Rj45 Twisted Pair Cable Pinout And An Overview Of Proper Crimping Technology

Internet cords, like other technical accessories, fail at the most inopportune moment. But if you have the crimping skills, a new connector and the right tool, the problem can be fixed in a few minutes.

Another difficulty is that Internet wires are multi-core, with 4-pair cable being the most common. Therefore, in addition to practical skills, you will need the correct RJ-45 pinout - a suitable color scheme. If you make a mistake with the conductor pinning, you could be left without internet.

In this material we will tell you about the features of twisted pair and give some crimp diagrams of the cable.

Article contents:

  • Peculiarities of twisted pair
  • Standard crimp diagrams
    • Option #1 - straight 8-conductor cable
    • Option #2 - 8-conductor crossover
    • Option #3 - straight 4 conductor cable
    • Option #4 - 4 conductor crossover
  • How to crimp RJ-45 cable correctly?
    • Selection and preparation of tools
    • Step-by-step instructions for crimping
  • Conclusions and useful video on the subject

Properties of twisted pair

A typical electric wire such as VVGng 3*2.5 consists of three cores. This can be understood by removing the upper plastic jacket. A twisted pair (in other words, a network wire, RJ-45 cable) may consist of one pair of wires, as well as several.

Usually ready-made patch cords are used - sections of cable of standard length (on average from 0.3 m to 30 m). The factory-made cord is crimped on both sides with connectors - small 8-pin plugs that can be plugged into an Internet socket, a connector on a router, PC, TV and other equipment.

RJ45 twisted pair cable pinout and an overview of proper crimping technology

Wire cables and multi-core cables are available for home use but the latter are used more often. Twisted pair is available in coils and sold by the meter

But a piece of pre-crimped cable is also useful: for example sometimes it is necessary to run the cable through a small hole in the wall up to 5 mm. Crimping in this case is done after installation.

Characteristics of an RJ-45 internet wire which may be useful:

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The conductors are generally made of copper or copper-plated aluminum. Each is insulated with a thin colored sheath. For added protection, the wires are twisted in pairs and placed in another insulation, an outer, denser one. Besides, shielding from Teflon or metal braid, foiling can be applied

The color of the outer insulation can determine the cable destination: gray - for indoor use, orange - for fire-hazardous areas, black - for outdoor use. But now on sale appeared ready-made patch cords all colors of the rainbow - the category and other characteristics can be determined by alphanumeric marking

All network wires by the number of copper conductors are commonly divided into two categories: single core and multi-core. With single-core, each wire is a monolith with a thickness of 0.3 to 0.6 mm, brittle and not flexible. All multicore conductors are bundles of very thin conductors that do not break when bent or twisted

Internet cable without protection - UTP is used for the home. But if you want to throw it through a window or lay in the general corridor, it is better to take FTP - foil or STP - with a metal braid. There are the most protected wires, with shielding of each strand, but they are much more expensive, and it is not reasonable to use them in the home

Copper core and plastic insulation

Color coding of the outer insulation

Number of cores in one cable

The way the Internet cable is shielded

The bandwidth of the RJ-45 cable is determined by the category. There are 10 categories in total - 7 main categories and 3 subcategories. The first four categories are recognized as obsolete because they do not support the necessary data rates.

RJ45 twisted pair cable pinout and an overview of proper crimping technology

The most popular is category 5e, which can consist of 2 or 4 pairs of conductors. This is a more flexible and thinner cable than its predecessor, Category 5 Class D

Virtually all the information you need about the cable is placed on the outer sheath. Labels vary from manufacturer to manufacturer, but characteristics such as category, brand code, shielding method (or lack thereof), number of pairs, and standard are usually specified.

The other types of cables which are used for the Internet connection can be found in our other article.

Standard crimping schemes

The twisted pair and connector installation fall within the scope of the international standard EIA/TIA-568 which describes the procedure and rules for the switching of domestic networks. The choice of crimping scheme depends on the intended use of the cable and the characteristics of the network - for example, the bandwidth.

