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Tech Tips:

What’s the Difference Between 208v and 240v?

The easy answer is 32v. Class dismissed. I’m only joking, of course. Finding the difference between 208 and 240v power supplies may sound quite simple, but there are some pretty sharp fundamental differences. Apart from the obvious differences in overall voltage, 208 and 240v power supplies use the electrical company’s power differently. The motors also […]

Multi Tap Primary Transformers

Have you ever seen a low-voltage transformer like the one shown above? It has multiple input (primary) taps for a good reason. It is common to find three-phase and single-phase equipment rated to operate on both 240v and 208v power. That is because three-phase power can either be 208v leg to leg when the building […]

Split-Phase vs. 3-Phase – Short #253

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 […]

Andrew Manuel
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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 sine wave from leg to leg (without neutral). Therefore, split-phase power really is just single-phase power with a center reference point, and split-phase power doesn’t matter to the HVAC unit.

We get three-phase power when all three phases of power come in from the utility, not just one. Each individual phase is 120V, and all three can make up 208V power because the phases are 120 degrees out of phase.

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Search Episodes

Split-Phase vs. 3-Phase – Short #253

08/19/2025

Bryan Orr

IAQ for the HVAC Technician w/ Brynn Cooksey

08/14/2025

Bryan Orr