Telecommunication cabling is a wide topic. Most generally when we talkabout telecommunication cabling, we are talking about twisted pair cablingused to carry telephone and other telecommunication signals insidebuilding and in the cabling otn the telephone company outside plant.In some applications some other cable types (twisted pair, coaxial cable,fiber) are used, but twisted pair is the most commonly used cable type.The customer premises cabling can be divided to the following parts:
EIA/TIA-568A cabling standard is for USA markets. EIA/TIA-568A standard gives two options for cable color coding TIA568A and TIA568B. EIA/TIA 568A and 568B are two wiring methods used to indicate which colors are assigned to which pin of the modular jack. From those color coding the most commonly usedone is TIA568B (I recommend using this). The T568-A standard standard also defines the categories used to grade UTP cable. These categories have become the industry standard for UTP cable performance and are widely used by many manufacturers. Europe has it's own (quite similar in main details)cabling standard EN 50173.
Computing and data communications are fast-moving technologies where equipment often has a practical lifetime of a few years, at most, before it is overtaken by something newer and better. In a few year's time, the unified wiring technology that is now recommended may be inadequate. However, modern networking technologies are being developed around the use of twisted-pair wiring so, although none of us can see into the future reliably, the best advice that can be given now is that new building wiring should be category 5 UTP or better (CAT6). Wiring using structured cabling becomes (CAT 5 UTP) relevant in homes.Here are some common cable types you might encounter in telecommunication installstions:
The typical cable copper wire thickness used here is 24 AWG. The most common jacketed cable consists of four tightly twisted pairs of #24 gauge insulated copper conductors. It is extensively used in commercial applications and is finding its way into new homes to meet rising consumer demand. In a typical UTP cable some pairs are more tightly twisted than others. Thats exactly the way it should be. Cables are built with different twists in the pairs, to minimize crosstalk. All pairs are good enough to run ethernet and other applications . Different twists mean that that radiation pattern for that pair is slightly different than the next pair, reducing cross-talk along the whole length of the cable between the different pairs. Because different pairs are twisted differently, there is possibility of different wire lengths. This concern is taken care of by specifying a parameter that's called "delay skew". Up to the maximum distance the signal can travel (100 meters), the length of the "stretched out" pairs (or simply copper length) cannot be different more than in takes light to travel 45 ns in copper (approx. 0.67 speed in vacuum). So, multiplying it all up we get 4.5E-08 sec x 3E08 m/sec = 13.5 meters or 44 feet 3 inches if you like. That's roughly how much copper length difference a pair of devices talking over that cable can tolerate. This, in turn, means that the designers of those devices should allow enough memory buffer to hold the parts of the data stream for at least 45 ns. In many applications where only one wire pair is used for tranmitting one signal to one direction, the delay skew is not a concern. Delay skew is concern in applications that use many wire pairs at the same time to transmit same signal (for example Gigabit Ethernet over copper uses all four pairs). Interpair slew (different pair lengths) is a big problem for multi-pair video (YC or RGB).
Typical UTP cable has four pairs of wires in each cable. Not all four pairs are used in actual applications. For most LANs, only two pairs are used, one in each direction to allow full duplex, simultaneous bidirectional communications. Due to the limitation on bandwidth and emission of radiation that could potentially affect other electronic devices, the higher speed networks are migrating toward using all four pairs.The "quality" of the cabling systems to carry high frequency signals is expressed with the folloging marking (those are in use in USA):
When you are installing cable nowadays do use Cat5 or lower class cables for data wirings. CAT5 is not longer a recognized standard. The cable rating should be Cat5e or Cat6, depending on how much money you want to spend. CAT6 cable and connectors are more expensive to buy and harder to install. If you really want to future proof, use 50/125 multimode fiber in your wiring in addition to copper.
Some naming for different cable types:
European cabling standards use different naming and classes than the standards in USA.The permanent links and channels are classified as follows:
In the data communications world, a lot of work has been done to keep actual running frequencies low. Below 30 MHz, the FCC has no radiation specifications and European specifications are quite free here as well. Therefore, one of the key drivers to technology has been to get systems at or near that number to avoid the requirements of the FCC and European standard.
In order to reduce emission significantly, the use of shielded cabling proves to be far the most straight forward solution. But balanced transmission or balanced transmission plus shielding are two different means to achieve good EMC performance. With a well balanced system, will shielding really be necessary? Will STP always give better EMC performance than UTP? The answer is no clear and depends on application. Both cable types have their good and bad properties. If the cable link and the transmit/receive circuits of the communications equipment were perfectly balanced, we would need no shielding at all. In differential mode both UTP and STP perform in the same way (STP only usually has typically somewhat higher attenuation and/or is harder to handle because is usually thicker). In the common mode, the UTP link acts as a long antenna, while the FTP or S-FTP cable behave more or less as a coaxial cable (=is well known that the radiation is low and susceptibility in the immunity case is good). Experiments with STP cable have demonstrated the necessity of maintaining continuity of the shield to get good performance. And well grounded STP can perform very well in very varying enviroments (for example STP is advantageous in cases when cable is surrounded with lots of metal objects). A well-designed and properly installed FTP cabling network undoubtedly offers improved signal integrity over anunshielded system. However, in order to work effectively, the shielding must be properly earthed. In practice this is notalways easy to achieve. A badly earthed, shielded system will actually offer poorer performance levels than one which is not shielded in the first place. In the worst case, the shield itself can become a radiating source, producing currentearth loops, or capturing ambient emissions and radiating harmful interference right next to the data cable. When STP is grounded at the both ends (for normal operation needed for good performance), the cable shield can start carry grounding current which affect the cable performance. If a ground potential differences of less than 1 V r.m.s. cannot be met, this can cause problems for STP installation. In those special cases, the wiring system needs to use non-continuous grounding where continuity (in high frequency terms) can still be achieved by using equipment cables with discontinous, but capacitively coupled shields.
