AC circuit big confusion after all these

SamR

Joined Mar 19, 2019
5,507
At one time I had a "water-cooled" heat pump in a hall closet (until it leaked and flooded the house). I awoke one night to a strange noise and when I went to turn on the bedroom light it was dead. I could see other lights on in the house. One leg of the underground feeder from the xfmr on the pole to the house panel had opened giving us only one leg of 120V at the panel which was pulling in the starter coil for the heat pump but no 220 to run it. The next day the power company had some device that allowed them to find the exact spot where the feeder failed to dig it up and splice it without having to dig up over ~150' of buried cable.
 

killivolt

Joined Jan 10, 2010
836
At one time I had a "water-cooled" heat pump in a hall closet (until it leaked and flooded the house). I awoke one night to a strange noise and when I went to turn on the bedroom light it was dead. I could see other lights on in the house. One leg of the underground feeder from the xfmr on the pole to the house panel had opened giving us only one leg of 120V at the panel which was pulling in the starter coil for the heat pump but no 220 to run it. The next day the power company had some device that allowed them to find the exact spot where the feeder failed to dig it up and splice it without having to dig up over ~150' of buried cable.
TDR Meter https://www.google.com/search?client=safari&rls=en&q=TDR+meter&ie=UTF-8&oe=UTF-8

But, I found an interesting trick as well on a another forum.. https://www.garagejournal.com/forum/showthread.php?t=100071

I expected the poco to come in with a fancy TDR or other such fancy method. What they used worked perfectly and pinpointed the break exactly. There were three major parts to the apparatus, a low-end Fluke DMM, a metal stick, and a long roll of cheap speaker wire. The wire gets rolled out, and one end gets clipped to the neutral at the meter socket, the other plugged into the low terminal of the DMM. A short test lead goes from the stick to the volts input of the DMM. I tell the guys the path where the wire is buried (I staked this out for the poco when I built the place 22 years ago). The guy pokes the stick into the ground along the path of the cables. The closer he got to the house, the higher the reading got. From a couple hundred millivolts at the start, to about ten volts at ground zero. The target happened to be smack in the middle of a bush I had recently planted.
kv
 

VernonLS

Joined Oct 9, 2019
42
Now, what happened to my ALTERNATING current? My problem with earth/dirt being used as a current-carrying conductor is a subject all by itself, ( the earth is sure no copper wire with free electrons. I don't want to talk about this. I guarantee it will change the subject). I want to see electrons jiggling back and forth to the load on the two wires equally as we are told what AC is.
The issue with hot/neutral/ground is not one of how does it work, but one of safety. The illustration with the power transformer with a middle tap is very good. The potential between the two ends of the transformer is twice that as between the middle tap and either end. The middle tap is connected to ground at the transformer, but not at your house (unless something was incorrectly connected). Now because the earth is not a perfect conductor, the voltage between the so called neutral conductor back to the earth (your hand on the faucet at your sink) could well be non-zero - probably wouldn't kill you, but it can tingle a bit. Thus the practice is to wire a solid connection to ground again when the power enters your house. This connection is usually made with either plain un-insulated copper wire or a wire with green insulation. The neutral connection is usually white/gray and the so-called hot connection is black. Ideally there should never be any current flowing in the green wire because the white wire which goes all the way back to the transformer is a far better conductor than relying on the earth. This is why most newer homes/shops use outlets with 3 jacks. One is called hot, the other neutral and the last (round one) is ground (green). Your tools that are not double insulated have a connection to that ground and the metal case of the tool is connected to that ground(green) line, any breakdown in the internal insulation or malfunction will go to ground rather than through your body and to the faucet you are holding. This is also how ground-fault interrupters on your bathroom outlets work. Ideally there should never be a flow of current through the ground connection, so if it detects one, something is wrong and the interrupter interrupts the current before it rudely interrupts your day.

So, I am sorry if I made this so long. It is a safety issue, not an electrical issue. All that is really needed is two wires or one wire and the earth, but the earth is not a very good conductor so there would be lots of losses due to the resistance of the earth, so we use two wires to conduct the current and the third is just there for your safety. I hope that makes it clear. Now as to whether the electrons actually flow/move/oscillate or whether they are waves or particles, I leave that to the physicists.
 

nsaspook

Joined Aug 27, 2009
16,363
Suppose the earth was made of solid copper (a good conductor). Drive a 8 foot copper coated spike into the surface. Measure 'ground' resistance. A good 'normal' earth ('not a very good conductor') ground resistance might be 5.0 ohms.

