Asking again

Think of a flashlight. One wire carries current from the battery to to the bulb, the other returns it to the battery. On an electrical system, current flows from the source to the load on one wire (the faucet), and from the load back to the source on the other wire (the drain). Don't get confused by a neutral wire. It may or may not be one of the circuit wires involved, and it doesn't matter. Current flows through a complete circuit.
AC current reverses direction 50 or 60 times/second so the "out" and "in" wires constantly reverse, but that doesn't change the principle.
--
Benjamin D Miller, PE

We're talking about 220 volt system no? req

If you like a water (hydraulic) analogy, understand that energy is transmitted by the pressure and flow rate in a continuous loop from a pump to a motor. It can be confusing to think of a faucet and drain, think "supply" and "return". If you have 2 pipes, the fluid comes in one pipe and goes out the other. In an alternating system, the flow reverses every so often but you can still send power from the pump to the motor. For a hydraulic analogy of the 110/220 system, imagine three parallel pipes and two pumps, one from the center pipe to the top and one from the bottom to the center (with a tee connection). The top pump pushes the fluid out the top pipe.while the bottom pipe sucks the fluid from the bottom pipe. You can connect a motor from the top to the bottom pipes and have both pumps in series pushing the fluid thru it (high pressure like 220V). You can also connect motors from the center pipe to either outer pipe and have only one pump running them (low pressure like 110V). No matter how many motors you have connected, if the top pipe is flowing 20 gallons per minute toward the motors and the lower pipe is flowing 20 GPM away from the motors, no fluid is flowing in the middle pipe. If you have more flow on the top pipe than the bottom pipe, the difference flows thru the middle pipe.
If you draw this out on paper, it should help you understand.
Don Young

The water analogy is the one I know, feel free to give others :-) Supply and return 110v: Postive to neutral. Supply and return 220v: postitive to positive to:? Where is the flow in the 220 circuit with 2 wires?
req

You are thinking incorrectly about the polarities. The two lines are not both positive at the same time! One is + and the other is -, so current flows between them. AC voltage alternates, so the + & - conductors switch every half cycle, but one is always more positive than the other and the direction of current flow changes accordingly.

"Drain" is not a good analogy for the neutral. Even though the neutral is grounded, the neutral current still does not go to ground but rather back to the transformer supply.
RE

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Supply and return 110V positive to neutral Supply and return 110V neutral to negative Supply and return 220V positive to negative
negative (- 110V +) -----neutral-----(- 110V +) ---- positive ||
Consider 2 1.5 V AA cells in series. You can tap between the negative of one and the positive of the other to get 3V or you can tap from the negative of one cell to its positive end to get 1.5V -------------------------------- | I-> /\ | + | | 1.5V | | - | line | | to -------------- | line | + load at 3V + 3V | 1.5V - | - | | ------------------------\/-------

Yes in two batteries there are 2 postives and 2 negatives.But, in a 220v system there are no negatives, only two positives , 110v and 110v . You understand what I am trying to figure? req

? which is ground no? or can it be used again? :-) req

There aren't "two positives". At any given time one of the "legs" is negative (with respect to "neutral").

So it's only 110v sytem them? You understand what I am trying to figure? If 110 goes from positive to negative and 220 goes from postive to negative(one of the legs being used as negative) how do I get 220volts? Why do I need the other 110 line if it's only going to be used as a negative.. I might as well use the same negative that I use in the 110v system. You see what I'm getting at? req

