What exactly is your plan?

3 phase is usually never available in single family and light multi-dwelling residential areas, or allowed in a residential dwelling even if it is on the street. All utility distribution is three phase, look at the top of utility poles on main roads and you will see three wires at the very top.

3 Phase is widely used for light commercial, such as stores, plazas, etc. 3 phase is widely used as the main feed for large residential building, such as large condos, apartment buildings, however only single phase is brought to the actual units. But having 3 phase brought to the building allows for the large motors such as elevators,boilers, etc.

To illustrate the typical service available from utilities:

Single phase 120/240 volt service at 100 amps can provide 24000 watts of power.
The largest single phase motor available is approximately 10 HP.

Typical 3 phase 120/208 volt service at 100 amps can provide 35984 watts of power.
3 Phase motors are available up to 3000 HP.

There is a 240 volt 3 phase service available, thou is rarely used, and is only for industrial applications, so I di not use that as an illustration.

Here are a couple of websites that explain three theory, the math is a bit more than you need, but the explanation is good:

http://en.wikipedia.org/wiki/Three-phase_electric_power

http://www.allaboutcircuits.com/vol_2/chpt_10/2.html

If you do have only single phase available, and only need 3 phase for a one or two 3 phase machine, consider using a three phase converter, here is a popular manufacturer: http://www.phaseconverter.com/about.html