No matter if the cable is shielded or not, there are two types of cables: flexible stranded core cable and solid core cable. Solid core cable is usually less expensive and is used for inside wall wiring. Solid core cable is easy to work with on inside-wall wiring (easy to terminate well to sockets) and usually has better performance characteristics than the flixible cables. Solid core cable is a poor choose for patch cords since it isnot very flexible and difficult to terminate correctly to RJ-45 plug. You can try to make patch cords from solid core cable, but you will soon find out that they are very unreliable, because standard RJ-45 plugs do not connect to solid core cable reliably. All the patch cables should be built from flexible stranded cable. When installing cables, be careful when handling the cable. There are many things that can cause Cat 5 or higher specification cable not to meet spec including bending, stress, and etc.
When installing communication cabling, the communication cabling should be installed enough far away from power cabling to avoidinterference pickup from power cables to LAN wiring. Power cables and LAN wiring should never be installed inside some electrical wiring pipe for both safety and interference reasons. When installing cables, the communication cables should be keptat least 15 cm away from 230V AC lines and 20 cm away from 400V AC lines (those recommendations are taken from industrial cabling recommendations and are good starting point forresidential installations also).
It is relatively easy to install cables around the house when the house is being built. Here are few installation tips:
Nowadays you can wire a building with nothing but Category 5 UTP and do almost anything one might want. You can theoretically even run more than one service over one four pair cable in some applications. However, there are no standards within TIA/EIA 568A currently for "sharedsheath" non-data applications. Installers should be aware that in TIA/EIA 568A, while it does not specifically disallow multiple uses for any cable, if such multiple uses are installed, that cable will not be certifiable as being 568A compliant. This does not mean that the cable next to it in the bundle is or isn't compliant. So the best idea is to designate which cables will be 568A compliant and to install them to that standard. The shared-sheath, non-standard cables, can be wired as needed. It is also possible to install all cables to be 568A compliant, and to make the non-standard applications appear outside each wall jack. In that way, all wiring could, at any time, be part of a 568A compliant network and yet, at the change of a connector, be a video feed,telephone, T-1 line, RGB cable, or many other uses.
Grounding in the electrical world generally centres around personal protection by providing a low impedance path for fault currents to travel to a safe earth for dissipation. In the area of data transmission the fault currents are not lethal to humans, rather to the integrity of the data being transmitted. Depending on the nature of the interference various grounding philosophies are available, however there may be conflicts between grounding methods within a single system. Trade-off is a key part of designing an EMC compatible system.Three types of grounding are commonly used, not necessarily in isolation to each other:
Nowadays by installing twisted pair wiring to all rooms in the home or office, you can virtually provide any type of service required to each room. Those services include 10/100BaseT data feeds for computer networking, Internet access, printer-sharing, fax machines, telephony feeds for phones, conferencing, intercoms, audio feeds and video feeds. This home networking setup is of a simple design. By terminating these different media into a sophisticated multiplexing device which can split audio/video and voice/data input signals without degradation, a home owner will have the ability to branch these signals across the twisted pair wire to any location in the home.
Radio audio (550kHz - 108MHz), TV broadcasts, cable TV and satellite TV signals are traditionally distributed using coaxial wiring. With good enough twisted pair wiring you can even use the same wiring also for most of the services traditionally done with coaxial antenna cabling. Home networking will allow central location of satellite and cable receivers, AM/FM antennas, computer resources, etc., which plug into these multiplexers. Then by simply making patch cord changes to a small rack, located in a closet, the homeowner can control what piece of information is fed to each room.
Most commonly used connectors in telecom and datacom wiring are:
There are special safety considerations with telephone wiring that may be unknown by workers new to this field.The following hints and guidelines should be followed closely to help avoid safety hazards, and ensure trouble-free installations and high-quality telephone service:
Cabling standards are developed to provide specifications and design criteria for cabling manufacturers, suppliers, building designers, network architects, service technicians, and others. One of the first cabling standards was TIA/EIA-568-A, which was developed by the TIA (Telecommunications Industry Association) and the EIA (Electronic Industries Association). TIA/EIA-568-A is a uniform wiring system, designed for voice and data networks, that supports multivendor products and environments. It defines how to design, build, and manage a structured cabling system. The standard defines a structured, hierarchical star-topology network in which high-speed cables (usually fiber optic) feed slower periphery networks. By far the most commonly used standard for structured wiring systems is EIA/TIA-568, or 568A. This standard is important even for residential networks because it is the source document that the Residential Cabling Standard (ANSI/TIA/EIA-570-A) is derived from. ISO/IEC-11801 is an international cabling standard (also referred to as Generic Customer Premises Cabling). The standard was published in 1995. It is based on the ANSI/TIA/EIA-568 cabling standard (initial document is now considered obsolete, now updated by ISO/IEC IS11801 AM2-1999, and later with ISO/IEC 11801 2nd Edition - 2000).
There are also some other relevant cabling standards. Here is list of some relevant cabling standards:
Some of the parameters of EIA/TIA 568 are the following:
Category-rated cable is used for high-speed data transmission, and is increasingly being used for other communications uses. For several years Cat. 5 cabling was the primary cable being used for networking. Recently, many installers have begun using Cat. 5e (e for extended) and Cat. 6 cabling.
The minimum bending radius for Cat. 5 cables is typically four times the cable diameter. This is not especially difficult for installers, although it can be difficult in tight areas. When being pulled into place, not more than 25 pounds of tension can be applied to the cable. One easily missed hazard of Cat. 5 cabling is that the use of tie-wraps can damage the cable's performance. When tie-wraps are cinched down tightly on these cables, they deform the pattern of the twists, and can permanently damage the electronic characteristics of the cable badly enough that it will not handle high frequency signals.
In October 1999, the EIA/TIA approved a formal standard for residential networks. The title is ANSI/TIA/EIA-570-A Residential Telecommunications Cabling Standard. As mentioned above, this standard is derived from the usual EIA/TIA 568 standard for structured cabling systems.
Following are several of the EIA/TIA 570 standard's key points:
The required testing for residential networks is not as rigorous as that for commercial networks. Commercial systems go through a difficult testing process called certification: home cabling systems go through a less difficult process called verification. Verification assures that the cabling system is continuous (that is, it has no shorts or open circuits) and that the correct terminations have been made. Verification, unlike certification, does not measure the information-carrying capacity of the link. This is considered unnecessary because residential links are nearly always considerably shorter than commercial links and suffer much less from attenuation a significant factor in a link's capacity. In the shorter links, near-end cross talk (NEXT) and far-end cross talk (FEXT) are a much-reduced concern.