A copper bar example: 1000cm long, 1000mm wide and 1000mm has a Rectangular Cross Section Conductor Resistance of ~2e-7 ohm.
https://chemandy.com/calculators/rectangular-conductor-resistance-calculator.htm
 

Thread Starter

Alchemy One

Joined Oct 5, 2019
217
The issue with hot/neutral/ground is not one of how does it work, but one of safety. The illustration with the power transformer with a middle tap is very good. The potential between the two ends of the transformer is twice that as between the middle tap and either end.
 
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shortbus

Joined Sep 30, 2009
10,049
The middle tap is connected to ground at the transformer, but not at your house (unless something was incorrectly connected)
Have you ever looked into your circuit breaker box? You will find if it was installed correctly, that the neutrals(white wires) are connected to ground there. And that ground is connected to a grounding rod .

Everyone has kept hammering on me that the so-called neutral hardly conduct any current,
Then do an experiment, disconnect all of the neutral wires to all of your house circuits. Since you seem to think they aren't necessary.

Seems like electrical engineers for all these years have been wrong, according to you.
 

Reloadron

Joined Jan 15, 2015
7,893
Everyone has kept hammering on me that the so-called neutral hardly conduct any current, maybe a little to balance the load if need be, and at the same time how the ground carried current because earth is a giant vast spacious conductor.
Where was any of that mentioned? Please reference a post in this thread where that was said? I sure as heck never mentioned that. If only the high side (hot) carried current and only the ground then how does a GFCI (Ground Fault Circuit Interrupt) work? Matter of fact tell me how a GFCI works? When that is done then how does a simplex telegraph work?

Ron
 

MaxHeadRoom

Joined Jul 18, 2013
30,699
Suppose the earth was made of solid copper (a good conductor). Drive a 8 foot copper coated spike into the surface. Measure 'ground' resistance. A good 'normal' earth ('not a very good conductor') ground resistance might be 5.0 ohms.
5 ohms is the cap/limit generally in most conditions, a lot less.
Max.
 

nsaspook

Joined Aug 27, 2009
16,363
5 ohms is the cap/limit generally in most conditions, a lot less.
Max.
Sure the earth resistance grounding for safety spec is 5 or less but less is usually not much better unless it's something like what's used here in Oregon/California for a HVDC backup connector. The magnitude of resistance values between a good conductor and 'earth' is very large for a X cross-section of mass. Earth resistance Grounding for safety doesn't need to be a good connector to be effective (who cares if there are IR losses in dirt if you have effective single point grounding) from most high impedance leakage sources or lightning induced transients. Internal circuit ground wiring from the neutral/ground bond to loads should be a good conductor for fault detection and voltage shunting until protection devices trip.
 

nsaspook

Joined Aug 27, 2009
16,363
In grounding Hydro towers on the Canadian shield (Precambrian igneous rock) and ground mats for under sub stations, a lot lower than 5 ohms was achieved.
Max.
Sure, these are utility scale grounding systems but are still several orders of magnitudes higher resistance than a good conductor (micro-ohms) for the same cross section.

It's been said many times, the utility earth ground systems is primarily for safety, not electrical power transmission. A shunting conductor just needs to be effective, not efficient.

 

Thread Starter

Alchemy One

Joined Oct 5, 2019
217
Have you ever looked into your circuit breaker box? You will find if it was installed correctly, that the neutrals(white wires) are connected to ground there. And that ground is connected to a grounding rod .



Then do an experiment, disconnect all of the neutral wires to all of your house circuits. Since you seem to think they aren't necessary.
 
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Thread Starter

Alchemy One

Joined Oct 5, 2019
217
Have you ever looked into your circuit breaker box? You will find if it was installed correctly, that the neutrals(white wires) are connected to ground there. And that ground is connected to a grounding rod .



Then do an experiment, disconnect all of the neutral wires to all of your house circuits. Since you seem to think they aren't necessary.

Seems like electrical engineers for all these years have been wrong, according to you.
This is what I mean:
 
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Reloadron

Joined Jan 15, 2015
7,893
This is what I mean:
When I say current-carrying, I am referring to when the load is connected, the "neutral" and the "hot", both carry current equally as in the current alternate. (i.e. AC alternating current, back and forth)
Uh yep, that's how I learned it and to the best of my knowledge it hasn't changed from all those years ago.

Ron
 

shortbus

Joined Sep 30, 2009
10,049
You don't want to install a switch on any of the black wires nonetheless.
In a three-wire circuit ( My diagram), two loads are hooked up in series not parallel while at the same time each load is hooked up to its own hot wire on the breaker panel ( i.e. pole, two black wires). The wire that hooks the two load is then connected to the neutral. If you disconnect the neutral wire the two loads still have power. And if you balance the two loads just right you won't be needing the neutral wire ( certainly).
If your either an electrician, licensed or not, or a student, you really need to find some other line of work. The black wire is the one you put a switch in.
 

