Fibre, RJ45, Cat3, Cat5e, Cat6 and Cat7 Explained
Network cables carry data between computers, switches, routers and other devices. The correct cable depends on speed, distance, environment and installation requirements.
What Is an RJ45 Connector?
RJ45 is the common modular connector used with Ethernet twisted-pair network cables. It has eight contact positions and is normally attached to Cat5e, Cat6 or similar cables.
The connector is often fitted using either the T568A or T568B wiring standard. A cable should use the same standard at both ends for a normal straight-through connection.
Copper Cable Categories
| Category | Typical use | General description |
|---|---|---|
| Cat3 | Older telephone and low-speed networks | Mostly obsolete for modern computer networking. |
| Cat4 | Older token-ring installations | Rarely used today. |
| Cat5e | Homes, offices and general Ethernet | A common and cost-effective choice for modern networks. |
| Cat6 | High-speed Ethernet and new installations | Improved performance and better control of interference. |
| Cat7 | Specialised, shielded installations | Designed for high performance but may require compatible hardware. |
Fibre-Optic Cable
Fibre-optic cable sends data as pulses of light through glass or plastic strands. Fibre can support high bandwidth and long distances while being resistant to electromagnetic interference.
Single-Mode Fibre
Designed for long distances and commonly used by service providers.
Multi-Mode Fibre
Used for shorter distances in buildings and data centres.
Copper Ethernet
Affordable, easy to install and widely used for desks and local devices.
T568B Wiring Order
A commonly used T568B wiring order is shown below:
1. White-orange
2. Orange
3. White-green
4. Blue
5. White-blue
6. Green
7. White-brown
8. BrownImportant: Always follow local standards and use the correct cable tester after terminating an Ethernet cable.
Summary
Cat5e and Cat6 are practical choices for many modern networks. Fibre is preferred for long distances, high bandwidth and areas affected by electrical interference.
