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How to choose the network POE switch cable

The non-standard network cable materials in the market mainly include copper clad steel, copper clad aluminum, copper clad iron, etc. These cables have large resistance values and are not suitable for POE power supply. The POE IEEE 802.3af standard requires that the output power of the PSE output port be 15.4W or 15.5W. The PD device receiving power after 100 meters transmission must be no less than 12.95W.


According to the 802.3af typical current value of 350ma, the resistance of the 100m network cable must be (15.4-12.95W) / 350ma = 7 ohms or (15.5-12.95) / 350ma = 7.29 ohms.

The standard network cable is natural to meet this requirement, because the IEEE 802.3af poe power supply standard itself is based on standard network cable. The reason why the POE power supply network cable is required is that many network cables on the market are non-standard network cables, and are not strictly produced according to the requirements of standard network cables.

Which network cable is most suitable for POE power supply?

The POE power supply must use a network cable made of oxygen-free copper, that is, a standard network cable.

The network cable must be connected to the network cable according to the standard of 568A or 568B. Eight wires must be connected, and the length is required to be within 100 meters. The better the quality of the network cable, the higher the transmission stability, at least the super five network cable. If the budget cost is sufficient, you can choose the 6 types of network cable with longer transmission distance and better effect.

inside the cable

Super five line:

The Super Category 5 line has the advantages of low attenuation, low crosstalk, and higher attenuation crosstalk ratio (ACR) and signal-to-noise ratio (Structural Return Loss), and smaller delay error. The Super Category 5 cable is mainly used for Gigabit Ethernet (1000 Mbps).

Category 6 line:

The transmission frequency of this type of cable is from 1MHz to 250MHz. The Category 6 cabling system has a large margin in the integrated attenuation crosstalk ratio (PS-ACR) at 200MHz, which provides twice the bandwidth of the super five. The transmission performance of Category 6 cabling is much higher than the Category 5 standard and is best suited for applications with transmission rates above 1Gbps.

Another important difference between the six categories and the super five categories is:

Category 6 lines improve performance in terms of crosstalk and return loss, and excellent return loss performance is extremely important for a new generation of full-duplex high-speed network applications. At the same time, the basic link model is eliminated in the six standards. The wiring standard adopts a star topology. The required permanent link length of the wiring distance cannot exceed 90 m, and the channel length cannot exceed 100 m.

How to identify the true and false of the network cable?

1, look at the material

Network cable material corresponding to resistance, POE transmission distance

A. Pure copper, low resistance, suitable for POE power supply, long distance power supply

B. Aluminum wire resistance short-range POE power supply

C. Copper clad aluminum wire, large resistance, short distance POE power supply

D. Copper clad wire, large resistance, not suitable for POE

E. Iron core wire, large resistance, not suitable for POE power supply

F. Mixed wire, large resistance, short distance POE power supply


2, look at the logo of the network cable

Network cable identification and transmission bandwidth

A,  The third type of line CAT3 10M is suitable for 10M network has been basically eliminated

B,  Category 5 line CAT5 100M is suitable for networks below 100M

C,  Super Category 5 CAT5E 155M mainstream product, suitable for POE power supply

D,  Category 6 line CAT6 250M is used to set up Gigabit network, suitable for POE power supply


3, look at the feel

In addition to seeing, you can also feel the difference between the material of the true and false type 5/super 5 line by touching. True 5/Super 5 line texture is relatively soft, mainly to adapt to different network environment needs. Twisted pair cables generally use copper wire as the wire core, which is relatively soft, because some network environments may require the cable to be bent at a small angle. If the wire is hard, it is easy to cause an open circuit. In order to reduce the cost, some unscrupulous manufacturers add other metal elements to the copper in order to make the wires harder, less flexible, and easy to break during use.

4, with a knife

Use a pair of scissors to remove the plastic wrap from the outside of a small line to expose the four pairs of core wires and watch the core wires. True 5/Super 5 line 4 pairs of white in the core should not be pure white, but with the pair of core colors of the white, this is mainly for the convenience of users in the production of crystal The first time distinguishes the pair. The fakes are usually pure white or the color is not obvious.

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