reqluq snipped-for-privacy@hotmail.com wrote previously in alt.engineering.electrical:
Your problem seems to be in understanding AC current. This kind of current changes as a sinusoidal 60 FULL cycles (from "0" to + to "0" to - to "0") per second. That's 120 changes per second: +0-0+0-0+0.....
Let's analyze the parts of the system:
1.- There are two distinct and different HOT wires (what you call 110v). They are "in opposite phases" or "opposite voltages". They are not equal. When one wire is 110V positive in relation to neutral, the other one is 110v negative in relation to neutral. This changes with time.
2.- Let's stop time for a moment. The electrical laws work exactly the same. Let's assume that HOT1 is positive, that is +110v. Then HOT2 is -110v. That's is 220v measured from HOT1 to HOT2. Exactly as the voltage of the two batteries is summed when they are in series. Current could flow from positive HOT1 to neutral (110v) or from positive HOT1 to negative HOT2 (220v).
But in a little more time (1/120 of a second) this voltages are reversed and HOT1 would be -110v while HOT2 will be +110v measured in relation to neutral.
So, as time passes, both HOT's change voltage, but in a specific relation between them. If one is getting positive, the other is getting negative.
Hope this helps.

What neutral? there are two hot wires hooked up, no neutral connected. How are they in opposites phases? If I run two identical 110v generators I have 110 coming from one and 110 from the other that would run a 220v appliace no? Are they in "opposite voltage"?
How so? suppose hot2 wants to be positive? what makes them at a given time opposed? I could see if some computer system was running it but...
yes, but as I said before I can see the positive and negative ends of the two batteries, and I have to hook up the positive to one end of somethng and negative to the other for it to work. Flow.
What synchronises this? suppose they both want to be positie at the same time?how does one know the other s positive at a given time so it can be negative..and what of 3 or 4 phase then? I ran a welding machine once that used three 110v lines. Well as u can see I'm still a bit lost..what of 360 or 440 (80?) volts then? req

reqluq snipped-for-privacy@hotmail.com wrote previously in alt.engineering.electrical:
Sorry, I'm am out of here.
You better take a basic electrical course, then ask again.
Have a nice day.

Thanks Roy , Antonio and others for trying to help with this. I'm just trying to see it in its simplest terms. Not just taking it for granted that that is how it is. Thanks again req

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-------------- You are getting all wound up to the point of confusion with regard to positive and negative. You have a supply which has one "hot" terminal positive with respect to the reference or neutral point. The other "hot" terminal is, at the same time, negative with respect to the neutral. This is the same as with the two batteries in series. Positive and negative are relative terms with respect to some given reference. This applies to temperature, elevations, etc. The reference point is arbitrary and is taken as the neutral for a few practical reasons. One could take one end of the 220V supply and call it the reference and then the "neutral" or center tap would be at +110v and the other end would be +220V. Deal with the two battery DC equivalent then deal with the concepts of AC before trying to combine the two. The you will find that transformer supplying 110/220V is a 220V (rms) winding center tapped so that one end is negative with respect to the center tap at the same time that the other is positive. This is exactly the same circuit condition as the two battery case (OK: For AC 110Vrms is a mathematical fiction which you should learn about when you study AC).
Don Kelly snipped-for-privacy@shawcross.ca remove the X to answer

It's 120V, but there are two of them to make 240V (between them).
Yes, you're over-figuring. ;-)
Here is where your misconception is. True, each "leg" goes from positive to negative (with respect to neutral), but at different times. When one leg is positive the other is negative. The *difference* between them is 240V.
Sure, I see what you're where your misconception is but it's buried deep in your mind. ;-) The other line is not being used "as a negative". Both are positive and both are negative (hence "alternating" current), but at opposite times. The *difference* (voltage is always a difference - there is no absolute) between one leg and neutral is 120V. The difference between the other leg and neutral is 120V. The difference between the two is 240V, since when one is positive other is equally negative, at any given time. 1/120th second later they're at opposite polarities.

So you are saying I get 220v from one transformer? So if I had to separate generators each putting out 110v, could I take a line from each and connect it to a device and it would work? req

So why can't you run 110v with one wire? The positive would come up and the negative could run back down the same line; theoretically no? req
Keith
If one is positive at one given time and the other negative at that same time, where is the 220v? I see 110v at one time from one or the other, not simultaneously, so how 220v? req