computer room cabling installations
sypplying of cables

Cable Installers - Different Cables

Interesting Information On different Cables:

Datacom Computer Cabling are specialised cable installers.

Ethernet Plug:

Each eight-conductor data cable (cat 5) contains 4 pairs of wires. Each pair consists of a solid colour wire and a white wire with the same colour binder. Each of the pairs is twisted together. To maintain reliability on Ethernet, you should not untwist them any more that centimetre.

The pairs designated for 10 / 100 Base T Ethernet are orange and green. The other two pairs, brown and blue, are unused unless running Gigabit Ethernet. The connections shown are specifically for an R1, 45 plugs, used on a patch cord. Solid core wire should not be used for patch cords, as it will break more easily when bent or kinked.

There are two wiring standards for these cables, called T -5684 and T -568B. They differ in pin assignments. The illustration shows both standards. With the T-568A specification reserves the orange and green connections, so that the blue and orange pairs are on the centre 4 pins, which makes it more compatible with Telco voice connections.

T-568A is supposed to be standard for new installations and
T-568B in the alternative.



Pin Number Designations:

In LANS, as specked by 568, there are two possible pin outs, called T568A and T568B, that differ only in which colour coded pairs are connected- pair 2 and 3 are reversed.

Jack Pin Colour Pair Description

1 White/ Green 3 Recvdata +
2 green 3 Recvdata –
3 white/orange 2 TxData +
4 blue 1 unused
5 White/blue 1 unused
6 Orange 2 Txdata –
7 white / Brown 4 unused
8 brown 4 Unused

Jack Pin Colour Pair Description

1 white/ Orange 2 TxData +
2 Orange 2 TxData –
3 white/green 3 RecvData
4 Blue 1 Unused
5 White / Blue 1 unused
6 Green 3 Recvdata –
7 White / Brown 4 Unused
8 brown 4 Unused

Straight - Through vs. Cross- Over Cables:

In general, the patch cords that you use with your Ethernet connections are “straight-through”, which means that pin 1 of the plug on one end is connected to pin 1 of the plug on ether end ( for ether standard ). The only time you cross connections in 10BaseT Is when you connect two Ethernet devices directly together without a hub or connect two hubs together. Then you need a “Cross-Over” patch cable, which crosses the transmit and receive pairs. An easy way remembers how to make a cross-over cable is to wire one end with T-568A standard and the other with T-568B standard.

Cat 5E OR Ethernet Termination:

Unshielded twisted pair cables are terminated with standard connectors, Jacks and Punch Downs. The plug is often referred to as a “RJ-45”, the plug is often referred to as a “ RJ – 45”, the male connector on the end of a patch cord called a “ Plug” and the receptacle on the wall outlet is a “Jack” .

The cable pairs are colour coded as follows:

- Pair 1 is white – blue/ blue,
- Pair 2 is white –orange / orange,

Pair 3 is white-Green / Green

- Pair 4 is White-Brown/ Brown

Jacks usually have punch downs on the back or can be terminated without punch downs using special manufacturer’s tools or even a cover for the connector. Again, you must keep the twists as close to the receptacle as possible to minimize cross talk.

Note Cat 3 jacks and all plugs are going to use these colour codes. However, Cat 5 jacks have internal connections that continue the twists as close to pins in the jacks as possible. Thus the pin out on the jacks will not usually follow these layouts!

Always follow the colour codes on the back of the Jacks to insure proper connections!

Crossover Cables:

Normal cables that connect a PC/NIC card to a hub are wired straight through. That is pin 1 is connected to pin 1, Pin 2 to pin 2, etc. However, if you are simply connecting two PC’s together without a hub, you need to use a crossover cable made by reversing pair 2 and 3 in the cable, the two pairs used for transmission by Ethernet. The easy way to make a crossover cable is to make one end to T568A colour coding and the other end to T568B. Then the pairs will be reversed.

Punch Downs:

Punch Downs come in 4 varieties: 110, Bix, 66 and Krone. The most popular termination style for Data cabling is the 110 punch down. For telephone cabling is the Bix Block. The 66 Block is the old style bix termination, & the Krone style is rarely used in North America.

Colour Codes for Punch Downs:

Punch downs of all types are always with the pairs in order with the White/ Stripe wire first, then the collared wire, Pair 1 (w/blue – blue), Pair 2 ( w/ range – orange), Pairs 3 ( w/Green – Green), Pair 4 ( W/ Brown – Brown). This colour code is remembered by BLOG- Blue, Orange, Green and Brown.

