CABLING
Twisted Pair Cable

General

This section covers the requirements for multi-pair customer-owned OSP twisted-pair cables that are used in campus environments. Coaxial cable and fiber optic cable are covered later in the the section. OSP cables are intended for the distribution of communications signals which carry voice and data. Enhanced performance, referred to as Broad Band Outside Plant (BBOSP) cables are intended for the distribution of signals to carry voice, high-speed data, and video. Cables used shall:

meet the requirements of the AHJ and applicable codes
consist of 19 AWG, 22 AWG, 24 AWG, or 26 AWG thermoplastic insulated solid copper conductors in one of the designs listed below.
Cable Construction Types

OSP and BBOSP cabling is installed in aerial, duct (underground), and direct-buried applications. A filled cable may be used in all applications, whereas an aircore cable is not recommended for direct buried use.

Aerial (self-support and lashed)

Aerial cables come in two major classifications, self supporting and non self supporting. Self-supporting cable has a steel support messenger designed into the cable. This type of cable is more sometimes referred to as "Figure 8" cable because its cross sectional view looks like an "8". OSP cable intended for aerial use without a support messenger shall be lashed to a support messenger.

Direct Buried Cable

Direct buried cables are placed directly into the ground through a variety of methods such as vibratory plough or trenching. These cables shall have a moisture barrier compound within the cable to prevent moisture from entering the cable should the outer sheath be penetrated.

Underground Cable

Underground cables are placed in a duct system rather that directly into the ground. This helps prevent against rodent and environmental damage. Cables placed in a duct system may, or may not contain a moisture barrier compound.

Buried Service Wire

Buried service wire is intended for use when extending from the distribution cable to the entrance facility of a building.

Aerial service wire

Aerial service wire is used when extending from the distribution cable terminal to the entrance facility of a building. The maximum span length shall not exceed 60 m (200 ft).

Screened Cable (internally)

Internally screened OSP cable is for use with pulse code modulation (PCM) transmission. The screens separate cable pairs within the core into compartments (i.e., one containing the transmit pairs, and the other the receive pairs) for improved crosstalk performance over regular OSP cable.

75 Ohm Coaxial Cabling

General

Coaxial cable used in backbone OSP applications is 75 ohm semi-rigid cable referred to as trunk, feeder and distribution coaxial cable. The cable is available in sizes ranging from 10 mm to 29 mm (0.412 in to 1.160 in) in diameter. In designing a coax system, the designer must understand the relationship between attenuation and the diameter of the cable. Since attenuation is lower with a larger diameter cable, the cable choice will affect the number of amplifiers in the system.

Cable Performance

Performance, mechanical and electrical requirements of coaxial cable are goverened by the Society of Cable Television Engineers (SCTE). This group is somewhat equal to ANSI/TIA/EIA in that they specify the criteria for proper installation, testing and performance of coaxial systems and products.

Mechanical and electrical requirements for 75 ohm trunk, feeder and distribution coaxial cable are found in the Society of Cable Television Engineers (SCTE) document IPS-SP-100.

Connecting Hardware

Connecting hardware used with OSP Coaxial Cable is referred to as "N" type connecting hardware, and it is designed to fit each particular cable size and type. Connecting hardware includes connectors, taps and splitters. The designer should verify with the cable manufacturer regarding connecting hardware that is compatible with their cable.

Installation Requirements

The SCTE document "Recommended Practices for Coaxial Cable Construction and Testing, Issue 1, Section 1" provides the necessary information required for proper installation practices.

Testing

The minimum test requirements for 75 Ohm coaxial cable shall include a continuity test for the center conductor and shield. The installer may test the following parameters;

Optical Fiber Cabling

General

This section details the requirements of fiber optic cables as they apply to an OSP system. Although connecting hardware and splices may be part of this sytem, they are described in more detail in their respective sections.

The designer should take into consideration the following:

Recognized Cables

Both multimode fibers and singlemode fibers or a combination of these fiber types are acceptable. When both types of optical fibers are combined, some means of segregating the fibers by type shall be used.

Cable Performance

OSP optical fiber cable shall meet the performance requirements of ANSI/ICEA S-83-640 and ANSI/TIA/EIA-568-B.3.

Cable Construction Types

OSP optical fiber cable shall meet the physical requirements of ANSI/ICEA S-83-640. Optical fiber cables come in several designs with many construction options.

Duct Cables

Duct cables are generally non-armored cables. All-dielectric versions(no metallic components), which incorporate a nonmetallic central member, are available and are suitable for duct, aerial or conduit placement.

Armored Cables

Armored cables have a steel armor layer added under the outer cable jacket. The armor is added to improve the rodent resistance capability of a direct-buried cable, and also provides an extra layer of protection against other factors, such as rocky soil.

Aerial Cables

Aerial cables typically have the same cable construction as duct cables and com in two versions, self supporting and Figure 8.

All-dielectric optical cables are recommended when practical since these cables are not as susceptible to lightning strikes, are not subject to induced voltages and are not required to be grounded as are cables with metallic components.

Self-Supporting Cables

These cables are designed to be installed without the need for a pre-installed messenger (Figure 8). These cables may or may not have metallic components in them. An All Dielectric cable contains NO metallic components. Self supporting cables require no lashing and may therefore be easier to install than a Figure 8 cable or a lashed cable.

There may be load, length and span length limitations on these cables depending on wind and ice conditions in the geographic area the cable is being installed in. The designer should check for any special hardware required.

Figure 8 Cables

As with copper, these self-supporting cables incorporate a metallic messenger in a common sheath.

Indoor/Outdoor Cables

Some cables can be installed in both outdoor and indoor locations. This type of cable combines the attributes of an outdoor cable, ie: water blocking and UV resistance, as well as a flame resistant jacket (riser rated)suitable for indoor applications. This avoids transitioning to an indoor fiber, thereby reducing costs and system losses due to splicing and/or connectorization. However, the designer should be aware that the cost of this type of fiber is higher than regular outdoor fiber, and that there is a cost point where using the two individual fiber types is more advantageous.

Drop Cables

Drop cables are typically small diameter, low fiber count cables with limited unsupported span distances. They are used to feed a small number of fibers from a higher fiber count cable into a single location.