As any professional industrial electrician is likely to point out, there are two main ways you can connect a building to the main electricity supply in Australia. The first is to dig a trench and run power lines underground. The other is to install overhead power lines that are suspended from poles. Both have their pros and cons, but overhead cabling is often not given the thought it deserves. Of course, underground connections have a lower visual impact than overhead power lines, but this does not mean that they cannot be installed. In many areas, there are already overhead telegraph cables in place anyway, so fitting overhead power lines won't make much of a difference. Why else should you consider overhead cables?
To begin with, when you dig a trench that is capable of accommodating several power cables, you will need to examine the local soil. Not all groundwork for digging culverts and ducting can be low-level. Given the type of soil you have, deeper trenches may need to be formed, which pushes the cost of the project up. Any chance of land subsidence or slippage may mean that deep foundations may need to be dug to ensure the cables don't become stressed as the soil moves around. Just conducting the surveys for such work to begin can cost a great deal.
Exposure to Water
Many main electrical power cables get exposed to water. Overhead power lines are obviously out in the open come rain or shine. They are designed for the elements and can even withstand hailstorms without too much bother. Although you might think that underground cables are better protected, they often face the more serious issue of standing water, which collects in their conduit channels. All too often, this can lead to short-circuiting and power outages.
Buried power lines are also susceptible to damage from burrowing creatures that might disturb them. Things from rabbits to subterranean termites have been known to cause thousands of dollars worth of destruction to buried cables and the infrastructure that goes with them. Damage from wildlife can occur to overhead power lines, but if it occurs then it is likely to be much less costly to put right.
Cost of Installation
Finally, the difference in cost per metre of installing suspended overhead power lines versus placing them in the ground is quite dramatic. Unless you have a specific reason for using the subterranean method, it is much less expensive to connect with overhead cables for any distances over a few metres that need to be covered.
To learn more about overhead power lines, contact an electrician.