In Melbourne, Australia I see a lot of utility poles like the one in the picture below. There are power lines on two levels. Three lines on the top level and four lines in the lower level.
I assume, that the lower level carries the three phases of AC plus the neutral line. From the lines on the lower level, all the lines to individual premises branch off, so I assume that these lines carry 230/400 V.
As there are only three lines on the top level, I assume, that these are the three phases of AC at a higher voltage. Is this the case?
Bonus question: Is the box at the top level a switch to disconnect the top-level power line?
After my question has already been answered, I will nevertheless answer my own question. A couple of streets from where I took the initial picture, there is a utility pole, which would have answered my question all by its own. It even features the fuse holders mentioned in the accepted answer to my question.