Does the earth "complete the circuit" to become ground?

[Thomas G. Marshall]

Something I've never quite had a model for understanding about: Why does
electricity want to flow to the earth-ground? Is it because the generator
producing it somehow is involved with the earth such that touching the earth
completes the circuit?

If there is no need to complete the circuit when the earth is concerned,
then for what size planet-body or planetoid does this still hold true?

 

[R. Steve Walz]

Something I've never quite had a model for understanding about: Why does
electricity want to flow to the earth-ground? Is it because the generator
producing it somehow is involved with the earth such that touching the earth
completes the circuit?

If there is no need to complete the circuit when the earth is concerned,
then for what size planet-body or planetoid does this still hold true?

------------------
Doesn't, it doesn't.

First, RF uses:
Earth being mostly metal and salt water is a passible RF and E field
reflector, nothing more. Not all planetoids are. That's useful for
transmission, so let's use it as one arm of an antenna. Most fixed
broadcasters do. You get better reception from one of them with a
ground, but as portable radios show, that's not necessary.

And also:
Power supplies really have no need of the earth as "ground", and
AC power systems only use it to replace expensive copper wire, by
grounding one arm of the generator plant's alternator to the earth.
This enables us to use earth as a protective shield ground from either
pole of the alternator, as well as eliminating most of the danger from
the grounded pole also used as "return-neutral".


Now, finally:
Ground symbols on a schematic are simply a convenience to drawing and
reading the schematic, as it eliminates all return paths back to the
power supply, thus making the flow of signals and power OUT TO their
targets more obvious, instead of having all these lines/wires looping
back to the supply and confusing things. Just pretend the negative
battery ground is the paper/screen background color, and the wires
are insulated conductors from it.

 

[[email protected]]

Something I've never quite had a model for understanding about: Why does
electricity want to flow to the earth-ground?

It doesn't.

For example, connect a battery to a flashlight bulb so that the bulb
lights up. Now suddenly connect one side of the circuit to a ground-
rod. The brightness doesn't change one bit. Try it with a 120VAC
hand-cranked generator and the results will be the same. "Grounding"
one side of the circuit has no discernable effect.

On the other hand, the earth is important when dealing with
single-plate
capacitor effects. This is where you see "electricity wanting to flow
to the Earth."

If you charge up a SINGLE capacitor plate, then whenever you touch that

plate to a large conductive object, the excess charges will share
between
them in proportion to the capacitance of the plate and the conductive
object. For example, if you hold a metal screw with plastic tongs,
then
you charge up the screw to 10KV, then touch the screw to a steel mixing

bowl, the screw will lose most of its charge-imbalance. Touch the
charged screw to a large object (such as the earth,) and the screw
will essentially lose all of its charge imbalance.

Is it because the generator
producing it somehow is involved with the earth such that touching the earth
completes the circuit?

Yes, there's a third issue here as well. One prong of the two-prong
electric outlets in your home is connected to the Earth. This is done
for safety; mostly for lightning safety. Since one side of the AC
system is connectd to a ground-rod, then whenever you stand on wet
ground with bare feet, YOUR BODY is also connected to one side of the
AC system. If you touch the other side of the circuit, then 120VAC is
connected across your body.

If the AC power system had no connections to ground-rods, then the
entire
AC circuit would be electrically "floating" (just like a flashlight is
floating.) In that case, touching ground would have almost no effect.
But if lightning struck the power lines many miles away, it would have
a very lethal effect to anyone who was near an electrical outlet.

Also see:

WHY THREE PRONGS
http://amasci.com/amateur/whygnd.html

(((((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))))))
William J. Beaty SCIENCE HOBBYIST website
[email protected] http://amasci.com
EE/programmer/sci-exhibits amateur science, hobby projects, sci fair
Seattle, WA 206-789-0775 unusual phenomena, tesla coils, weird sci

 

[[email protected]]

Power supplies really have no need of the earth as "ground", and
AC power systems only use it to replace expensive copper wire, by
grounding one arm of the generator plant's alternator to the earth.