Thread Starter

Alchemy One

Joined Oct 5, 2019
217
Where was any of that mentioned? Please reference a post in this thread where that was said? I sure as heck never mentioned that. If only the high side (hot) carried current and only the ground then how does a GFCI (Ground Fault Circuit Interrupt) work? Matter of fact tell me how a GFCI works? When that is done then how does a simplex telegraph work?

Ron
Let me see,
 
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VernonLS

Joined Oct 9, 2019
42
That has been my point all along that the neutral wire is absolutely necessary as the black wires unless you only want 240 volts, Even 240V appliances need 120V for their dials, controls, etc. You don't want to install a switch on any of the black wires nonetheless.
On a typical house like mine or any homes most likely each load, being it outlets or lights are wired in parallel. For more than one reason.
If a wire to one outlet is off, all the other outlets still work. Secondly, there is no issue of voltage drop in parallel wiring.

In a three-wire circuit ( My diagram), two loads are hooked up in series not parallel while at the same time each load is hooked up to its own hot wire on the breaker panel ( i.e. pole, two black wires). The wire that hooks the two load is then connected to the neutral. If you disconnect the neutral wire the two loads still have power. And if you balance the two loads just right you won't be needing the neutral wire ( certainly). And if one load is disconnected the other load is out automatically.
In regular parallel wiring if you unhook a neutral you will get no power to that load or circuit or if any wire is severed at a load all the other loads on that circuit works perfectly fine. Hince my stance on how important the neutral wire is and why it carries current, Earth doesn't cut it. Earth is for safety issue and it does work.
My number one complain right from the get-go was to name such a wire neutral is misleading. There is nothing neutral about it.
That is when every attempt was made from all sides collectively that the neutral was indeed neutral. It is there just to balance the load.
That is where the collective went on with their own plight and since I refused to go on board, I came to realize that the collective got themselves defending something other than the subject on hand.
If the neutral word was the correct word, I had to find out if I was a lost nut and can't get such a simple principle or could it that the entire gang is inattentive off the subject in a plight of their own.
If there is anywhere that the word neutral can be used to mean neutral (and it is in a very smallest sense alright) it refers to what I have shown in my diagram.
In my world the so-called neutral wire carries current at all times ( as one thing or another is running in a house day or night unless of course the breaker is off) and in AC since the current alternates, the neutral is participating fully with respect to the so-called hot.
{{{Each half cycle the so-called neutral becomes hot and the hot becomes whatever you want to call it, electrons jiggle back and forth, that is what AC means}}
(R1 and R2 are hooked up in SERIES and the neutral is described as being neutral, gives and takes as needed and if not needed in a perfectly balanced load it is then indeed neutral which would be one in a.....?)
What part of what I just said is not crystal clear that you can't get or What part of what I have said in many previous posts that made you scratch your head or anyone else's for that matter?
Remember that voltage is measured as the electrical potential difference between two points. In a DC circuit, the positive or hot wire has a positive charge with respect to the other point. In an AC (sine wave) circuit that potential difference switches with each half cycle of the sine wave. If neither wire is connected to the earth, they both have some (probably different) potential with respect to the a point connected to the earth. Thus if you have a transformer or generator with neither conductor connected to the earth and you try to measure the potential difference of either conductor with respect to the earth with a sensitive oscilloscope or voltmeter you will see that difference, but it will be variable and in our country what you will see is some AC sinusoid signal that will be (probably) about half of the potential difference between the two conductors. Should you connect an ammeter between one of the conductors and the earth, you would observe a short flow of current until the voltage between the conductor and the earth drops to zero.

Most of this is just a matter of convention. By convention one wire is called "hot" and the other is called "neutral". These are the wires that carry the current. The third or ground wire is there for safety. If for some reason the "neutral) wire was not grounded at the transformer and you measured the potential difference between that wire and the grounded wire you would observe the situation just described.

If you want to check this out and can get your hands on two old 120 to 12VAC transformers. First with no other connections verify that neither wire on the secondary of each transformer is connected to one of the primary wires. Connect the primary side of each one to the house voltage. Now measure the voltage between the secondary conductors or each one and you should see about 12VAC. Neither is considered hot or positive. The output voltages of each transformer are unrelated and if you try to measure the potential difference between a conductor of the first transformer and the second transformer you will again see something with a sensitive oscilloscope, but as soon as you actually connect one conductor to the other, that potential difference will disappear. Don't try to connect the other two secondary conductors to each other or you will probably make the transformer smoke as the windings of the first transformer will be nearly shorted out by the windings of the second transformer.

Yes, all the talk in the world won't make this clear in the classroom, but a lab experiment will quickly make it clear. If you are being taught about electricity by a physics instructor it is likely that they have no more experience with how practical electricity is distributed than an English Literature instructor. The equations are the same, but it is in the practical world that we live in.
 
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