RJ45 twisted pair cable pinout and an overview of proper crimping technology

Thanks to the transparent connector housing, it is visible that the conductors are placed in a specific order, not at random. If a pair of conductors is mixed up, the commutation is broken

Other types of cables - of 4 or 8 cores - can be crimped in a straight or cross-over way as well as type A or type B.

Option #1 - straight 8-conductor cable

The straight crimp method is used when two devices are to be connected:

  • PC, printer, copier, TV on one side;
  • Router, switch on the other side.

The same crimping of both ends of the wire is considered a special feature and for this reason it is called the direct method.

There are two interchangeable types: A and B. In Russia the type B is typical.

RJ45 twisted pair cable pinout and an overview of proper crimping technology

The pinout diagram of an 8 wire cable for the direct connection of a computer with a switching device (HAB, SWITCH). The first position has an orange and white wire

In the United States and Europe, on the other hand, Type A crimping is considered more common.

RJ45 twisted pair cable pinout and an overview of proper crimping technology

Type A differs from type B in the positioning of the conductors located in positions 1,2,3 and 6, i.e. white/green interchanged with white/orange

You may crimp both ways and data transmission will not suffer. The main thing is to observe the wire order.

Choice #2 - 8 wire crossover

Cross-crimping is used less often than direct crimping. It is needed when two desktop computers, two laptops or two switching hubs need to be connected.

Crossover is used less and less often as modern equipment is able to automatically detect the cable type and change the signal if needed. The new technology is called auto-MDIX. However, some home devices have been working properly for years and there is no point in changing them, therefore a crossover crimp can also be useful.

Crossover crimping retains the possibility to use types A and B.

RJ45 twisted pair cable pinout and an overview of proper crimping technology

Crossover circuit, designed for high speed network equipment (up to 10 gbit/s), made with type B. All 8 wires are engaged and the signal goes in both directions

To engage type A the same 4 positions have to be interchanged: 1, 2, 3 and 6 - white/green with white/orange.

For networks with lower data rates 10-100 mbit/s the rules are different:

RJ45 twisted pair cable pinout and an overview of proper crimping technology

Type B circuit. The two pairs of twists, white/blue and white/brown/brown, are connected directly, without crossing

The Standard A circuit is exactly the same as B, but in a mirror image.

Option #3 is a straight 4-wire cable

While an 8-wire cable is required for high-speed data transmission (e.g. Ethernet 100BASE-TX or 1000BASE-T), a 4-wire cable is sufficient for \"slow\" networks (10-100BASE-T).

RJ45 twisted pair cable pinout and an overview of proper crimping technology

The 4-wire network cord crimp diagram. Usually two pairs of conductors are used - white/orange and white/green/green, but sometimes two other pairs are used

If the cable has failed due to a short circuit or a wire break, free conductors may be used in place of the used ones. To do this cut the connectors and crimp two pairs of other wires.

Option #4 - 4 Wire Crossover

Crossover crimping also uses 2 pairs, and any color of twist can be chosen. Traditionally, green and orange conductors are often chosen.

The 4-wire crossover crimp circuit is used very rarely, mostly in home networks if you want to connect two old computers. The choice of core color has no effect on the quality of the data transfer.

How to crimp an RJ-45 cable correctly?

There are various ways to crimp an RJ-45 cable, among which you can even crimp the connector without special pliers, using an ordinary flathead screwdriver.

But we will look at how to correctly make a reliable and functional working patch cord with the same features as the bought-in models.

Selection and preparation of tools

Having a set of special tools at hand, it is much easier to crimp the patch cable. Of course, you will have to allocate a sum for the purchase of a crimper, stripper, tester or crosser, but if you buy a quality tool it will last for years.

