30A wiring advice

[Joe 90]

They ARE NOT in phase. The fact that you have to ask this question
indicates that you are in out of your depth. There is no blame for not
knowing, but there IS for dealing with things that you don't know about.

Or that I am thinking things through very logically. The confusion stems
from page 23, of Wiring Simplified 39th edition based on NEC 1999 by Richter
and Schwan. It implies that supplies in USA are in single phase whereas I
would have expected a 180deg phase differential which has indeed been
confirmed by a few posters.

Also just to underline, when dealing with any such DIY projects I do get a
qualified electrician in to validate the work before switching on. As far
as I am aware I have not broken any Swiss regs.

 

[Dr John Stockton]

JRS: In article <3f79f827$1_4@news.bluewin.ch>, seen in news:sci.engr.e
lectrical.compliance, Joe 90 <donot@usethisaddress.com> posted at Tue,
30 Sep 2003 23:39:45 :-

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.

Your location, Switzerland, is reasonably obvious to those who consider
your message's header. However, you should have stated it explicitly.
Those who do not do so are generally assumed to be Americans - and thus
generally non-conversant with international standards.

Perhaps, personally, you are American - no born-and-bred European should
expect to find "gauge" size wire available retail within the EU - and CH
is within, though not of, the EU.

There must be a professional need for wire rated at well over 30A;
consult a friendly professional, or your local equivalent of RS
Components

--
Š John Stockton, Surrey, UK. ?@merlyn.demon.co.uk / ??.Stockton@physics.org Š
Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
Correct <= 4-line sig. separator as above, a line precisely "-- " (SoRFC1036)
Do not Mail News to me. Before a reply, quote with ">" or "> " (SoRFC1036)

 

[s]

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 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??
"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:+odasYAY+6e$EwRJ@jmwa.demon.co.uk...

I read in sci.engr.electrical.compliance that s <sim.mich@cwcom.net
wrote (in <rFNeb.9$TJ3.5@newsfep1-gui.server.ntli.net&gt about '30A
wiring advice - a complication?', on Wed, 1 Oct 2003:

it isnt two phase!i know that and im a british sparky living and working
in the uk!!it IS single phase,fed from either end of a centre tapped
transfomer,in exactly the same way as our 110 volt transformers we use
for site tools.120v----0v(neutral)----120v.240v end to end,120 end to
middle.if you need to know how this works,think of a sine wave with the
centre line being the centre tap on our transformer!!(rant over).

Well, I'm a Chartered Electrical Engineer, living and working in UK, and
although your detailed explanation is correct, that IS the description
of a two-phase system.

Just as the phase angles between the conductors of a 3-phase system are
120 degrees, so that the three angles add to 360 degrees, the angles
between the phases of a 2-phase system are 180 degrees, adding up to 360
degrees.
--
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!

 

[John Woodgate]

I read in sci.engr.electrical.compliance that Joe 90
<donot@usethisaddress.com> wrote (in <3f7ad039$1_5@news.bluewin.ch&gt
about '30A wiring advice - a complication?', on Wed, 1 Oct 2003:

The confusion
stems from page 23, of Wiring Simplified 39th edition based on NEC 1999
by Richter and Schwan. It implies that supplies in USA are in single
phase whereas I would have expected a 180deg phase differential which
has indeed been confirmed by a few posters.

Yes, well, you and me both. I have had scorn and derision heaped by US
citizens for describing their system as 'two-phase'. But it IS! (;-)
--
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!

 

[obsidian]

3 phase....
380 phase to phase gives you more or less 220
phase to neutral


--
obsidian


"Wade Lippman" <toller@frontiernetnospam.net>
wrote in message
news:w2teb.4366$1m2.3354@news02.roc.ny...

"Joe 90" <donot@usethisaddress.com> wrote in
message
news:3f7a16db$1_1@news.bluewin.ch...
I just knew I would get asked about the supply
problem!!! I live in
Switzerland now. The heavier wiring is simply
not available in the DIY
shops
here - its probably a safety precaution by the
authorities, also
Switzerland
supplies approx. 380V/220V to each dwelling so
large gauge wires are not
really essential.

