OK, I’m the new guy here. Hoping that I can get an ‘official’ answer to how 220 volt AC power works. I have heard everything that could be imagined by many ‘experts’, yet they disagree with each other. I’m thinking that this site will be one of the best sources for an accurate answer. Sooo, are there 2 phases for 220, out of phase with each other, producing 220 a volt differential? This seemed to be the best answer so far.

Not that I know all, but my guess is:

It depends on where you are. In the US and other places where 110/120V is the norm then 220V is normally made of two opposing phases. In much of the rest of the world where 220/240V is the norm then it is usually a single phase.


In the USA , any area that I am aware of has there phases at the point of generation. Now during power transfer it is 3 phase as well over long distances. At the point of local dispersion the voltage is dropped drastically to several thousand volts . Now this 4200 volts called 4160 is common at telephone poles and could be primary at 13k volts as well. Now on your block or development there should be a transformer or multiples of them . Now this is where we get the last drop in voltage to 120/230 or so . The reason for the two voltages in this pattern is cause the higher voltage is in relation to another phase and the lower voltage is to ground or neutral. At some point usally at your home panel . The ground becomes the neutral as they are bonded. I say this this way cause until the voltage gets down to house voltage normalcy there is no neutral. Now you may only have two of the three phases at you transformers secondary. This secondary is the house voltage you receive. Now why do you want to know anyway?

Al. D

Thank you sir. Actually, I found that the 220 V used in the Philippines is just what you said, and it was a surprise to me. I never thought of how many ways power can be produced/used.

I believe that they use a ‘split phase’ for my house feed, but I still want to see it on an ocsilliscope. Sorry for the improper spelling, I had better find a way for spellcheck here.

One more thought since I read your post again. The electrical power is generated at 120 electrical degrees apart. Total,of course is 360

You can it will be 60 cycles in the USA. I think Europe is 50 cycles or hertz. If you use a scope to see it , there will most likely be other noise riding the sinusoidel wave .

Well, 120 degrees out of phase(each phase) makes perfect sense to me. I have ALWAYS had a curious sense about power, so it is something that I would like to understand correctly.

Welcome, 4krow!

In the U.S., we have single-phase with two voltages 180 degrees apart with neutral and ground halfway between the two voltages. Each side is a leg.

Elk, thank you for the welcome.

Now guys, already I am seeing a difference about the phases. It should be either 120 degrees out of phase, or 180. Not trying to stir the pot, but just want to better understand AC

The legs are at 180 degrees at from each other, perfect mirror images.

Elk . They are at the same phase to each other . The voltage potential is different due to the winding ratio.

Look at it like a 110 volt input and split secondary winding used for Ac to dc power supplies with two diodes.

They are on oppiset ends of the sign wave that is 120 degrees. 60 up one diode and 60 down second diode.

Al. D

It just so happens that my neighbor has a ‘scope’. This will help us understand the relationship of phasing/degrees. I will try to have some kind of response soon.

Your should have two of the three phases and if so you will see the two overlap . However you may have a single phase primary transformer and as such you will have what elk has shown and only one phase. In power distribution it is only needed for three phase motors and certain kinds of electric tropic equipment that require a, b ,c phases . But I am open to the scope results .

Al. D

alrainbow said: They are on oppiset ends of the sign wave that is 120 degrees.

These are the three phases that come out of a power plant (with four wires; one for each phase and one ground common to all three). These are indeed 120 degrees apart. Three phase power goes into factories, shops, etc. as three phase has a lot of efficiency advantages.

Our houses are single phase however. The power passes through a transformer with a single winding before entering our homes. (I'm lucky enough to have my own transformer with no other house on it. :) )

The power in our homes is split-phase distribution, each with 120V to ground. The two legs are connected for air conditioners, stoves, etc. to supply 240V.

Oh, to have 3 phase power in my shop! 8->

You can , there is two ways . First a motor gen set. The second is silent it’s a specialized transformer . Single phase in three phase out. I think it’s called a Scott transformer . But you need two of three phase,s as the input. This is very old in my head the name cpuld be wrong.

Originally Posted by strantor

A while back, a guy came around asking about a furnace in this thread. He made mention of his “wild leg” 3 phase service that takes 2 wires and turns it into 3 phase for his shop. I thought he was mistaken until he posted the schematic from his electrical provider (attached).

Looking at the schematic provided, what I see is a single phase (2 phases of a 3 phase system) with a neutral, going into 2 transformers wired in some crazy manner that I don’t understand, and supposedly 3 separate phases coming out.

If that’s actually what’s going on, could I use this setup to produce 3ph from my 220V household mains?

Why or why not?

How could this work? Would it actually create 3 phases that are 120 degrees apart?

The motor option would be the thing for me. I once thought about getting one to run a huge bandsaw. Then I would start spending money on heavier tools that I lusted after. Shortly, I would be living in my garage, surrounded by all my tools and an occasional dog. I would be visited only in passing by my wife as she comes and goes, casting scornful looks in my direction, knowing that I had spent our retirement on said power tools…

Nah, I think I’ll stick with single phase after all. #-o

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Well, there we go again eh gentlemen? So it is not just myself that has all kinds of ideas, potions, remedies with AC. But then, who’d thunk it about power regenerators with MULTI-WAVE no less! Before I chance an understanding of it all, I run to tackle the basics first. We WILL have an answer, agreed upon or not, in due time. “Howdy neighbor, say do you mind if I borrow a cup of tubes, and maybe a ‘scope’ ?” heh heh

wglenn said: The motor option would be the thing for me.

Three phase motors are smaller, instantaneous, smoother, more powerful - what's not to like?