Here is a picture of the incoming wires to my main circuit breaker:
http://farm3.staticflickr.com/2886/10915925156_0e21cf1404_o.gif
If we follow those three wires *back* to the nearest transformer, what
do they look like (in terms of phase relationship to each other)?
If we follow those three wires *forward* to the first circuit breaker,
what do they look like (in terms of connection to the literal earth of
the ground)?
Note: This question is an offshoot of a 220v dryer question; but this
question is asked to get to the root of *what* it is that is entering
the house in the first place.
Hmmm,
Your question has been answered more than once throughout this thread.
If still did not get it. You really ought to follow the wires upto the
main breaker panel. One note: Gnd and Neutral is connected together but
they are not same in functionality in the circuit.
Hi,
How is your house electric system grounded? I still think your dryer is
not grounded well. Measure between the dryer chassis(body) and ground
point in Ohm scale on your meter. Do you read zero Ohm or fraction of Ohm?
Also you should read zero Ohm between gnd(dryer body) and neutral on
your dryer.
If it is all OK, some one else mentioned heating element sagging when
hot rubbing on the dryer chassis not enough to kick the breaker but give
spark and shock specially when hand is moist(doing washing)
I think this thread is coming to an end.
This web page won't put up my posts if they're more than about 10 or 15
lines long.
Danny:
In the following e-mail address, each letter has been replaced with the
letter or symbol to the right of it on a standard Qwerty keyboard.
If you can e-mail me, I'll send you a write-up that answers your
question on what goes on both upstream and downstream of your electrical
panel.
m l r ; r n s u # o ; p d / m r y
Leave out the spaces and type the letters to the left of the ones shown
above to get my correct e-mail address. I put spaces in because if you
type the letters r and n without a space between them, it looks like an
m, and for this to work, the e-mail address you type has to be exactly
correct.
So far as an electrical spark inside the dryer goes, I would look for
any wires inside the dryer that are rubbing against the rotating dryer
drum. In time, the drum will rub it's way through the insulation, and
contact the copper conductor. Then, depending on WHICH wire is rubbing
against the drum, you can get a shock from the dryer by touching the
drum while it's running, or only when the heating element is heating, or
only during the Permanent Press cool down cycle, or whatever. I'd at
least make sure that no wires are touching the rotating drum.
I hate to display ignorance, and I know I should know this.
But maybe somebody can explain.
The power lines are 3 phase, meaning they're 120 degrees out of phase to ea
ch other allowing 3 wires to carry what 6 wires should (since they're gener
ated by 3 sets of coils at the power plant).
The house is fed by just one of these wires, through a center tap transform
er. That transformer sends 3 wires to the house: Neutral, +120 volts, -12
0 volts. Connect the two hots and you get 240, connect either hot to the n
eutral and you get 120. Your safety ground is bonded to the neutral and so
you should also have 120 from any hot wire to the ground. Neutral is the
center tap.
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 t
he 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 pret
ty sure it is.
On Monday, November 18, 2013 9:39:55 AM UTC-5, TimR wrote:
each other allowing 3 wires to carry what 6 wires should (since they're gen
erated by 3 sets of coils at the power plant).
The 6 vs three makes no sense.
rmer. That transformer sends 3 wires to the house: Neutral, +120 volts, -
120 volts. Connect the two hots and you get 240, connect either hot to the
neutral and you get 120. Your safety ground is bonded to the neutral and
so you should also have 120 from any hot wire to the ground. Neutral is th
e center tap.
hat 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, righ
t? Which would mean that house neutral is NOT at ground level. But I'm pr
etty sure it is.
All the neutrals are tied to ground. Why would you expect
the neutral on the secondary to not be at ground level?
In the strictist sense, if you take a center tap transformer,
the secondary side doesn't have to have any relationship
to the potential on the primary side. It's can be completely
seperate, it's a seperate winding not connected to the primary.
What and how you hook it up
determines what level anything is referenced to. In the power
transformer case, the center tap (neutral) is tied to ground.
On Monday, November 18, 2013 9:48:27 AM UTC-5, snipped-for-privacy@optonline.net wrote:
that transformer? If it is 3 phase leg to neutral on the primary side, th
en the center tap should be above neutral on the secondary (house) side, ri
ght? Which would mean that house neutral is NOT at ground level. But I'm
pretty sure it is.
Well, you're not seeing the problem. I wish I could draw here.
Your transformer has two wires going in, and three going out.
I don't know what primary is in my neighbor hood, let's say 2400 vac for an
example. Which two wires do we use? You only have the choice of leg to l
eg, or leg to neutral.
Choose leg to neutral: use a 10 to 1 turns ratio, your secondary will be 2
40 volts line to line. Then center tap it, and you get 120 from each line
to center.
BUT: why would center tap be anywhere near neutral?
Choose leg to leg: does the same problem exist?
Once it gets into the house I understand how it works, but on the pole I'm
hazy.
By the way you are dead wrong on the 6 wires thing. That part I do remembe
r.
The secondary centertap is the "neutral" because it carries the
imballance of the current in the secondary hot wires - the ends of the
240V winding. That is a common definition of a "neutral".
The secondary has no relationship to the primary, it is isolated from
the primary.
The secondary relationship to earth depends on how the secondary is
connected. The "neutral" (centertap) is earthed at the transformer. The
neutral is then also earthed at the building. That limits the maximum
voltage in the building with respect to the earth.
On Monday, November 18, 2013 10:08:23 AM UTC-5, TimR wrote:
:
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.
an example. Which two wires do we use? You only have the choice of leg to
leg, or leg to neutral.
