Ask Donna

Do you know of any codes, regulations, or industry standards that state which type of coaxial cable should support analog and digital cable TV as well as digital satellite systems?

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Wiring up for cable TV and satellite

Q: Do you know of any codes, regulations, or industry standards that state which type of coaxial cable should support analog and digital cable TV as well as digital satellite systems? I have seen both RG-59 and RG-6 used for this application, and I believe RG-6 is the appropriate type. However, I have been unable to locate any documentation addressing the issue.

Phillip D. Stowe
Phill the Phone Man
Los Lunas, NM

A: Yes, there is an industry standard-the ANSI/TIA/ EIA-570A Residential Cabling Telecommunications Standard, drafted by the TIA/EIA Subcommittee TR-42.2 and published in May 1999. TIA/EIA-570A was intended to standardize requirements for residential telecommunications cabling, including coaxial cabling. The standard replaced the TIA/EIA-570, which was originally published in May 1991 and did not include coaxial cabling.

According to TIA/EIA-570A, coaxial cable, other than backbone cable, shall be either Series 6 or Series 11, according to the corresponding specifications within SCTE IPS-SP-001. That standard specifies a minimum shield construction consisting of a laminated metal tape and a 60% coverage braid-a dual-shield construction. Because applications using the cable's return path are sensitive to noise, I suggest you use Series 6 with a quad shield as a minimum between the distribution device and the outlet.

Install an impedance-matching termination cap on each unused energized coaxial connector that is part of the connecting block, splitter, or amplifier. Also, install an impedance-matching termination cap on each unused coaxial outlet.

When installing coaxial cabling, keep in mind a few important practices: minimum bend radius, maximum pulling tension, and slack or maintenance loops.

Do not exceed the manufacturer's recommended minimum bend-radius specifications. If the manufacturer does not provide any specifications, do not bend the cable into a radius less than 20 times the cable's outside diameter when pulling cables or to less than 10 times the outer diameter when placing or dressing the cable.

When pulling a Series 6 cable, do not exceed 35 lbs of pulling force. Leave at least 8 inches of cable slack at each outlet, just in case the cable has to be reterminated in the future.

Either Series 6 or Series 59 cabling can be used as patch cords and crossconnect jumpers. Be certain you are using the correct size F-type connector for the cable you're terminating.

Finally, keep in mind that while most of us are familiar with the RG designation for coaxial cables, the SCTE documents speak of "Series" designations; thus, to ensure consistent technical requirements between the two groups, TIA also refers to the Series 59, Series 6, and Series 11, rather than RG-59, RG-6, and RG-11.

Consolidated voice-data systems

Q: My background is in central-office maintenance and administration, and I supervise customer-premises installations. I am a proponent of a consolidated infrastructure, meaning I wire a premises entirely with Category 5 cabling and use one outlet at each workstation for voice. What is the appropriate method for wiring the central-office lines into the patch-panel racks so that service can be patched to the proper customer outlet? Also, what is the reference?
Senior Master Sgt. Dudley D. Allen
Offutt Air Force Base, Nebraska

A: The question is simple, but the answer is not. I see two options: Terminate the backbone cable from the central office on a termination field (such as 110, Krone, or BIX) and patch discrete pairs from the field to the 8-pin modular connectors on the patch panels using a special patch cable. Or terminate the backbone cable from the central office on patch panels and patch using patch cables with 8-pin modular plugs on each end. The second option is a very costly solution and wastes a lot of space accommodating the additional patch panels.

I first began looking at available options for this type of configuration back in 1989, when the University of Texas at Austin began deploying 10Base-T and the information-technology folks all wanted patch panels. Over the years, I have managed to keep most of the cabling terminated on 110-style termination blocks, which facilitates either patching (by discrete pair) or use of jumper wire. My arguments: lack of termination space and money. Ironically, when the cabling Categories were established by the Telecommunications Industry Association (TIA-Arlington, VA), we learned that the 110-style termination blocks we had been using actually met Category 5, while the 8-pin modular connectors on the patch panels did not.

My argument-that it's all just cable and can be used for data one day and voice the next-held for a while. But there was still that need to give each trade the ability to remain true to the stance, "that's the way we have always done it." So we jumpered the voice and patched the data. Sounds plausible, but in practice, trying to punch down a jumper wire between two patch plugs on a 110-style termination field became problematic. And patching voice was met with equal disdain. Next, the voice and data fields were separated in the telecommunications rooms. It was still entirely Category 5 cabling, but the voice cabling and data cabling were on separate walls or racks. This practice continues today, but with Category 5E cabling.

My advice to you: Continue to treat all cabling equally. Do not separate the voice cable from the data cable in the telecommunications room. If you are using 8-pin modular connectors on patch panels to terminate cables from the work area, and you have the space and the budget, then continue to do so. Terminate the backbone cables on a termination field (such as 110, Krone, or BIX) and patch discrete pairs using special patch cables.

The lines between voice and data continue to blur. Your telephone central office is nothing more than a big, expensive computer that makes dial tone. Remember: Voice is just one of many data applications that we are cabling to support.


First of three 568A updates issued

The TIA/EIA Subcommittee TR-42.8, TIA/EIA Engineering Committee TR-42, and the American National Standards Institute (ANSI) recently approved the ANSI/TIA/EIA-568B.3, Optical Fiber Cabling Components Standard, for publication.

TIA/EIA-568B.3 contains significant technical changes from and replaces, in part, ANSI/EIA/TIA-568A and TIA telecommunications systems bulletin TSB-72, both of which were last published in October 1995.

While TIA/EIA-568B.3 is targeted primarily at cabling-component manufacturers, it also contains a few points of interest for designers, installers, and end users of structured cabling. The standard provides performance specifications for 50/125-micron fiber-optic cables, in addition to 62.5/125-micron and singlemode fiber-optic cables. It also provides a minimum bend radius and maximum pulling tension for horizontal cable, inside-plant (ISP) cable, and outside-plant (OSP) optical-fiber cable. Additionally, the standard allows for the use of any connector with a corresponding Fiber Optic Connector Intermateability Standard (FOCIS) and meets the performance specifications in Annex A.

The minimum bend radius specified for 2- and 4-fiber cables intended for horizontal or centralized cabling is 1 inch under no pull load and 2 inches when subject to tensile loading up to the cable's rated limit. The minimum bend radius specified for all other ISP cable is 10 times the cable's outside diameter when not subject to tensile load and 15 times the outside diameter when subject to tensile loading up to the cable's rated limit. The minimum bend radius specified for OSP cables is 10 times the cable's outside diameter when not subject to tensile load and 20 times the outside diameter when subject to tensile loading up to the cable's rated limit.

ISP cable is to be manufactured to withstand at least the pull load of 50-lbs force. OSP cable is to be manufactured to withstand at least a pull of 600-lbs force.

Parts one and two of this trilogy should be released later this year.

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Donna Ballast is a communications analyst at the University of Texas at Austin and a bicsi reg-istered communications distribution designer (rcdd). Questions can be sent to her at Cabling Installation & Maintenance or at PO Drawer 7580, the University of Texas, Austin, TX 78713; tel: (512) 471-0112, fax: (512) 471-8883, e-mail: ballast@utexas.edu.

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