Socket rj-45: pinout, connection instructions, specifications

Despite the rapid development of wireless communications, RJ-45 sockets still remain indispensable elements of a structured cabling system in a modern building. We suggest considering their device, types, pinout options and installation methods. The apparent simplicity of the question can be misleading, since there are certain nuances that need to be addressed.


  1. Design Features
  2. Types and characteristics
  3. Pinout RJ-45
  4. Detailed connection instructions
  5. Some useful tips

Design Features

Despite the variety of types of sockets for twisted pair, their design is almost identical, with the exception of small details. For example, a typical external single-port device.

Elements of an external outlet RJ-45
Fig. 1. The main elements of an external outlet RJ-45


  • A - a plastic cover.
  • B is the base.
  • C - function board with a standard connector installed on it.
  • D - convectors for connecting twisted pair.
  • E - cable tie.
  • F - connector for the connector.

Outwardly, the socket resembles the telephone standard of RJ-11, the main difference is in the number of connector pins, there are eight, not four. Accordingly, a computer outlet can be used as a telephone, but not vice versa.

Different types of devices may have minor characteristics, but in general, the design concept remains unchanged.

Types and characteristics

The main parameters of these switching devices are determined by the following criteria:

  1. The number of ports.
  2. Category.
  3. Execution.

Briefly describe each of them.

More doesn't mean better.

One of the main parameters is the number of ports. As a rule, they can be from one to four. If you need to use a larger number of connections, it is easier to install a patch panel, but such a need indicates an ill-conceived network wiring. In addition, it should be borne in mind that a large number of patch cords connected nearby causes some inconvenience.

External Krauler Outlet
Fig. 2. 4-port external Krauler outlet

In practice, when organizing an office or home LAN, they mainly use one and two-unit modules.


This parameter is directly related to the characteristics of the cable used to install the computer network. We are talking about the bandwidth, on which both the data transfer rate and the ability to use special network technologies depend. The table below shows the relationship of the category with the bandwidth.

Dependence of the technical parameters of the cable on its category
Dependence of the technical parameters of the cable on its category

Currently, when installing a LAN, cables with a category below 5e are practically not used.

Keep in mind that the category of the outlet must be no less than that of the connected cable, otherwise there is a high probability of loss, which will negatively affect the transmission speed.


The method of mounting the switching device depends on this parameter. There are two options:

  • for external (external) installation (such sockets are shown in figures 1 and 2);
  • for indoor installation.
Two-port socket RJ-45 disassembled and assembled
Disassembled and assembled RJ-45 internal two-port socket

As a rule, the choice of one or another design depends on how the LAN wiring is performed. If it is external (for example, laid in boxes), external outlets are used. In cases where hidden wiring is performed, internal devices look more aesthetically pleasing.

Separately, it is necessary to highlight the sockets that are installed directly on the box. Technically, such a design can be considered both internal and external.

Double RJ-45 socket mounted on the box
Double RJ-45 socket mounted on the box

The performance does not affect the technical characteristics of the LAN.

Modular designs.

Speaking about the performance, one cannot but mention the modular designs. This solution allows you to assemble a socket in a standard case for a specific combination, for example, install it in RJ-45 and RJ-11 modules or with a different category.

Modular outlet
Modular outlet

Pinout RJ-45

There shouldn’t be any problems with this, since the opposite of each contact group is the color marking complying with T568A and T568B standards (can be marked with letters “A” and “B”, as in the figure below).

Marking in red for the T568A standard, in blue - T568B
Marking in red for the T568A standard, in blue - T568B

It doesn’t matter which standard is used, the main thing is that it be the same for the LAN, otherwise problems are guaranteed. It is believed that we have adopted the "crimp" type T568B, but this is a rather conditional statement.

If you do not know what standard your provider uses, then you can install it by pinout the connector installed on the cable entering the apartment.

Pinout RJ-45
Pinout RJ-45

Detailed connection instructions

Let's start with the tool that you will need to seal out sockets for twisted pair. Ideally, it is desirable to purchase a universal extractor (shown in Figure 9). It allows you to press and cut off the remainder of the wire in one motion. Thanks to Chinese manufacturers, such a universal tool costs about 3-4 dollars. The price of branded products can be 2-3 times more expensive.

Universal extractor
Fig. 9. Universal extractor

This tool has a special mechanism that allows you to press the wire between two contact knives and cut off its excess (3 in Fig. 9). In addition, it is equipped with a flat screwdriver (2) and a hook (1), which allows you to remove the wire in case of improper termination. The cost of a universal extractor is relatively small, and the benefits are quite tangible.