It's one of the 3 primary phases to primary neutral.
240 volts line to line. Then center tap it, and you get 120 from each lin
e to center.
The center tap has no relation in terms of potential
difference to anything other than the two ends of the
secondary, until you connect it to something. The
center is called the neutral and as part of the
installation, it's run to the house and also tied
to ground. Now the neutral of the transformer
is at the same potential as ground.
m hazy.
ber.
You would go from 6 wires to 3 wires in a distributions system
if and only if you were to consider the 6 wire system as the only
other alternative to deliver power. That is that you have fixed
in stone that you're to have a generator with 3 windings, delivering
3 phases via 6 wires to the load. Of course if you start with that,
then a balanced 3 phase load reduces the wires in half.
But that isn't the real world. No one would do it that way to begin
with. There are other alternatives and even a single phase system can
deliver the same power without 2X the wires. 3 phase does use less
copper and is better for other reasons as well. But it's not a miracle.
The current carrying capability of the conductors is what it is and
3 wires can't suddenly carry the same current as 6. As i recall,
the reduction in copper you get with 3 phase is around 25%.
Because that's how it's wired. You *DEFINED* it as being 0V and
connected it to ground.
No. There is no problem. Remember that transformers isolate. The
secondary can be at any voltage you desire it to be, regardless of the
primary (within the breakdown limits of the transformer, obviously).
You connected one of it's secondary terminals to ground, defining that
as 0V. Everything else falls out from there. You could have
connected it to 1000V, but that wouldn't be smart. ;-)
There isn't any difference how it's connected there. You may have
heard of "Delta" or "Wye" connections. Delta, connects the primary of
the transformer between phases. A "Wye" connection would be from
phase to ground. In the US, almost all loads are connected as "Wyes"
and generators as "Deltas". I'm sure there are exceptions but that's
what you'll find on your pole.
On Monday, November 18, 2013 2:01:42 PM UTC-5, snipped-for-privacy@attt.bizz wrote:
e:
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.
an example. Which two wires do we use? You only have the choice of leg t
o leg, or leg to neutral.
e 240 volts line to line. Then center tap it, and you get 120 from each li
ne to center.
'm hazy.
mber.
So you too believe that the same amount of power that's delivered by 3 wire
s with 3 phase would require 6 wires, twice the amount of copper to deliver
any other way?
Remember when you insisted that it was illegal for employers to
help pay for their employees Obamacare? Made an ass out of you on
that one.
Remember when you didn't know the difference between how a 4 wire
oven and a 3 wire is hooked up? Even with RBM, Bud and I all telling
you that you were wrong. Made an ass of you on that one too.
And now we have your insistence that the two legs of a 240V
service are not 180 deg out of phase. That no such usage of
the wording would ever be used in engineering.
Well, here it is, from the IEEE. A paper delivered at a conference
for power systems engineers:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber4520128
Distribution engineers have treated the standard "singlephase" distribution
transformer connection as single phase because from the primary side of th
e transformer these connections are single phase and in the case of standar
d 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. Whic
h now brings into focus the reality that standard 120/240 secondary systems
are not single phase line to ground systems, instead they are three wire s
ystems with two phases and one ground wires. Further, the standard 120/240
secondary is different from the two phase primary system in that the second
ary phases are separated by 180 degrees instead of three phases separated b
y 120 degrees.
There it is folks, in context, about the very specific point
that krw claims is a lie.
Here's the essential cliff notes version, just for you krw:
"Which now brings into focus the reality that standard 120/240 secondary sy
stems are not single phase line to ground systems, instead they are three w
ire systems with two phases and one ground wires."
That's from an engineering paper presented at an IEEE conference.
I suppose they are all idiots, liars, etc too, because they recognize
that you have two phases that are 180 deg apart.
But keep digging your fools hole deeper if you like.
Well... There are two AC wires that are opposite, yes. If you said
they were +120wt and -120wt, you would have a point (w being the
angular frequency, or 2*Pi*f and t=time).
Yes.
Assuming no faults and ideal wires, sure.
Yes. ...which is grounded.
Yes. Almost always, though it really doesn't matter.
No. The center tap is grounded at both the transformer and the
entrance panel. It *is* ground.
It is. I don't see your problem. You described things pretty well.
On Monday, November 18, 2013 1:54:55 PM UTC-5, snipped-for-privacy@attt.bizz wrote:
And if you said they were 180 different in phase from
each other, relative to the neutral, you would also be correct.
KRW only understands opposites, not phase.
Yes because the two hots are 180 deg out of phase with each
other. If they weren't you wouldn't get 240V
The center tap is by definition the neutral. Connecting it to
ground ties it to ground potential. It's like if you had a battery
in your hand, and someone saying the negative terminal is above earth/ground
potential. It makes no sense. It has no realtion to anything when
it's not hooked up to anything. Hook the neg end of the battery to
ground and now that end is at ground potential.
On Monday, November 18, 2013 4:52:51 PM UTC-5, snipped-for-privacy@attt.bizz wrote:
Here, so everyone can see who's a liar and who knows what they
are talking about. From the IEEE (Institute of Electrical and
Electronic Engineers), a paper delivered at a rural electric
power conference:
"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. "
Anyone following the discussion can read it and see that the
IEEE engineers are saying EXACTLY what I've been saying all along.
It couldn't be any more specific and on point. That IEEE paper is
100% in agreement with everything I've said. Of course krw will
snip it and ignore it, instead of learning.
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.
