[walrus01]

One thing to clarify there's no power injecting going on, unless you mean optically through things like Raman amps and EDFAs...

Long haul terrestrial fiber cables aren't like submarine fiber which has copper lines to carry high voltage power for submarine repeaters/amps. The power at each site is self contained, usually a fairly normal feed from local grid utility, backup generators (diesel or propane), and -48vdc rectifier + battery setups of normal Telco grade equipment.

[jcrawfordor]

Yeah I'm just wrong about that, my knowledge is mostly historical and it's hard for me to get out of the mindset of the L-carriers where amplifier interval was 2-10 miles. The amplifier interval on the fiber these days is long enough they just build one of these points each time instead of having line-powered amplifier vaults.

That said out west where I am it's very common for fiber routes to follow the L-carrier routes and reuse the formerly line-powered amplifier sites for add-drop, but I believe they've had the utility install conventional power everywhere they've done that.