Fibre Optic Cabling:

Datacom Computer Cabling cc has been, installing fibre optic cabling since 1990. We offer a variety of fibre optic cabling solutions: indoor, outdoor, loose tube, tight buffered. Do you require a high – speed backbone? Or point –to-point installations within a building complex? Would you like to run fibre to the desktop? Let our professionals guide you through your fibre optic cabling installations. We would be happy to perform a complimentary site survey.

In recent years it has become apparent that fibre –optics are steadily replacing copper wire as an appropriate means of communication signal transition. They span the long distances between local phone systems as well as providing the backbone for many networks systems. Other system users include cable television services, university campuses, office buildings, industrial plans, and electric utility companies.

Fibre-optics use light pulses to transmit information down fibre lines instead of using electronic pulses to transmit information down copper lines. Looking at the components in a fibre-optic chain will give a better understanding of how the system works in conjunction with wire based systems.

At one end of the system is transmitter. This is the place of origin for information coming on to fibre-optic lines. The transmitter accepts coded electronic pulse information coming for copper wire. It then process and translates that information into equivalently coded lights pulses. A light emitting diode (LED) or an injection – Laser diode (ILD) can be used for generating the light pulses. Using a lens, the light pulses are funneled into fibre –optic medium where they transmit themselves. Using a lens, the light pulsed are funneled into fibre-optic medium where they transmit themselves down the line. Think of a fibre cable in terms of a very long tube that is coated with a mirror. If you shine a flashlight in one end you can see light at the fair end; even if the tube has a bend in it.

Light pulses move easily down fibre optic line because of a principle known as total internal reflection. “This principle of total internal reflection states that when the angle of incidence exceeds a critical value, light cannot get out of the glass.; instead, the light bounces back in. When this principle is applied to the construction of fibre-optic strand, it is possible to transmit information down fibre lines in the form of light pulses.

For more information on our data installers or other services such as ups installation, contact us.

Types of Fibre Optic Cables:

These are three more types of fibre optic cable commonly used:

- Single Mode
- Multimode
- Plastic Optical Fibre ( POF)

Fibre optic cable functions as a “Light Guide” guiding light introduced at one end of the cable through to the other end. The light source can either; the light- emitting diode (LED) OR A LASER. The light source is pulsed on and off, and a light sensitive receiver on the other end of the cable converts the pulses back into the digital; ones and zeros of the original signals. Even laser light shinning through a fibre optic cable is subject to loss of strength, primarily through dispersion and scattering of the light, within the cable itself. The faster the laser fluctuates, the greater the risk of dispersion. Light strengtheners, called repeaters may be necessary to refresh the signal in certain applications. While fibre optic cable itself has become cheaper overtime – a equivalent length of copper cable cost less per foot but not when you factor in the bandwidth capacity. Fibre optic cable connectors and the equipment needed to install them are still more expensive than their copper counterparts.

Single Mode Cable:

Single Mode cable is a single strand of glass fibre with a diameter of 8.3 to icons that has one mode of transmission. Single Mode fibre with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth that multimode fibre but requires a light source with a narrow spectral width. Synonyms mono-mode optical fibre gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-Mode fibre has a much smaller core that multimode. The small core and single light –wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least attenuation and the highest transmission speeds of any fibre cable type. Single-Mod3e optical fibre in witch only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320mm

Multimode Cable:

Multimode cable is made of glass fibres, with common diameters in the 50 – to-100 micron range for the light carry component (The most common size is 62.5). POF is a newer plastic-based cable, which promises performance similar to glass cable on very short runs, but at a lower cost. Multimode fibre gives you high bandwidth at high speeds over medium distances. Light waves are dispersed into numerous paths or modes , as they trough the cables care typically 850 or 1300mm. Typical multimode fibre core diameters are 50,62.5 and 100 micrometers. However, in long cable ruins (Greater then 3000 feet {914.4ml), multiple paths of light can cause signal distortion at receiving end, resulting in an unclear and incomplete data transmission.

The use of fibre-optics was generally not available until 1970 when Corning Glass Works WAS ABLE TO PRODUCE a FIBRE WITH a LOSS OF 20dB/Km. It is recognized that optical fibre would be for telecommunication transmission only if glass could be developed so pure that attenuation would be 20dB/Km or less. That is, 1% of the light would remain after traveling 1 Km. Today’s optical fibre attenuation ranges from 0.5B/Km to 1000B/Km depending on the optical fibre used. Attenuation limits are based intended application.