The old practice od daisy chaining of telephone circuits is out. Instead, each outlet must have its own home run. This is called a star topography. The primary test for residential links is the wiremap test, verifying the pin connections on both ends of the link. This is not to say that there is anything wrong with doing a complete certification with the much more expensive Cat. 5 tester; but it's not necessary for normal residential links.
A strutured cabling system can be used to carry many different kind of signals. Other than the structured cabling system, voice, data, video, and building management systems (BMS) have nothing in common except similar transmission characteristics (analog or digital data signals) and delivery methods (conduit, cable tray, raceway, etc.) that support and protect the cabling investment. It is possible to use the same type of 24�AWG UTP cable and share a common cable delivery method for all power-limited services. The same wiring can carry the signals and also power to some devices. With proper planning, the only limiting factor for complete systems integration of the voice, data, video, and building management system (BMS) may be the fire alarm (FA) system. In the United States, Article 760-54 (b) of the 1996 National Electrical Code (NEC) allows conductors of power-limited FA systems and signaling/communications circuits (Article 725/800) to share the same cable, enclosure, or raceway. In addition, Article 760-61 (d) of the NEC allows the use of the same type of cable for FAs that is typically used for the signaling/communications (voice and data) circuits. Some local codes however, especially codes in other countries, may invoke limitations or require special approvals for integrating the FA system. Yet, even if the FA cabling is installed separately, there are still substantial cost reductions and benefits that can be derived from integrating the remaining BMS.
Typically, 24�American wire gauge (AWG) unshielded twisted-pair (UTP) cable has the capacity to handle 1 Ampere (Amp) of current draw per conductor, with a maximum of 3.3 Amps per four-pair cable. typical 24�AWG UTP cable pair has 57.2 Ohms of resistance per one-thousand feet or .0572 Ohms per foot. Circuit resistance can be measured by dividing the voltage drop by the current draw. If a 24 Volt (V) device requires .05 Amps of current to operate and the allowable voltage drop is �10 percent, or 2.4V, the maximum circuit distance using 24�AWG UTP cable is 839 feet (256 meters).
Many cables are color-coded to make it easier to identify different conductors inside one multiconductor cable.
There are many wiring standard, some more common than other.There is a difference between telephone wiring and LAN wiring.The most differences are the way pairs are allocated in the cables and the cable type used (data applications generally demand higherspec cable).
Telephone Wiring in USA is defined by USOC (Universal Service Order Code - now handled and maintained by the TIA). The standard connector for telephone equipment in the US and for data connections everywhere is the modular connector. For voice service, the 4-pin or 6-pin connector, called "RJ-11" is used. For data, an 8-pin version, called "RJ-45" is used.
LAN Wiring is defined by EIA/TIA. The most important wiring standard in this is EIA/TIA 568 wiring standard. EIA/TIA 568A and 568B are two wiring methods used to indicate which colors are assigned to which pin of the modular jack
Phone wiring in the home generally contains two pairs of wires, for two phone lines and is terminated to RJ-11 jack. The first pair is green and red; the second is black and yellow. The wiring on RJ-11 plug on the telephone equipment cable is wires in the "BRGY" from left to right when you hold the plug pointing up (wire down) the hook underneath. Note that the connector on the other end of an RJ-11 connector is wired in reverse order (if you stretch the cable out flat, the Black wire stays on the left all the way to the other end, including through the connector with the hook oriented down also). RJ-11 connector has six potential terminals on it. Only the middle 4 are normally used, and sometimes only the middle two. Line 1 is the center pair: red and green. Second line uses black and yellow wires. The wiring for the plug side of an RJ-11 connector is the following: black, red, green, yellow ("BRGY"). Those wires go to the four center pins on the connector (in case you use 6 pin version instead of 4 pin). The color arrangement is this when you hold your connector the connector contacts pointing up (cable going down) and the "hook" (the little thing you press on to get the plug out) underneath. In case ypu have six contacts RJ-11 connectors with six conductor cable, then the colors for those six wires are two extra The RJ-11 wall sockets usually have the colors indicated on the terminals to help you to ghet the wiring right.
The standard wire colors combinations for telephone systems wires are:
When telephone wire has at leat four wires, you may run 2 lines within 1 wire. At the end of the wire you can break out the 2 lines using an adapter which allows you to connect line 1 to an RJ-11 plug and line 2 to another RJ-11 plug, or if you have a 2-line phone, you can just plug an RJ-14 plug into the phone.
Most telephone wires are one or more twisted pairs of copper wire. The most common type is the 4-strand (2 twisted pair). This consists of red and green wires, which make a pair, and yellow and black wires, which make the other pair. One telephone line needs only 2 wires. Therefore it follows that a 4-strand wire can carry 2 separate phone lines. The twisting keeps the lines from interfering with each other. If you need to run more lines than just 2, you may want to use a 6-strand, or higher. Telephone wire comes in 2 gauges, 22 gauge and 24 gauge, 24 gauge being today's standard. Telephone wiring often also uses a kind of cable called "Silver Satin". This is the relatively flat cable usually used from the wall to the phone itself. This kind of cable should not be used for data, as it does not have the twists in it that are essential to reducing electrical noise that will cause data errors.
Data wirings are nowadays construted using structured cabling system that terminates to RJ-45 connectors. There are two wiring standards for structured wiring cables, called "T568A" (also called "EIA") and "T568B" (also called "AT&T" and "258A"). They differ only in connection sequence - that is, which color is on which pin, not in the definition of what electrical signal is on a particular color. T-568A is supposed to be the standard for new installations, while T-568B is an acceptable alternative. Most off-the-shelf data equipment and cables seem to be wired to T568B (also AT&T standard).
