30A wiring advice
Joe 90
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.
Wade Lippman
If your #10 gets disconnected, the circuit opens. No problem.
If one strand of your double #12 gets disconnected, your house burns down.
Problem.
Wade Lippman
"Wade Lippman" <tol...@frontiernetnospam.net> wrote in message
news:5Tmeb.7273$N57....@news01.roc.ny...
faster than brain, sorry.)
Zathera
"Joe 90" <do...@usethisaddress.com> wrote in message
news:3f79f827$1...@news.bluewin.ch...
The NEC is pretty clear about parallel wiring in section 310-4. 1/0 (that
is one/zero) and larger are allowed to be paralleled. Smaller is not
allowed unless it is for instrumentation.
Andrew Gabriel
UK regs allow it providing each conductor has its own current
protection. In the case of more than 2 in parallel, protection
is required at both ends of the parallel run, as fault current
can be back-fed too, via the other parallel conductors.
Having said that, you'd have to be nuts to do all that just
to save using the right sized conductor in the first place.
--
Andrew Gabriel
Consultant Software Engineer
Robert Calvert
where you can't find #10 wire or something equivalent.
In any case, this reminds me of some 'African engineering' I did to my
electric oven one time. One evening, my oven suddenly stopped working. After
looking in the back to see what might be wrong, I found that one of the
wires somehow burned in two. Instead of going to an appliance parts store
and buying the proper part, I just took a cord from an old lamp, cut it into
five short pieces, bundled the pieces together and used them to replace the
wire that was there. I don't know how safe it was, but it worked. :-)
Robert
"Joe 90" <do...@usethisaddress.com> wrote in message
news:3f79f827$1...@news.bluewin.ch...
Don Phillips
news:vnk1tea...@corp.supernews.com...
> I can't think of any place in the world (except maybe the African jungle)
> where you can't find #10 wire or something equivalent.
My guess is it is the same place where there are not too many noisy
inspectors telling you how to build your house.
Sincerely,
Donald L. Phillips, Jr., P.E.
Worthington Engineering, Inc.
145 Greenglade Avenue
Worthington, OH 43085-2264
dphi...@worthingtonNSengineering.com
(remove NS to use the address)
614.937.0463 voice
208.975.1011 fax
http://worthingtonengineering.com
Robert A. Barr
> 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.
Sorry, can't help it: Why can't you get #10, when you can get #12?
Tony Hwang
No #8 either?
Tony
Brian
Dude, give me your mailing address and the length of wire and I will frigging send it to you. You
can buy online form several suppliers. Or better yet call a qualified electrician!!!
"Joe 90" <do...@usethisaddress.com> wrote in message news:3f79f827$1...@news.bluewin.ch...
Joe 90
Switzerland now. The heavier wiring is simply not available in the DIY shops
here - its probably a safety precaution by the authorities, also Switzerland
supplies approx. 380V/220V to each dwelling so large gauge wires are not
really essential.
The dryer works fine following some modifications I made - basically
disconnecting internal 120V circuits that only served to provide some
advanced functions which we don't miss like moisture sensor based automatic
drying. I connected the heating element across a 240V supply and the motor
(5.2A, 1/2hp) and timer across a stepped down 120V. But whilst running, the
wires do feel a litle warm (note the unit has been running fine for the last
2 years in Switzerland and continues to do so) and this bothers me.
Wade thanks for your feedback, I feel really stupid not having realized that
in the first place. I think the best solution will be to get some #8 wire
from a friend in the USA.
Thanks everyone. More feedback is of course welcome.
"Brian" <spam...@mail.com> wrote in message
news:meoeb.1358$Gb....@news2.central.cox.net...
John McGaw
Damned difficult to believe that 10-gauge wire is unavailable in
Switzerland. One might simply drive to a neighboring coutry and buy it if it
is. Or is CH simply a convenient posting location? In any case, I surely
wouldn't mess around with using multiple conductors to overcome the
problem -- for all the reasons that others have cited.
--
John McGaw
[Knoxville, TN, USA]
Return address will not work. Please
reply in group or through my website:
http://johnmcgaw.com
Wade Lippman
> 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.
>
does the additional 160v come from?