How do they supply 380v/220v? Presumably the
220v is single pole. Where
does the additional 160v come from?

 

[Gary Tait]

Whereas On Tue, 30 Sep 2003 20:48:43 -0400, "John McGaw"
<nowhere@all.xyz> scribbled:
, I thus relpy:

Or is CH simply a convenient posting location?

CH is the TLD for Switzerland.
--
Gary J. Tait . Email is at yahoo.com ; ID:classicsat

 

[Gary Tait]

Whereas On Wed, 1 Oct 2003 01:50:42 +0200, "Joe 90"
<donot@usethisaddress.com> scribbled:
, I thus relpy:

The dryer works fine following some modifications I made - basically
disconnecting internal 120V circuits that only served to provide some
advanced functions which we don't miss like moisture sensor based automatic
drying. I connected the heating element across a 240V supply and the motor
(5.2A, 1/2hp) and timer across a stepped down 120V. But whilst running, the
wires do feel a litle warm (note the unit has been running fine for the last
2 years in Switzerland and continues to do so) and this bothers me.

Wade thanks for your feedback, I feel really stupid not having realized that
in the first place. I think the best solution will be to get some #8 wire
from a friend in the USA.

No, the best solution would be to hire a Swiss electrician to wire it
up., or forget it and buy a Swiss/EU approved dryer, instead of trying
to make the NA one to work.
--
Gary J. Tait . Email is at yahoo.com ; ID:classicsat

 

[Gary Tait]

Whereas On Wed, 1 Oct 2003 10:43:11 +0200, "Joe 90"
<donot@usethisaddress.com> scribbled:
, I thus relpy:

After making the original changes 2 years ago, I had the results verified by
a local electrician and he was satisfied that there were no potential
problems.

However I just recently looked at the wirirng diagrams again and there are
two points that I don't understand. I have always understood voltage as
being a potential difference. Current flows from a high potential to a low
potential. This means that the input to a device has to be at a higher
potential relative to the output, typically connected to Neutral or Ground.
This would be the case even when using ac current.

Yet when one looks at the power supply in the USA you have a common Neutral
and two 120V single phase hot lines. The typical heating element in a dryer
in the USA is connected across the two 120V lines (making a 240V supply).

Now my first point is surely if both lines are in phase at 120V then there
is no potential difference and so how can the current flow? Or is the
current only really oscillating left and right along the wires in sync. with
the phase variance, in which case why bother with the neutral (except as a
safety ground) in many ac appliances.

120V ------------------------------------- a
Neutral ----------------------------------- b
120V ------------------------------------- c

Vab =Vbc = 120V, Vac = 240V - dryer heating element is across Vac.

It is Vab= -Vbc=120, Vac=240V. Note the -Vbc, it is 180 degrees out of
phase of Vab.

My second point concerns the wiring ampacity. The dryer is rated at max
30A, so one would expect the heater wires to be AWG 10 (NEC guidelines), but
in fact they are AWG 12 (max 20A). Is this because in fact the heater is
being fed by two 120V circuits? And does this mean that if I connect a
European 240V setup as follows:

N --------------------------------------- d
240V ----------------------------------- e
Dryer heater element is across Vde

Don't forget there is a motor and a timer in the dryer also, and they
need 120V.

that these AWG 12 wires are being stressed beyond NEC recommendations?

They seem to allow it, so it is okay.

Thanks in advance for any responses.

--
Gary J. Tait . Email is at yahoo.com ; ID:classicsat

 

[Spehro Pefhany]

On Wed, 01 Oct 2003 16:45:12 -0400, the renowned Gary Tait
<seesig@xxx.yyy> wrote:

Don't forget there is a motor and a timer in the dryer also, and they
need 120V.

And generally a light bulb. Since the neutral only carries an amp or
two, it could probably be recreated with a compact 230:120 control
transformer or autotransformer, but I have no idea what getting that
intalled to code for a Swiss residence would involve.


