How to choose the right ethernet cable for an installation

How to choose the right ethernet cable for an installation

The choice of the best Ethernet cable for an installation depends upon several factors, and it’s not always a given that the best cable is the fastest. Other factors need to be taken into account, including the Internet connection speed, the capabilities of connected devices and the cable lengths.

Cable Characteristics

The commonly available Ethernet cables range from Category 5 (Cat 5) to Cat 6a, although a higher specification Cat 7 cable is also available. Cat 5 and Cat 5e cables are designed to operate at 100 MHz and are suitable for Internet speeds up to 100 Mbps (100BASE-T). However, Cat 5e cable has lower crosstalk thanks to minor improvements in the manufacturing process and can also be used for 1 Gbps Internet.

Cat 6 cable has more stringent specifications than Cat 5e cable and is capable of operating at 250 MHz. It has slighter thicker wires, and the cores are more tightly twisted together. This means the cable is thicker and less flexible than Cat 5e cable. Its performance on 1 Gbps Internet is better than Cat 5e, and it’s suitable for 10 Gbps service to a maximum distance of 180 feet. Cat 6a cable has improved properties and can operate at 500 MHz and can support 10 Gbps (10GBASE-T) to a maximum distance of 328 feet. It should be noted that cable termination requirements for Cat 6 and 6a cable are stringent, and the cable requires better protection than Cat 5e cable.

Cat 7a cable is designed for extremely high Internet speeds of 40 Gbps and 100 Gbps, but is of limited application as the technology is still being developed.

Speed Limitations

Before selecting an Ethernet cable, it’s essential to establish the maximum capabilities of each piece of equipment because the actual speed will be determined by the slowest device. The actual speed of the Internet connection should also be verified because this is rarely as fast as advertised. Also remember that the link speed is influenced by the distance between switches.

Ethernet Cable Selection

The best Ethernet cable is the one that meets the current and anticipated Internet connection speeds at the lowest cost. Bear in mind that Cat 6a cable costs significantly more than Cat 5e cable and that installation requires more care and takes longer.

However, if the requirement is for ultra-fast Internet and the distance between switches exceeds 108 feet there’s no question that the best cable is a Cat 6a. But if the cable lengths are short, or the connection speed doesn’t exceed 1 Gbps, a Cat 5e cable is a better choice due to its lower cost, robust construction and easier installation. Although Cat 7 cables may offer superior performance, the additional cost doesn’t warrant their use except for very specialized applications.

Testing Ethernet Cables

The actual performance of Ethernet cable depends upon numerous factors including the cable specification, the quality of the installation and the connected devices. For this reason it is not sufficient to assume an installation will perform at the desired speed; its actual performance should be checked. This can be done using a specialized digital cable tester. T3 Innovation has three models that are suitable for this application. The Cable Prowler™ can measure the link speed, identify cable faults and poor connections and measure cable length. If additional testing requirements exist, the Net Prowler™ may be a better choice with its ability to ping IP addresses, discover VLANs and map networks. The additional ability of the Net Chaser™ to measure the signal-to-noise ratio and bit error rate gives installers additional capabilities to verify the performance of high-speed networks.