On Monday, November 18, 2013 4:52:51 PM UTC-5, email@example.com wrote:
Yes you have to snip them because they are irrefutable and
show that you;re wrong.
Typical, more name calling when you've lost an argument.
Is the IEEE lying too? Here from the peer reviewed IEEE, a paper
presented at a conference of power engineers:
"Distribution engineers have treated the standard "singlephase" distributio
n transformer connection as single phase because from the primary side of t
he transformer these connections are single phase and in the case of standa
rd rural distribution single phase line to ground. However, with the advent
of detailed circuit modeling we are beginning to see distribution modeling
and analysis being accomplished past the transformer to the secondary. Whi
ch now brings into focus the reality that standard 120/240 secondary system
s are not single phase line to ground systems, instead they are three wire
systems with two phases and one ground wires. Further, the standard 120/240
secondary is different from the two phase primary system in that the secon
dary phases are separated by 180 degrees instead of three phases separated
by 120 degrees. "
Or how about this:
A split-phase (240/120V) power system is a 3-wire, single-phase, mid-point
neutral system, which consists of two 120V "voltage sources"; connected out
-of-phase by 180 electrical degrees with a neutral connection between them.
"The phase of hot leg 2 (phase B) is in the opposite direction,
ie 180 deg apart from the phase of hot leg 1 (phase A)"
"The secondary of the distribution transformer has a grounded
center tap and is wound in a manner that supplies two 120V AC
phases which are 180 deg out of phase with each other (split phases)"
They even go on to talk about using a oscilloscopet to look
at them and say:
"This indicates that the two 120V AC voltages are 180 deg out of
Go ahead, snip those truths too and keep making an ass of yourself.
Here's what I'm not getting at the moment. What are the connections to tha
t transformer? If it is 3 phase leg to neutral on the primary side, then th
e center tap should be above neutral on the secondary (house) side, right?
Which would mean that house neutral is NOT at ground level. But I'm pretty
sure it is.
your confusion is becasue you don't understand how a transformer works. Th
e pri and secondary are isolated from each other. The center tap of the se
c has NO RELATIONSHIP to the primary. Think of the secondary as seperate f
loating power supply not related to the primary. The center tap of the sec
ondary is neutral or ground ONLY becasue it gets connected to ground. Sinc
e it is connected to ground the two ends become +120 and -120 relative to n
> Here's what I'm not getting at the moment. What are the connections to
> that transformer? If it is 3 phase leg to neutral on the primary side,
> then the center tap should be above neutral on the secondary (house)
> side, right? Which would mean that house neutral is NOT at ground level.
> But I'm pretty sure it is.
> The pri and secondary are isolated from each other. The center tap of
> the sec has NO RELATIONSHIP to the primary. Think of the secondary as
> seperate floating power supply not related to the primary. The center
> tap of the secondary is neutral or ground ONLY becasue it gets connected
> to ground. Since it is connected to ground the two ends become +120 and
> -120 relative to neutral.
I find the first diagram on this web page that was posted by SRN
It shows the primary side of the distribution transformer connected
between the 7200 VAC carried by the single phase wire and ground.
What I can't figure out here, tho, is that if the distribution
transformer on the telephone pole is connected to ground, then it's
connected via the ground wire that goes down the pole and is wrapped
around the base of the telephone pole. So far as I know, that ground
wire is not insulated, so that anyone that touches that ground wire
would get a 7200 volt shock, which would surely kill them.
So, I think that wiring diagram is mostly correct, but I think there's a
problem with the primary side of the transformer connected to ground via
the telephone pole's grounding wire.
On Tuesday, November 19, 2013 12:03:14 PM UTC-5, nestork wrote:
Don't let krw see that. The reference clearly says that
with a spit-phase 240v/120v service, there are two phases present
and they differ by 180 degrees. He says that just can't be.
Even if it were only connected that way, you would only get a shock
if the ground wire were broken and you grabbed the energized end.
Otherwise if you grabbed an intact wire, the only voltage present
would be whatever there is due to the small resistance of the wire,
which would result in a small voltage drop across the wire run.
