Why are the unused wires in a cat5 cable, unused?

Question

Ok.. so there are 8 Pins on a standard ethernet plug, Why are only 4 used, and the others remain supposidly, untouched?

Answer 1

Normally a manufacturer may make a multiple conductor cable to accommodate several type of applications and types of wire/cable assemblies.

I believe this to be the case regarding CAT5. They only use certain conductors in the CAT5 application and the other wires are not needed.

I would be very expensive to make a specific multi-conductor wire/cable for each end application.

Hope this helps.

Answer 2

It is possible with this surplus to run TWO networks over one cable.

Why? Maybe it costs very little more to make an eight pin plug/socket or an 4 pair cable and gives flexibility and the option to swop pairs (of cable) if there is a break somewhere.