Not quite true. AC systems normally use metal ground return lines.
They
only occasionally use "Single Wire Earth Return" way out in rural
areas,
in situations where putting an AC current into the dirt will not cause
much trouble. In heavily civilized areas, railroad rails as well as
sewer
and water lines would intercept such earth currents, occasionally
creating
lethal hazards.

And as the OP guessed, one side of the AC system is connected to a
ground rod for lightning safety.

(((((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))))))
William J. Beaty SCIENCE HOBBYIST website
[email protected] http://amasci.com
EE/programmer/sci-exhibits amateur science, hobby projects, sci fair
Seattle, WA 206-789-0775 unusual phenomena, tesla coils, weird sci

 

[R. Steve Walz]

Not quite true. AC systems normally use metal ground return lines.

---------------
Yes, but only because earth grounds often have poor conduction. If they
were as adaquate as wires they wouldn't bother with wires.

They
only occasionally use "Single Wire Earth Return" way out in rural
areas,
in situations where putting an AC current into the dirt will not cause
much trouble.

-----------------
Even where they use wire returns they use earth ground, to place the
earth's potential at a well defined and controlled value.

In heavily civilized areas, railroad rails as well as
sewer
and water lines would intercept such earth currents, occasionally
creating
lethal hazards.

 

[w_tom]

To understand grounding principles (earthing is only one type
of ground), begin with electrical nature of wire. Electricity
is never same on both ends of a wire. All wire is an
electronic component. Some electrical currents are so small
that electricity 'appears' to be same at both ends. But one
factor necessary to understand grounding - wire is an
electronic component. Electricity is different at both ends.

Many different grounds exist. Motherboard logic ground
connects to chassis ground, connects to wall receptacle safety
ground, connects to breaker box neutral bus (the breaker box
safety ground), connects to earth ground, connects to
telephone NID (surge protector) ground, connects to TV antenna
ground, connects to CATV shield, connects to utility's
transformer neutral, connects to utility pole earth ground,
connects to water pipes ... All are interconnected and all
have electrical differences.

Primary reason for connecting all grounds together - human
safety. We take one point in each electric circuit and call
that point ground. Which point is selected as ground is based
upon engineering principles. But the selected point is mostly
a standard - and primarily for human safety reasons.

Some of the exampled grounds are also isolated from others
by using only a single point connection. For example,
motherboard logic ground is best connected to chassis ground
at a single point. And motherboard logic ground must make no
direct connection to earth ground. Blender safety ground
cannot connect direct to motherboard logic ground even though
motherboard eventually connects breaker box safety ground.
Lightning rod cannot connect to chassis even though chassis
eventually connects to earth ground.

Reasons why grounds are unique involve their functions.
Antenna may require earth ground for lightning protection AND
may use earth as part of the antenna. Two functions share a
same ground. Logic ground and analog ground on a printed
circuit board may be kept separate except at one point so that
noise in one ground does not cause problems to circuits on
other ground. Stereo components are grounded at a single
point to avoid hum. But in each case, the grounds have some
type of interconnection for human safety reasons. Exactly why
the rock and roll band microphone should share a common ground
point with the electric guitar.

Some grounds do float. Many have damaged oscilloscope
probes inside computer power supplies or inside monitors
because the ground is not connected to other grounds. These
are called 'floating' grounds. Floating grounds are encased
so that humans do not touch those grounds. A human could
suffer a hundreds volt shock by touching the floating ground.
When they put that high voltage warning on the case, it is
quite likely that a floating ground threatens human life.

We ground for so many reasons. Grounds have unique names
because they have different functions. For example, the wall
receptacle ground is a safety ground and is not an earth
ground. We are careful to plan how we interconnect those
ground to avoid electrical phenomena such as ground loops (ie
hum). Reason why grounds are slightly different: wires
(conductors) are electronic devices.

