Confused About Cabling?

At Solwise we sell a lot of Ethernet cable but sometimes there is some confusion about which cable is suitable for a particular job, so this short article will aim to answer the common questions such as when should I be using Cat6 over Cat5? How far can I run Ethernet cable for PoE? What is the difference between Solid-Core and Stranded cable?

What Is Ethernet Cable?

When we talk about Ethernet cable, we are actually referencing the Ethernet standard but within that standard, there are further categories of cable; Cat5e, Cat6, Cat6a, etc, that dictate the twisted-pair cabling inside that provides the connectivity. More specifically, the two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility.

This is an advantage over using a single conductor or an untwisted balanced pair because the twisted pair reduces the electromagnetic radiation from the pair and any crosstalk between any neighbouring pairs. As a result, this improves rejection of any external electromagnetic interference. This means the cable is protected from any other electrical sources nearby, although it is a common myth that you cannot run Ethernet cables alongside mains power lines.

Since Ethernet cable uses copper wiring as the base, the maximum distance you can run a single length of Ethernet cable is 100m. This limitation only really becomes a problem if you want to power a device using PoE (Power over Ethernet), as it is unlikely you would have a distance between two switches of more than 100m, in that case, it might be better to use Fibre cable that can be run for several kilometres.

The standard for PoE states that it has a maximum distance of 100m, although our recommendation would be to use a length no longer than 80m. You also have to consider that the longer the cable, the more loss will occur on the cable, i.e. the less power (Watts) is likely to reach the other end.

In other words, if you have 30 Watts at the start of the cable, there is no guarantee that you will still have 30 Watts at the other end of the cable, so if you have a device that requires 24 Watts, for example, a Wi-Fi 6 (802.11ax) access point, you may find that the unit will not power. In this case, you would either use a shorter cable or a PoE extender.

What Is Stranded and Solid-Core Cable?

Solid-Core Stranded

A solid-core cable will use one solid wire per conductor, so in a four-pair cable there would be a total of eight solid wires.

It is also designed to be used in permanently installed runs, mainly because it is less flexible than stranded cable and more prone to breaking if the cable is repeatedly flexed.

A stranded cable uses multiple wires that are wrapped around each other in each conductor, so in a four-pair with seven strands per conductor cable, there would be a total of 56 wires.

It is designed to be used for fly leads at patch panels or for connecting wall ports to end devices. It has the advantage of resisting the cracking of the conductors.

Another consideration is connectors, more specifically the RJ45 connectors, because both solid-core and stranded cabling have unique connectors, and using the incorrect connector type can lead to unreliable cabling.

Categories of Ethernet Cabling

Category Description

Category 5 cable or Cat5 is a twisted pair cable used typically for networking. The current standard is Cat5e that provides performance of up to 100Mhz and is typically used for Ethernet over twisted pair for up to 1000BASE-T or Gigabit Ethernet. Cat5e should not be confused with Cat5 that was made largely obsolete in 2001. Cat5 only supported 100BASE-T or Fast Ethernet.

Cat5e will provide PoE power over a distance of 100m according to the PoE standard.

Cat6 is a twisted pair cable that improves upon Cat5e, providing a performance of up to 250Mhz, and can also be used for 1000BASE-T or Gigabit Ethernet. However, Cat6 can also support 10GBASE-T or 10Gigabit Ethernet, although only over a distance of 55m.

Cat6 provides PoE over a distance of 100m.  Most Cat6 is shielded.

Cat6a improves upon Cat6, and provides performance of up to 500Mhz due to improved alien crosstalk. Cat6a cabling can run 10GBASE-T or 10Gigabit Ethernet over the same 100m as previous Ethernet variants.

Cat6a also provides PoE power over a distance of 100m. Most Cat6a is shielded.

Category 7 or Cat7 is an improvement upon Cat6a, providing a performance of up to 600Mhz, and has even stricter specifications on crosstalk. This is achieved by using shielding for the individual wire pairs and the cables as a whole.

Whilst unshielded cabling will rely on the quality of the twists to protect from electromagnetic interference, Cat7 instead relies on the shielding and thus has pairs with longer twists.

Cat7 allows you to run 10GBASE-T or 10Gigabit Ethernet over 100m but also 100Gbs over a distance of 15 metres.

In conclusion, unless you have equipment that supports 10Gigabit, then use Cat6a, otherwise, Cat5e would be perfectly acceptable.