T568A goes like this:
| Color Codes for T568A | |||
| Pin | color | pair | name |
|---|---|---|---|
| 1 | white/green | 3 | RecvData+ |
| 2 | green | 3 | RecvData- |
| 3 | white/orange | 2 | TxData + |
| 4 | blue | 1 | |
| 5 | white/blue | 1 | |
| 6 | orange | 2 | TxData - |
| 7 | white/brown | 4 | |
| 8 | brown | 4 | |
Pin Number Designations for T568B:
| Color Codes for T568B | |||
| Pin | color | pair | name |
|---|---|---|---|
| 1 | white/orange | 2 | TxData + |
| 2 | orange | 2 | TxData - |
| 3 | white/green | 3 | RecvData+ |
| 4 | blue | 1 | |
| 5 | white/blue | 1 | |
| 6 | green | 3 | RecvData- |
| 7 | white/brown | 4 | |
| 8 | brown | 4 | |
The only difference between T568A or T568B is that the green and orange pairs are reversed. Generally it has not been much difference if the wiring is made according T568A or T568B as long as the whole wiring is made with the same system. Different countries use different practices. For example US Federal Government publication NCS, FTR 1090-1997 recognizes designation T568A only. When you are aiming to highest possible performance, even the selection of wiring pratice frhom those combined with the cable properties can have measurable effect on cable performance. Your hoice of wiring scheme can affect the test results for return loss. The reason is that some there is a pair pair performed worse for the connector and cable, and those can be different on different connectors and cables. If you are cabling to T568A, the worst performing pair of the cable (orange pair) is terminated to the worst performing pair of the connector and hence the marginal return loss margin. When the link was cabled to T568B, the worst performing pair of the cable is terminated to pair 1,2 of the connector, which is not the worst performing pair. Be careful here. If the cables worst performing pair was the green pair, T568A would be the preferred wiring scheme. Make sure you verify the components performance first if you are aiming for highest performance. Usually the worst performing pair in the connector is the pair that uses pins 3 and 6, this is because of the design of the RJ-45 connector and selected wiring practices (there is not much the connector manufacturer can do to this).
On the markings above the information on the "name" column refer to twisted pair Ethernet signals (10BaseT and 100Base-TX), the most common use for this kind of wiring. NOTE: If you plug RJ-11 plug to RJ-45, pairs 1 and 2 are on the center 4 pins of RJ-45 connector.
The RJ-45 wall jacks are available in various different forms. There are typically jacks built to faceplate mechanics and keystone jacks. Those jacks that are built toghet with faceplace typically consist of RJ-45 jack that is soldeted to a small circuit board that has also the 110 or Krone type IDC punch-down terminal. The 'keystone' jacks are the most flexible solution. The 'keystone' jacks are just small RJ-45 connectors integrated together with the wire termination connectors (can be normal punch-down type or tool-less model). The most flexible are called 'keystone' wall-plates and provide blank plates with the right number of empty holes (available with typically 1, 2, 3, 4 and 6 holes). Into these 'keystone' holes you plug the 'keystone' jacks of the type that you need e.g. 1 RJ45 (for LAN) and 1 or 2 RJ11/12 (for Telephony), video etc.
End connections are critical and if poorly done can be a huge source of loss and poor performance. Use high quality and correctly rated connectors.
Male Modular connectors are numbered LEFT to RIGHT when viewed from the TOP (TOP is when the plastic lever is on the bottom). Female connectors are numbered from LEFT to RIGHT when viewed from the FRONT.
There are many common wiring practices in telecom and LAN world. EIA/TIA 568A and 568B are two wiring methods used to indicate which colors are assigned to which pin of the modular jack. Those are the standard of modern "stuctured cabling" and "LAN" world. In telephone installetion the coloring practice has traditionally been the following: "Ring" is normally assigned to the RED wire, "Tip" is normally assigned to the GREEN wire.
The normal modular phone cord has one end flipped over from the other, sousing a four conductor flat cord, black on one end is on the left, andright on the other end. For some other applications cable very likely does not have that flipped end, but uses the straight thru connection(for example datacom application use straight thru connection).
Nowadays UPT systems are generally installed with CAT5 or better cable.CAT5 wiring will have certain characteristics including:
AWG Feet/Ohm Ohms/100ft Ampacity* mm^2 Meters/Ohm Ohms/100M diameter/mmThese Ohms / Distance figures are for a round trip circuit. Specifications are for copper wire at 77 degrees Fahrenheit or 25 degrees Celsius. The most commonly used wire in structured cables inside walls is 24 AWG. Patch cables generally use 26 AWG wire. Typical transmission characteristics of CAT5 wiring:
22 30.3 3.30 2.1 0.644 9.24 10.8 0.64
24 19.1 5.24 1.3 0.511 5.82 17.2 0.51
26 12.0 8.32 0.8 0.405 3.66 27.3 0.41
28 7.55 13.2 0.5 0.321 2.30 43.4 0.33
Frequency Attenuation NEXTThe limits above are derived from TIA TSB-67 Cat 5 Channel Specifications. (Data from http://www.chem.ox.ac.uk/it/staff/Network%20Documentation/standards.html. The cable iself gives you much better performance, but the performance of of a channel is reduced by crosstalk and attenuation on connectors and patch cables. For 100 meters if a good solid core CAT5 cable (cable only) the specications at 100 MHz frequency is impedance 100+-15 ohms, attenuation 22 dB, NEXT 32.3 dB and return loss 16 dB. Typically the transmission delays vary somewhat between different pairs (I have seen somewhere figure of easily at least 1% difference on CAT5 cable).
(MHz) (dB) (dB)
1.0 2.5 60.0
4.0 4.0 50.6
8.0 6.3 45.6
10.0 7.0 44.0
16.0 9.2 40.6
20.0 10.3 39.0
25.0 11.4 37.4
31.25 12.8 35.7
62.5 18.5 30.6
100.0 24.0 27.1
Then installing the wiring keep in mind that CAT5 UTP wire is more fragile than coax cable. Per specifications, CAT5 will withstand about 25-30 lbs of pull when the wire is being run. This means that the cable should move fairly freely when being pulled through ceilings and walls. Otherwise, the cable will stretch and distort and no longer meet specification when subjected to too much pull.