Not all electricity seeks earth ground. Static electric
discharge from your hand my never use earth ground. The
circuit up through your body, through door knob, into linoleum
tile, and back to bottom of your shoe has no earth ground in
that circuit. A complete circuit is now defined. Which point
would you like to call ground? The floor? Your finger? Take
your choice. But usually we define that 'ground' point at a
place where other circuits also share a common point.

 

[Thomas G. Marshall]

R. Steve Walz coughed up:

---------------
Yes, but only because earth grounds often have poor conduction. If
they were as adaquate as wires they wouldn't bother with wires.


-----------------
Even where they use wire returns they use earth ground, to place the
earth's potential at a well defined and controlled value.


------------------------------------------
Nonsense. Current is unimportant, only potential drops are important.
Occasionally would have to be VERY near major inlets of current to
ground.


--------------------------------------
There's no need for that either, a non-grounded system is not more
subject to lightning. A grounded system is.

-Steve

Now I'm really confused. I've read through all of this.

Let me unwind this a bit at a time. I was unaware that the return/neutral
was actually attached to earth-ground. I thought it simply led back to the
power source by wire and that the 3rd plug was the only earth-ground. Given
that the neutral is now earth ground, doesn't that indicate that electricity
already wants to return to the earth (in a fashion).

Note---My electrical understanding is as follows (I'm a software guy), so
you can (if you like) tailor explanations accordingly. However, please be
patient, since the gaps in this understanding is odd.

Car wiring
A/C simple wiring (switches, etc.)
Stereo line/level, and video signal issues.
multi-meter testing, including resistance.
Vague understanding of impedance.
Digital TTL in college, including wiring up flip/flops, up/down counters,
karnaugh maps, etc.
Physics: hole-charges, electron propagation (some)

But in all that, I'm missing the role of earth-ground, and /why/, as I
stated.

 

[Charles Schuler]

Now I'm really confused. I've read through all of this.

Let me unwind this a bit at a time. I was unaware that the return/neutral
was actually attached to earth-ground. I thought it simply led back to
the
power source by wire and that the 3rd plug was the only earth-ground.
Given
that the neutral is now earth ground, doesn't that indicate that
electricity
already wants to return to the earth (in a fashion).

There are at least two important reasons why buildings are wired with a
grounded neutral: (1) If lightning strikes the building, the wiring system
will be able to conduct and dissipate most of the charge. (2) If a
high-voltage line falls across a service entrance, the grounded neutral will
prevent the wiring system from reaching a dangerous potential with respect
to ground.

So, what is going on here is safety (first and foremost). There is no way
to prevent occupants from achieving a ground reference through their feet or
hands or whatever. So, the grounded wiring system tries to prevent
equipment from reaching a dangerous potential with respect to ground.

 

[Thomas G. Marshall]

R. Steve Walz coughed up:

....[rip]...

AC power systems only use it to replace expensive copper wire, by
grounding one arm of the generator plant's alternator to the earth.
This enables us to use earth as a protective shield ground from either
pole of the alternator, as well as eliminating most of the danger from
the grounded pole also used as "return-neutral".

Ok, so I see two scenarios, and the world seems to have picked the 2nd:

1. A generator extending two lengths of cable/wire, which propagate
everywhere. The hot, and return to all reaches of the universe.

---The way it is?---> 2. A generator extending only the hot, and using the
earth as the return, sort of one big round horribly conductive wire.

Correct so far?


....[rip]...

 

[w_tom]

Earth as an electrical conductor was true for early
telegraph. But earth was not sufficient which is why
telephones could not use earth. Earth is a conductor just
like wire. Earth is also an electronic component of the
circuit.

Earth is not used by AC electric generators to transmit
electricity for same reason. In the case of an electric
system, where you find a transformer, instead think of that
transformer as a battery (an AC battery). Then forget about
everything from that transformer back to generator. You are
now ready to discuss earthing from the perspective of that
circuit. That circuit and the circuits inside the house are
many different electrical loops.