The applications of optical fibre communications have increased at a rapid rate. Since first commercial installation of a fibre optic systems with optical fibre lines. Today’s telephone companies use optical fibre throughout their system as backbone architecture and as long-distance connection between city phones.

Cable television has also begun integrating fibre-optics into their cable systems. The trunk lines that connect central offices have generally been replaced with optical fibre. Some providers have begun experimenting with fibre tot the curb using a fibre/coaxial hybrid. Such a hybrid allows for the integration of fibre and coaxial at a neighborhood location. This location called node, would provide the optical receiver that converts there light impulses back to electronic signals. The signals could then be fed to individual homes via coaxial cable.

Local Area Networks (LAN) is a collective group of computers, or computers, or computer systems, connected to each other allowing for shared program software or databases. Colleges, Universities, office buildings, and industrial plants, just name a few, all make use of optical fibre within their LAN systems

Step-Index Multimode Fibre:

Has a large core, up to 100 microns in diameter. As a result, some of the light rays that make up the digital pulse may travel a direct route whereas others zigzag as they bounce off the cladding. These alternative pathways cause the different groupings of light rays , referred to as modes, to arrive seperately at a receiving point. The pulse, an aggregate of different modes, begins to spread out, losing its well-defined shape. The need to leave spacing between the pulses to prevent overlapping limits the bandwidth that is, the amount of information that can be sent. Consequently, this type of fibre is best suited for transmission over short distances, in endoscopes for instance.

Graded-Index Multimode Fibre:

Contains a core in which the refractive index diminishes gradually from the centre axis out toward the cladding. The higher refractive index at the centre makes the light rays moving down the axis advance more slowly than those near the cladding. Also, rather than zigzagging off the cladding, light in the core curves helically because of the graded index, reducing its travel distance. The shortened path and the higher speed allow light at the periphery to arrive at a receiver at about the same time as the slow but straight rays in the core axis. The result: a digital pulse suffers less dispersion.

Single-Mode Fibre:

Has a narrow core (eight microns or less) and the index of refraction between the core and the cladding changes less than it does for multimode fibres. Light thus travles parallel to the axis creating little pulse diversion. Telephone and cable television networks install millions of kilometres of this fibe every year.

Loose Tube vs Tight buffered Fibre Optic Cables:

Loose tube cables, the older of the two cable types, are specifically designed for harsh outdoor environments. They protect the fibre core, cladding and coating by enclosing everything within semi-rigid protective sleeves or tubes. In loose-tube cables that hold more than one optical fibre, each individually sleeved core is bundled loosely within an all-encompassing outer jacket.

Many loose-tube cables also have a water-resistant gel that surrounds the fibres. This gel helps protect them from moisture, so the cables are great for harsh, high humidity environments where water or condensation can be a problem. These gel-filled tube can expand and contract with temperature changes. Gel-filled loose-tube cables are not the best choice when the cable needs to be submerged or when it is routed around multiple bends because excess cable strain can force fibres ro emerge from the gel.

Tight-buffered cables, in contrast, are optimised for indoor applications. Because they are sturdier than loose-tube cables, they are best suited for moderate-length LAN/WAN connections, long indoor runs and even direct burial.

Instead of a gel layer of sleeve to protect the fibre core, tight-buffered cables use a two-layer coating. One is plastic, the other is waterproof acrylate. The acrylate coating keeps moisture away from the cable, like the gel filled sleeve does for loose-tube cables. The acrylate later is bound tightly to the plastic fibre layer, so that the core is never exposed (as it can be with gel-filled cables) when the cable is bent or compressed underwater.

Tight-buffered cables are easier to install because there is no messy gel to clean up and they don't require a breakout kit for splicing or termination. You can crimp connectors directly to each fibre saving valuable time and labour.

Wall Mount Cabinets

Datacom Computer Cabling provides a wide variety of Wall Mounted Cabinets

Wall mounted cabinets / Swing out cabinets provides 19" rack mounting in a distribution panel enclosure. A simple finger pushing "push-pull" type catch located inside the acbinet opens the 18.00" deep centre swing section. The centre swing out feature provides outstanding front and rear access to cables and equipment.

The reversible cabinet mounting design makes left or right hand swing possible. This is convenient when conserving valuable wall space. Front and rear sections lock independently for added security.