Be careful not to deform the cable shape to much. Do not bend cables to less than four times the diameter of the cable. If you bundle a group of cables together with cable ties (zip ties), do not over-cinch them. It's okay to snug them together firmly; but don't tighten them so much that you deform the cables. Do not use a stapler to secure UTP cables. If you need to secure the cable to wall use telephone wire/RG-6 coaxial wire hangers (available at most hardware stores).
Specifications also instruct installers to cut back no more than 2 inches of the outer jacket when attaching the line to a punch-down block. If you cut back much more than 2 inches of the cable's jacket to make it "pretty" in their wiring rack, you risk installing the wire out of spec and may experience unpredictable communication problems. This happens for a simple reason, electromagnetism. Our environment is saturated with it. When the wires are all inside the jacket and twisted around each other in pairs, they are affected in the same way, at the same point by these external forces.
Try to avoid running cables parallel to power cables. CAT5 should not be laid directly on fluorescent lighting or parallel to power cables. In those places the cable will pick up interference easily. There is another reason to keep the power cables and data wiring some distance away: electrical safety. When cables are some distance away, is very unlikely that some common accident can cause mains power getting to low voltage wiring. Keep cables away from devices which can introduce noise into them. Such devices include copy machines, electric heaters, speakers, printers, TV sets, fluorescent lights, copiers, welding machines, microwave ovens, telephones, fans, elevators, motors, electric ovens, dryers, washing machines, and shop equipment.
A patch panel is a mounted hardware unit containing an assembly of port locations in a communications or other electronic or electrical system. In a network, a patch panel serves as a sort of static switchboard, using cables to interconnect computers within the area of a local area network (LAN) to the network equipment (hubs, switches)and cabling going to different locations. The reason the patch panel is there is that you can use your cabling for more that just one service (like telephone or Ethernet). If the system is designed properly, you can easily switch between Ethernet, digital or analog phone or fax, CCTV camera and other devices, provided by you connect to proper equipment in the closet. The patch panel gives you ability to move your cable's connection between different devices and not only Ethernet hubs or switches. Typically all telephone connections and data outlets in a modern office are wired to some sort of patch panel, from there they are connected where-ever needed (networking equipment end incoming telephone lines). Nowadays there is a network hub/switch also nearby the patch panel, and the LAN data connections are wired from patch panel to it. A patch panel uses a sort of jumper cable called a patch cord to create each interconnection.
In office and control room installations the best bet seems to be to use female/female patch panels and then use pre-made patch cords for both the switch/hub connection and for the horizontal section. This allows one to go directly to the end device or wall outlet with a tested, certified cable obviating the need for on-site certification. For industrial plant installations, it is probably best to use a pre-made patch cord to go directly from the switch/hub to the end device. So many connections in the way with the traditional patch panel in the route degrade network (connector) reliability and complicate documentation, testing, tagging, and maintenance troubleshooting.
There are many different types of patch panels in use in telecommunication wiring. Most modern patch panels designed for data communication applications use patch panels which have RJ-45 connectors in them. This is convientin data communication wiring applications, where one four pair cable isused for one application. Patch panels designed for easy wire pair interconnection have been used for long time also in telephone wiring applications. In this kind of applications the patch panels are designed such that there is easy access for separate telephone wire pairs and where plain wires (no connector on the end) can be easily terminated.
The most common types of patch panels:
Modern telecom patch panels are generally built as modules that mount in EIA standard 19" relay rack cabinet or wall-mount brackets. Punch-down blocks come in many sizes. They are made up of grooves/slots the individual wires are punched into and look very much like what you will find in telephone closets. Most blocks use an insulation displacement type pin for termination of the conductors. Depending on the block style, some pins may be conductively the same. The more common blocks used today are 66 sytle; 110 style, BIX style and Krone style. Each have a unique punch down tool for terminating conductors. Specifications for CAT5 wiring instruct installers to cut back no more than 2 inches of the outer jacket when attaching the line to a punch-down block. Please note that most punch blocks don't work well with fine-gauge (24 or higher) stranded wire. The stranded stuff doesn't offer as much physical resistance to the pressure of the clip, so it ends up compressing such wire more than biting through its insulation. This leads to intermittents or opens. Punch blocks work best with solid wire.
The modern patch panels with IDC connections are typicaly wired with punch tool that terminates the wires to the block. There are different punch-blades for 66, 110 and Krone blocks. A good-quality punch tool should need no more than one punch per wire, assuming it's held correctly and the block itself is in good shape. A multi-punch tool does a best job of seating the wires on the blocks quicly and reliably. I would reocmmend to get a proper impact punch-down tool to install the 110 or Krone type patch panels. Typically this kind of tools come with a with reversable cutter and non-cutting blade. For jobs where you need to terminate just few wires, you can use simpler tools. There are expensive simple plastic tools to install wires to 110 blocks (come with some RJ-45 outlets with 110 contacts), those can be used for some repair work, but they do not last long in real use. And the last option is to punching both ends of the connection with a single tool (small screwdriver, piece of wood), this will generally work also, but is not the recommended way to install the cables.
Telephone centrals hav a large patch panel called MFD (main distribution frame). MFD (main distribution frame) connects the cables coming from the field to telephone central equipment ports. MDF is typically divided to the vertical side (VMDF) and the horizontal side (HMDF). Underground cables are terminated to the vertical side (VMDF). OE (office equipment) blocks appear at the horizontal side (HMDF). Those two sides of the frame are interconnected with suitable patch cabling (a two wire tip + ring patch cable) that connects then together as needed (the subscribers that have telephone service connected are wired to the central office equipment and completely unused lines are not connected). Typically the horizontal side of the MDF is permanently wired to the vertical side of the IDF using over head cabling. Each line on the VMDF typically also contains electrical protectors known as "heat coils" and "carbons". The heat coils work like a very-slow-blow fuse protecting the telephone switch from too much current while the carbons protected against lightning. Modern protectors employ gas cartridges in the place of carbons.
