The fault on the end of the distribution line will certainly have an effect on the current drawn by loads closer to the source as well. An example: If you had a line with a total reistance of 0.04 ohm (and ignoring the source impedance of the transformer), then a dead short at the far end would give rise to a fault current of 6000A. An installation tapped from that line at the 75% point would see a terminal voltage of 240 - (0.75 * 0.04) * 6000), or only 60V, so at the moment of the short occurring the current drawn by installations upstream will certainly drop.
But back to the main point, if the loop values are already close to tolerance, then if the voltage at the supply terminals of the installation is low due to other loads, the short-circuit current may be too low for protective devices to open in a timely manner.