Robert Calvert
> 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
<snip>
I guess I should have known that bureaucracy had something to do with this.
It seems to me that a law like this would actually increase the danger since
it would create the temptation for the do-it-yourselfer to use smaller wire
than he should be using.
Robert
John Woodgate
<do...@usethisaddress.com> wrote (in <3f7a16db$1...@news.bluewin.ch>)
about '30A wiring advice', on Wed, 1 Oct 2003:
>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.
All the advice you were given applies, AIUI, to installations in US. In
Switzerland, the rules are quite different. What you are doing may even
be illegal there. Switzerland controls what is connected to the
electricity supply VERY tightly.
You won't get #10 wire in Europe because European cables are described
by the conductor area in square millimetres. I don't have a conversion
chart from AWG to square mm; for 30 A you probably need 6 mm^2 cable,
but it depends on exactly what sort of cable and how it is installed.
--
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
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.
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
that these AWG 12 wires are being stressed beyond NEC recommendations?
Thanks in advance for any responses.
"John Woodgate" <j...@jmwa.demon.contraspam.yuk> wrote in message news:h0rdLp
AAtme$Ew...@jmwa.demon.co.uk...
Isaac
> 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.
You should not be connecting to ground as a means of providing power flow
to anything. Don't confuse neutral (the grounded supply conductor) with
Ground (the groundING conductor).
> 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
The current in one 120 phase is at opposite polarity (with respect to
the neutral) as the other 120v phase. The neutral is there so you
can get 120 volts too. You don't want to dry clothes in the dark do
you?
Isaac
C What I Mean
First of all, it is most likely not up to code where you might be. With
that said, #12 is actually rated for 25 amps under certain conditions. NEC
(USA) just requires a 20 circuit protection on it in construction. In
panels, we can use the full rating of the wire but must allow for #10 field
wiring if between 20 and 30 amps..
Second of all, most likely your load my not be a full 30 amps. If you have
a way to do it, test it.
Next, the wires in parallel will have no problem with 30 amps from a
technical stand point. Yours is a code issue, which may be a safety issue.
I don't recommend you do it, but there is an answer.
John Woodgate
'30A wiring advice - a complication?', on Wed, 1 Oct 2003:
>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.
NOT TO GROUND! That would be deadly dangerous!
>
>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?
They ARE NOT in phase. The fat 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.
Simple logic would tell you that your assumptions are wrong, because the
US system works, whereas you 'proved' it couldn't.
>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.
The neutral is very definitely not a safety ground and must not ever be
used as one.
>
> 120V ------------------------------------- a
> Neutral ----------------------------------- b
> 120V ------------------------------------- c
>
>Vab =Vbc = 120V, Vac = 240V - dryer heating element is across Vac.
>
>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).
Are these wires internal to the dryer? If so, the NEC ampacity tables
don't apply, because the installation conditions are different.
> Is this because in fact the
>heater is being fed by two 120V circuits?
No.
>And does this mean that if I
>connect a European 240V setup as follows:
>
> N --------------------------------------- d
> 240V ----------------------------------- e
> Dryer heater element is across Vde
>
>that these AWG 12 wires are being stressed beyond NEC recommendations?
No, not if the dryer was designed correctly in the first place. Does it
have a UL sticker?
>
AWG10 has an area of 0.008155 sq. in., which is 5.26 sq. mm. AWG 12 has
0.005129 sq. in., which is 3.3 sq. mm. As multicore building
installation cables, these would, if they were standard sizes, be rated
at roughly 30A and 20 A respectively in Europe. But as single-conductor
cables, inside an appliance, the current ratings might be MUCH higher
(around 43 A and 35 A), depending on the insulating material and the
local ambient temperature.
Joe 90
> 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.
John Woodgate
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! (;-)
Dr John Stockton
lectrical.compliance, Joe 90 <do...@usethisaddress.com> posted at Tue,
30 Sep 2003 23:39:45 :-
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
--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk / ??.Stoc...@physics.org ©
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)
obsidian
380 phase to phase gives you more or less 220
phase to neutral
--
obsidian
"Wade Lippman" <tol...@frontiernetnospam.net>
wrote in message
news:w2teb.4366$1m2....@news02.roc.ny...
