Australian suburban power distribution

The conductors at the top are a three-wire (delta), three-phase HV supply. In Australian suburbs, this is usually 11kV or 22kV. On Springvale Road in Glen Waverly, Melbourne, for example, it's 22kV. Where I live in outback Queensland, it's 11kV.

The object at the top of the pole is likely to be a sectionaliser - basically a switch with a few sensors and some crude logic. In the event of a fault, the sectionaliser will determine whether the fault is in front or behind of itself, and will lock out the faulty portion.

It could also be a simple fuse-holder, as Sparky256 suggests, though Australian utilities would normally use a simpler drop-out fuse holder, like the one shown below.

The conductors at the bottom are a four-wire (wye), three-phase + neutral LV supply. That would be 230/415 VAC, as you suggest.

The very bottom-most cable is usually telecommunications of some sort, i.e. phone lines.

The distribution standard for five continents is

• Distribution via 3-phase delta (no neutral) at various voltages
• A delta-wye transformer for the neighborhood (dozens of houses)
• The transformer taps all 3 phases
• 415V 3-phase "Wye" (230V to neutral) to each home - typically delivering 1, 2 or 3 phases depending on requirement.

North American strategy is totally different.

• Distribution via 3-phase delta at various voltages
• A single-phase center-tap transformer for the block (maybe a dozen houses)
• Each transformer taps 1 phase (2 wires of 3). The next transformer taps another phase etc.
• 240V split-phase (120 and 120) to the houses

The difference shows up when a customer wants something fairly big, like a machine shop. When a 5-continent user wants a big load, they drop him all 3 phases - if you ever notice larger on-demand water heaters always have three 240V hookups, that is why. This gives the European user 415/3phase. When a North American user wants a big load, she gets 240V single-phase, which is weak tea. If she needs bigger (typically US 480V or Canada 575/600), they have to fit a transformer just for her, and that has 5-digit expense.

North America does have all-electric homes in the snowbelt, and they provision staggering amounts of current to it - as high as 400A. Conductors the size of your thumb, and aluminum. (after we botched aluminum wiring, we un-botched it and it's now the standard for anything over about 100A.)

It is impossible for North America to retrofit to the 415/3phase system because the neutrals conflict. Well, not impossible -- the Philippines is doing it --but the neutral issues are driving them crazy and getting people killed.