Some telephone central installations also use IDF (intermediate distribution frame). An IDF (intermediate distribution frame) is primarily a three wire (tip, ring, sleeve) frame allowing connections between the vertical side (VIDF), where the OE (office equipment) blocks appear, and the horizontal side (HIDF) where the telephone number blocks appear. The vertical side of the IDF is permanently wired to line relays (OE) in the line finder bays. The horizontal side of the IDF is permanently wired to telephone connector switch banks. Typical connector for IDF is Telephone Switchboard Plug (looks like 6.3 mm stereo plug seen on headphones in hifi equipment).
The T568-A standard published by the Electronic Industry Association and Telecommunications Industry Association defines a system for building a data and voice communications network in an office environment that will have a lifespan of at least ten years and support networking products made by multiple vendors. This standard also defines the categories used to grade UTP cable. These categories have become the industry standard for UTP cable performance and are widely used by many manufacturers.
Besides telecom and datacom wiring applications, like telephone lines and LAN applications, typical structured wiring can be used for many non-traditional uses. This is a short description for what CAT5 is suitable an for what not.Good ideas:Video signals can be carried over CAT5 UTP wiring with suitable adapter. There are different kind of adapters to send video signals areas where there is no coax in place. Baluns are available for Composite Video plus Stereo Audio, SDI Serial Digital Video, S-VGA and UHF up to 850MHz. Line level audio can be carried over CAT5 wiring if suitable audio adapters are connected to both ends of cable to convert the typical unbalanced audio (RCA connectors) to balanced signals that can travel nicely over CAT5 wiring. Directly soldering RCA jacks to CAT5 wire does not give any good results (will pick up lots of humming and noise). Balanced signal source and receiver combinations can be directly wired to CAT5 UTP usually with quite good results (you need to think custom special wiring practice for this, there are no standards for this).Bad ideas:CAT5 wiring inside wall is not a good choise for speaker wiring (for normal 4-8 ohm speakers). It is too too thin for this. The resistance of long runs will effect sound quality and if you turn the volume up a lot, you will heat the cable with considerable amount of amplifier power. CAT5 for low voltage lights is a bad idea. They can draw decent amounts of current at low voltages, overheating the wire. Check the manufacturer to see what gauge wire they recommend sine lights draw all sort of current based on their power/intensity. Do not use CAT5 wiring for smoke detectors, because smoke detectors should be always wired with a special listed fire resistant cable designed for smoke detector control. Most building codes require this. Should check:CAT5 for temp sensors and such? It will work, especially if they are the digital type. If you are using analog temp sensors, this is where the length issue will most affect you since you are working with very low votlage readings anyway and losses in small wire (22-24 gauge) is high at low voltage levels.
Proper testing of wiring system after installation is essentialto guarantee good operation later. The cabling system needs to bemeasured after installation and the results of those measurements should be documented for later use. In many countries the the regulations about telecommunications wiring say that the installed wiring system must be well documented, including the results of the performance tests (at least on commercial installations).
Many of the problems encountered in UTP cable plants are a result of miswired patch cables, jacks and crossconnects. Cable testing verifies you've completed an installation in accordance with all of the terms and conditions of the contract and industry standards. When you're testing copper cabling, it's important to understand and follow three distinct phases:
Induction amplifier/tone generator, also known as a toner or cable tracer, enables installers to identify a specific pair by generating a tone on one end of the pair - with an inductive amplifier identifying it at the opposite end. Most units are now a combination of tone generator and continuity tester, commonly known as a wand and toner set. This solution is ideal for cable identification and troubleshooting in field. Application Hints for induction amplifier/tone generator system: When tracing wires terminated to a terminalblock such as a "66 block", attaching both generator leads to the cable or pair tends tocontain the signal within the cable. The tracer must nearly touch the end of the cable to detect the signal, which is helpful when the wires are close together, as when terminated. When tracing along cable runs and to maximize radiated signal, connect one lead of the generator to the wire or cable, and the other end to ground (for example grounded telecom rack metal frame or grounding bar, grounded metal case of an electrical box, metallic electrical conduit, metallic water pipe or ground rod). If no ground is available, do not connect the other lead to anything, let it dangle as near to the earth as possible. When testing coaxial cable installations, connect the generator to the ungrounded shield of a coax cable (if you connect the signal to center wire only, the shield will do it's job and you can't get much signal out of cable). Inductive amplifier are generally available with two types of probing tips. Nickel plated brass tips offer maximum performance when probing insulated wires or making direct metallic contact. The other type is partially conducting plastic tip specially formulated with a carbon powder and carbon fiber blended plastic, these tips perform much the same as traditional metal tips while reducing the risk of shorting terminals (typical resistance around 300 ohms). The signal generators generally connect to the wiring through modular connector, "alligator" clips (for use on uninsulated wires and 66 style punch-down blocks) or "bed-of-nails" penetrator (for use on insulated wires).
Wire map testers, also known as pair scanners, are low-cost cable testers that usually test for opens, shorts, crossed pairs, and miswires (such as reversed pairs in a 4- or 25-pair cable). Some testers in this category also test for split pairs. These devices are good for quick, basic tests. Good Wiremap tester a checks a cable for open or short circuits, reversed pairs, crossed pairs and split pairs. This is essential tool for checking stuctured datacom wiring.
Installers use certification field testers to verify a cabling system meets the transmission performance requirements as specified in TIA/EIA TSB-67. All variations of these units test a cabling system up to at least 100 MHz. In the autotest mode, they include length, attenuation, wire map, and near-end crosstalk (NEXT) tests. When operating in autotest mode, the field tester compares the actual measured values with required values for Cats. 3, 4, or 5, and displays pass or fail for the entire battery of tests. It also displays pass or fail and the actual tested values for each parameter. Usually this kind of devices can also perform other measurements, including impedance, capacitance, resistance, delay, delay skew, equal level far-end crosstalk (ELFEXT), and attenuation-to-crosstalk ratio (ACR) calculations. In addition to the TIA/EIA TSB-67 standard, they usually include the classes of ISO/IEC and the pass/fail criteria in their database. Certification testers can store test data and export it to a database on PC or output it to a printer. Certification test units test a UTP and ScTP cabling system to at least 100 MHz, and measure/record the following parameters: wire map length; attenuation; NEXT, as well as return loss; ELFEXT; ACR; propagation delay; delay skew; power sum NEXT; power sum ACR; and power sum ELFEXT.
