Fiber vs Copper: Which Cable and When
The core difference: copper carries electrical signals (cheaper, easier, distance-limited), while fiber carries light (faster, far longer distances, immune to electrical interference, more expensive). Networks use both — copper to devices, fiber for backbones and long runs.
Side by side
| Factor | Copper (Ethernet) | Fiber Optic |
|---|---|---|
| Signal | Electrical | Light |
| Max distance | ~100m (typical) | Kilometres |
| Speed ceiling | High (10 Gbps+) | Very high (100 Gbps+) |
| Interference | Susceptible (EMI) | Immune |
| Cost | Lower | Higher |
| Best for | Devices, short runs | Backbones, long distance |
The details that matter
Copper (twisted-pair Ethernet) is the workhorse for connecting end devices — cheap, flexible, and fine over the ~100-metre standard limit. But it degrades over distance and is susceptible to electromagnetic interference. Fiber transmits light through glass, so it runs for kilometres without degradation, carries enormous bandwidth, and is completely immune to electrical interference — ideal for building backbones, data-centre interconnects and long-distance links. The trade-off is cost and more delicate handling. Real networks combine them: fiber for the high-capacity backbone and long runs, copper for the last hop to desktops and devices. Knowing when to specify each is a genuine design skill.
Frequently asked questions
What is the difference between fiber and copper cable?
Copper carries electrical signals (cheaper, ~100m limit, interference-prone); fiber carries light (faster, runs kilometres, immune to interference, more expensive).
When should you use fiber over copper?
For long distances, high-bandwidth backbones, data-centre links, or environments with electrical interference — anywhere copper's limits are reached.
Why is fiber immune to interference?
It transmits light through glass rather than electrical signals through metal, so electromagnetic interference has no effect on it.
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