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Telecom Cabling. CATV systems and coax cable. Telecom Cabling. Community antenna TV is covered in the NEC article 820, and is covered in a limited capacity in TIA/EIA 570 residential and light commercial standard.
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Telecom Cabling CATV systems and coax cable
Telecom Cabling • Community antenna TV is covered in the NEC article 820, and is covered in a limited capacity in TIA/EIA 570 residential and light commercial standard. • The TIA/EIA recognizes coax for its role in providing cable TV and satellite services. • Coax is used by broadband providers to deliver voice, data and video services, so coax cable plays a greater role in communications than the TIA/EIA recognizes.
Telecom Cabling • In the low voltage field you will be exposed to three of the most commonly used types of coax; RG-59U, RG-6U and RG-11U. • RG-6U is the most commonly used type of coax cable and is listed as “Series 6”. • Coax cable markings are CATVP, CATVR, CATV and CATVX.
Telecom Cabling • Just like any other cable we install we have to make sure that if coax cable is installed in a riser system it has to have the “R” designation at the end of the cable marking and a “P” for plenum environments. • Plenum: A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.
Telecom Cabling • CATVX limited use cable for use in residential and conduit and CATV general purpose for use anywhere other than risers or plenums. • Both of these cable types are listed as being resistant to flame spread, NEC article 820.179 (C) & (D). • Remember that any plenum cable type is at the top of the cable hierarchy and is the preferred substitution for any other cable type.
Telecom Cabling • The color of the cable jacket is no indication of whether the cable is a plenum or general use cable. • The majority of coax cable is black jacketed and white jacketed is available.
Telecom Cabling • The coax cable used by ISPs (internet service provider) is an RG-6U with an aluminum braid and shield. • The copper braided coax is strongly recommended for CCTV (closed circuit TV) installations and live sound reinforcement applications.
Telecom Cabling • For CATV and satellite installations we use series 6 coax with compression style F connectors.
Telecom Cabling • In CCTV installations we use RG-59U coax with BNC compression type connectors.
Telecom Cabling • Here are some other types of BNC connectors that you may end up installing in the field. On the left is a twist on connector, the middle is a 3 piece crimp style and a compression fitting with a separate bayonet piece that goes over the center conductor.
Telecom Cabling • Notice that there is not much difference between RG-6U and RG-59U, especially if the RG-59U has an aluminum braid. • You may not even notice the difference if you’re working with either type unless you read the cable jacket.
Telecom Cabling • What do the numbers and letters mean…..RG is usually referred to as radio grade however that designation isn’t entirely correct.
Telecom Cabling • BNC stands for bayonet Neil Concelman named for the man who originally designed the connector. • You may hear that BNC stands for British Naval connector, that as you now know is not the case. • There are more types of coax connectors that you may come across in the field……………..
Telecom Cabling • Here are TNC connectors that are associated with WiFi. TNC-RP (reverse polarity) TNC-RP (reverse polarity)
Telecom Cabling • Here are SMA connectors also associated with WiFi. SMA-RP SMA-RP
Telecom Cabling • Here a N style connectors. • TNC, SMA and N connectors are typically used for antennas, in some cases you can extend antennas with an LMR (high quality coax) cable and one of these connectors.
Telecom Cabling • RG-11U is used as a backbone cable or for longer distances where RG-59U and RG-6U may experience too much signal loss. • Manufactures recommendations for distances of 750 feet or less at low frequency (500MHz or less) RG-59U will work, for distances greater than 750 feet RG-6U should be used and for distances greater than 1000 feet RG-11U should be used.
Telecom Cabling • Cable TV operates in the 550MHz to 1GHz range so RG-6U is used because of the higher frequency. • Today cable providers are installing RG-11U from the pole to house for their broadband services to reduce the amount of attenuation loss at high frequencies and long distances.
Telecom Cabling • What is attenuation….? • It is a measure of signal loss, measured in dBs. • The low voltage mantra is “the larger the cable the lower the loss”. • This holds true in everything we install in the low voltage field.
Telecom Cabling • Here are some of the cable and connector losses that must be considered, any barrel splices will add 1.5dB loss to the link. Barrel connector
Telecom Cabling • We can install BNC connectors on RG-6U or F connectors on RG-59U, however the connectors have to be specified for the type of cable that they will terminate on. • A common problem in the field is trying to install RG-59U F connectors on RG-6U cable and RG-6U BNC connectors on RG-59U cable, doing this is a recipe for frustration and aggravation.
Telecom Cabling • On some of the cabling projects where you will be installing voice and data cables, you may also end up installing coax, which will normally be pulled to an employee lounge or conference room and will be used strictly for cable TV use. • These CATV drops will normally be installed at a location that is at least six feet AFF (above finished floor).
Telecom Cabling • There are some guide lines to follow when installing any type of coax cable. • The pulling force for coax is 35 lbs of pulling force. • What is the pulling force for UTP (CAT 5e/6)? Pulling the cable to hard will result in signal degradation
Telecom Cabling • The bend radius for coax is 10 X the cable diameter this radius should be maintained for the entire pull. • What is the bend radius for UTP (CAT 5e/6)? • The installer must be careful not to kink the cable, a kink in coax cable renders it useless.
Telecom Cabling • When you pull the cable off the reel it has memory and will want to stay looped which could result in kinks, its important to not let those little loops catch the ceiling grid and kink.
Telecom Cabling • We can cross electrical and power cables at a perpendicular angle but you should maintain at least a two inch separation from electrical cables in parallel spans, it is recommended to maintain a six inch separation. Electrical running perpendicular to coax Notice that a metal plate is install over the cable pathway to protect it from sheet rock screws.
Telecom Cabling • Poor connections degrade the signal, if you get even 1 strand of the braid touching the center conductor it will affect the signal quality.
Telecom Cabling • Low voltage rings help maintain the bend radius and are preferred over work boxes, if a work box is required by code it should be a double gang square box.
Telecom Cabling • You may hear the term quad shield coax, this type of coax offers the best signal quality for high bandwidth needs. This type of cable as you can see has 4 layers of shielding.
Telecom Cabling • Cellular technology also utilizes coax cable for their cell towers.
Telecom Cabling • It should be noted that all unused coax cables connected to the network along with unused splitter ports should be capped off with a 75 ohm end of line (EOL) terminator.