To understand grounding, one must first take the perspective
of each circuit - each loop. Then step back, look for a
common point between each of the many circuits, and declare
that common point ground.

You are having trouble with grounding because you are trying
to think in terms of only one circuit - one electric loop.
Furthermore all conductors are electronic components.
Everywhere in that loop, the electricity can be different even
though the entire loop may share a common current.

From that transformer into the house are numerous circuits -
loops - again because wire is an electronic device. We wire
the many loops so that one point in each loop is common to
other loops. We then declared that one point a 'ground'.
Then we take the many different 'grounds' and connect them to
a common point. Eventually all different 'common point
grounds' come together at one 'big time common point' - the
earth ground. We have constructed circuits that protect human
life.

The point of earth ground is not to conduct electricity. It
conducts electricity because we have weaknesses, leakages, or
unexpected transients. The most important of these
adversities are the currents that can kill humans. Earth
ground is first and foremost to create a safe human
environment. The primary reason why we arbitrarily select a
point in each electric circuit and call it ground: human
safety. There are secondary reasons. But first we must
define the primary reason - human safety - so that AC electric
does not kill humans.

Earth is not a good conductor - depending on the parameters
we are discussing. But when it comes to keeping electricity
out of a human body, then earth becomes a superb conductor.

Sidebar - what happens to a car when we go all plastic
body? Now we have a major grounding (not earthing) problem -
involving things not related to human safety. IOW there are
other reasons for declaring a point in each circuit as
ground. But for Grounding 101, the only reason to first worry
about is human safety - so that utility AC electric cannot
even harm even when you are at greatest risk - in the shower
or steel bathtub.

Ok, so I see two scenarios, and the world seems to have picked the 2nd:

1. A generator extending two lengths of cable/wire, which propagate
everywhere. The hot, and return to all reaches of the universe.

---The way it is?---> 2. A generator extending only the hot, and using
the earth as the return, sort of one big round horribly conductive
wire.

Correct so far?

...[rip]...

 

[R. Steve Walz]

R. Steve Walz coughed up:

...[rip]...

AC power systems only use it to replace expensive copper wire, by
grounding one arm of the generator plant's alternator to the earth.
This enables us to use earth as a protective shield ground from either
pole of the alternator, as well as eliminating most of the danger from
the grounded pole also used as "return-neutral".

Ok, so I see two scenarios, and the world seems to have picked the 2nd:

1. A generator extending two lengths of cable/wire, which propagate
everywhere. The hot, and return to all reaches of the universe.

---The way it is?---> 2. A generator extending only the hot, and using the
earth as the return, sort of one big round horribly conductive wire.

Correct so far?

----------------------
Has nothing to do with any "all reaches of the universe".

Potential only exists BETWEEN the two poles of a generator/alternator.
If you drag around the hot, you have to drag around the neutral, or
have a damned good ground stake.

-Steve

 

[[email protected]]

Let me unwind this a bit at a time. I was unaware that the
return/neutral

was actually attached to earth-ground.

Yep, that's the key concept.

I thought it simply led back to the
power source by wire and that the 3rd plug was the only earth-ground. Given
that the neutral is now earth ground, doesn't that indicate that electricity
already wants to return to the earth (in a fashion).

Nope. While it's true that the neutral is connected to a ground rod,
that doesn't affect the currents in the circuit. Think: if the
neutral
WASN"T connected to a ground rod, the charges in the "hot" wire
would still want to flow to the neutral (since hot and neutral are
essentially
the two terminals of an AC generator.)

Under normal conditions, the value of current in the wire which leads
to the ground rod is zero. Under normal conditions, the ground rod
does
nothing.

electricity already wants to return to the earth (in a fashion).

That really only applies to unbalanced charges on single capacitor
plates, i.e. "static electricity" physics. Where power circuits are
concerned, there will be no currents leading to ground UNLESS you
connect some OTHER part of the circuit to a different ground rod, then
use the dirt between the two ground rods as a conductor.