The 7200 volts is across the transformer. The 25 ft of copper wire
only drops a few volts, depending on the current flowing in it and
the resistance of the wire.
Actually the transformer is typically connected to a
primary neutral. The primary neutral is in turn connected
to ground much like on the secondary (house) side. It's not
necessarily at every transformer, but periodically along
the run. Other transformers connected to the same neutral,
but from different phases, will balance out and reduce the current
flowing in the neutral.
Yes, IMO, they should have shown the primary connected to
a neutral, not just ground.
On Tuesday, November 19, 2013 12:03:14 PM UTC-5, nestork wrote:
to neutral on the primary side, > then the center tap should be above neutr
al on the secondary (house) > side, right? Which would mean that house neut
ral is NOT at ground level. > But I'm pretty sure it is. > > your confusion
is becasue you don't understand how a transformer works. > The pri and sec
ondary are isolated from each other. The center tap of > the sec has NO REL
ATIONSHIP to the primary. Think of the secondary as > seperate floating pow
er supply not related to the primary. The center > tap of the secondary is
neutral or ground ONLY becasue it gets connected > to ground. Since it is c
onnected to ground the two ends become +120 and > -120 relative to neutral.
> > Mark Mark: I find the first diagram on this web page that was posted b
y SRN helpful: http://tinyurl.com/ly24tjo It shows the primary side of the
distribution transformer connected between the 7200 VAC carried by the sing
le phase wire and ground. What I can't figure out here, tho, is that if the
distribution transformer on the telephone pole is connected to ground, the
n it's connected via the ground wire that goes down the pole and is wrapped
around the base of the telephone pole. So far as I know, that ground wire
is not insulated, so that anyone that touches that ground wire would get a
7200 volt shock, which would surely kill them. So, I think that wiring diag
ram is mostly correct, but I think there's a problem with the primary side
of the transformer connected to ground via the telephone pole's grounding w
ire. -- nestork
in the diagram, the top of the primary is connected to 7200Volts and the bo
ttom of the primary is connected to ground. THe voltage on the wire connec
ted to ground is close to 0. It doesn't matter that some of the current pa
ssing through that wire started out at 7200 Volts. As long as the wire is
connected to ground, it is ground. So someone can touch that wire with no
BUT.. if the ground connection to the wire should come loose, then the wire
will have a high voltage on it and would be dangerous, becuase it has curr
ent in it "that is trying to get to ground" and can't.
That is actually the same danger in the 3 wire dreyer circuit. The ground
and neutral share the same wire and if the connection to that wire comes lo
ose, the "ground wire" will have dangerous voltage on it.
On the pole transformer, ther bottom side of the primary coil is connected
to ground, but the wire you see running down the pole is NOT the ONLY conne
ction to ground. All the grounds in the entire distribution system are con
nected together so if the ground to one particular pole should come loose,
the wire is still probably at ground due to all the other connections. But
if I saw a loose ground wire running down a pole, I still would not want t
o touch it.
But, if what you're saying is true, then there is power flowing to
ground through the primary coil of every distribution transformer in the
USA and Canada 24 hours per day, 7 days per week, 365 days per year.
And, with a voltage of 7200 volts driving that current, it would seem to
me there would be a significant current flowing in the 40 or 50 foot
cable going down from the transformer to the ground.
Why don't those cables get warm to the touch?
Is it entirely the impedance of the primary coil in the transformer?
There is a 24 VAC doorbell transformer in every house in the USA and
Canada. 120 Volt power is flowing through the primary coil of those
transformers 24/7/365 and yet no one seems to be concerned about that
power wastage. And, the only thing that makes sense here is that the
impedance of the primary coil is so high that the current flow to ground
is actually very small. Ditto for household transformers.
On Tuesday, November 19, 2013 8:50:23 PM UTC-5, nestork wrote:
All the power isn't flowing in those ground wires. You
typically have a neutral that is shared by multiple
transformers. Each transformer isn't connected to the
same phase, they are connected to phases in a distributed
fashion. That means that the current in the neutral is
only the unbalanced portion. If you had 3 transformers
for 3 groups of houses, each on a seperate primary phase,
with equal loads, the neutral current would sum to zero.
