LaCarrubba Electric
3 Phase vs. Single Phase wiring
When you hear the term, “Phase” in electricity, it refers to the timing that magnets pass over electrical coils.  The main difference between 3 Phase and Single Phase wiring is reflected in the amount of coils, but there are some additional distinguishing characteristics between the two.
3 Phase Single Phase
Wires are out of phase or are 120 degrees out of alignment with one another. All of the wires are hot.
Coils are in alignment.
Many different wiring patterns are available and there is no uniform manner in which coils are wound.
All coils are wound in a uniform manner. The first coil is wound clockwise, then counter clockwise, and the pattern coninues.

3 Phase Electrical Circuit Wiring

3 phase power is a common form of electrical power and a popular method of electric power transmission.  This is due to its inherent benefits for high power transmission and its smooth wave form quality which allow 3 phase electrical equipment to run smoothly and last longer.  There are many other benefits to 3 phase power.  Three phase has properties that make it very desirable in power distribution. First, all three wires can carry the same current. Secondly, power transfer is constant into a linear and balanced load.  Most domestic utility supplied power is single phase only. In most cases three phase power either is not available from a utility company to domestic houses, rural business and farms, at all, or in rare cases where it is, it is split out at the main distribution board.  In these situations single phase power can be converted to 3 phase power with a phase converter.

3 Phase Power Wave Form

Conductors of a 3 phase system are usually marked by color code, to allow for balanced loading and to assure the correct phase rotation for 3 phase induction motors. Colors used vary widely and may adhere to old standards or to no standard at all, # Phase Diagramand sometimes vary even within an installation. However, the current National Electrical Code (2005) does not require color identification of conductors other than that of the neutral (white or white with a color stripe), the ground (green or green with a yellow stripe), or in the case of a High Leg Delta system, the High Leg must be identified with orange. 

One voltage cycle of a three-phase system, labeled 0 to 360° ( 2 π radians) along the time axis. The plotted line represents the variation of instantaneous voltage (or current) with respect to time. This cycle will repeat 50 or 60 times per second, depending on the power system frequency. The colors of the lines represent the American color code for three-phase. That is black=VL1 red=VL2 blue=VL3

Three phase systems may or may not have a neutral wire. A neutral wire allows the three phase system to use a higher voltagewhile still supporting lower voltage single phase appliances. In highvoltage distribution situations it is common not to have a neutral wire as the loads can simply be connected between phases (phase-phase connection).

3 Phase Power Generation
3 Phase Power Distribution and Transmission

There are several types of 3 phase power generators.  These can vary from a utility power station, to a prime source power generator to portable diesel (and other fuels) generators, to 3 phase generators which run on 1 phase power (some models of phase converters).  The most common fuel type are generally diesel generators.  At a utility power station, an electrical generator converts mechanical power into a set of alternating electric currents (AC), one from each electromagnetic coil or winding of the power generator. The currents are sinusoidal functions of time, all at the same frequency but with different phases. In a three phase power system the phases are spaced equally, giving a phase separation of 120°. The frequency is typically 50 Hz in Europe and 60 Hz in the US . 

After numerous further conversions in the transmission and distribution network the 3 phase power is finally transformed with a power transformer to the standard mains voltage (the voltage of "house" or "household" current in American English). This is done with step down 3 phase transformers. The power may already have been split into single phase at this point or it may still be three phase power. Where the step-down is 3 phase, the output of this transformer is usually star connected with the standard mains voltage (120V in North America and 230V in Europe) being the phase-neutral voltage. Another system commonly seen in the USA is to have a delta connected secondary on the step down transformer with a center tap on one of the windings supplying the ground and neutral. This allows for 240V 3 phase as well as three different single phase voltages (120V between two of the phases and the neutral, 208V between the third phase (sometimes known as a wild leg) and neutral and 240V between any two phases) to be made available from the same supply.