# Speed of a current passing through a wire [duplicate]

The wire is at 50hz, and is an aluminum alloy (AAAC 1120). Resistance in the wire is at 0.0897 ohm/km. So for a length of conductor 135km long, the resultant resistance will be 12.1095 ohm. It's AC current at about 220 KV. Other data about the wire can be found here. The line will be carrying roughly 15 MW of current.

How fast (in any measurement, but in an actual number) would the current move through the wire? I know about electron drift already, what I need to know is how fast it would travel through a wire with those specs, so if a pulse starts/stops how long it takes for this change to reach the other point 135 km downstream.

Edit: have checked possible duplicates, and while they do cover the same matter, i'm looking for a number or a fraction. While I know it's a fairly high portion of the speed of light, it's not an actual number. Some say 2/3, some say 1/10, some say 8/10, and when you deal with almost 300000km/s it's a large difference. They all say it depends on the wire, and aluminum alloy wire for large amounts of current is no doubt very different to standard copper.

• Also of interest: Speed of light vs speed of electricity – John Rennie Sep 23 at 11:56
• The formula you reference in wikipedia does not refer to the speed of waves travelling along the conductor, but instead refers to speed of the wavecrests as a wave decays evanescently from a surface of the conductor into its bulk. The equation describing this is a diffusion equation rather than a wave equation. – mike stone Sep 23 at 13:02