What is phase in electrical wiring?

Answer 1

The proper use of the term refers to the timing difference between voltages in a multi-phase power system. This makes more sense if you know that one complete AC cycle is divided up into 360 degrees, the same as a circle is. At 0 deg. the voltage is zero. At 90 deg. the voltage hits the positive peak. At 180 deg. the voltage falls back to zero. At 270 degrees the voltage falls to the negative peak. At 360 (same as zero) degrees, the voltage rises back up to zero, then the whole process repeats. In a 3-phase power system, each of the three hot conductors carry a voltage that is offset 120 degrees, or 1/3 of a cycle, from the next conductor. The voltage on each wire peaks at a slightly different time. However, in everyday use, the term phase has also come to mean which one of the three wires you want, as in "connect phase A to terminal 6", etc. It is even used in 240 volt (US) household power systems, where there are two different hot wires, even though it is technically not a multi-phase power system. So, if an electrician says phase, he most likely means one of the three hot wires in a 3-phase system.

Answer 2

The word phase in an electrical sense describes what stage a process is currently in. It can also describe the stage of change or development in electrical services.

Phase is also used as a measurement in degrees that describes how far ahead or behind one alternating quantity is in relation to another. If a circuit has the current peaking a quarter-cycle after the voltage, the current is said to be lagging by 90 degrees of phase.

Answer 3

The term, 'phase', is often used incorrectly. If you are referring to a wire, then the correct term is 'line', NOT 'phase'. It is the conductor maintained at a potential with respect to the neutral, and is often called the 'hot' conductor.