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

 

[Joe 90]

No, the best solution would be to hire a Swiss electrician to wire it
up., or forget it and buy a Swiss/EU approved dryer, instead of trying
to make the NA one to work.
--
Gary J. Tait . Email is at yahoo.com ; ID:classicsat

The unit already works (has been working fine in Switzerland for past 2
years!) and has been checked over by a Swiss electrician for safety. I
simply wanted to extend the wiring but culd not find and awg8. Thx.

 

[jim]

Wade Lippman wrote:

Don't even thing about it.

If your #10 gets disconnected, the circuit opens. No problem.
If one strand of your double #12 gets disconnected, your house burns down.
Problem.
I thought he said he had been running it on #12 for years. I guess he

didn't notice his house had burnt down. Poor guy.
--
jim

 

[John Woodgate]

I read in sci.engr.electrical.compliance that s <sim.mich@cwcom.net>
wrote (in <rFNeb.9$TJ3.5@newsfep1-gui.server.ntli.net&gt about '30A
wiring advice - a complication?', on Wed, 1 Oct 2003:

it isnt two phase!i know that and im a british sparky living and working
in the uk!!it IS single phase,fed from either end of a centre tapped
transfomer,in exactly the same way as our 110 volt transformers we use
for site tools.120v----0v(neutral)----120v.240v end to end,120 end to
middle.if you need to know how this works,think of a sine wave with the
centre line being the centre tap on our transformer!!(rant over).

Well, I'm a Chartered Electrical Engineer, living and working in UK, and
although your detailed explanation is correct, that IS the description
of a two-phase system.

Just as the phase angles between the conductors of a 3-phase system are
120 degrees, so that the three angles add to 360 degrees, the angles
between the phases of a 2-phase system are 180 degrees, adding up to 360
degrees.
--
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!

 

[Joe 90]

Poor Jim, the #12 was what the manufacturer had installed in the dryer. You
have completely missed the point of my original posting - perhaps I did not
explain it very clearly.

"jim" <email@address.net> wrote in message
news:eWIeb.2559$mg.1716@twister.nyroc.rr.com...

Wade Lippman wrote:

Don't even thing about it.

If your #10 gets disconnected, the circuit opens. No problem.
If one strand of your double #12 gets disconnected, your house burns
down.
Problem.
I thought he said he had been running it on #12 for years. I guess he
didn't notice his house had burnt down. Poor guy.
--
jim

 

[John Woodgate]

I read in sci.engr.electrical.compliance that s <sim.mich@cwcom.net>
wrote (in <AOOeb.13$kC5.21047@newsfep1-win.server.ntli.net&gt 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!

 

[Beachcomber]

Perhaps, personally, you are American - no born-and-bred European should
expect to find "gauge" size wire available retail within the EU - and CH
is within, though not of, the EU.

There must be a professional need for wire rated at well over 30A;
consult a friendly professional, or your local equivalent of RS
Components

Many of us Americans are indeed ethno-centric, not realizing what the
standards are or differences in other parts of the word...

However, not all of us are like that and some of us even know that the
AWG stands for American Wire Gauge, and perhaps this might not be the
standard in use for European countries. And some of us do indeed
understand that CH is geographically within the EU (mostly) except
that sometimes a CH is actually an LI.

Beachcomber

 

[Joe 90]

It MUST be two phase between the two hot wires, because if it was in one
(the same) phase then the heating element would not heat up.

- +ve 120V
- -
- -
- -
- -
- -ve 120V

+

- +ve 120V
- -
- -
- -
- -
- -ve 120V

= no potential difference between the two hot wires and so no current flow.
Waves are in a single common phase.

- +ve 120V
- -
- -
- - -
- - -
- - -ve 120V

+

- +ve 120V -
- - - -
- - - -
- -
- -
- -ve 120V


= 180 deg phase shift, 240V potential difference at peaks therefore current
flows therefore heater heats up.