As I said before, if you have a flashlight circuit, and you connect one
side
of that circuit to a ground rod, it has no effect. All the current
remains in
the closed circuit. The current in the wire leading to the ground-rod
is zero.

But in all that, I'm missing the role of earth-ground, and /why/, as I
stated.

Under normal conditions, the ground connection HAS no role.

How about under abnormal conditions? For example, during a
lightning strike to the power lines? Or during a wind storm, when
a 14KV power line falls onto the 120V lines leading to your home?
Ah, that's totally different. In that case, having part of the AC
circuit
connected to a ground rod will keep your little body from being
turned into charcoal.

((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
[email protected] UW Chem Dept, Bagley Hall RM74
[email protected] Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/

 

[[email protected]]

Ok, so I see two scenarios, and the world seems to have picked the
2nd:

1. A generator extending two lengths of cable/wire, which propagate
everywhere. The hot, and return to all reaches of the universe.

---The way it is?---> 2. A generator extending only the hot, and using the

earth as the return, sort of one big round horribly conductive wire.

Correct so far?

No. There is a 3rd scenario, where a generator extends to lengths
of cable all over the place... and then we connect one of those
cables to a ground rod. Since the ground rod is not part of any
complete circuit, the ground rod normally does nothing at all.

However, if lightning strikes either of the cables, it can find a
direct
path to ground. Without that ground rod, you'd see long sparks
leaping out of the entire power system. If you happened to be
holding a blow-dryer while standing on a wet bathroom floor, and
then lightning strikes the power lines outside your home, the path
of the lightning could be out of the blow-dryer wiring, jump a small
gap to your hand, travel through your body (say, 500 amperes which
permanently destroys your nervous system), then flows out through
your wet feet and into the nearby metal bathtub and sewer lines.

Trust me. If your locality has lightning storms, or if sometimes a
broken HV power line falls across the 120V cables leading to your
house, you DO want one side of your electric outlets connected
to a ground stake!

((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
[email protected] UW Chem Dept, Bagley Hall RM74
[email protected] Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/

 

[Thomas G. Marshall]

R. Steve Walz coughed up:

R. Steve Walz coughed up:

...[rip]...

AC power systems only use it to replace expensive copper wire, by
grounding one arm of the generator plant's alternator to the earth.
This enables us to use earth as a protective shield ground from
either pole of the alternator, as well as eliminating most of the
danger from the grounded pole also used as "return-neutral".

Ok, so I see two scenarios, and the world seems to have picked the
2nd:

1. A generator extending two lengths of cable/wire, which propagate
everywhere. The hot, and return to all reaches of the universe.

---The way it is?---> 2. A generator extending only the hot, and
using the earth as the return, sort of one big round horribly
conductive wire.

Correct so far?

Figure of speech meaning the same thing you say about "dragging around the
neutral".

Potential only exists BETWEEN the two poles of a generator/alternator.
If you drag around the hot, you have to drag around the neutral, or
have a damned good ground stake.

Ok. So from all electrical power plants are extended a minium of two wires?
hot and neutral. And those two need to go everywhere in pairs. Right?

So it's not likely nor possible to have a power plant simply send 1 line
everywhere, and have everything return to the earth?

If so, that makes much more sense to me, since my electrical background, as
odd as it is, always speaks of completing the circuit without the earth
(wires, computer chassis, car chassis, etc.)

 

[w_tom]

No. Wires from power plant do not connect to your
building. There is no neutral wire leaving the power plant.
Your building is galvanically isolated from the power plant.
This was explained in previous posts. Earth ground (one of
many different grounds) does not become the conductor as also
explained in a previous post:

Earth is not used by AC electric generators to transmit
electricity for same reason. In the case of an electric
system, where you find a transformer, instead think of that
transformer as a battery (an AC battery). Then forget about
everything from that transformer back to generator. You are
now ready to discuss earthing from the perspective of that
circuit.

