Stranded aluminium, with a steel core.
Alluminium wire
There are essentially 2 types of connections for a 3 phase AC transmission lines Star and Delta , Star is a 4 wire connection with each phase supplying potential with respect to a common ground wire , while delta is 3 wire connection with any single phase at one given time acting as a ground , for transmission reducing one wire makes a lot of cost difference hence it is favored
It requires a special tool that releases the wire clips.
piggyback entry
Yes, aluminium's tensile strength isn't high enough to suspend its own weight, so a steel-wire core is used.
Multiple stranded cable is used in transmission lines because the high voltage potential of each line causes the electrons to tend to run only on the surface of the line due to repulsion. You want to maximize the surface area of the line, hence the multiple stranded lines, so that you maximize the efficiency of the line. In fact, some transmission lines have a non-conductive core, adding strength while maintaining low weight.
There is a special tool that releases the wire clips that hold them on.
Electric current is a transmission medium which can be used to transfer data across a wire for example ( copper wires). Radio waves is a transmission medium which can be used to carry data through the air. The above mention mediums are known as data transmission media.
2 types of copper wire which are surely not the only ones are coaxial, and cat 5,5 e, 6 etc. Now many people are bringing networking over power lines.
Color has nothing to do with it. Its' the wire type and application that determines the types of wire used.
1. Wire resistance 2. Leakage around insulators 3. People stealing the power
G. T. Lester has written: 'Reducing the effects of environment upon two-wire transmission lines'