Smart Building

Following OSP Standards & Selecting the Right Outdoor Cable

Ron Tellas

OSP cabling is known for its ability to extend between separated structures. The National Fire Protection Association (NFPA) requires that unlisted OSP cabling be terminated within 15 m from its point of entry into the building, either through a wall or through the flooring.


At this termination, the structured cabling then transitions to listed cabling and continues to connect the enterprise network. A listed cable is one that is certified by UL for specific flammability ratings and listed for its intended use: usually CM, CMR or CMX.


A listed OSP cable can extend beyond the 15 m limitation, and can also be used within enterprise buildings in other applications where the characteristics of OSP cabling are of great benefit.


What the OSP Standards Say

Not all OSP cables are the same. Each type is designed for a specific purpose, so there are many OSP standards to consider when selecting cabling.


When designing an enterprise network that needs OSP cabling, a good OSP standards guide to use is ANSI/TIA-758-B, the Customer-Owned Outside Plant Telecommunications Infrastructure Standard, developed by the Telecommunications Industry Association. It references all the relevant OSP standards for cabling in a harsh environment, and also references relevant OSP standards for performance.


It also specifies the minimum requirements for customer-owned OSP telecommunications facilities in a campus environment, and specifies the cabling, pathways and spaces needed to support the cabling, no matter the population type or size.


Selecting an OSP Cable

When searching for the right OSP cable, there are several factors to consider:

  • NEC ratings like CM or CMR allow the cable run to exceed the NFPA 50-foot maximum transition length and run long lengths within your building.

  • Performance stability can ensure that the cable will continue to perform mechanically and electrically even if the surrounding environment subjects the cable to potentially damaging forces.

  • UV resistance prevents the sun’s rays from embrittling and/or fading the cable’s outer jacket.

  • A wide temperature range will allow the cable to weather temperature extremes. Gel filling keeps moisture out of the cable’s core maintaining its electrical performance, ensuring consistent impedance and insertion loss for the life of the product. Gel-filled cables can be difficult to work with, however, so ensure that the gel is user friendly and clean to install, and requires minimal prep time.

  • Power over Ethernet (PoE) compatibility is recommended for outdoor cables with digital buildings moving to the forefront. OSP cables that support power and data over a single cable, make installations easier and faster. PoE cable in OSP applications can also be used to reach outside cameras without having to run electricity or conduit to the camera, or requiring a nearby electrical outlet.

As you search for the right OSP cabling for your next project, contact us if you have questions. We can help you expand your network beyond your building’s borders to improve and grow your business.


To learn more about Belden’s OSP cable solutions, which defend against failure, watch this short video.