To correctly fasten the connectors on the cable you will need:

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There are different kinds of crimper, but it is advisable to buy universal, that is designed to crimp several kinds of connectors simultaneously: RJ-45, RJ-11, RJ-12. With the multi-position crimper with different socket sizes you can work not only with network but also with telephone wires

Stripper helps remove the plastic jacket conductors, without damaging the strands. An ordinary construction or office knife is more difficult to do this, because you need to distribute the force and act very carefully. The only disadvantage - it is not suitable for cutting foil and shielded cables

Tester for twisted pair consists of two modules with sockets. To test the network cable you need to connect one end to the main module master, the second end to the remote remote. The indicators on the front panel will signal a green light if the conductors are correctly located and a red one if the cores are mixed up

The tool is a blade with a handle. It is equipped with a small hook for extracting wires. The cross-connector is not necessary directly for crimping, however it will be useful if you need to connect the cable to a network socket, plinth, crossbar or patch

Twisted pair crimping pliers - crimper

Insulation remover - stripper

Tester for diagnostic cables

Cutting tool

The main tools listed are the pliers and the tester - this is the minimum set, necessary for the correct unsoldering and crimping of a twisted pair.

Buying the pliers you must check their quality and it is advisable to test the tool beforehand.

Step instructions for crimping

To make a patch cord you must prepare the materials - cable and connectors, arm yourself with a tool and select a pinout scheme depending on the devices that will connect the finished cord.


  • a piece of twisted pair no longer than 100 m - according to the Ethernet pinout this is the maximum length of the standards for domestic use;
  • for one cable, two RJ-45 connectors (marked 8P8C);
  • a tool kit - crimper, stripper, tester.

The cable most often needed to connect the PC to the network device, so remember the direct crimping diagram, and for safety just put it in a prominent place, to be visible at the moment of wire distribution.

RJ45 twisted pair cable pinout and an overview of proper crimping technology

The finished color chart may be found on the Internet and printed on a piece of paper - the visual perception helps to remember and it is not needed anymore

Lest we forget that types A and B differ only in the position of the orange and the green strand, both variants may be applied.

Step-by-step instructions:

  • Step 1 - Cut a piece of cable to length, not overcut but long enough with wire cutters or crimper blades.
  • Step 2 - Cut 2-4 cm from the end, make a circular cut on the outside insulation with a wire cutter and then remove carefully.
  • Step 3 - The conductors are twisted in pairs, so before crimping untwist all pairs, straighten the cores and distribute them according to the chosen scheme. Except for the conductors there is a nylon strand underneath the jacket - just pull it back.
  • Step 4 - Trim the conductors. To do this, step back from the edge of the outer insulation 1.0-1.3 cm and cut the wires with wire cutters strictly perpendicular to the axis of the twisted pair. Make sure that the different colored tips are the same length.
  • Step 5 - Insert the conductors in the connector and push to the stop.
  • Step 6 - Crimp: insert connector with conductors in the right crimper socket (marked 8P) and squeeze the pliers handles. You may hear a click.
  • Step 7 - Check that it is firmly attached by lightly pulling the cable as if trying to pull the conductors out of the connector. If squeezed correctly the wires fit firmly.
  • Step 8 - Test the ready made patch cords for proper functioning. Insert the connectors in the sockets of the tester, switch on the device and watch the indication. If everything is OK, the lights will be green in pairs. If there is no indication or the light is red, the procedure has to be repeated.

The hand is built up quickly - after several crimps by itself. Crimping skills come in handy when you move into a new apartment, where the network wires are hidden in baseboards or sewn into the walls and plugged into computer outlets.

No need to worry if the cable is too long or short - you can always crimp a patch cord to the right length. If a dog bites or if the mains wire just kinks, it can be repaired quickly.

You might also be interested to see how you can connect the twisted pair to each other, follow this link.

Conclusion and useful video on the subject

Brief video instruction:

Category 5 and 6 Crimp Cable, what is the difference:

When no professional tool is available:

Knowing the twisted pair pinout you can quickly crimp a patch cable according to its purpose. This skill is useful for any personal equipment user, as it allows to react quickly to a broken signal in the local network - to replace the network cable completely or to make small repairs.

Any questions about twisted pair pinout? Please ask in the comment box and we will try to explain very clearly what you do not understand.


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