Gary Tait
<now...@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
<do...@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 Tait
>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.
--
Spehro Pefhany
<see...@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"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Joe 90
> 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
> 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
s
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). :-P
"John Woodgate" <j...@jmwa.demon.contraspam.yuk> wrote in message
John Woodgate
wrote (in <rFNeb.9$TJ...@newsfep1-gui.server.ntli.net>) 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). :-P
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.
s
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" <j...@jmwa.demon.contraspam.yuk> wrote in message
Joe 90
have completely missed the point of my original posting - perhaps I did not
explain it very clearly.
"jim" <em...@address.net> wrote in message
news:eWIeb.2559$mg....@twister.nyroc.rr.com...
John Woodgate
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.
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
(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....@cwcom.net> wrote in message
news:rFNeb.9$TJ...@newsfep1-gui.server.ntli.net...
Andrew Gabriel
"Joe 90" <do...@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
<sim....@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...
John McGaw
news:1demnv87hbna8862q...@4ax.com...
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
John Woodgate <j...@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
lwas...@charm.net
Doug Miller
>In article <+odasYAY+6e$Ew...@jmwa.demon.co.uk>,
>John Woodgate <j...@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,
Doug Miller (alphageek-at-milmac-dot-com)
Gary Tait
<now...@all.xyz> scribbled:
, I thus relpy:
>"Gary Tait" <see...@xxx.yyy> wrote in message
>news:1demnv87hbna8862q...@4ax.com...
>> Whereas On Tue, 30 Sep 2003 20:48:43 -0400, "John McGaw"
>> <now...@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."
I was under the impreddsion you wern't sure if CH was indeed
Switzerland, or some poor country that sold their TLD to companies for
anonymous users.
H. R. Bob Hofmann
What is being overlooked here is that the non-USA way of thinking is
not nearly as do it yourself (DIY) as we have here in the USA. Much
more wiring/painting/remodeling, etc is hired out than we are used to
here in the USA. So the availability of things like heavier gauge
wire is really limited. I would suggest looking for a commercial
demolition site and scrounging the wire, if it is not against the
local law to scrounge.
H. R. (Bob) Hofmann
Robert Calvert
"H. R. Bob Hofmann" <hrho...@att.net> wrote in message
news:deadaa59.03100...@posting.google.com...
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.
Just a thought. :-)
Robert
Dr John Stockton
ngr.electrical.compliance, John Woodgate <j...@jmwa.demon.contraspam.yuk>
posted at Thu, 2 Oct 2003 08:28:29 :-
>
>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.
If you count 3-phase as public : It is I believe delivered in the UK as
star, with a neutral near ground.
Connect a 1:1 transformer to one leg, neutral to live wire.
Connect a Root3:1 transformer between the other two live wires.
ISTM that one then gets two outputs in quadrature, of equal magnitude.
Admittedly it is impractical to use an integer multiple of Root3 turns,
but 97:56 is within 1 in 10^4.
<URL:http://www.merlyn.demon.co.uk/js-demos.htm#App>, enter Math.sqrt(3)
Note, though, that the three supply phases are not equally loaded, and
I've not worked out whether there is neutral current. Loading could be
made to balance with an auxiliary two-input transformer, driven from the
second two legs, and connected to buck/boost the output of the first
transformer, I think.
Untested.
--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 IE 4 ©
<URL:http://jibbering.com/faq/> Jim Ley's FAQ for news:comp.lang.javascript
<URL:http://www.merlyn.demon.co.uk/js-index.htm> JS maths, dates, sources.
<URL:http://www.merlyn.demon.co.uk/> TP/BP/Delphi/JS/&c., FAQ topics, links.
volts500
That's _exactly_ the line of thinking that makes overloading a circuit
dangerous. Quite often takes many years for the wire to deteriorate to the
point where it can start a fire. Like a lot of people like to say, it
ain't rocket science.....but it helps to know what you're doing and WHY.
eh...@bellatlantic.net
Lets go to the understanding of how it heats up and avoid
the controversy that surrounds what you label it.
Consider:
+ - + -
A--Battery1--B--Battery2--C
Let each battery provide 120 volts.