"s" <sim.mich@cwcom.net> wrote in message
news:rFNeb.9$TJ3.5@newsfep1-gui.server.ntli.net...

it isnt two phase!i know that and im a british sparky living and working
in
the uk!!it IS single phase,fed from either end of a centre tapped
transfomer,in exactly the same way as our 110 volt transformers we use for
site tools.120v----0v(neutral)----120v.240v end to end,120 end to
middle.if
you need to know how this works,think of a sine wave with the centre line
being the centre tap on our transformer!!(rant over).
"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:HtKEdNDFyve$EwGN@jmwa.demon.co.uk...
I read in sci.engr.electrical.compliance that Joe 90
donot@usethisaddress.com> wrote (in <3f7ad039$1_5@news.bluewin.ch&gt
about '30A wiring advice - a complication?', on Wed, 1 Oct 2003:

The confusion
stems from page 23, of Wiring Simplified 39th edition based on NEC 1999
by Richter and Schwan. It implies that supplies in USA are in single
phase whereas I would have expected a 180deg phase differential which
has indeed been confirmed by a few posters.

Yes, well, you and me both. I have had scorn and derision heaped by US
citizens for describing their system as 'two-phase'. But it IS! (;-)
--
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!

 

[Andrew Gabriel]

In article <3f7be979_4@news.bluewin.ch>,
"Joe 90" <donot@usethisaddress.com> writes:

It MUST be two phase between the two hot wires, because if it was in one
(the same) phase then the heating element would not heat up.

In terms of maths/physics/engineering you are clearly correct.

In terms of the US electricity supply industry, "2-phase" is
a specific jargon term which applies to only one 2-phase system.
In the UK electricity supply industry, the common US scheme was
called 2-phase (but is long obsolete and was never common).

--
Andrew Gabriel

 

[Spehro Pefhany]

On Wed, 1 Oct 2003 06:31:14 -0700, the renowned "s"
<sim.mich@cwcom.net> wrote:

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 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??

Not really. Many of us claim that two linearly dependent voltages
don't represent two distinct "phases", even if one of the
proportionalities happens to be -1. John disagrees.

A two phase supply with conventional 90° (or anything != n * 180°, n
is an integer) difference between the phases could be used in motors,
as your comments suggest, or converted by a Scott-T transformer to
make three-phase (or other polyphase) power. Canadian/US residential
power cannot, so those who want to bring an industrial machine tool
into their basement or garage have to use a static, rotary or VFD
phase converter.

This has been discussed before...

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

 

[John McGaw]

"Gary Tait" <seesig@xxx.yyy> wrote in message
news:1demnv87hbna8862qvtr4mrl9gvh35db7l@4ax.com...

Whereas On Tue, 30 Sep 2003 20:48:43 -0400, "John McGaw"
nowhere@all.xyz> scribbled:
, I thus relpy:
Or is CH simply a convenient posting location?

CH is the TLD for Switzerland.
--
Gary J. Tait . Email is at yahoo.com ; ID:classicsat

It would seem obvious that I knew that already. Why else would my reply
state "Damned difficult to believe that 10-gauge wire is unavailable in
Switzerland."
--
John McGaw
[Knoxville, TN, USA]

Return address will not work. Please
reply in group or through my website:
http://johnmcgaw.com

 

[Lawrence Wasserman]

In article <+odasYAY+6e$EwRJ@jmwa.demon.co.uk>,
John Woodgate <jmw@jmwa.demon.co.uk> wrote:
<...snipped...>

Well, I'm a Chartered Electrical Engineer, living and working in UK, and
although your detailed explanation is correct, that IS the description
of a two-phase system.

Just as the phase angles between the conductors of a 3-phase system are
120 degrees, so that the three angles add to 360 degrees, the angles
between the phases of a 2-phase system are 180 degrees, adding up to 360
degrees.
--
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!

That is just so wrong.


--

Larry Wasserman Baltimore, Maryland
lwasserm@charm.net