The TDR locates and tests all cable defects, splices, and connectors and gives loss values for each occurrence. Originally developed for use on coaxial networks, the TDR can measure the electrical length of a cable and is an excellent troubleshooting tool for UTP, ScTP etc. To measure the cable, you inject a high rise-time pulse into the cable, and then look for the reflections caused by impedance mismatches to return. Checking cable length is usually done using a time domain reflectometer (TDR), which transmits a pulse down the cable, and measures the elapsed time until it receives a reflection from the far end of the cable. Each type of cable transmits signals at something less than the speed of light.
A telephone test set is used to simulate the user's telephone equipment, identify circuits, telephone circuit diagnostics and troubleshoot.The cabling installer must have proper adapters available to connect the test equipment to the cable under test. Here are some notes for testing differnet media options:
Optical fibre testing
In twisted pair wiring testing you can sometimes see terms "Basic Link" and "Channel". The "Basic Link" configuration is intended for use by cable installers and contractors, testing the fixed wiring in a building. A Basic Link may consist of up to 90 meters of horizontal cable, only one transition connector on each end of the horizontal cable, and two Test Equipment Cords with a length of no more than 2 meters each. A "Channel" configuration is intended for LAN owners and LAN systems designers to test the end-to-end connections of their LAN cabling. A Channel may consist of up to 90 meters of horizontal cable, one or two transition connectors on each end of the horizontal cable, and up to 10 meters of user patch cables for a total maximum length of 100 meters. The user's patch cables are used to make the connection to the networking hardware, such as the HUB to Patch Panel and Workstation to Wall Outlet connections.
Sometimes there is need to identify cables in unknown cabling systems or physical location of them. There are many different tools available for this. Cable-end locator kit. Sometimes called an office locator kit, this is a set of numbered 8-pin modular plugs, which the cable test equipment can identify. With this option, you insert the plugs into outlets in the work area, then search with the tester until it finds the plug at the opposite end of the cable.
The task of single pair toning occurs mostly on Telecom backbone cabling, such as 25 or 50 pair cable between distribution frames. In the distribution frames, the pairs are often terminated on 66 or 110 blocks. When toning a single pair into a block, there are a various techniques for identifying, and optionally validating a pair for opens, shorts and reversals. Induction amplifier/tone generator, also known as a toner or cable tracer, enables installers to identify a specific pair by generating a tone on one end of the pair - with an inductive amplifier identifying it at the opposite end. Most units are now a combination of tone generator and continuity tester, commonly known as a wand and toner set. This solution is ideal for cable identification and troubleshooting. The idea is that the tone generator is connected to a wire line. It sends the indication tone to the cable. The Line Tracer is a hand held inductive tracer that will help to identify wires without piercing the insulation. The idea is the inductive tracer will hear the tone sent to the cable (usually indicated with a small speaker and indication LED) when it is near the cable. It can trace Tone Generator signals through dry wall, wood and many other non metal surfaces. More near the tracer gets to the right cable, the stronger the sound gets. So the audible signal will tell the user of the cirrect wire carrying the tone signal and a LED light provides visual indication. Cable tracing and identification is made easy with a professional tone generator and inductive probe. Simply connect the tone generator to a modular jack or wires. Trace the transmitted signal at the other end of the wires with the inductive or capacitive probe. The signal emitted by the tone generator can be easily traced by the probe even when cables are in a bundle or hidden in a tangle of punchdown blocks or wall plates. Tone Generator and Inductive Amplifier are often used to trace cable pairs, follow cables hidden in walls or ceiling. The tone generator will typically put a 1 kHz or 2 kHz audio tone on the cable under test, the inductive amp detects and plays this through a built-in speaker. Typically transmitter sends out a pulsating 2 KHz signal down the cable which is heard in the receiver when you are close to the cable. There are also systems which use different frequencies for testing. Many listening devices have two detectors in its tip which are tuned to pick up the electromagnetic signals ("short" mode) or electrostatic signals ("open" mode) generated by the other components. Most systems just listen to electrostatic signals. The inductive amplifier can detect this signal without having to cut or damage the cable being tested. The inductive amplifier usually has a range of about 1"-4" from the cable. Typically used to identify or trace cables. So the whole testing operation operates by injecting a "warbling tone" on one end and "listening" for a strong tone on each wire on the other end?. This kind of devices typically work at around 800-1100 Hz frequency, most typically the systems us 900/1100 Hz "warble" signal(there are also systems that use different frequencies, for example 2 kHz). The main drawback of this system is that if you have cross-coupling between wires (there is always soem capacitive or inductive coupling between the wires because they co-exist in parallel with other wires in a cable!) then you have to "listen" for the strongest signal! Since the Human ear has a logrithmnic response curve to sound, it can be sometimes hard to accurately identify which is the strongest signal source. Same listening ideas with suitable frequency transmitter and receiver are used to locate the location of cables, pipes etc. inside wall and in land (the signal is in this case usually sent between ground and the cable wires, signal is picked up then capacitively or inductively depending on the application). There is another way to trace the right pair: Feed the signal to the pair you want to trace between the wires in the pair. Take the probe to the distribution device or telecommunications closet. When the probe is heldnear the pair carrying tone, the tone will be quite strong. (Some lesser volume may be picked up onadjacent leads or pairs, but this is normal.) The pair carrying tone can be verified by touching the tip of the probe across the leads. The tones will cease if that pair is the one carrying the tone.