A to B = 120v; B to C = 120v; A to C = 240v
or in other words, a simple series circuit (the
circuit being completed by the voltmeter). Either
battery can be used independently of the other, providing
120v DC, or they can be used in series to provide 240v DC.
Now, substitute the secondary of a center tapped transformer
for Battery1 and Battery2. Again, it is a simple series
circuit. Either half of the secondary can be used independently
of the other half, and provide 120v AC, or the two halves
can be used in series to provide 240v AC.
In the US, the dryer uses points A and B (or B and C) to
provide 120 volts for lighting, timer circuit, motor circuit,
electronics, and points A and C to provide 240 volts to the
heating coil circuit. The dryer does not give a rat's ass
what we call it - single phase, two phase, split phase
or anything else - as long as it "sees" the required
voltage at the necessary current.
John Woodgate
<sp...@merlyn.demon.co.uk> wrote (in <GhltEHBBnIf$Ew...@merlyn.demon.co.uk
>) about '30A wiring advice - a complication?', on Thu, 2 Oct 2003:
>If you count 3-phase as public : It is I believe delivered in the UK as
>star, with a neutral near ground.
Well, the distribution itself isn't really either star or delta, but no
neutral comes with it. The neutral is earthed at the sub-station.
>
>Connect a 1:1 transformer to one leg, neutral to live wire.
So you would need this transformer to have three secondaries in star,
with only one used.
>Connect a Root3:1 transformer between the other two live wires.
I'm not sure whether you could incorporate such a secondary on the same
three-phase core as the first transformer, by winding it round two
'legs'. Possibly. Many such arcane transformer configurations exist.
>
>ISTM that one then gets two outputs in quadrature, of equal magnitude.
>
>Admittedly it is impractical to use an integer multiple of Root3 turns,
>but 97:56 is within 1 in 10^4.
>
><URL:http://www.merlyn.demon.co.uk/js-demos.htm#App>, enter Math.sqrt(3)
>
>Note, though, that the three supply phases are not equally loaded, and
>I've not worked out whether there is neutral current. Loading could be
>made to balance with an auxiliary two-input transformer, driven from the
>second two legs, and connected to buck/boost the output of the first
>transformer, I think.
>
>Untested.
Ingenious, though. Simple, for sufficiently difficult values of simple.
Dr John Stockton
ngr.electrical.compliance, John Woodgate <j...@jmwa.demon.contraspam.yuk>
posted at Fri, 3 Oct 2003 06:35:08 :-
>I read in sci.engr.electrical.compliance that Dr John Stockton
><sp...@merlyn.demon.co.uk> wrote (in <GhltEHBBnIf$Ew...@merlyn.demon.co.uk
>>) about '30A wiring advice - a complication?', on Thu, 2 Oct 2003:
>
>>If you count 3-phase as public : It is I believe delivered in the UK as
>>star, with a neutral near ground.
>
>Well, the distribution itself isn't really either star or delta, but no
>neutral comes with it. The neutral is earthed at the sub-station.
>>
>>Connect a 1:1 transformer to one leg, neutral to live wire.
>
>So you would need this transformer to have three secondaries in star,
>with only one used.
I think you did not read as much into "delivered" as I tried to write
into it. I meant it as four wires, one being almost safe to touch.
ISTM that any 3-phase transformer must contain (at least) three distinct
pieces of iron capable of being wound. As ISTM you suggest, with a
winding on one, and windings on the other two in series, one can get the
desired quadrature-phase output.
Sometimes I wonder what could be done with a winding around each edge of
a skeleton iron tetrahedron, using one face for input and the other
edges for output, or vice-versa, or ...
--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk / ??.Stoc...@physics.org ©
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
would'nt have thought,as phases 90 degs apart would have a much smaller
potential than a similar system at 120 degs apart,otherwise a four phase
system would be used for sheer economy,would it not?
"John Woodgate" <j...@jmwa.demon.contraspam.yuk> wrote in message
Spehro Pefhany
<sim....@cwcom.net> wrote:
>does four phase system exist in the real world?not very efficient i
>would'nt have thought,as phases 90 degs apart would have a much smaller
>potential than a similar system at 120 degs apart,otherwise a four phase
>system would be used for sheer economy,would it not?