And then you have the neutral grounded periodically along
it's run, with a heavy, properly sized, ground wire,
capable of handling the current through it.
On Tue, 19 Nov 2013 18:03:14 +0100, nestork wrote:
Here's a PNG of that diagram, for reference:
In the dryer thread, it was noted that most USA circuit breakers
are *not* arrayed in AB-AB-AB format; but in AA-BB-AA-BB format.
I'm not sure what that means though...
On Friday, November 22, 2013 4:37:03 AM UTC-5, Danny D'Amico wrote:
It's referring to where the two legs/phases show up in the panel.
But, I'm not sure what AB means either. You need to define what
the perspective is. Just saying AB is meaningless, because it could
mean A is on the left, B on the right, or it could mean A is above,
B is just below it. In any case, what you have, is the latter.
That is what is shown in your diagram.
Otherwise you would get zero from a double pole breaker instead
This is correct. My issue with the example provided was that there
were an A phase and a B phase shown, inline, left to right. I have
yet to see a panel with this layout. Even with three phase panels,
the layout is A, B, C. Top to bottom, identical on both sides of
the panel. The only deviation that I have seen is when the bus
tabs are used for the main breaker input, and this only causes the
loss of two connection points in the panel. This is a very common
practice in MCC distribution panels. So, 22 circuits... :-)
Your panel is ABABAB...AB from top to bottom, on both sides of
the breaker panel (left/right). The example given in your .png
showed AB....AB on the left, and BA....BA on the right. This is
a lay-out that makes zero sense and would require some goofy
bus work to accomplish. If you look at your breaker mounting
points you will notice that every other bus tab, from top to
bottom, is the same. So, the top two bus tabs, inline from left
to right are phase A. The next row down will be phase B, inline
from left to right. A 2-pole breaker will take up two spaces, top
to bottom and will give you both an A and a B phase. A 2-pole
breaker mounted to its right will pick up the same bus tabs as the
first breaker, but, of course, it will be to the right of the first
circuit breaker. Just look at the two breakers that currently
exist at the top of your panel. They are end to end with their
operators (handles) moving in opposite directions to achieve the
same action. Yet, the wiring is the same for both breaker, top
to bottom. Meaning that if you where to have black and red wires
denoting phasing, the black would go on A, and the red would go on
B. This is a universal construct in electrical work. Black is always
A, Red is always B, and if three phase, blue would be C. A three
phase Delta would replace the red with an orange, denoting the fact
that the system is Delta, and that the B phase to ground is a high
leg and is not 120v and is not to be used for 120v circuits.
Colors are important!
I worked in a 240 Delta panel once that was phase taped for a Wye
connection. Black, Red, Blue. I needed to move a single pole
breaker down one slot to install a 3 pole breaker. There was a
single pole breaker at the top of the panel, on that side, so this
put the breaker I had to move down onto the high leg. I did not
notice this and since my boss just said hurry up, get it done, and
lets get out of here, I did not check the voltage. Well, someone
went into the bathroom and the fart fan ran really fast for about
10 seconds before it went up in a puff of smoke and the incandescent
lamp was really bright, too. Until it blew up. Never take anything
for granted for when you do so, you or someone else might get hurt.
On Monday, November 25, 2013 2:50:25 AM UTC-5, Danny D'Amico wrote:
Which one you call A and which B is arbitrary. What matters
is that you wind up with the phases alternating on the breaker
slots, vertically. That way with a double pole breaker, you
get 240V. If they didn't alternate, you'd get 0v.
On Mon, 25 Nov 2013 05:15:29 -0800, firstname.lastname@example.org wrote:
I'm ok with that.
It was interesting to see the "C" shaped flat metal plates
under each of the breakers in my panel.
That shows that my panel is a row of AA, then a row of BB,
then a row of AA, and BB, etc.
Thanks to you guys, I can *look* at a panel and tell something
about it now. That feels good.
(I hate not knowing stuff.)
Notice each pair of your 6 wires is connected at the insulator so
although there are 6 WIRES ther are only 3 THREE conductors
Please before you demonstrate your ignorance and confuse people who
admit they dont know, go back to shcool. :-?
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.