What is an Ethernet cable and when should you use one?
Ethernet (or network) cables are used to connect your electric devices to a network which allows them to talk to each other or connect to the internet.
Whilst you can usually connect most of your devices wirelessly, there may be some that don’t have this option, so an Ethernet cable is used instead. Ethernet cables are also much more reliable than using a wireless connection.
Your Wi-Fi connection may not reach the device, or it could be made unstable by the environment (such as transmitting through walls). By using an Ethernet cable you can eliminate this problem and ensure you have a solid and reliable connection for your device.
What do the different Ethernet categories mean?
Ethernet cables are split into different categories depending on their usage.
You’ll often see this categorisation written as ‘CAT 5e’ or ‘CAT 6’ - ‘CAT’ simply being shorthand for ‘Category’, with the number or letter afterwards referring to the specification of the cable.
In general terms, the higher the number/letter you see, the faster the speeds and frequencies the cable supports. Higher numbers will mean support for higher bandwidths and faster internet speeds and connections.
The table below provides a brief overview of the most popular categories of Ethernet cable in use today:
| Category | Max Speed | Shielding | Max Bandwidth |
| CAT 5 | Up to 100Mbps | Unshielded | Up to 100MHz |
| CAT 5e | Up to 1Gbps | Unshielded | Up to 100MHz |
| CAT 6 | Up to 10Gbps within 55m | Unshielded or Shielded | Up to 250MHz |
| CAT 6a | Up to 10Gbps within 55m | Shielded | Up to 500MHz |
The different Ethernet categories
Below we’ve provided further information on each of these categories. Let’s take a look…
CAT 5 Ethernet cables
Whilst CAT 5 cables are still available, it’s really not worth purchasing them. Why? Because they have limited transmission speeds and the large majority of networks are now Gigabit (1Gbps) or above, which these cables won’t reach.
It’s best to stick to at least CAT 5e Ethernet cables.
CAT 5e Ethernet cables
These ‘enhanced’ cables are constructed under more stringent standards, which helps to remove crosstalk - unwanted signal transfers.
This allows CAT 5e cables to have a higher Gigabit max speed. CAT 5e cables are also the most common Ethernet cables in use at the time of writing.
CAT 6 Ethernet cables
By increasing the maximum bandwidth up to 250Mhz, CAT 6 cables offer much higher transfer speeds than CAT 5 or CAT 5e, supporting up to 10Gbps.
CAT 6 cables are usually available with shielding; this makes the cable thicker and less flexible, but the shielding helps prevent crosstalk and signal interference.
CAT 6a Ethernet cables
These ‘augmented’ cables support double the bandwidth of standard CAT 6 cables and only come shielded with a thick outer sheath. This results in a much less flexible cable than CAT 6, but CAT 6a cables can maintain their max transmission speed over a longer distance.
Newer Ethernet cable categories
There are also a few other newer categories such as CAT 7, CAT 7a and CAT 8. These offer even higher transfer speeds and bandwidth, however they are currently very rare and not of any real use unless you’re building a network which is beyond the boundaries of this guide.
What are shielded cables?
In order to reach higher bandwidths and transfer speeds, shielding is used to reduce interference from other signals.
Shielded cables do this by having the internal wiring covered with a layer of grounded foil, which reduces interference from power sources and wireless signals.
Each pair of cables inside are surrounded by their own foil wrapping - this not only helps prevent interference from external sources, but also from other wiring inside the cable. This kind of shielding is very important for complex networks or long distances, which is why it is now standard in CAT 6a cables or above.
What Ethernet cable should I pick?
When it comes to your home network, or connecting a device to your router, we recommend choosing either CAT 6 or CAT 6a cables (preferably shielded ones).
Almost all router hardware that you get now, whether you’ve bought a router yourself or been provided one by your internet service provider (ISP), utilises Gigabit connectors. As a result, you might think that using a CAT 5e cable will be fine.
The thing is, whilst CAT 5e supports up to 1Gbps, you’re pushing right to the limit of the cable and you’re also more at risk of interference too (due to the lack of shielding).
Picking up a shielded CAT 6 or CAT 6a cable will not only give you better reliability and bandwidth, but it will also be future proofed if 10Gbps network connections ever begin taking off more in the home.
The thing to be aware of with CAT 6 cabling is that these cables are much less flexible than CAT 5 - you can’t easily bend them 180º, so you need to be a bit more careful when planning your cable routing through your home. You need to ensure you leave sufficient room for the cable to get to its destination.
What if I need a cable for Power over Ethernet?
Power over Ethernet, or PoE, is a method of allowing Ethernet cables to carry power as well as data so that supporting devices plugged into the cable can be powered that way rather than by using a power adapter.
You need specific devices to use PoW - the technology is usually limited to devices such as switches, wireless access points, range extenders, or internet protocol (IP) and security cameras.
Choosing a cable for PoE is technically a little more difficult since you have to take into account the extra heat generated by the power running through the cable, the conductor resistance of the cable, and its shielding.
Luckily, all of this is met by using a CAT 6a cable.
The improved shielding and increased diameter of the cable keeps the temperature lower and reduces resistance, making CAT 6a cables perfect for use with PoE devices. The only thing to look out for would be the length of the cable; be careful not to select a cable that is too long. If you have to coil the cable or pack it into a tight bundle, this would lead to an increase in cable temperature which could potentially cause issues with PoE.
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