Everybody knows various flavors of the rule "don't connect too long electrical lines to an outlet / generator / whatever". They sometimes come in the form of "don't chain your extension cords". As far as I know, the main reason for this is that you might raise the wire resistance to a level that prevents fuses from blowing if you create a short-circuit.
Now, at the German TWH (Federal Agency for Technical Relief), there's an additional rule when working with (non-grounded) generators: You may connect anything up to 100m, measured over any pair of two phases. So, connecting 50m cords to all three phases is fine. Connecting 75m to L1 and 25m to L2 and L3 is fine, too. Connecting 75m to L1 and L2 would not be okay.
I wonder what's the reason for this? We sort of suspect that it's because the generator is not grounded, i.e., your neutral is "not really neutral". It would be great if somebody could elaborate on this in terms I understand. I'm not an electrical engineer (obviously, otherwise I should probably figure this out myself…?).