance for fiber cables and each level has two divisions which are the conductive and non-conductive cables. The higher rating cable is backward compatible to the lower rating cable and can be substituted while the lower rating cables can’t be used in place for the higher ratings.

  • OFNP and OFCP Fiber Cable Optical Fiber Nonconductive Plenum Cable and Optical Fiber Conductive Plenum Cable. OFNP and OFCP cables as the name implies are used for plenum areas and have resistance to fire and smoke.
  • OFNR and OFCR Fiber Cable Optical Fiber Nonconductive Riser Cables and Optical Fiber Conductive Riser Cables are used for the riser areas. These cables must prevent the fire from one floor to another.
  • OFNG and OFCG Fiber Cable Optical Fiber Nonconductive General-Purpose Cable and Optical Fiber Conductive General-Purpose Cable. These cables must not spread the fire for more than 4 feet, 11 inches.
  • OFN and OFC Fiber Cable Optical Fiber Nonconductive and Optical Fiber Conductive. To get this cable rating, the flame shall not infiltrate floors or ceilings and the cables are also used for general purpose areas.

Comparison between the OFNR and LSZH Cables

OFNR and LSZH cables are not the same with just a different term. Failure to properly understand these classifications may lead to unfortunate accidents.

OFNR Cables

To summarize, OFNR cables are used for riser applications. It is non-conductive and is resistant to oxidation and degradation. It cannot be used to plenum areas but OFNP cables are compatible to rise applications. If you want to use it in a building, the structure must have a confined ventilation system and fire exits.

LSZH Cables

LSZH in comparison are made of special flame-resistant coating, and outstanding fire protection features such as low smoke, toxicity corrosion. LSZH cable jacketing are made of thermoplastic or thermoset compounds that produce little smoke and no halogen in case of fire.

When looking for the best type of fiber cable to use for your network and business, it can be difficult to navigate all of this information. BigCatCables.com offers a variety of fibers cables that carry both ratings (OFNR and LSZH), or single rated (LSZH or OFNR) to meet your installation needs. 

Shop BigCatCables.com's full line of OM3, OM4 and OS1 fiber cabling today to find the solution that meets your needs.

Not sure which fiber cable is right for your project? Contact BigCatCables.com and speak to one of our experts.

Fiber cablesFire ratingsLszhOfnr