I have a 5000 watt generator head and a 10,000. What is the length I can run wires from the gen head???
First, a few questions:
At What Voltage?
At full rated power draw?
How far do you need to go or would like to be able to go?
And how much copper can you afford to buy?
Basically and within reason you can run that power any sensible distance with a big enough cable. That is the how much copper can you afford part.
The rest we cannot even speculate on until we know the volts and distance involved. From there we can do some math and give you an answer on what size cable you need to go for how long a run. That is the "more information" part.
So for your initial question the only answer we can provide is "It Depends .."
Good luck with it.
Tom