Roy Smith wrote:
I don't know much about the NEC, but I do understand polyphase
circuits (4 years of EE in college). I don't think I've ever heard
the term J-factor. What is it?

The "J" factor is the square root of -1. No, really.
it is mainly used for plotting how voltage/current leads/lags
current/voltage in inductive or capacitive circuits. I am no
electrical/electronic engineer, just a simple tech with enough knowledge
to know that everyone's argument is "a little" right.

The 2 110vAC "phases" that come into your home are 180deg "out of phase"
with respect to one another as a simple product of the physics of the
windings (secondary) of a transformer. You could, in fact, produce a
transformer where the 2 legs are in phase, but that would only go so far
until the "electrical lengths" of the 2 legs become different.

Two true phases of electricity deal with the physical location of the
wires as they come from the generator, and their phase relationship is
relative to their respective location. If you have a generator, and you
place 3 "brushes" equidistant around the amature, those 3 "phases" will
be 120deg "out of phase" with each of their neighbors. if you increase
the brushes to four, and place them equidistant, each will be 90deg out
of phase to its neighbor, and 180deg out of phase with its diametric
opposite cousin. Take any number, place it around the armature, divide
by 360, and you will get the phase relationship between any 2 legs. see

http://www.tpub.com/content/neets/14.../14177_67.html

take a look @ fig. "B". on the right side of the figure, you see the
three windings labelled "7". Those are 120deg out of phase with one
another.

Since, I believe, the original question was about wiring 110 and 220 on
the same circuit, and the dryer/oven timer wiring was mentioned,
remember that the 220 is stepped down to 110 usually as a
convenience(because the 110 is readily available, existing only to
become one of the additives for 220 when necessary to perform the
primary function of the device; i.e. the heating element), and is tapped
off of in parallel to run the power supply of the "convenience"
items(clock, timer, motor) at a much more friendly voltage-5 or 12vDC in
the case of the newer appliances.

The simple answer to the question is yes. 110 and 220 co-exist quite
nicely in a circuit. If you try to make up a home-brewed solution to
allow them to co-exist, it would be a good idea to get advice not from a
newsgroup, or the web itself. Consulting with a live electrician, an
electrical inspector, AND your homeowner's insurance carrier is a must!
Insurance will not cover incidents caused by wiring not done to code.
DAMHIKT!

"David G. Sizemore" wrote in message
...
Roy Smith wrote:
I don't know much about the NEC, but I do understand polyphase
circuits (4 years of EE in college). I don't think I've ever heard
the term J-factor. What is it?

The "J" factor is the square root of -1. No, really.
it is mainly used for plotting how voltage/current leads/lags
current/voltage in inductive or capacitive circuits. I am no
electrical/electronic engineer, just a simple tech with enough knowledge
to know that everyone's argument is "a little" right.

Well, I'm not an EE, but where I went to engineering school, sqrt(-1) = i.
I also can't find a reference for it via Google. Do you have a reference
for it? I'm not saying you're wrong, just that I've never heard of it, and
I've been exposed to enough EE back in my school daze to know what reactance
is and power factor and some of that cool polyphase stuff.

todd

Hello all,
First i want to say Merry Christmas all.
For the curious the point of three phase was to provide a better power
feed for motors.
the concept of the rotating magnetic field works better when instead of
a single coil; you have three . It gives you much more power available
at any one spot on the armature.
The three phases are 120 degrees out of phase with each other. A.C.
starts at 0volts and goes to +120v then return to 0v then goes to -120
then completing the cycle returns to 0v.
When you have 3 phases they(the power company) stagger them so the
first phase starts to rise then the second then the third and they
follow each other thru the cycle so they reach 120v slightly after each
other. Instead of only getting 120v 60 times a second we now get three
separate phases providing 120vac. So 3* 60 times a second = 180 times
a second we now get power, 3 phase motors run much smoother because of
this.
240v motors do run slightly more efficently than 120v motors but only
because of increased voltage, it has none of the advantages that the 3
phase motor does.
Three phase allows much more power to be used by a device by sending it
to the load at slightly different times so there is time to cool yet
always have potential between at least any two legs.
Power as used above means voltage not watts. This is a term
electricians abuse.
Also note that in actually three phase systems there are many
arrangements of voltages available. Depending on the system and the
need you could find 277v, 208v, 240v, 120v.. etc.....so ignore the
simplification above that they all go to +-120v.
M.E.Farmer

Todd Fatheree wrote:
....
Well, I'm not an EE, but where I went to engineering school, sqrt(-1) = i.
I also can't find a reference for it via Google. Do you have a reference
for it? I'm not saying you're wrong, just that I've never heard of it, and
I've been exposed to enough EE back in my school daze to know what reactance
is and power factor and some of that cool polyphase stuff.

j for sqrt(-1) is quite common in EE, probably more so than i which is
more prevalent in mathematics or physics. One reason is that "i" is so
often used for current in EE.

As for reference, let's see...

Ok, here

T(jw) = G(jw)/(1 + G(jw)) -- ~1, |G(jw)| 1 Eq (8-60)

Closed-loop transfer function frequency response.

Feedback Control Systems, Phillips & Harbor, Prentice-Hall. ISBN
0-13-313917-4

In article ,
"David G. Sizemore" wrote:

Roy Smith wrote:
I don't know much about the NEC, but I do understand polyphase
circuits (4 years of EE in college). I don't think I've ever heard
the term J-factor. What is it?

The "J" factor is the square root of -1. No, really.

We called that "j". Always lower-case, and never with a "-factor" on
the end.