There exist 5-phase synchronous motors (steppers). They run more
smoothly than the more common 2-phase type. Of course the power for
them does not come directly out of a plug in the wall.
s
"Joe 90" <do...@usethisaddress.com> wrote in message
news:3f79f827$1...@news.bluewin.ch...
> 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.
>
>
Gary Tait
<j...@jmwa.demon.contraspam.yuk> scribbled:
, I thus relpy:
FWIW, the UK MV distribution system is 11KV delta, and is transformed
to a 230/380V Wye, with one phase per home.
The US usually uses a Wye system for the MV, with one phase (hence
single-phase) Hot-Neutral, with a center tapped 240V transformer, the
center tap being gorund/neutral.
Gary Tait
scribbled:
, I thus relpy:
>would'nt have thought,as phases 90 degs apart would have a much smaller
>potential than a similar system at 120 degs apart,otherwise a four phase
>system would be used for sheer economy,would it not?
You could do that with two genuine 2 phase supplies.
--
daestrom
> does four phase system exist in the real world?not very efficient i
> would'nt have thought,as phases 90 degs apart would have a much smaller
> potential than a similar system at 120 degs apart,otherwise a four phase
> system would be used for sheer economy,would it not?
I guess it depends on how you 'count' four phases. Obviously you could call
it 'two phases' with center-taps tied together I suppose. But you're right,
three phase on a watt/wire basis is more economical. Do the math assuming a
fixed current capacity and you'll find three phase is the most economical on
a watt/wire basis. Five, seven, nine, eleven, any higher number of phases
do not do as well as three. Kind of a geometry/math thingy.
IMHO, anytime one phase is exactly 180 out from another, I don't count that
as a separate 'phase'. So a 'four phase' system is really just a two phase
system with some center-taps. Kind of like residential supply in US (the
so-called Edison connection). Whole flame wars have gone on for days over
whether to call that a two-phase system, or just a single phase system with
center-tap. FWIW, if one wire is exactly 180 out from another wire, isn't
that just like the two wires of a single phase AC supply? Well, don't want
to start another war over that, but just pointing out there are differences
of opinion.
There have been two phase systems where the two phases are 90 apart. They
can produce a rotating field for self-starting machinery. Conventionally,
this would take four wires to distribute. But an obvious economy is to tie
one leg of each phase together so you only need three wires. This requires
a larger conductor for the common conductor and is 'unbalanced' with respect
to ground. Causes some problems with telephone service and the like.
daestrom
daestrom
"Dr John Stockton" <sp...@merlyn.demon.co.uk> wrote in message
news:mgq10UC8zZf$Ew...@merlyn.demon.co.uk...
> into it. I meant it as four wires, one being almost safe to touch.
>
> ISTM that any 3-phase transformer must contain (at least) three distinct
> pieces of iron capable of being wound. As ISTM you suggest, with a
> winding on one, and windings on the other two in series, one can get the
> desired quadrature-phase output.
>
> Sometimes I wonder what could be done with a winding around each edge of
> a skeleton iron tetrahedron, using one face for input and the other
> edges for output, or vice-versa, or ...
>
That's an interesting thought. Wonder which way the flux would align in it.
I have seen three-phase transformers that were three vertical irons tied
with cross bars at top and bottom. Kind of like 'III'. The primary and
secondary were wound on top of each other, one phase per leg. Took up less
space than three conventional single phase units. It was were 'space and
weight considerations' were more important than money (i.e. military).
daestrom
John Wilson
> I read in sci.engr.electrical.compliance that s <sim....@cwcom.net>
> wrote (in <AOOeb.13$kC5....@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.
You're right; it's a single-phase system with a center tap.
>
>
> 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??
You're right. There were two-phase power systems before there were
three-phase systems, and they are still used for a few special purposes.
>
>
> 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.
Yes it does.
> 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
No, it's a two-phase three-wire system. A four-phase system has
conductors with phase angles that differ by 45 degrees. More explanation
below.
> - 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.
