I have an Ethernet cable with no printed markings - how can I determine what Category it is?

Question

Whilst upgrading a switch and re-cabling to suit I discovered on of my ethernet cables has no printed markings on it.

Is there a non-invasive way for me to tell if it's Cat5, 5e or 6?

Answer 1

The "gold standard" way is to put it on an ethernet tester and have it check out.

As I'm assuming you don't have one of these (maybe you can bribe a friendly technician?), it might be difficult to non-evasively tell.

That said, the thickness of the cable might give you some clues - Cat6 cable is generally thicker and less flexible because it has a plastic divider seperating the 4 pairs to reduce cross-talk (see this link for a diagram of the cross section). These cables also often use slightly thicker copper cables. The thicker cables may - I believe - to the very trained eye - mean slightly different connectors.

That said, from a practical POV, plug the cable in to the fastest things you need and see how well it works. If it performs with the desired speed who cares what its labelled as?