If you have a generator, and you
place 3 "brushes" equidistant around the amature, those 3 "phases" will
be 120deg "out of phase" with each of their neighbors. if you increase
the brushes to four, and place them equidistant, each will be 90deg out
of phase to its neighbor, and 180deg out of phase with its diametric
opposite cousin.

It is interesting that you mention that. It certainly is possible to
build a 4-phase generator. I've never seen or heard of one, but it
would be no big deal to build one. You would really have 4 windings,
not four brushes, but that's a detail.

Now, let's try an experiment. Label the 4 phases A, B, C, and D, in
order. Assume the windings are star-connected, so there's a common
neutral, which we'll label N. Let's further assume that the leg-neutral
voltage of each phase is 120 VAC.

I'm going to give you two panels, each having three terminals on it.
One both panels, the terminals are labeled X, Y, and N. One one panel,
X and Y are connected to phases A and C from our 4-phase generator, and
N is connected to the neutral. On the other, X and Y are connected to
L1 and L2 from a typical center-tapped 240V residential pole drop, and N
is connected to the center tap. On both panels, N is tied to earth at
the panel.

Can you describe a measurement that you can make, which will tell you
which panel is connected to the 4-phase generator and which is connected
to the pole drop? You can use voltmeters, ammeters, power meters, phase
meters, oscilloscopes, or any other tool or instrument you desire.
Assume, however, that both are ideal voltage sources, i.e. you can't
draw enough current from them to significantly load them down.

My claim is that you can't tell the difference.

"Todd Fatheree" wrote:
Well, I'm not an EE, but where I went to engineering school, sqrt(-1) = i.

If you had been an EE, you would have learned that sqrt(-1) = j. In
electrical engineering, the symbol i was already taken (it means
current). So, electrical engineers just break with tradition and use j
for sqrt(-1) instead of i. It looks a little weird at first, but you
get used to it.

When I was in school, the EE courses used j and the math and physics
courses used i. You just learn to shift mental gears depending on which
class you're in.

The only other place I've seen j used for sqrt(-1) is in the Python
programming language (http://docs.python.org/lib/typesnumeric.html)

On Sat, 25 Dec 2004 09:52:23 -0500, Roy Smith wrote:

"Todd Fatheree" wrote:
Well, I'm not an EE, but where I went to engineering school, sqrt(-1) =
i.

If you had been an EE, you would have learned that sqrt(-1) = j. In
electrical engineering, the symbol i was already taken (it means current).
So, electrical engineers just break with tradition and use j for sqrt(-1)
instead of i. It looks a little weird at first, but you get used to it.

When I was in school, the EE courses used j and the math and physics
courses used i. You just learn to shift mental gears depending on which
class you're in.

....and the reason it's "i" in mathematics is that it stands for the
"imaginary" number = sqrt(-1).

- Doug

--

To escape criticism--do nothing, say nothing, be nothing." (Elbert Hubbard)

Roy Smith wrote:

....
The only other place I've seen j used for sqrt(-1) is in the Python
programming language (http://docs.python.org/lib/typesnumeric.html)

And Matlab matrix analysis computation and display system
(www.themathworks.com) for at least one other...

"David G. Sizemore" wrote in message
...

If you try to make up a home-brewed solution to
allow them to co-exist, it would be a good idea to get advice not from a
newsgroup, or the web itself.

Very sound advice. Newsgroups, while full of very good advice are also full
of wive's tales and anecdotal experiences which get stretched to become
trueisms.

Consulting with a live electrician, an
electrical inspector, AND your homeowner's insurance carrier is a must!
Insurance will not cover incidents caused by wiring not done to code.
DAMHIKT!

The insurance company part of this statement is one of those truisms.
Insurance companies pay off every single day on house fires that the Cause
and Origin Team has determined started with faulty wiring. Bad wiring, not
simply wiring that mice worked on, etc. In most, if not all states,
insurance companies have to pay against acts of stupidity. Check with an
adjuster.
--

-Mike-

Roy Smith wrote:
It is interesting that you mention that. It certainly is possible to

build a 4-phase generator. I've never seen or heard of one, but it
would be no big deal to build one. You would really have 4 windings,

not four brushes, but that's a detail.

Now, let's try an experiment. Label the 4 phases A, B, C, and D, in
order. Assume the windings are star-connected, so there's a common
neutral, which we'll label N. Let's further assume that the
leg-neutral
voltage of each phase is 120 VAC.

I'm going to give you two panels, each having three terminals on it.

One both panels, the terminals are labeled X, Y, and N. One one
panel,
X and Y are connected to phases A and C from our 4-phase generator,
and
N is connected to the neutral. On the other, X and Y are connected
to
L1 and L2 from a typical center-tapped 240V residential pole drop,
and N
is connected to the center tap. On both panels, N is tied to earth
at
the panel.

Can you describe a measurement that you can make, which will tell you

which panel is connected to the 4-phase generator and which is
connected
to the pole drop? You can use voltmeters, ammeters, power meters,
phase
meters, oscilloscopes, or any other tool or instrument you desire.
Assume, however, that both are ideal voltage sources, i.e. you can't
draw enough current from them to significantly load them down.

My claim is that you can't tell the difference.

Ok this is a bit dirty but you didn't mention bonding the 4 phase
generator to ground anywhere but at the panel.
So I would take both panels and remove the ground wire from the ground
bus in the panel ( watch for all the heavy arcing! ) then i would take
my voltage meter and read voltages from any leg to the ground wire
coming from the ground. Since you did not bond your generator anywhere
but at the panel if you ever lose ground ( screw loosens ,cooper loss,
thermal stretching) at that panel voltage will float and be different

M.E.Farmer

In article , "Chuck Hoffman" wrote:
This has become an obvious standoff and it will serve no purpose to continue
it.

ROTFLMAO!! It's a "standoff" only because you won't [cant'?] answer the
question.


"LRod" wrote in message
.. .
On Fri, 24 Dec 2004 17:14:26 GMT, "Chuck Hoffman"
wrote:

For the critics, I've been in electronics for 40-some years and have been
a
technical school instructor. And I worked for an electric utility. I
do,
in fact, know what I'm talking about.

I, also have been in electronics for more than 40 years. I have a
pretty good idea of what I'm talking about, too. I've known all sorts
of people over those years; some with the golden finger who didn't
even need schematics to fix complex equipment but who couldn't pour
**** out of a boot with the instructions on the heel.

I've known people that couldn't pass a Morse code exam if it was sent
one character every two minutes but who could teach brilliantly.

And now I know someone with more background and experience perhaps
than I have who can't explain a simple concept involving a single
phase, two pole, center-tapped electrical circuit without complicating
it beyond measure, and then when trying the simple answer gets it
completely WRONG.

Now let's talk about your comments. First you say:

"Phase angle, as a concept, is perfectly suited for all sorts of
theoretical discussions...."

It is far more than theory, I'm afraid. It's an important consideration
when working with multi-phase circuits. Then you say:

Excuse me, but when you're discussing phase angles, AC circuits,
impedance, etc., THEORY is EXACTLY what you're talking about. Or, to
be even more precise, anything involving the movement of electrons is
electrical theory. Want me to prove my point? Let's discuss current
flow; electron or conventional current?

"Opposite legs have opposite values (because they are 180° out of
phase)"

That seems diametrically opposed to your first disdainful comment. It
is,
however, precisely the point I was making.

But the issue at hadn is a special circumstance; it is the set of
properties that becomes simple, additive arithmetic when the phase
angle is 180°. It uniquely occurs in the center tapped, two pole
circuit that is residential house wiring. Discussion of other phase
angles overly complicates the simple additive (albeit with negative
numbers) process required to understand and calculate resultant
current in a two pole, shared neutral circuit.

You also said:

"I don't recall J-factor in the NEC.

I've known people who could recite the NEC chapter and verse but had no
clue
about the physical properties of electricity or AC circuit analysis. Do
you
really understand alternating current and its physical properties ?

Yes, I'm afraid I do. But with all your experience and expertise,
explain this:

That WOULD double the current on the neutral and result in a potential
overload.

That was your response to a question about running a 120V load on one
half of a 240V circuit. I said then:

This is the part that Doug describes as utter nonsense. And he's
right. The ONLY current on the neutral would result from the
connection across one LEG of the 230V circuit (to get 115V). There is
NO current in the "neutral" of a 230V circuit because there is no
"neutral" in a 230V circuit.

And I stand by that question; how do you explain this?

You should have left well enough alone.

- -
LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

http://www.woodbutcher.net



--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)

Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter
by sending email to autoresponder at filterinfo-at-milmac-dot-com
You must use your REAL email address to get a response.

In article , "Chuck Hoffman" wrote:
For the critics, I've been in electronics for 40-some years and have been a
technical school instructor. And I worked for an electric utility. I do,
in fact, know what I'm talking about.

Actually, you haven't the first clue what you're talking about. I hope that
your time in the tech school wasn't spent teaching how residential electrical
service works.

You wrote that adding a 120V load to a 240V three-wire ["Edison"] circuit
doubles the current in the neutral wire, and creates a dangerous overload.

It does nothing of the kind.

And I'd love to see your explanation of how it could.

My late father-in-law was a union electrician and he didn't fully understand
AC. He could follow the code, pull wires, bend conduit, install boxes,
switches and outlets, etc., but he had no clue about the physical properties
of electricity.

Apparently, neither do you.

--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)

Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter
by sending email to autoresponder at filterinfo-at-milmac-dot-com
You must use your REAL email address to get a response.

On Sat, 25 Dec 2004 07:34:46 -0700, Duane Bozarth wrote
(in article ):

Todd Fatheree wrote:
...
Well, I'm not an EE, but where I went to engineering school, sqrt(-1) = i.
I also can't find a reference for it via Google. Do you have a reference
for it? I'm not saying you're wrong, just that I've never heard of it, and
I've been exposed to enough EE back in my school daze to know what reactance
is and power factor and some of that cool polyphase stuff.

j for sqrt(-1) is quite common in EE, probably more so than i which is
more prevalent in mathematics or physics. One reason is that "i" is so
often used for current in EE.

As for reference, let's see...

Ok, here

T(jw) = G(jw)/(1 + G(jw)) -- ~1, |G(jw)| 1 Eq (8-60)

Closed-loop transfer function frequency response.

Feedback Control Systems, Phillips & Harbor, Prentice-Hall. ISBN
0-13-313917-4

Hey, I have that book!
-Bruce (EE control systems engineer)

Bruce wrote:
....
Hey, I have that book!
-Bruce (EE control systems engineer)

It's one of many I've picked up over the years -- not too bad although
I've not used it too much...I was NE at the time I was doing most
control stuff so most of my early exposure was to reactor controls...I
picked up the EE controls stuff much, much later...

I have to confess that I never understood what the square root of -1
was. The product of what times itself will equal -1? I guess I have a brain
molded around neutonian physics, now a little too old to understand....

Dave

"Duane Bozarth" wrote in message
...
Bruce wrote:
...
Hey, I have that book!
-Bruce (EE control systems engineer)

It's one of many I've picked up over the years -- not too bad although
I've not used it too much...I was NE at the time I was doing most
control stuff so most of my early exposure was to reactor controls...I
picked up the EE controls stuff much, much later...

Dave wrote:

I have to confess that I never understood what the square root of -1
was.

"i" or "j" depending on whose notation you want...

... The product of what times itself will equal -1?

"i" or "j" ... think of it simply as "by definition" that j*j = -1 and
anywhere you need it you make the substitution and carry on...leads to
the expansion of the "real" numbers to include the "complex" numbers of
the form "a +/- jb", for 2 + 3j. Rules for things like
addition/subtraction are add real and imaginary parts separatel,
multiplication is like algebraic...

(2+3j)*(1+2j) = 2*1 + (2*2j+3j*1) + 2j*3j
= 2 + 7j + 6j**2
= 2 + 7j + 6*(-1)
= 2-6 + 7j
= -4 + 7j

Clear as mud? Notice all that was done in last simplification was
to associate terms and substitute -1 for the j-squared term.

The breakers you have may have a **very** short time current curve (you can
always get different breakers with longer curves) or the motor may pull
excessive startup currrent (tho this isn't my area of expertise). Once the
motor is up to speed, the current will stablize -- so you can judge by ear
how long the surge will last.

Matthew

The general idea is that larger overcurrents trip quickly, but that 2x or
3x currents can run for a long time. This protects the wiring, which is
one of the reasons for circuit breakers; a "shorted curcuit" level of
overcurrent would damage wires quickly, but lower overcurrents would take
a long time to overheat the wiring.

Hmm. I do have trouble tripping the breaker on the current (present) 15A
circuit. Could be that the breaker is old and trips easier? From what
you're saying, starting up a TS or planer shouldn't draw a high current
long enough to trip the breaker.

On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:
I know I'm going to get the "DAGS" for this question, but I just came from
there, and I didn't see this specific information. Lots of debate about how
much current the neutral wire carries, though :-)

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended? Maybe this is the
main reason for this type of circuit, so I didn't see reference to it on
Google. Much of the discussion I read was on balancing the load, which could
imply using the 3-wire circuit with all 120V outlets.

I've got a dust collector coming soon, and the extra 6-7 continuous amps is
going to result in some frequent breaker trips when I start a saw or planer.
Looked at my electrical service, and found there's an unused double-pole 30A
breaker, feeding an unused dryer outlet (house had a gas dryer when I moved
in). That should give me the 2 hots for a 3-wire circuit.

My thought on this type of circuit is to wire one outlet at 240V (re-wire DC
motor to 220V), and the rest wired at 120V. With that 30A breaker and 10 AWG
wire, should have no problem handling the loads from a DC and air cleaner
running, and startup surge from another tool.

An electrician would be a good idea, too. Hopefully I can find someone
willing to consult with me; I can do the wiring myself.
But I'm hoping to get some idea if this is the way I want to go so I can
cost materials. Won't get an electrician or the inspector on the phone
until next week.

TIA

There is a common misconception about watts and volt-amperes. People misunderstands both

the same. But there is a whole different way of calculating the both.
W and VA are both units of measurement for power, but that's where the similarity ends.

Watts do work or generate heat, while volt-amperes simply provide you with information you

need to size wires, fuses, or circuit breakers. Watts add linearly, while volt-amperes doe

not. And to measure W, you need a special wattmeter. You can calculate VA by using a

standard multimeter to measure VRMS and IRMS and finding the product
The idea for determining the Real power VS apparent power for ac is uncomplicated,
We care less of apparent power, its the utilitys problem! it is true true,or CONSIDERED

true for all practical purposes for circuits having motors,etc.
Electronic products list ac line voltage,frequency, and Amp ratings.

100Watts = 100 VA

1 watt
Watts (W) is calculated by multiplying Volts (V) times Amps (A), so 1W = 1VA
true true,or CONSIDERED true for all practical purposes
In reality A pf OF .9 WILL MAKE 1 AMP ABOUT .93 AMPS.

On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:
I know I'm going to get the "DAGS" for this question, but I just came from
there, and I didn't see this specific information. Lots of debate about how
much current the neutral wire carries, though :-)

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended? Maybe this is the
main reason for this type of circuit, so I didn't see reference to it on
Google. Much of the discussion I read was on balancing the load, which could
imply using the 3-wire circuit with all 120V outlets.

I've got a dust collector coming soon, and the extra 6-7 continuous amps is
going to result in some frequent breaker trips when I start a saw or planer.
Looked at my electrical service, and found there's an unused double-pole 30A
breaker, feeding an unused dryer outlet (house had a gas dryer when I moved
in). That should give me the 2 hots for a 3-wire circuit.

My thought on this type of circuit is to wire one outlet at 240V (re-wire DC
motor to 220V), and the rest wired at 120V. With that 30A breaker and 10 AWG
wire, should have no problem handling the loads from a DC and air cleaner
running, and startup surge from another tool.

An electrician would be a good idea, too. Hopefully I can find someone
willing to consult with me; I can do the wiring myself.
But I'm hoping to get some idea if this is the way I want to go so I can
cost materials. Won't get an electrician or the inspector on the phone
until next week.

TIA

YOU RESPONDED TO A 10 YEAR OLD POST.

In the U.S. I don't believe there is any such thing. Household supply
is obtained from a single phase of a three phase system. For all
intents and purposes, when the power grid appears in your
neighborhood, forget about two of those phases. You will never be
involved with them. Only single phase is getting into your house.

The single phase current is transformed from a fairly high voltage off
the feeders to 240V from the output of a center tapped transformer up
on the pole. With regard to that 240V, there is no neutral. The 240V
comes from the two secondaries of the transformer. And there is no +
or -. This is AC, not DC. It is 240V across the two poles.

Our well known 120V supply comes, as you know, from one hot leg and
the center tap of the transformer. Either hot leg will work.

Here is the most important thing: ALL of this; the 240V, and each 120V
is developed from the same single phase of the three phase system. It
is single phase power. There is no "two phase" power.

...or "2 phase" 240v (two 120v hots 180 degrees out of phase).

There is no "two phase" power. The two legs or poles are 180° out of
phase, as you say, because they come off the opposite legs of the
secondary of the transformer. They are NOT two phases of the three
phase system. It is single phase. All of the current in your house
comes from the same, SINGLE phase of the three phase system.

However 3 phase electricity is very different. Or so I have heard.

Yes and no, but I will leave that discussion to those with experience
with it. I have none.

I think that is why 240v is not called "2 phase"; it can be thought of as 1
phase,

It IS single phase. There's no "thinking" about it.

but is completely different than 3 phase.

Sigh. Yes, you have stated a tautology.


- -

In the U.S. I don't believe there is any such thing. Household supply
is obtained from a single phase of a three phase system. For all
intents and purposes, when the power grid appears in your
neighborhood, forget about two of those phases. You will never be
involved with them. Only single phase is getting into your house.

The single phase current is transformed from a fairly high voltage off
the feeders to 240V from the output of a center tapped transformer up
on the pole. With regard to that 240V, there is no neutral. The 240V
comes from the two secondaries of the transformer. And there is no +
or -. This is AC, not DC. It is 240V across the two poles.

Our well known 120V supply comes, as you know, from one hot leg and
the center tap of the transformer. Either hot leg will work.

Here is the most important thing: ALL of this; the 240V, and each 120V
is developed from the same single phase of the three phase system. It
is single phase power. There is no "two phase" power.

...or "2 phase" 240v (two 120v hots 180 degrees out of phase).

There is no "two phase" power. The two legs or poles are 180° out of
phase, as you say, because they come off the opposite legs of the
secondary of the transformer. They are NOT two phases of the three
phase system. It is single phase. All of the current in your house
comes from the same, SINGLE phase of the three phase system.

However 3 phase electricity is very different. Or so I have heard.

Yes and no, but I will leave that discussion to those with experience
with it. I have none.

I think that is why 240v is not called "2 phase"; it can be thought of as 1
phase,

It IS single phase. There's no "thinking" about it.

but is completely different than 3 phase.

Sigh. Yes, you have stated a tautology.


- -

On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:
I know I'm going to get the "DAGS" for this question, but I just came from
there, and I didn't see this specific information. Lots of debate about how
much current the neutral wire carries, though :-)

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended? Maybe this is the
main reason for this type of circuit, so I didn't see reference to it on
Google. Much of the discussion I read was on balancing the load, which could
imply using the 3-wire circuit with all 120V outlets.

I've got a dust collector coming soon, and the extra 6-7 continuous amps is
going to result in some frequent breaker trips when I start a saw or planer.
Looked at my electrical service, and found there's an unused double-pole 30A
breaker, feeding an unused dryer outlet (house had a gas dryer when I moved
in). That should give me the 2 hots for a 3-wire circuit.

My thought on this type of circuit is to wire one outlet at 240V (re-wire DC
motor to 220V), and the rest wired at 120V. With that 30A breaker and 10 AWG
wire, should have no problem handling the loads from a DC and air cleaner
running, and startup surge from another tool.

An electrician would be a good idea, too. Hopefully I can find someone
willing to consult with me; I can do the wiring myself.
But I'm hoping to get some idea if this is the way I want to go so I can
cost materials. Won't get an electrician or the inspector on the phone
until next week.

TIA

On 4/13/14, 11:00 PM, Leon wrote:
YOU RESPONDED TO A 10 YEAR OLD POST.

He wanted to reply then, but it took him this long to get his PhD in
electrical engineering. :-)


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On 4/13/2014 11:34 PM, -MIKE- wrote:
On 4/13/14, 11:00 PM, Leon wrote:
YOU RESPONDED TO A 10 YEAR OLD POST.

He wanted to reply then, but it took him this long to get his PhD in
electrical engineering. :-)


LOL!

Sorta...

I have a degree in Physics and retired as an EE after 20+ years.

Watts is the value in power if it were a resistive load.
VA is the voltage times the current (and ignoring the phase angle
between them) Which gives a completely different wattage for a reactive
load like a motor.

ELI the ICE man.
Voltage leads current (in time) in inductive (coil) circuits.
Current (I) leads Voltage in a capacitive circuit -
starting coil with cap. Cap larger than coil
in reactive values. XL == ac resistance XC == ac resistance.

Martin

On 4/13/2014 10:53 PM, wrote:
On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:
I know I'm going to get the "DAGS" for this question, but I just came from
there, and I didn't see this specific information. Lots of debate about how
much current the neutral wire carries, though :-)

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended? Maybe this is the
main reason for this type of circuit, so I didn't see reference to it on
Google. Much of the discussion I read was on balancing the load, which could
imply using the 3-wire circuit with all 120V outlets.

I've got a dust collector coming soon, and the extra 6-7 continuous amps is
going to result in some frequent breaker trips when I start a saw or planer.
Looked at my electrical service, and found there's an unused double-pole 30A
breaker, feeding an unused dryer outlet (house had a gas dryer when I moved
in). That should give me the 2 hots for a 3-wire circuit.

My thought on this type of circuit is to wire one outlet at 240V (re-wire DC
motor to 220V), and the rest wired at 120V. With that 30A breaker and 10 AWG
wire, should have no problem handling the loads from a DC and air cleaner
running, and startup surge from another tool.

An electrician would be a good idea, too. Hopefully I can find someone
willing to consult with me; I can do the wiring myself.
But I'm hoping to get some idea if this is the way I want to go so I can
cost materials. Won't get an electrician or the inspector on the phone
until next week.

TIA

There is a common misconception about watts and volt-amperes. People misunderstands both

the same. But there is a whole different way of calculating the both.
W and VA are both units of measurement for power, but that's where the similarity ends.

Watts do work or generate heat, while volt-amperes simply provide you with information you

need to size wires, fuses, or circuit breakers. Watts add linearly, while volt-amperes doe

not. And to measure W, you need a special wattmeter. You can calculate VA by using a

standard multimeter to measure VRMS and IRMS and finding the product
The idea for determining the Real power VS apparent power for ac is uncomplicated,
We care less of apparent power, its the utilitys problem! it is true true,or CONSIDERED

true for all practical purposes for circuits having motors,etc.
Electronic products list ac line voltage,frequency, and Amp ratings.

100Watts = 100 VA

1 watt
Watts (W) is calculated by multiplying Volts (V) times Amps (A), so 1W = 1VA
true true,or CONSIDERED true for all practical purposes
In reality A pf OF .9 WILL MAKE 1 AMP ABOUT .93 AMPS.

On Mon, 14 Apr 2014 17:43:21 -0500, Martin Eastburn
wrote:

Sorta...

Sorta (as long as we're being pedantic ;-)

I have a degree in Physics and retired as an EE after 20+ years.

Watts is the value in power if it were a resistive load.

Sorta, kinda, perhaps poorly worded. Power is measured in watts. W=VA
if the load is resistive.

VA is the voltage times the current (and ignoring the phase angle
between them) Which gives a completely different wattage for a reactive
load like a motor.

Assuming there are no harmonics, which is a good approximation for an
induction motor but may not be a good assumption for other situations.
Electronic loads are often particularly bad. Fluorescent lighting is
another example where the power factor (W/VA) is often particularly
bad.

ELI the ICE man.
Voltage leads current (in time) in inductive (coil) circuits.
Current (I) leads Voltage in a capacitive circuit -
starting coil with cap. Cap larger than coil
in reactive values. XL == ac resistance XC == ac resistance.

The important thing is that wiring and circuit elements (switches,
breakers, connections, generation) must be sized for volt-amperes,
where the power consumed (heat load, electric bill, etc.) is
quantified by watts. VA is always equal (only for purely resistive
loads) to or greater (all other cases) than watts. Reactive (either
inductive or capacitive) loads cause additional problems not
quantified by either.

You got it wrong. it is this : Power (measured in the watt) - Voltage
(measured in the Volt) Times Current(measured in Amps) Times Cos(phase
angle) (1 to 0 in value).

P = V*I*Cos(theta). When in DC Cos(0)=1. V is DC voltage in that case.

When in DC - it becomes : P = E*I where E is the DC voltage. I is the
DC current and there isn't a phase angle or Theta is Zero and COS(0) = 1.

A Watt is the unit of power. Not the plural form.

When V is used it is AC. When V is used I is AC.
They are in R.M.S. scaling. Root of the Mean Square.
(A.C. volt meters and current transforms 'translate to these'.)
Some times special voltages are used as design needs.

Harmonics from inductive and capacitive circuits are very small
compared to the main current / voltage waveform. They are ignored
if anything normal.

One should always use the phase angle in the AC model. Meters do.
So the task for the technician is just measure it using a quality meter.

Even a reasonable multi-meter from Radio-Shack can measure Correctly
(enough). I like three or four major makers and for the lab I use two.

V means AC voltage. E means DC voltage. I is the current that
matches. Cosine(phase-angle) is Always used in AC.

One should design for several times that of V*A*Cos(0).

Martin - Senior Scientist and former Technologist serving between and
working for both Intel and the Schlumberger.
I'm working on my computer I built in the late 50's and early 60's. It
has just under a thousand gates. All hand wired.



On 4/14/2014 7:19 PM, wrote:
On Mon, 14 Apr 2014 17:43:21 -0500, Martin Eastburn
wrote:

Sorta...

Sorta (as long as we're being pedantic ;-)

I have a degree in Physics and retired as an EE after 20+ years.

Watts is the value in power if it were a resistive load.

Sorta, kinda, perhaps poorly worded. Power is measured in watts. W=VA
if the load is resistive.

VA is the voltage times the current (and ignoring the phase angle
between them) Which gives a completely different wattage for a reactive
load like a motor.

Assuming there are no harmonics, which is a good approximation for an
induction motor but may not be a good assumption for other situations.
Electronic loads are often particularly bad. Fluorescent lighting is
another example where the power factor (W/VA) is often particularly
bad.

ELI the ICE man.
Voltage leads current (in time) in inductive (coil) circuits.
Current (I) leads Voltage in a capacitive circuit -
starting coil with cap. Cap larger than coil
in reactive values. XL == ac resistance XC == ac resistance.

The important thing is that wiring and circuit elements (switches,
breakers, connections, generation) must be sized for volt-amperes,
where the power consumed (heat load, electric bill, etc.) is
quantified by watts. VA is always equal (only for purely resistive
loads) to or greater (all other cases) than watts. Reactive (either
inductive or capacitive) loads cause additional problems not
quantified by either.

On Tue, 15 Apr 2014 23:01:32 -0500, Martin Eastburn
wrote:

You got it wrong. it is this : Power (measured in the watt) - Voltage
(measured in the Volt) Times Current(measured in Amps) Times Cos(phase
angle) (1 to 0 in value).

No, I certainly don't. That formula only for SINE WAVES (i.e. no
harmonics on either current or voltage waveforms). OTOH, PF=W/VA
*always* works.

P = V*I*Cos(theta). When in DC Cos(0)=1. V is DC voltage in that case.

So? Again, sine waves are the trivial case. That formula doesn't
work for nonlinear situations. The DC case is more than trivial. PF
is meaningless.

When in DC - it becomes : P = E*I where E is the DC voltage. I is the
DC current and there isn't a phase angle or Theta is Zero and COS(0) = 1.

Trivial cases are irrelevant. Not sure why you insist on lecturing on
the trivial.

A Watt is the unit of power. Not the plural form.

Plural is plural. Two times a watt is two watts. ...and if you really
want to get pedantic about the language, "watt" is not capitalized.
Proper names, when used as names of units are *not* capitalized.
Abbreviations for proper names are.

Correct Incorrect
W, V, A w, v, a
watt Watt
volt Volt
ampere Ampere
meter Meter
m M

When V is used it is AC. When V is used I is AC.

Whatever that means.

They are in R.M.S. scaling. Root of the Mean Square.

May be. That's the point, though. Your assumptions only work for
sine waves and the conversion between Peak, RMS, whatever, is trivial,
in that case. RMS is the voltage (or current) of a waveform that will
give the equivalent power of a DC value. It's one of many meaningful
numbers. The root of the mean square (for voltage or current) can be
calculated, as can the average of the voltage X current (power).

No periods in RMS.

(A.C. volt meters and current transforms 'translate to these'.)

Again, "translate to" means "only valid for sine waves". If you
aren't dealing with sine waves, these "translations" are meaningless.
Worse, actually. They're wrong. A "true RMS" meter is always right
(within it's physical capabilities).

Some times special voltages are used as design needs.

Was that supposed to mean something?

Harmonics from inductive and capacitive circuits are very small
compared to the main current / voltage waveform. They are ignored
if anything normal.

Oh, good grief! Stop with the word salad, already. Harmonics from
inductors and capacitors are ZERO. They're linear devices. Switching
elements (semiconductors) are a whole different kettle, as is the real
world.

One should always use the phase angle in the AC model. Meters do.

Wrong. Meters certainly do not. They integrate V, A, V*A, or measure
heat.

So the task for the technician is just measure it using a quality meter.

No, one should always use reality. It may be impossible to measure
phase angle. It's always possible to measure V, I, and P. PF can then
be derived from that, if necessary.

Even a reasonable multi-meter from Radio-Shack can measure Correctly
(enough). I like three or four major makers and for the lab I use two.

If they're "true RMS" meters, they're integrating type. If they're
peak or average (rectified) meters, then they're calibrated assuming a
sine wave. If you have something else (harmonics) then they're wrong.


V means AC voltage. E means DC voltage. I is the current that
matches. Cosine(phase-angle) is Always used in AC.

Now you making stuff up. Wrong.

One should design for several times that of V*A*Cos(0).

Whatever that means.

Martin - Senior Scientist and former Technologist serving between and
working for both Intel and the Schlumberger.
I'm working on my computer I built in the late 50's and early 60's. It
has just under a thousand gates. All hand wired.

Don't break your arm.

On 4/13/14 9:53 PM, wrote:
On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:
I know I'm going to get the "DAGS" for this question, but I just came from
there, and I didn't see this specific information. Lots of debate about how
much current the neutral wire carries, though :-)

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended? Maybe this is the
main reason for this type of circuit, so I didn't see reference to it on
Google. Much of the discussion I read was on balancing the load, which could
imply using the 3-wire circuit with all 120V outlets.

I've got a dust collector coming soon, and the extra 6-7 continuous amps is
going to result in some frequent breaker trips when I start a saw or planer.
Looked at my electrical service, and found there's an unused double-pole 30A
breaker, feeding an unused dryer outlet (house had a gas dryer when I moved
in). That should give me the 2 hots for a 3-wire circuit.

My thought on this type of circuit is to wire one outlet at 240V (re-wire DC
motor to 220V), and the rest wired at 120V. With that 30A breaker and 10 AWG
wire, should have no problem handling the loads from a DC and air cleaner
running, and startup surge from another tool.

One problem I see is you are wiring a 110V outlet on a 30A circuit. That
is fine, but you need to get an outlet rated for 30A. The typical 110V
duplex is 20A max (NEMA 5-20), Your outlets will need to be NEMA 5-30
(which may have issues with your 110V plugs on your tools).

-Bruce


An electrician would be a good idea, too. Hopefully I can find someone
willing to consult with me; I can do the wiring myself.
But I'm hoping to get some idea if this is the way I want to go so I can
cost materials. Won't get an electrician or the inspector on the phone
until next week.

TIA

There is a common misconception about watts and volt-amperes. People misunderstands both

the same. But there is a whole different way of calculating the both.
W and VA are both units of measurement for power, but that's where the similarity ends.

Watts do work or generate heat, while volt-amperes simply provide you with information you

need to size wires, fuses, or circuit breakers. Watts add linearly, while volt-amperes doe

not. And to measure W, you need a special wattmeter. You can calculate VA by using a

standard multimeter to measure VRMS and IRMS and finding the product
The idea for determining the Real power VS apparent power for ac is uncomplicated,
We care less of apparent power, its the utilitys problem! it is true true,or CONSIDERED

true for all practical purposes for circuits having motors,etc.
Electronic products list ac line voltage,frequency, and Amp ratings.

100Watts = 100 VA

1 watt
Watts (W) is calculated by multiplying Volts (V) times Amps (A), so 1W = 1VA
true true,or CONSIDERED true for all practical purposes
In reality A pf OF .9 WILL MAKE 1 AMP ABOUT .93 AMPS.




--- news://freenews.netfront.net/ - complaints: ---

On Fri, 18 Apr 2014 08:20:12 -0600, Brewster wrote:

On 4/13/14 9:53 PM, wrote:
On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:
I know I'm going to get the "DAGS" for this question, but I just came from
there, and I didn't see this specific information. Lots of debate about how
much current the neutral wire carries, though :-)

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended? Maybe this is the
main reason for this type of circuit, so I didn't see reference to it on
Google. Much of the discussion I read was on balancing the load, which could
imply using the 3-wire circuit with all 120V outlets.

I've got a dust collector coming soon, and the extra 6-7 continuous amps is
going to result in some frequent breaker trips when I start a saw or planer.
Looked at my electrical service, and found there's an unused double-pole 30A
breaker, feeding an unused dryer outlet (house had a gas dryer when I moved
in). That should give me the 2 hots for a 3-wire circuit.

My thought on this type of circuit is to wire one outlet at 240V (re-wire DC
motor to 220V), and the rest wired at 120V. With that 30A breaker and 10 AWG
wire, should have no problem handling the loads from a DC and air cleaner
running, and startup surge from another tool.

One problem I see is you are wiring a 110V outlet on a 30A circuit. That
is fine, but you need to get an outlet rated for 30A. The typical 110V
duplex is 20A max (NEMA 5-20), Your outlets will need to be NEMA 5-30
(which may have issues with your 110V plugs on your tools).

-Bruce


An electrician would be a good idea, too. Hopefully I can find someone
willing to consult with me; I can do the wiring myself.
But I'm hoping to get some idea if this is the way I want to go so I can
cost materials. Won't get an electrician or the inspector on the phone
until next week.

TIA

There is a common misconception about watts and volt-amperes. People misunderstands both

the same. But there is a whole different way of calculating the both.
W and VA are both units of measurement for power, but that's where the similarity ends.

Watts do work or generate heat, while volt-amperes simply provide you with information you

need to size wires, fuses, or circuit breakers. Watts add linearly, while volt-amperes doe

not. And to measure W, you need a special wattmeter. You can calculate VA by using a

standard multimeter to measure VRMS and IRMS and finding the product
The idea for determining the Real power VS apparent power for ac is uncomplicated,
We care less of apparent power, its the utilitys problem! it is true true,or CONSIDERED

true for all practical purposes for circuits having motors,etc.
Electronic products list ac line voltage,frequency, and Amp ratings.

100Watts = 100 VA

1 watt
Watts (W) is calculated by multiplying Volts (V) times Amps (A), so 1W = 1VA
true true,or CONSIDERED true for all practical purposes
In reality A pf OF .9 WILL MAKE 1 AMP ABOUT .93 AMPS.




--- news://freenews.netfront.net/ - complaints: ---
Really simple to get around the 30 amp problem. Install a fused
outlet. In the UK they are common devices, but not here, so you would
install a fused (or breaker protected) disconnect on the 30 amp
circuit, and connect the 115 volt outlets to that "sub panel"

On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended?

It used to be common, and my stove and clothesdryer both have 120V as
well as 240V loads, and a three wire plug. This is now not recommended,
and there's good reasons for a four-wire connection instead.
In stoves, a convenience outlet is sometimes supplied, and this would
have a separate fuse (or circuit breaker) so that the 30A fused stove
doesn't cause a fire hazard on the 15A wiring plugged into that
convenience outlet.

The clean solution (ask an electrician to be safe) is to run a four-wire
line from your main breaker to a subpanel; then put any combination
of 240V and 120V breakers into the subpanel, and wire your sockets
from that subpanel. There's lots of rules on subpanel size and
wiring, but it's what an inspector would want to see.

On Sat, 19 Apr 2014 12:16:04 -0700 (PDT), whit3rd
wrote:

On Thursday, December 23, 2004 10:59:07 AM UTC-8, Keith Carlson wrote:

With a 3-wire circuit, is it okay to wire both 120V and 240V outlets on that
same circuit? I know it's *possible* by using the two hots for 240 and
either hot and neutral for 120, but is it recommended?

It used to be common, and my stove and clothesdryer both have 120V as
well as 240V loads, and a three wire plug. This is now not recommended,
and there's good reasons for a four-wire connection instead.
In stoves, a convenience outlet is sometimes supplied, and this would
have a separate fuse (or circuit breaker) so that the 30A fused stove
doesn't cause a fire hazard on the 15A wiring plugged into that
convenience outlet.

The clean solution (ask an electrician to be safe) is to run a four-wire
line from your main breaker to a subpanel; then put any combination
of 240V and 120V breakers into the subpanel, and wire your sockets
from that subpanel. There's lots of rules on subpanel size and
wiring, but it's what an inspector would want to see.
I think most were asuming 3 wire+ground (nmd3) cable. I know I was.
The 3 terminal drier plug is history.