Hvac School - For Techs, By Techs

In this short podcast episode, Bryan breaks down the differences between split-phase and 3-phase power in HVAC systems. Split-phase is a form of single-phase power, and it's common in residential HVAC. Three-phase power is more common in commercial and industrial applications. Single-phase power uses only one of the three phases of power produced by the power company. When there is a neutral and two sides of 120V power, that is split-phase power. Transformers on power poles for residential service only have one line going into them (and only one sine wave). That power gets stepped down to ~240V. Most household appliances and electronics we use are rated for 120V or 240V power. However, we use split-phase power by tapping the center of the transformer secondary; there are two 120V halves. We can see the "differences" between split-phase and single-phase power with an oscilloscope. These halves may look like two different sine waves if we use neutral as a reference, but an oscilloscope will only show one 240V s