# What are “phases” in terms of electrical systems?

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I work with equipment that operates on three phase electrical circuits. I can’t get my head around the concept of “phases.”

In: 17

imagine electricity as a wave and there is a limit to how much of that wave you can force down a wire. But, if you could start another wave, in between when the first one starts and ends, you can get more power down the same line with less loss.

In electricity, a phase refers to the distribution of a load. there is two-phase and three-phase. Think of it as a group of people working together to get a job done. in 2 phase, two people work together to get the job done. in three phase, three paper are working to get the job done. in essence, three phase will be more efficient because load is distributed to three people compared to 2 in 2-phase.

therefore, a three-phase power supply better accommodates higher loads and is mostly used in commercial and industrial facilities while 2 phase is used for domestic purposes.

A wrong answer for the sake of ELI5.

Imagine you’re rowing a boat. You have half of the stroke pushing against the water propelling the boat forward, but the other half of the stroke the boat isn’t actually being propelled forward since you’re picking up the oars and getting ready for a 2nd stroke.

Imagine if you add a 2nd rower to the boat who times his rows to “push” while yours are pulling. Now the boat will be propelled twice as much in the same amount of time as the original stroke.

Add a 3rd rower and you have 3 phase power.

Are you in the US? Your workplace likely runs a 480V/277V system.

Each phase carries 277V. And your equipment can be made to run on a hot and neutral. But, the higher the voltage the smaller the wire can be so it is desirable to run equipment at the highest safe-ish voltage possible to keep components smaller.
(That is why high voltage lines are not 6′ in diameter even though the feed a city)

Each phase moves in a wave from +277V to 0V to -277V and so on. But the waves peak at different moments in time on each phase so connecting phase to phase instead of phase to neutral gives you 480V.

“But 277+277 is 554, not 480!” you say.
Take a peek at how the waves go. Pick a peak of any wave, look straight down at where another phase is. You’ll see the other phase isn’t peaked in the negative so you get 480V instead of 554V.

Single phase works the same, except 120V/240V and the math is simpler because the phases peak at the same time.