To understand the circuit, think of that utility pole
transformer as a battery. Pretend there is no other
connection. Pretend that utility pole 'battery' provides all
the power to you building. Now you are ready to understand
how your AC electricity works, and how earthing and other
different grounds works.

You are confusing earth with ground. Earth is one type of
ground. A long previous post explained this in detail. Your
car, computer chassis, etc. have no earth ground. They have
other grounds (car chassis ground, household safety ground,
etc) Only some grounds have a connection to earth ground.
They are grounds - car chassis ground (which has no connection
to earth ground), safety ground, logic ground, floating power
supply ground (which also has no earth ground connection)
etc. Many electrically different grounds that can be
interconnected - but remain different and separate grounds.

 

[John Bäckstrand]

You are confusing earth with ground. Earth is one type of

ground. A long previous post explained this in detail. Your
car, computer chassis, etc. have no earth ground. They have
other grounds (car chassis ground, household safety ground,
etc) Only some grounds have a connection to earth ground.
They are grounds - car chassis ground (which has no connection
to earth ground), safety ground, logic ground, floating power
supply ground (which also has no earth ground connection)
etc. Many electrically different grounds that can be
interconnected - but remain different and separate grounds.

To complicate the matter further: in Swedish, the word for "earth" and
the word for "ground" is the same: jord.

 

[Thomas G. Marshall]

w_tom coughed up:

No. Wires from power plant do not connect to your
building. There is no neutral wire leaving the power plant.
Your building is galvanically isolated from the power plant.
This was explained in previous posts. Earth ground (one of
many different grounds) does not become the conductor as also
explained in a previous post:

But this itself is vague. It says /transmit/. I was referring to simply
using the ground as a return.

And besides, R. Steve Walz just got done telling me:

R. Steve Walz:
If you drag around the hot, you have to drag
around the neutral, or have a damned good
ground stake.

This implies what then? That either:

1. the generator is sending two wires
or
2. the generator is sending one wire, and the ground is the return to
the generator(?)

The generators I've fooled around with always have two leads, just like a
battery does. Where does that neutral lead of the power plant generator go.
To the earth?

In the case of an electric

To understand the circuit, think of that utility pole
transformer as a battery. Pretend there is no other
connection. Pretend that utility pole 'battery' provides all
the power to you building. Now you are ready to understand
how your AC electricity works, and how earthing and other
different grounds works.

Yep, that part was explained already. I'm trying to phathom the generator
part now.

That's fairly easy to understand. What I don't understand is how that
"battery" can be fed by only a hot wire from the generator. How is that
circuit completd?

You are confusing earth with ground. Earth is one type of
ground. A long previous post explained this in detail. Your
car, computer chassis, etc. have no earth ground. They have
other grounds (car chassis ground, household safety ground,
etc) Only some grounds have a connection to earth ground.

They are grounds - car chassis ground (which has no connection
to earth ground), safety ground, logic ground, floating power
supply ground (which also has no earth ground connection)
etc. Many electrically different grounds that can be
interconnected - but remain different and separate grounds.

Yes, yes, yes, I understand all that. I've done car wiring, pc wiring, and
even wired up counters using all TTL.

But given that you need to *always* complete a circuit, how is the circuit
completed from, say, a diesel generator at the plant outward to that
transformer on the pole.

A generator has two leads. One for power and one for.....the return?

....[rip]...

 

[R. Steve Walz]

R. Steve Walz coughed up:

R. Steve Walz coughed up:

...[rip]...

AC power systems only use it to replace expensive copper wire, by
grounding one arm of the generator plant's alternator to the earth.
This enables us to use earth as a protective shield ground from
either pole of the alternator, as well as eliminating most of the
danger from the grounded pole also used as "return-neutral".

Ok, so I see two scenarios, and the world seems to have picked the
2nd:

1. A generator extending two lengths of cable/wire, which propagate
everywhere. The hot, and return to all reaches of the universe.