If the wiring is used for Ethernet networking, then there are some procedures to check operation and performance of wiring by using just normal Ethernet equipment (computer and hub/switch). Most Ethernet devices for UTP cabling have a link indicator. If you have your computer wired to the bub/switch correctly, you should see link lights on both switch/hub lights and on you Ethernet card (if it has link light). When this is OK, it is a good idea to do network level tests. You can check network connectivity between individual stations in network using the "ping" command. Ping will transmit a single packet of data to another station and listen for a reply. To perform this tests you need to have at least two IP capable devices on your network, one being you computer and other being som eother computer or intelligent network device. Let's assume here that you have two computers. First, you need to identify the IP address of the two computers that you want to test. From a DOS window on a Windows 98 or Windows 2000 computer, type "ipconfig". The IP address, subnet mask and default gateway values will be displayed. On Linux/UNIX systems you have "ifconfig" command that tells those same things. Once you have the IP address of both machines, you can test the network connectivity between the machines using the ping command. For example, if one of the machines has an IP address of "192.168.0.5", you would run ping from the other machine as follows (works for Windows and Linux):
ping 192.168.0.5The result should be a list of replies listed each one on one line and in the end of those tests some results of test statistics. If the connection is not working you generally just get "Request timed out" responses. To test for a degraded or intermittent connection, run a continuous ping test with large data packets as follows (this is for Windows systems):
ping -l 1500 -t 192.168.0.5For Linux/UNIX system the same command is:
ping -s 1500 192.168.0.5Note that you have to press Cntrl-C to interrupt the test. If there are some timeouts during the continuous ping test, it is likely that your network connection is degraded.
Telephone lines are normally carried through telephone cables that have tenst to hundreds of wire pairs in it. What normally prevents the two signals from interfering with each other is the use of a "balanced circuit" and twisted pairs on the telephone cable. Balanced circuit condiguration combined with twisted pairs (different pairs in wire pair group having different twist rates) gives very good isolation between signals. The ability of that configuration to prevent interference depends on the cable pairs being very well balanced. Any imbalance, and other signals get mixed into your telephone connection. There are three "signals" that are usually strong enough to be detected first, when a cable become unbalanced for whatever reason. The number one is ringing current! The others are 60 Hz from power lines and the clicks from the 48 VDC loop voltage anytime a telephone goes on/off hook or uses pulse dialing. Other indications of an unbalanced line are actually hearing signals from the other lines! For example, the voice caller being able to actually hear the modem tones on the other line. The most likely causes are damaged house wiring, or use of the wrong type of cable for house wiring. Anything that causes the modem lines to be unbalanced will cause them to pick up "crosstalk" from the other lines. Examples would be defective telephone sets, corrosion on terminal, staples through the cable, broken insulation allowing contact with other wires or objects, kinks in the wire, and/or being damp. These are the "six signal killers" (corroded, wet/damp, bent/cinched, insulation problems, impedance/gauge/cable differentials, and bad termination.). Telephone people can measure them individually with suitable test instruments. Corroded wires give effects that fine-tuned transistor/diode testers pick up. Wet and badly terminated wires show up on capacitance. bent, Impedance/gauge and termination show op on inductance. This includes non-twisted lines. Insulation problems show up on current leak tests. All of this can be done with a good line tester; like a specialized multimeter and a few termination blocks and signal generators for the other end. It used to be part of a lineman's set; but now telephone companies usually send specialized crews with suitable special equipment that does all the tests in one go and writes a certification sticker.
Modern homes are nowadays filled with lots of electronic gadgetry.Currently there are more than 15 million homes with multiple PCs in USA alone.Computer networking, whole-house audio, home theater, video distribution, home controls and security systems are becoming increasingly commonplace.All of this electronic gadgetry requires proper wiring if the devices are to function in harmony. With homenetworking, their households receive the benefits of simultaneous, shared Internet access, printer/peripheral sharing, file and application sharing, and networked gaming. In addition, consumers can enjoy the use of each of these home entertainment and information services using existing wiring in the home.It is estimated that about 15-20% of new homes in USA are now (2002) being fitted with what the industry calls "structured" wiring, and perhaps 42% of new homes will be so equipped by 2004.This phenomenon isn't limited to new homes. It is surprisingly affordable to retrofit structured wiring systems into existing structures, thereby increasing their functionality as well as their value. A proper communications wiring system allows the home's electronic devices to work together.Wiring using structured cabling becomes (CAT 5 UTP) relevant in homes.It is extensively used in commercial applications and is finding its way into new homes to meet rising consumer demand. To build a home network, several conditions must be met. First, a home must be wired properly for a computer network. All cables are home runs back to a central location (star topology). And each room has sufficient outlets to support the desired applications and equipment. Next, each computer or peripheral to be connected to the network must have an Ethernet card, called an adapter, or a Network Interface Card (NIC). These cards connect to a computer or peripherals' bus (circuit board) and convert data into electrical signals for transmission through the network. Many computer products ship with such cards preinstalled. An Ethernet hub or switch is also required. Ethernet switch or hub is at the center of the network, the interchange point that permits data to flow among devices. The front of the hub or switch contains a number of RJ-45 connections, linked by an internal printed-circuit board electronics. Through the hub and its connected cabling, any computer on the network can talk to any other computer, compatible peripheral, or Internet service provider (typically through cable modem or ADSL router with Ethernet interface). With a hub the data sent by one computer is sent to all other computers in the network and they use it if they need. An Ethernet switch is a more advanced device that sends each part of data to only those devices that they are ment for, thus increasing the network speed and security in networks where there are many users in the network.There has been standardizing efforts on home wiring. TIA has published a standard EIA/TIA 570 "Residential Telecommunications cabling standard". This standard addresses the wiring for residential premises. It applies to telecommunications premises wiring systems installed within an individual building with residential (single family or multioccupant) end users. The standard was approved September 1, 1999 to standardize requirements for residential telecommunications cabling. The Cabling infrastructure specifications within this Standard are intended to include support for security, audio, television, sensors, alarms and intercom. This Standard is intended to be implemented for new construction, additions, and remodelled single and multi-tenant buildings.TIA-570-A is a comprehensive standard that provides expertly conceived models, recommendations and considerations, not only for cabling media types, but demarcation, topology, pathways, separation from sources of EMI, space requirements, distribution devices (DD), auxiliary disconnect outlets (ADO), equipment and patch cords, single or multi-tenant property layouts, link and channel performance criteria and field test requirements, among others. TIA-570-A establishes minimum "Grades" of Residential Cabling to serve today?s requirements and, more importantly, the more stringent demands of the future:
