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30A wiring advice

N

No Spam

Guest
John Woodgate wrote:
I read in sci.engr.electrical.compliance that s <sim.mich@cwcom.net
wrote (in <AOOeb.13$kC5.21047@newsfep1-win.server.ntli.net>) about '30A
wiring advice - a complication?', on Wed, 1 Oct 2003:

im sorry to disagree but i dont consider this to be a true two phase
system,as only one phase is entering the transformer,one leaving.the
centre tap being there for safety/alternate voltage.

If you look at it like that, you get the confusion that troubled the OP.
You have chosen the explanation of the centre-tap to 'prove' your
assertion. But one 120 V supply behaves exactly as a single-phase
supply, and so does the other. When you look at the two together, the
important phase-difference comes into consideration. Your explanation
'hides' the phase-difference.

if this were a true
two phase,then it could be fed straight into a squirrel cage motor
without the need of a starting capacitor to phase shift the feild,or am
i missing something quite fundamental here??

Yes, you are missing something. A two-phase system does not create a
rotating magnetic field, as a 3- or higher- phase system can do. So the
motor won't start. The starting capacitor and the second winding DO
create a rotating field.

A 'two-phase' system with 90 degrees between the legs (which is really
half a 4-phase system - the angles must add up to 360 degrees) would
create a rotating field, but it is not easy to derive such a supply from
the public electricity system.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
Then a 3-phase system is half a six phase system.

John, this is just a matter of semantics. If you prefer to
call the North American centre tapped SINGLE phase system
"two-phase", go for it. It's your God given right. And
those across the pond choose to call their centre tapped
system "single phase, it is their right as well.

According to what you are saying, you take a single
transformer winding and tap it in the middle, that gives you
two phases. Then you should be able to tap that same
winding in another spot and get 3 phase. Couple more spots
and you get 5-phase.

You say the two phase system is really 4 phase system
because the phase angles have to add to 360. Look at it
this way. Phase 1 to Phase 2 is 90 degrees. Phase 2 to
phase 1 is 270 degrees. You have to count in the same
direction. You the way you are doing it adds to zero
degrees.
 
J

John Woodgate

Guest
I read in sci.engr.electrical.compliance that No Spam
<no.spam@hotmail.com> wrote (in <3F7F33BF.81D93964@hotmail.com>) about
'30A wiring advice - a complication?', on Sat, 4 Oct 2003:

John, this is just a matter of semantics. If you prefer to call the
North American centre tapped SINGLE phase system "two-phase", go for it.
It's your God given right. And those across the pond choose to call
their centre tapped system "single phase, it is their right as well.
I agree; that's why I don't understand the violent reaction of some US
people on the subject.
According to what you are saying, you take a single transformer winding
and tap it in the middle, that gives you two phases. Then you should be
able to tap that same winding in another spot and get 3 phase. Couple
more spots and you get 5-phase.
No, that's specious. With one winding, you have the choice of 0 or 180
degrees phase. There is no way to get 120 or 72 degrees.
You say the two phase system is really 4 phase system because the phase
angles have to add to 360. Look at it this way. Phase 1 to Phase 2 is
90 degrees. Phase 2 to phase 1 is 270 degrees. You have to count in
the same direction. You the way you are doing it adds to zero degrees.
Well, that's yet another way of looking at it, better than appealing to
a sum of angles being 360 degrees. My point is that a 2-phase 90 degree
system is unsymmetrical, unlike a two-phase 180 degree system or a
3-phase 120 degree system. A three-phase 60 degree system would also be
unsymmetrical. Unsymmetrical systems of this type can be made
symmetrical by doubling the number of phases, **and this can be done by
means of 1:1 transformers**. This last point applies to a single-phase
supply as well, with conclusions that should now be obvious.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
 
J

John Wilson

Guest
No Spam wrote:
John Woodgate wrote:

I read in sci.engr.electrical.compliance that s <sim.mich@cwcom.net
wrote (in <AOOeb.13$kC5.21047@newsfep1-win.server.ntli.net>) about '30A
wiring advice - a complication?', on Wed, 1 Oct 2003:


im sorry to disagree but i dont consider this to be a true two phase
system,as only one phase is entering the transformer,one leaving.the
centre tap being there for safety/alternate voltage.

If you look at it like that, you get the confusion that troubled the OP.
You have chosen the explanation of the centre-tap to 'prove' your
assertion. But one 120 V supply behaves exactly as a single-phase
supply, and so does the other. When you look at the two together, the
important phase-difference comes into consideration. Your explanation
'hides' the phase-difference.


if this were a true
two phase,then it could be fed straight into a squirrel cage motor
without the need of a starting capacitor to phase shift the feild,or am
i missing something quite fundamental here??

Yes, you are missing something. A two-phase system does not create a
rotating magnetic field, as a 3- or higher- phase system can do. So the
motor won't start. The starting capacitor and the second winding DO
create a rotating field.

A 'two-phase' system with 90 degrees between the legs (which is really
half a 4-phase system - the angles must add up to 360 degrees) would
create a rotating field, but it is not easy to derive such a supply from
the public electricity system.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!


Then a 3-phase system is half a six phase system.

John, this is just a matter of semantics. If you prefer to
call the North American centre tapped SINGLE phase system
"two-phase", go for it. It's your God given right. And
those across the pond choose to call their centre tapped
system "single phase, it is their right as well.
Abraham Lincoln once asked, "If you call a dog's tail a leg, how many
legs does a dog have?". His answer; "Four; calling a tail a leg doesn't
make it one." Particularly in a technical field, getting the terminology
wrong has caused more errors than any other single factor in my
experience. As I said in a previous post, this issue is defined in the
same way in various standards and in every electrical engineering text
I've ever seen, and the definition is as I have explained it before. Do
I have the right to call a capacitor a transformer? NO!

Every hot conductor in a power system is not a "phase".

According to what you are saying, you take a single
transformer winding and tap it in the middle, that gives you
two phases. Then you should be able to tap that same
winding in another spot and get 3 phase. Couple more spots
and you get 5-phase.

You say the two phase system is really 4 phase system
because the phase angles have to add to 360. Look at it
this way. Phase 1 to Phase 2 is 90 degrees. Phase 2 to
phase 1 is 270 degrees. You have to count in the same
direction. You the way you are doing it adds to zero
degrees.
73,
JohnW
 
J

John Woodgate

Guest
I read in sci.engr.electrical.compliance that John Wilson
<johnwilson@alum.mit.edu> wrote (in <1uWfb.499575$Oz4.348500@rwcrnsc54>)
about '30A wiring advice - a complication?', on Sun, 5 Oct 2003:
As I said in a previous post, this issue is defined in the
same way in various standards
You cited one ANSI standard.

I do not wish to continue this futile exchange. You are not prepared to
see any other point of view than your own.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
 
R

Rowbotth

Guest
In article <1uWfb.499575$Oz4.348500@rwcrnsc54>,
John Wilson <johnwilson@alum.mit.edu> wrote:


Abraham Lincoln once asked, "If you call a dog's tail a leg, how many
legs does a dog have?". His answer; "Four; calling a tail a leg doesn't
make it one." Particularly in a technical field, getting the terminology
wrong has caused more errors than any other single factor in my
experience. As I said in a previous post, this issue is defined in the
same way in various standards and in every electrical engineering text
I've ever seen, and the definition is as I have explained it before. Do
I have the right to call a capacitor a transformer? NO!

Every hot conductor in a power system is not a "phase".
Good answer. Accurate and to the point.

Unfortunately it won't change the minds of the fanatics; but you have
the satisfaction of having answered the question for the rationale ones.

HR.
 
M

Michael Moroney

Guest
John Woodgate <jmw@jmwa.demon.contraspam.yuk> writes:

Well, that's yet another way of looking at it, better than appealing to
a sum of angles being 360 degrees. My point is that a 2-phase 90 degree
system is unsymmetrical, unlike a two-phase 180 degree system or a
3-phase 120 degree system. A three-phase 60 degree system would also be
unsymmetrical. Unsymmetrical systems of this type can be made
symmetrical by doubling the number of phases, **and this can be done by
means of 1:1 transformers**. This last point applies to a single-phase
supply as well, with conclusions that should now be obvious.
Au contraire. A 90 degree 2 phase system is symmetrical. The whole thing
transmits constant power (remember: sin(x)^2+cos(x)^2=1, and
cos(x)=sin(x+90) A center tapped transformer doesn't transmit constant
power, and its power is identical to a single phase non-center tapped
transformer. A 3 phase system (with all phases available and used)
is also symmetric.

--
-Mike
 
J

John Wilson

Guest
John Woodgate wrote:
I read in sci.engr.electrical.compliance that John Wilson
johnwilson@alum.mit.edu> wrote (in <1uWfb.499575$Oz4.348500@rwcrnsc54>)
about '30A wiring advice - a complication?', on Sun, 5 Oct 2003:

As I said in a previous post, this issue is defined in the
same way in various standards


You cited one ANSI standard.

I do not wish to continue this futile exchange. You are not prepared to
see any other point of view than your own.
I cited one ANSI standard, because it's the one I remember offhand. I
have access to many others at work; this entire exchange has taken place
on a weekend. If you want more references, I can supply them.

Anybody have access to a collection of IEC standards, to see what the
European definition is?

In any case, most terms, including many others that are frequently
misused, such as "metalclad switchgear", "circuit breaker", and so
forth, are each defined in a particular standard.

73,
JohnW
 
T

Trevor Barton

Guest
On Thu, 2 Oct 2003 16:17:44 -0400, Robert Calvert wrote:
Could this mean that status inconsistency is more rampant here in the US
than it is in Europe? After all, in Switzerland, it might be that if my
income is higher than an electrician's income, I would probably hire
somebody to do my electrical work because it wouldn't be worth my time to do
it myself. And if my income is lower than an electrician's income, I
probably wouldn't be able to do what an electrician can do - in which case I
would probably hire this work out anyway. In the US, on the other hand, it's
not inconceivable that there are many more people who can do what an
electrician can do but who don't make as much money as an electrician. In
such an environment, you would probably find many more do-it-yourselfers.
It depends how you cost your free time. If you were going to be earning
money during the time you were DIYing it might make more sense to get
someone else to do it. If you were on the other hand doing nothing
else at the time, then you've effectively earned the electrician's
fee for yourself by doing it yourself. In between those two extremes
there's a cost-benifit tradeoff - will you pay someone to do the job
to increase your leisure time?

--
Trevor Barton
 
S

Spehro Pefhany

Guest
On Mon, 06 Oct 2003 14:22:44 GMT, the renowned Trevor Barton
<tmb@Xisotek.co.uk> wrote:

On Thu, 2 Oct 2003 16:17:44 -0400, Robert Calvert wrote:
Could this mean that status inconsistency is more rampant here in the US
than it is in Europe? After all, in Switzerland, it might be that if my
income is higher than an electrician's income, I would probably hire
somebody to do my electrical work because it wouldn't be worth my time to do
it myself. And if my income is lower than an electrician's income, I
probably wouldn't be able to do what an electrician can do - in which case I
would probably hire this work out anyway. In the US, on the other hand, it's
not inconceivable that there are many more people who can do what an
electrician can do but who don't make as much money as an electrician. In
such an environment, you would probably find many more do-it-yourselfers.

It depends how you cost your free time. If you were going to be earning
money during the time you were DIYing it might make more sense to get
someone else to do it. If you were on the other hand doing nothing
else at the time, then you've effectively earned the electrician's
fee for yourself by doing it yourself. In between those two extremes
there's a cost-benifit tradeoff - will you pay someone to do the job
to increase your leisure time?
When doing personal projects, the taxation regime enters into it. If I
gross 50 Euros/hour and work an *extra* hour in Europe I might only
net 25 (assuming a *marginal* rate of 50%- the average rate will be
lower, of course). If I pay the electrician (who has his or her own
taxes to pay) more than 25 Euros for an hour's work, I'm in a loss
position compared to not working the extra hour and doing it myself.
If he's charging 50 then I can take 1-1/2 hours to do that job and buy
a few tools and still come out even (and get to keep the tools). If
it's a business expense, then the taxation considerations disappear
and I can use the 50 Euros figure.

As taxation is (was?) highest in the Scandinavian countries, that may
account for the popularity of DIY-type stuff like Ikea.
Here in Canada, this problem is solved in the home renovation field by
a large contribution from the underground economy, which evens out the
tax thing- the $1000 cash after tax to put a carpet down (less
expenses) goes right into the pocket of some guy with a pickup and a
free weekend. Not everyone does it, but enough that it's a factor.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
A

AC/DCdude17

Guest
X-No-Archive: Yes

Someone here mentioned main entry wires for multi-thousand ampere service uses
paralleled wires. If this is ok, why not in smaller scale?


Joe 90 wrote:

I am making some changes to an electrical dryer. Where I live, I cannot get
hold of 10 gauge wire for the 30A circuit - I know, don't ask why, pls. Can
I use two 12 gauge wires connected in parallel? Based on my electrical
knowledge, this would split the max current between the two wires allowing
the wires to run cooler and well below max capacity.
 
P

Paul A

Guest
"AC/DCdude17" <JerC@prontoREMOVETHISmail.com> wrote in message
news:3F8A507E.AE72F2E3@prontoREMOVETHISmail.com...
X-No-Archive: Yes

Someone here mentioned main entry wires for multi-thousand ampere service
uses
paralleled wires. If this is ok, why not in smaller scale?
Short answer:Because the NEC dose not allow it for wires smaller than 1/0.
Longer answer: Because if one wire was damaged, opened up, etc, the entire
load would be carried by the other wire, which is greatly over the rating of
the other wire and is a fire waiting to happen.
 
S

Spudley

Guest
"Paul A" <nospam@nospam.com> wrote in message
news:Nixib.6383$fv4.108@nwrdny02.gnilink.net...
"AC/DCdude17" <JerC@prontoREMOVETHISmail.com> wrote in message
news:3F8A507E.AE72F2E3@prontoREMOVETHISmail.com...
X-No-Archive: Yes

Someone here mentioned main entry wires for multi-thousand ampere
service
uses
paralleled wires. If this is ok, why not in smaller scale?



Short answer:Because the NEC dose not allow it for wires smaller
than 1/0.
Longer answer: Because if one wire was damaged, opened up, etc, the
entire
load would be carried by the other wire, which is greatly over the
rating of
the other wire and is a fire waiting to happen.
Then use 4 wires in parallel and solder them together at the ends to
ensure this doesn't happen.


>
 
B

Ben Miller

Guest
"Spudley" <antispam@bigpond.net.au> wrote in message
news:5LgGb.64183$aT.56575@news-server.bigpond.net.au...
Then use 4 wires in parallel and solder them together at the ends to
ensure this doesn't happen.
In the US, parallel conductors are not allowed in the smaller sizes, and
connections that depend on solder are not allowed for service conductors.
Also, if this was allowed, wouldn't it be a lot more material and labor than
just using a single wire of the correct size?

Ben Miller
--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com
 
P

PJx

Guest
On Wed, 24 Dec 2003 15:17:23 GMT, "Ben Miller"
<benmiller@worldnet.att.net> wrote:

"Spudley" <antispam@bigpond.net.au> wrote in message
news:5LgGb.64183$aT.56575@news-server.bigpond.net.au...
Then use 4 wires in parallel and solder them together at the ends to
ensure this doesn't happen.

In the US, parallel conductors are not allowed in the smaller sizes, and
connections that depend on solder are not allowed for service conductors.
Also, if this was allowed, wouldn't it be a lot more material and labor than
just using a single wire of the correct size?

Ben Miller
I like the way you quote the source of your misinformation.

Besides, this is posted in alt.home.repair, not engineering specs for
the space shuttle.

Get a life.

PJ
 
T

Texan

Guest
On Wed, 24 Dec 2003 15:17:23 GMT, "Ben Miller"
<benmiller@worldnet.att.net> wrote:

"Spudley" <antispam@bigpond.net.au> wrote in message
news:5LgGb.64183$aT.56575@news-server.bigpond.net.au...
Then use 4 wires in parallel and solder them together at the ends to
ensure this doesn't happen.

In the US, parallel conductors are not allowed in the smaller sizes, and
connections that depend on solder are not allowed for service conductors.
Also, if this was allowed, wouldn't it be a lot more material and labor than
just using a single wire of the correct size?

Ben Miller
Just for the techs who wonder why solder isn't allowed. When a
connection gets hot the solder would melt and create all kinds of
problems.. Solder has a much lower melt temp than copper. That's why
in higher load carrying circuits we use crimp or compression type
connectors.
 
J

John Woodgate

Guest
I read in sci.engr.electrical.compliance that PJx <me@privacy.net> wrote
(in <stkjuvgm2prd272b71q7983tjnd810p5l2@4ax.com>) about '30A wiring
advice', on Wed, 24 Dec 2003:
On Wed, 24 Dec 2003 15:17:23 GMT, "Ben Miller"
benmiller@worldnet.att.net> wrote:

"Spudley" <antispam@bigpond.net.au> wrote in message
news:5LgGb.64183$aT.56575@news-server.bigpond.net.au...
Then use 4 wires in parallel and solder them together at the ends to
ensure this doesn't happen.

In the US, parallel conductors are not allowed in the smaller sizes, and
connections that depend on solder are not allowed for service conductors.
Also, if this was allowed, wouldn't it be a lot more material and labor than
just using a single wire of the correct size?

Ben Miller

I like the way you quote the source of your misinformation.
I would expect soldered connections in terminal blocks to be banned,
because the solder creeps under pressure and the clamping screws loosen.
Soldered connections are not allowed in Europe.
Besides, this is posted in alt.home.repair, not engineering specs for
the space shuttle.

It's posted in four newsgroups, including sci.engr.electrical.compliance
, where people know about wiring codes.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
 
B

Ben Miller

Guest
"PJx" <me@privacy.net> wrote in message
news:stkjuvgm2prd272b71q7983tjnd810p5l2@4ax.com...
I like the way you quote the source of your misinformation.
National Electrical Code (2002):

230.81 Connection to Terminals.
The service conductors shall be connected to the service disconnecting means
by pressure connectors, clamps, or other approved means. Connections that
depend on solder shall not be used.

310.4 Conductors in Parallel.
Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and
larger, comprising each phase, neutral, or grounded circuit conductor, shall
be permitted to be connected in parallel (electrically joined at both ends
to form a single conductor).


Ben Miller
--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com
 
A

Andrew Gabriel

Guest
In article <WuYw9tEebd6$EwkE@jmwa.demon.co.uk>,
John Woodgate <jmw@jmwa.demon.contraspam.yuk> writes:
I would expect soldered connections in terminal blocks to be banned,
because the solder creeps under pressure and the clamping screws loosen.
Soldered connections are not allowed in Europe.
I agree with your comments about soldered connections in terminal blocks.
However, soldered (or crimped or brazed) connections are required in the
UK if the join will not be accessible for maintenance and inspection.

One way which is acceptable to do this is to use screw terminals, and
then also solder the conductors to the terminals. Solder creep is not
an issue in this case. However, most commonly, such connections are
done by crimping -- soldering is a skill which installation electricians
would rarely have.

--
Andrew Gabriel
 
D

Doug Miller

Guest
In article <pukjuvcp3hfh4k6nu4bbn0lirkn29ovbie@4ax.com>, Texan <texasoilfinder@yahoo.com> wrote:

Just for the techs who wonder why solder isn't allowed. When a
connection gets hot the solder would melt and create all kinds of
problems.. Solder has a much lower melt temp than copper. That's why
in higher load carrying circuits we use crimp or compression type
connectors.

Ummm, well, no, not exactly. It has more to do with solder's lack of
mechanical strength. The melting point of solder, while indeed well below that
of copper, is well *above* the temperature rating of any conductor insulation
that I've ever heard of -- IOW, the insulation would burn off of the conductor
*long* before it got hot enough to melt a soldered connection.


--
Doug Miller (alphageek at milmac dot com)

How come we choose from just two people to run for president and 50 for Miss America?
 
J

John Woodgate

Guest
I read in sci.engr.electrical.compliance that Doug Miller
<spambait@milmac.com> wrote (in <WEVHb.19442$P%1.18025049@newssvr28.news
..prodigy.com>) about '30A wiring advice', on Mon, 29 Dec 2003:

How come we choose from just two people to run for president and 50 for Miss
America?
Almost all the people with the necessary qualities to be President have
too much sense to want the job. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
 
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