---The way it is?---> 2. A generator extending only the hot, and
using the earth as the return, sort of one big round horribly
conductive wire.

Correct so far?

Figure of speech meaning the same thing you say about "dragging around the
neutral".

Potential only exists BETWEEN the two poles of a generator/alternator.
If you drag around the hot, you have to drag around the neutral, or
have a damned good ground stake.

Ok. So from all electrical power plants are extended a minium of two wires?
hot and neutral. And those two need to go everywhere in pairs. Right? ------------
Yup.


So it's not likely nor possible to have a power plant simply send 1 line
everywhere, and have everything return to the earth?

--------------------
If the earth was a perfect conductor, sure, but since...

If so, that makes much more sense to me, since my electrical background, as
odd as it is, always speaks of completing the circuit without the earth
(wires, computer chassis, car chassis, etc.)

-----------------------
Yes, the whole "ground" mystique is baloney. It gets confusing because
of RF broadcast and the use of the earth as one arm of a reflective
antenna. Combine that with the safety uses to determine relative voltage
to a universal level for power distribution and it makes it
completely so.

-Steve

 

[R. Steve Walz]

No. Wires from power plant do not connect to your
building. There is no neutral wire leaving the power plant.

----------------------
Sure there is, sortof, it consists of the three-phases WRT each
other, and this finally goes through transformers that DO connect
an arm of the supply to a more local ground stake.

-Steve

 

[R. Steve Walz]

w_tom coughed up:

No. Wires from power plant do not connect to your
building. There is no neutral wire leaving the power plant.
Your building is galvanically isolated from the power plant.
This was explained in previous posts. Earth ground (one of
many different grounds) does not become the conductor as also
explained in a previous post:

But this itself is vague. It says /transmit/. I was referring to simply
using the ground as a return.

And besides, R. Steve Walz just got done telling me:

R. Steve Walz:
If you drag around the hot, you have to drag
around the neutral, or have a damned good
ground stake.

This implies what then? That either:

1. the generator is sending two wires
or
2. the generator is sending one wire, and the ground is the return to
the generator(?)

The generators I've fooled around with always have two leads, just like a
battery does. Where does that neutral lead of the power plant generator go.
To the earth?

In the case of an electric

To understand the circuit, think of that utility pole
transformer as a battery. Pretend there is no other
connection. Pretend that utility pole 'battery' provides all
the power to you building. Now you are ready to understand
how your AC electricity works, and how earthing and other
different grounds works.

Yep, that part was explained already. I'm trying to phathom the generator
part now.

That's fairly easy to understand. What I don't understand is how that
"battery" can be fed by only a hot wire from the generator. How is that
circuit completd?

You are confusing earth with ground. Earth is one type of
ground. A long previous post explained this in detail. Your
car, computer chassis, etc. have no earth ground. They have
other grounds (car chassis ground, household safety ground,
etc) Only some grounds have a connection to earth ground.

They are grounds - car chassis ground (which has no connection
to earth ground), safety ground, logic ground, floating power
supply ground (which also has no earth ground connection)
etc. Many electrically different grounds that can be
interconnected - but remain different and separate grounds.

Yes, yes, yes, I understand all that. I've done car wiring, pc wiring, and
even wired up counters using all TTL.

But given that you need to *always* complete a circuit, how is the circuit
completed from, say, a diesel generator at the plant outward to that
transformer on the pole.

A generator has two leads. One for power and one for.....the return?

...[rip]...

------------------
Sort of, instead the alternator at the power plant has three wires
coming out, three phases of AC that are sine waves 120 degrees apart.

It goes into a three-phase transformer to crank it up for transmission
and then back down locally for lower voltage, and it passes through
a delta-wye transformer to separate the phases and then center-tapped
transformers are used to generate 240VAC for local home supply. It is
this local center-tap that gets connected to the ground stake to
reference the local voltage to the ground for safety.

Is that better, everyone?
-Steve