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240 w/o a neutral


mgbinspect

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Originally posted by mgbinspect

Well, here's a fascinating little bit of food for thought. I had the pleasure of meeting with that master electrician again who said he had pondered my question and soon after I left recalled this interesting phenomenon regarding neutral wires:

He explained that if you were able to turn off everything in a home and merely hook up two 2 amp light bulbs, one to each of the two 120 entry cables and turn on only one of the bulbs you'll read 2 amps at the neutral returning to the power company. However, if you turn on both bulbs, the neutral to the power company will now read "0"! He said that the neutral handles imbalanced load.

Actually, the neutral service wire handles all of the load that's directed to it, not just the imbalanced part. But much of that load -- all of it in your two 2-amp example -- is self canceling. That is, we can't read it because the pulses of electricity from one leg cancel out the pulses from the other leg. They are neutralized. That's why we call it a "neutral" wire.

That tid bit added with the fact that parallel circuits are said to enjoy decreased resistance and offer multiple paths for current to travel nails down the fact that in a 240 circuit the current may travel or return via it's own cable or the parallel cable and in fact ultimately seeks balance. Interesting!

I'm not sure what parallel circuits have to do with this. A parallel circuit is one in which you use two small wires instead of one big wire. (Big wires are more expensive.)

I really think you're making this much more complicated than it is. A 240-volt circuit is really very simple, much simpler than a 120-volt circuit. In a 240-volt circuit the electricity travels out one end of the transformer coil, travels along a wire, does some work (like lighting up a light), then returns via a wire to the other side of the transformer. It forms a circle. That's where we get the term "circuit." (Since we use AC power, the electricity changes directions 60 times a second. One side is always pushing while the other is pulling, then they change, 60 times each second. Perhaps this is where the confusion comes in?)

If there's no load, the electricity doesn't actually "travel" it just exerts pressure. As soon as you connect a load, the "traveling" begins. This is what the power company meter reads: traveling electricity.

- Jim Katen

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Ooops, My bad? I was gathering that a 240 was a "parallel circuit" made up of two 120s? Is that not so?

This is becoming clearer, Jim and thanks for your patience and assistance.

I just HATE accepting "because that's the way it is" or "just accept it." Comprehending hows and whys is so much more satisfying and sometimes far more useful in applying that understanding to troubleshooting and theory.

Frankly, Jim and Bob, any time I'm truly learning, I'm having a flat out blast!

"INPUT!"

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Originally posted by mgbinspect

Ooops, My bad? I was gathering that a 240 was a "parallel circuit" made up of two 120s? Is that not so?

Nope. A 240-volt circuit is just a plain-Jane circuit. There's really nothing simpler. In most of the rest of the world, the electricity coming out of a wall receptacle is 240 volts. There is no 120 there. (Of course they also use a 50-cycle system - bad idea - but that's another story.) A 120-volt system is really more complicated and ought to be more difficult to understand.

A parallel circuit just uses two sets of wires instead of a single set. We never see it in residential wiring, well almost never. In big commercial services though, it's not unusual. Instead of using great big wires that are very expensive and a real pain in the butt to work with, they'll use two smaller wires that, combined, provide the same capacity as the bigger wire. Your observation that they offer decreased resistance is correct. As I understand it, this is because the electricity tends to travel mostly on the outside of the wires rather than on the inside (don't ask, I have no idea why). Two smaller wires have greater surface area on the outside than a single larger wire.

This is becoming clearer, Jim and thanks for your patience and assistance.

I just HATE accepting "because that's the way it is" or "just accept it." Comprehending hows and whys is so much more satisfying and sometimes far more useful in applying that understanding to troubleshooting and theory.

Frankly, Jim and Bob, any time I'm truly learning, I'm having a flat out blast!

"INPUT!"

Me too. I've found that one of the best ways to learn something is to explain it to someone else. Well, that and to take it apart and stare at it.

- Jim Katen, Oregon

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Want to really hurt your head...

A theory of quantum mechanics says an electron does not exist until it is observed. It only has a potential for existence.

Furthermore, when an electron in an atom changes orbit, it does not move through what we perceive as physical space. It simply disappears, then re-appears in its new orbit.

Put that in your bank and cash it.

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Originally posted by Jerry Simon

Want to really hurt your head...

A theory of quantum mechanics says an electron does not exist until it is observed. It only has a potential for existence.

Furthermore, when an electron in an atom changes orbit, it does not move through what we perceive as physical space. It simply disappears, then re-appears in its new orbit.

Put that in your bank and cash it.

Thanks to Mike Sterling for turning me on to this http://www.physorg.com/news11087.html

- Jim Katen, Oregon

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Originally posted by mgbinspect

Well, I'm going to tee this question up and see where it goes.

In a 220v circuit with no neutral, what path does the current take to return to ground since there is no neutral?

It doesn't return to ground. The earth is part of our electrical system only because we choose to connect the system to it for safety reasons, but it has nothing to do with the "flow" of electrons in a circuit.

In any circuit, the electrons don't flow, contrary to popular belief. They wiggle back and forth. The electromagnetic field around the conductor races forward and does the work. The electrons stay put. Otherwise we would eventually run out of electrons.

BTW, before you tell me what an idiot I am, be aware that many textbooks are wrong.

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"In any circuit, the electrons don't flow, contrary to popular belief. They wiggle back and forth."

Not that you don't already know it, but as explained to me by a knowing type of guy, you're right; though he said the electrons jiggled. I s'pose wiggle is okay too.

He also said we have no clue how electricity really works...we just sort of (try our best to) control it.

Hey, you got a *Table of Contents* feature in your software...now that's Wigglin'-Jigglin' Cool!

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Far be it from me to ever tell anyone they're an idiot! You know what they say about living in glass houses.

My all time favorite saying is from Fireside Theatre... "We're all Bozos on this bus!"

The only idiots are those that aren't convinced they're just one of us Bozos, and they make their own bed.

I guess a 120 needs a neutral for wiggle/jiggle room. [:-angel]

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  • 2 weeks later...

I always taught it like this.

The Service transformer is just a 240 V AC transformer with a 120 v center tap.

In our electrical world, current doesn't always try to flow to earth or ground, it tries to get back to it's source.

Earth and ground and neutral is negligable in your scenario since you are referring to 240v.

I can explain the 240 v potential but I think you are not ready for it. hehe

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Mutual inductance theory... Transformers, etc. La-la. 120V is a 'tap' that sort of makes the transformer on the secondary-side of the transformer 'shorter', thus lower voltage. The neutral is the return path for that 120V 'circuit'. The 240V's two legs 'are' the return path for this mutually induction-caused 'circuit' on the 'residential' side of the nearby transformer. Brain hurts. Gotta go.

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Some of that stuff is really cool to get a handle on. (Electromagnetic fields, etc). Being an electric guitar player, I was interested many, many years ago in the concept of the electric guitar pickup (a moving steel wire, aka 'the string' thru an electromagnetic field in the pickup 'coil'). Kind of like a 'flat' electric motor in a way. Tiny electrical signal generated gets amplified by 'the amp'.

There is a lot of voo-doo in electrical stuff that can boggle your head. Same for radio. Gets hairy. Check out "FM" generation sometime. Brilliant concept. Stolen by a rat from a genius (Edwin Armstrong). Thread drift. CU Later

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