How far can I make a wire go?
Solution 1:
The Longer Power Lines mod increases this value and its description lists the default:
fWorkshopWireMaxLength – 1100
I do not know the units, but that's the value.
Solution 2:
There is an item called a Power Conduit from thee Contraptions Workshop DLC that allows you to continue your network further throughout your settlement.
Without it though, you might need to set up multiple generators throughout your settlement, since the cables do only have a limited range (what that range is though, specifically, I can't exactly define).