Universal mites for stripping insulation will be equally useful. They cost about the same as an extractor, they can cut a cable Ø3.5-9 mm type UTP, STP, FTP. It is possible to adjust the depth of cut.

Universal stripping pliers
Universal stripping pliers

It is undesirable to use a knife to remove insulation, since in this case there is a high probability of damage to one of the twisted pair cores.

Having dealt with the necessary tool, we will move on to the algorithm for plugging the twisted pair into the switching device. We will proceed from the fact that the cable is already laid, the seat for the outlet is prepared. The procedure is as follows:

  1. Using universal pliers, we cut off the layer of external insulation from the end of the wire. It is enough to expose 4-5 centimeters. You need to act carefully so as not to damage the veins. If this happens, cut the damaged area, adjust the incision depth and repeat the operation.
  2. After stripping, level each pair. Please note that there is no need to clean them. Each contact of the site has special micro knives that cut the insulation and provide reliable contact and fixation of the wire.
  3. Disassemble the outlet. To do this, remove the front panel. To do this, you need to unscrew the fixing screw or unfasten the special latches (depending on the design). If a modular socket is used, then modules must be removed from it.
  4. We fix the cable on the module with a cable tie (E in Fig. 1) or in another manner provided by the design.
  5. We insert the wires into the clamps, while it is necessary to adhere to the color marking of the selected standard. Do not try to deeply drown the veins, just fix them with a little effort (A fig. 11).
  6. Using the extractor, we press in (In Fig. 11).
A - cable with wires separated by clamps, B - press-fit with extractor
Fig. 11. A - cable with wires separated by clamps, B - press-fit with extractor

At this stage, we will make a small digression regarding the use of improvised tools for mounting. Sometimes you can find tips in which, in the absence of the necessary tool for pressing, it is recommended to use a clerical knife or a thin slotted screwdriver. This approach can be applied only in the most extreme case, when access to the network is urgently needed, but there is no tool at hand. But in the future, such a socket must be squeezed. Otherwise, there is a high probability of loss of contact of the wire with the clamp after a while.

Also note that many branded manufacturers attach a simple plastic to each outlet an extractor that allows you to reliably seal the wire, after which it remains only to carefully cut it surplus.

  1. After mounting the module is installed in place. If the outlet is external, then its base is screwed to the prepared site, so that the cable is supplied from above and the connector for the connector is from below. When installing an internal outlet, its base is installed in the prepared glass and fixed in it.
  2. We fasten the front panel, after which we check the operability. This can be done using a special tester, but it’s easier to connect a computer and check for a network connection. If problems arise, first of all check the correct pinout, as practice shows, in 90% of cases the reason lies precisely in this.

Some useful tips

When using a shielded cable, you must install the appropriate outlet, which has a screen connection. Otherwise, it turns into a large antenna, which will not slow down to affect the bandwidth, and, consequently, the data transfer speed. For the same reason, you should not use an STP or FTP cable if ungrounded equipment is connected to it.

Twisted pair LAN technology requires the use of integral lines. Twisting, adhesions are unacceptable, this leads to serious losses. If nevertheless there is a need to increase a piece of cable, special connectors should be used for this purpose.

Twisted Pair Connectors
Fig. 12. Twisted Pair Connectors

These devices are a box in which a board with two RJ-45 connectors is installed (A in Fig. 12), or with clamps for twisted pair, as with sockets (B in Fig. 12).

It is not recommended to use sockets with more than two ports in a domestic environment. A large number of patch cords in one place will cause them to become confused. It is better to spread the sockets at some distance.

Similar articles:
  1. What should I do if the outlet sparks?
DIY twilight switch: instructions, diagram

DIY twilight switch: instructions, diagramSockets And Switches

To turn on the light on the street or in public places very often a complete automation of the process is required. The twilight switch with a photocell completely eliminates the human factor when...

Read More
Light switch: types, do-it-yourself connection, schemes

Light switch: types, do-it-yourself connection, schemesSockets And Switches

To control lighting systems, it is necessary to use special devices. A remote light switch with a remote control and a classic contact option are necessary devices in an apartment and a private ho...

Read More
DIY cotton light switch

DIY cotton light switchSockets And Switches

Lighting can be controlled not only with the help of classic switches, but also using special modules that allow you to remotely turn on or off the light. A cotton light switch refers specifically...

Read More