I haven't been in a rural enough area in years to even look for one.
The fact that it isn't common doesn't mean that it doesn't still exist.
Some farms were 20 miles from the nearest highway, on a private dirt or
clay road. They were electrified by either a co-op or the TVA and 20
miles of copper wire was expensive.
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
On 11/25/13 5:33 PM, Danny D'Amico wrote:
Cut a bunch to keep AIOE happy.
Article here http://preview.tinyurl.com/mxd4xb2
talking about power distribution. It was written by a fella with a BSEE
and an MSEE. He spent a bunch of years working in the power industry.
He writes about a possible project in Alaska. Single wire earth
return similar to what the Aussies do.
A single wire, ground return circuit will require a waiver from the
Alaska legislature or Department of Labor since it does not comply with
the NESC. However, the author does not believe that the single
conductor, earth return circuit should be considered and firmly believes
that a multi-grounded, neutral be considered on all single phase and
three-phase, four-wire circuits.
The fact that using the earth return system requires a waiver implies
that it is used very infrequently.
On Monday, November 25, 2013 3:18:49 AM UTC-5, Danny D'Amico wrote:
Most of the current doesn't have to flow back via the earth. You
have a transformer that is connected on one phase of the primary.
It serves several houses. Further down the street, there is another
transformer, it is on a different phase. Even further down, there
is another transformer on the third phase. The other sides of all
those transformers are all tied together on the primary neutral.
If those loads are equal, then the sum of the currents in the
neutral is zero, you have a balanced wye configuration and the only
net current flow is in the 3 primary phase wires.
The earth does not complete the circuit. Wires complete the circuit.
The electrons that flow are in the wire.
If you had DC, an electron flowing out one end of a wire would be
matched by an electron flowing in the other end. A single electron may
not move very far, it can be replaced by another electron. A property of
a metal is that there are electrons that are not tightly bound that can
With AC, electrons move in one direction, then the other.
The do have a wire for any intentional electrical path.
Since early power distribution days there is a metal connection for the
entire path. Earth is not an intentional path.
The earth is not used as an intentional path.
The connection to earth is used to limit the voltage between the wires
and the earth. The earth is also a sink for lightning and similar
events, and is used to trip overcurrent protection with crossed wires.
The earth is not allowed to be a path to trip a circuit breaker in your
house if there is a short between a hot wire and ground at, for
instance, a drill. The short circuit current goes through the N-G bond
at the service and returns to the utility transformer through the
service neutral. The earth is not allowed to be the path because it is
not an effective path.
Bud, until recently I would have agreed with you. But, whomever wrote
this web page obviously knows something about electric power generation
and distribution and seems to disagree:
Look at the bottom paragraph in the section entitled "The Power Plant:
Three Phase Power" where it says:
And what about this "ground," as mentioned above? The power company
essentially uses the earth as one of the wires in the power system. The
earth is a pretty good conductor and it is huge, so it makes a good
return path for electrons. (Car manufacturers do something similar; they
use the metal body of the car as one of the wires in the car's
electrical system and attach the negative pole of the battery to the
car's body.) "Ground" in the power distribution grid is literally "the
ground" that's all around you when you are walking outside. It is the
dirt, rocks, groundwater, etc., of the earth.
I don't think he could have said it any clearer.
On Monday, November 25, 2013 2:43:01 PM UTC-5, nestork wrote:
And just before that, the author, said:
"There are four wires coming out of every power plant: the three phases plus a neutral or ground common to all three."
That sentence alone shows that he doesn't know what he's talking
about. A netural or ground wire are not the same thing. And even if they
were, if the earth were used as the return path, then why would you
need the 4th wire? The 4th wire carries the unbalanced current. The
current is flowing in the 3 phase wires and neutral, not the ground.
And he COULD have been more accurate. He is wrong, for instance, in
stating each tap takes off 2 phases. It GENERALLY takes off ONE phase
- which feeds a center tapped step-down distribution transformer. The
primary of that thansformer has only 2 conductors, and a single
winding. The secondary has 3 wires, and a center tapped winding,
providing SINGLE PHASE power to the local residential grid..
There are 2 basic 3 phase connection schemes, delta and wye. Wye has a
neutral (so requires 4 wires) while delta uses only 3 wires. Delta
connections take power from l1 to l2, l2 to l3, and l3 to l1. Wye
takes power from l1 to n, l2 to n and l3 to n.
BOTH are used. A 3 phase generator can be either delta or wye. In
North America MOST systems are wye, while in other parts of the world
delta is more common. (but in europe, 4 wire(wye) is used
Japan, on the other hand, uses a full 3 phase distribution system and
does not use center tapped transformers to provide high/low voltage to
homes - they actually feed 2 phases to each house like many MURBs in
North America - so they get nominal 120/208 instead of 120/240. Both
50 and 60 hz are used, and much of the country is 100 volt, instead of
120 - and some is 115. (must be fun if moving from place to place
within the country to get the right equipment ----)
On 11/26/2013 1:09 PM, email@example.com wrote:
My recollection is transmission is wye at the source and delta at the
end (that is transmission line connections to the transformers). This is
not something I ever work anywhere near.
Distribution at my house is 13.8kV phase-to-phase and 8kV phase to
neutral. I have an 8kV distribution wire (and distribution neutral)
running down my alley. I believe most distribution is wye. All the
distribution transformers I see have one high voltage insulator, which
has to be wye.
Most, that I have installed, are Wye. Onsite protection of these units
is simpler and more cost effective. 3+ units going straight onto grid
as Wye (stepped up, of course) or a Wye-Delta step-up. However, most
long range delivery is done via a pure Delta (no neutral) system.
