Installing power lines in a neighborhood and setting up the wiring for houses has been under a bit of a microscope for the past few years as the push to put power lines underground garners more interest. So much above the ground can damage power lines and cause blackouts — not to mention that a falling, live line can spark fires, as has happened in California in the U.S. — that putting power lines underground can seem like the sensible thing to do. It's not as simple as that, however, because the type of line and the type of area all influence how feasible it really is to place a power line underground.
What's Your Budget?
First, you need to consider money. Underground lines are expensive. You have to dig a trench (which in itself can be expensive if the ground is rocky or consists of clay soil), determine what sort of insulation you need for the wires, bury the wires, and then dig them up again when you need to repair or replace them. Contrast that with aboveground lines, where you install a pole and drape standard wiring between that pole and another or attach it to a building. If you're trying to keep costs low and just don't have the money for underground lines, those lines will be installed aboveground.
Are You in an Area With a High Flooding Risk?
Natural disasters are a real problem for power lines no matter where they're installed. While some disasters, like lightning storms and high winds, affect mainly aboveground lines, and some disasters, like earthquakes, affect both types of lines, flooding has a particularly bad effect on underground lines. A flood may still leave a power pole standing and not take down any wiring, but that same flood can erode soil and shift or break the underground line once it's exposed. You can't always predict how a flood will affect an underground line, but the risks are known and real.
Which Lines Are You Thinking of Placing Underground?
Another issue is that some lines, mainly high-voltage lines, get very hot as they transmit power. You'd think the ground could absorb that, but the heat isn't the main issue. When a line overheats, it can move, and overheating underground lines often move up. These lines need to be insulated carefully, or any underground line placement has to be restricted to low-voltage lines (which still need to be insulated but are easier to deal with).
You need an electrician to properly plan power installation for both exterior lines and interior wiring. Start consulting with electricians who offer power installation services during the design phase of your project to ensure you have enough time to work out all the details.