Outside plant

Network connections between devices such as computers, printers, and phones require a physical infrastructure to carry and process signals.

[3] In older large installations, cabling is sometimes protected by air pressure systems designed to prevent water infiltration.

[5] In civilian telecommunications, the copper access network (also known as the local loop) providing basic telephone or DSL services typically consists of the following elements:[6] Active equipment (such as a POTS or DSL line circuit) can then be connected to the line in order to provide service, but this is not considered part of outside plant.

Telcordia GR-3108, Generic Requirements for Network Equipment in the Outside Plant (OSP), contains the most recent industry data regarding each Class described above.

Handholes are plastic or polymer concrete structures set below ground with their lids flush to the surrounding soil, turf, footpath, or road surface.

[9] Corrosion in outside plant telecommunications network components is caused by exposure to the effects of temperature, humidity, electrical power, and contaminants.

Industry requirements document Telcordia GR-2836 defines these environments and provides corrosion resistance criteria for the telecommunications equipment in each.

Near large cultivated areas, where fertilizers are applied by airplanes, the wind may carry nitrates, phosphates, and ammonium compounds to settle on metallic components of the above-ground telephone plant.

Finally, chewing by rodents may expose metallic components, normally protected by a polymer or paint coating, to a corrosive environment.

Utility holes often show evidence of corrosion of support hardware and bonding ribbons that is caused by sulfate-reducing bacteria.

The environment in utility holes and ducts can be made corrosive by man-made chemicals such as industrial effluent, fertilizers, and de-icing salts.

The most aggressive contributor to corrosion of underground plant is dc stray current from electrified rail transportation systems, cathodic protection rectifiers, or welding and mining operations.