The type of transformer system depends on where on the grid the sub-system
is pulling from, and if the utility wants to cooperate with the end-user.
In certain situations they will tell you to bugger off since you might be
the only service trying to pull a Wye drop in a 90%+ Delta grid. I know
of one machine shop that begged for a Wye service to gain 1/3 more 120V
branch circuits out of their almost overloaded 1200 amp Delta service.
The answer was no, unless they wanted to pay for the entire switch over.
It was cheaper to purchase a Delta-Wye transformer and have a new drop
brought in and have all of the 120V circuits transferred over to the 120/
208 panels. Total PITA to accomplish, but allowed the original service
to gain some breaker spaces, equalize the load distribution to all phases,
and permitted the installation of a couple more three phase mills and some
headroom for that poor, old, tired Delta service. On hot days that thing
would be around 1% away from going critical. This was with cooling added
to the distribution panel.
I used to install power-plant generators, yes. Not utility
generators. These private plants fed the grid and were under
the ultimate control of the utility, meaning that the utility
could kick them off-line, at will. Most of the plants were
not stand-alone. If the grid went down, they went down. The
gas-turbine plants were stand-alone, and some city service
generation facilities were, also.
A Wye system only has the standard voltage/amperage/frequency/
ground-fault protective systems. Each phase has one bus, two
detection transformers (CT and PT), and the neutral is grounded
through a current transformer. The neutral does not go out
of the plant. The ground fault and generator detection trans-
formers are installed on the generator side of the 52G breaker.
The utility only has one set of detection devices in the plant,
right after the service entry switch. This set-up provides the
best user safety for power generation.
Delta systems are set up primarily the same way with the exception
that they usually do not have a grounded leg, hence, no reference
to ground. To get a reference to ground requires a complicated
and costly system that is separately derived from the direct gener-
ation process. These things take up a lot of space. There is no way
to have these units inside the control room as with the Wye set-
up. Each phase of each generator will have a transformer 1/3 the
size of a standard pole pig. This is quite a footprint. My
memory of the exact set-up is rather vague, but I do recall
a set-up that only sensed the outgoing feed to the step up
transformer. That took up a roughly 8' dia. area of ground.
I might try to pull up a picture via Google maps.
In industrial/commercial building(s)/complex(s), the service is
brought into a distribution panel. This service is 1200 amps
and up. The distribution panel feeds other distribution panels
directly (building), via meters (complex--separate business'), or
a combination of the two. The primary distribution panel uses
large form factor circuit breakers that have adjustable magnetic
trip settings and are sized, amperage wise, for the load anticipated,
either via load calc, or other means. Say, a 400 amp feed to what
will be a production facility that uses large machinery and other
devices that draw heavy current loads. A 200 amp feed to another
section that does not have a purpose at the time of installation
and so on until all of the spaces in the dist. panel are used up,
or only the immediate (known) service sourcing is to be powered.
Why waste the money before the use for the space is known?
(I have to step out for a bit, so I will not be able to finish
at this time)
As trader noted, the author says "there are four wires coming out of
every power plant: the three phases plus a neutral or ground common to
The 4th wire is a neutral, which is grounded.
The author has a problem of identifying neutrals as grounds throughout
Nowhere does the author describe how earth is used as a conductor in
"The fourth wire lower on the poles is the ground wire"
The 4th wire is a neutral which is earthed.
"Past a typical house runs a set of poles with one phase of power (at
7,200 volts) and a ground wire (although sometimes there will be two or
three phases on the pole, depending on where the house is located in the
The "ground wire" is in fact a neutral wire (which is earthed).
"There are two things to notice in this picture:
There is a bare wire running down the pole.
This is a grounding wire. Every utility pole on the planet has one."
Actually every utility pole does not have one. With the overhead
distribution in Minneapolis poles with transformers have an earthing
wire. Other poles may or may not have one.
Continuing "If you examine a pole carefully, you will see that the
ground wire running between poles (and often the guy wires) are attached
to this direct connection to ground."
The wire is a neutral that is earthed.
The distribution voltage in my area has one of the 3-phase wires tapped
off the distribution and feeding 4-8 blocks. The 3-phase neutral is
tapped off the supply neutral at the same place and runs with the phase
wire. As above, the neutral is earthed at multiple locations. The same
primary neutral is used as the secondary neutral, and so the secondary
neutral at the transformer is earthed.
"There are two wires running out of the transformer and three wires
running to the house.
The two from the transformer are insulated, and the third one is
bare. The bare wire is the ground wire."
As about everyone here knows, the 3rd wire is a neutral, not a ground.
There is an electrical diagram of a transformer with the secondary
center tap labeled "ground".
Also is obviously a neutral.
There are multiple pictures of distribution lines, all of which have a
neutral. Sometimes the author misidentifies the neutral as "ground".
Transmission lines also have a neutral. Sometimes it is run on the top
for lightning strikes.
"When a 120-volt power line connects directly to ground, its goal in
life is to pump as much electricity as possible through the connection."
The electricity does not flow to earth. It returns to the utility
transformer through the N-G bond at the service and through the service
The author consistently misidentifies neutral wires as "ground" wires.
His pictures show neutrals along with distribution wires. He does not
explain how the earth is used in power distribution. He does not appear
to understand power distribution.
This piece is fatally flawed.
On Tuesday, November 26, 2013 11:13:49 AM UTC-5, bud-- wrote:
My hat's off to you Bud. Excellent job taking it apart piece by
piece. What's ironic is Danny came in here not knowing the difference
between a neutral and ground with a house service. Now he's hitched
his wagon to an author that clearly doesn't know the difference between a
neutral and a ground either.
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