It's trivial, using a standard device called a Scott-connected
transformer. It consists of two transformers, one connected between
phases A and B, and the other connected between the center tap of the
first one and phase C. If you choose the ratios of the two transformers
correctly, the other windings of the two transformers are 90 degrees out
of phase, giving you two-phase power. How you make the connections on
the two-phase side determines whether you're dealing with two-phase
three-wire, two-phase four-wire, or two-phase five-wire. Being a
transformer, this can pass power either from the three-phase system to
the two-phase system, or vice versa.
The US standard center-tapped single-phase system is just that; single
phase. Three-phase systems can have either three or four wires,
depending on whether the neutral is carried along with the phase
conductors to allow phase-neutral loads to be connected.
Two-phase systems are more complicated. It can be done with three wires;
call them X, Y, and Z, with VXZ leading VYZ by 90 degrees. If VXZ=VYZ=1,
then VXY=1.414. With this system, Z is normally grounded and called the
"neutral". Two-phase four-wire can be done, too, with no neutral.
Calling the wires W, X, Y, and Z, VWY leads VXZ by 90 degrees. If
VWX=VXY=VYZ=VZW=1, then VWY=VXZ=1.414. The phase angle between any two
adjacent wires is 90 degrees. To make it more complicated, you can do
two-phase five-wire, which is just like two-phase four-wire with the
addition of the neutral.
AIUI, the original Niagara Falls system was two-phase. The beauty of a
three-phase system is that the voltage between any two wires other than
the neutral is the same.
73,
JohnW
John Woodgate
<johnw...@alum.mit.edu> wrote (in <tJofb.399729$2x.1...@rwcrnsc52.op
s.asp.att.net>) about '30A wiring advice - a complication?', on Sat, 4
Oct 2003:
>No, it's a two-phase three-wire system. A four-phase system has
>conductors with phase angles that differ by 45 degrees. More explanation
>below.
You've just chosen definitions that suit your denials.
>
>> - 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.
>
>It's trivial, using a standard device called a Scott-connected
>transformer. It consists of two transformers, one connected between
>phases A and B, and the other connected between the center tap of the
>first one and phase C. If you choose the ratios of the two transformers
>correctly, the other windings of the two transformers are 90 degrees out
>of phase, giving you two-phase power. How you make the connections on
>the two-phase side determines whether you're dealing with two-phase
>three-wire, two-phase four-wire, or two-phase five-wire. Being a
>transformer, this can pass power either from the three-phase system to
>the two-phase system, or vice versa.
That is TRIVIAL?
daestrom
"John Woodgate" <j...@jmwa.demon.contraspam.yuk> wrote in message
> I read in sci.engr.electrical.compliance that John Wilson
> <johnw...@alum.mit.edu> wrote (in <tJofb.399729$2x.1...@rwcrnsc52.op
> s.asp.att.net>) about '30A wiring advice - a complication?', on Sat, 4
> >transformer. It consists of two transformers, one connected between
> >phases A and B, and the other connected between the center tap of the
> >first one and phase C. If you choose the ratios of the two transformers
> >correctly, the other windings of the two transformers are 90 degrees out
> >of phase, giving you two-phase power. How you make the connections on
> >the two-phase side determines whether you're dealing with two-phase
> >three-wire, two-phase four-wire, or two-phase five-wire. Being a
> >transformer, this can pass power either from the three-phase system to
> >the two-phase system, or vice versa.
>
> That is TRIVIAL?
> --
Given that most service comes from one, two or three stepdown transformers
(single, open-delta, delta) anyway, reconnecting them into the Scott-T
connection isn't much of a difference. Many commercial transformers have
the center tap and one at 86% (the tap needed on the single-phase to center
transformer to get the same voltage).
So, reconnecting a set of service transformers is kind of trivial when you
think about it.
daestrom
John Wilson
> I read in sci.engr.electrical.compliance that John Wilson
> <johnw...@alum.mit.edu> wrote (in <tJofb.399729$2x.1...@rwcrnsc52.op
> s.asp.att.net>) about '30A wiring advice - a complication?', on Sat, 4
> Oct 2003:
>
>>No, it's a two-phase three-wire system. A four-phase system has
>>conductors with phase angles that differ by 45 degrees. More explanation
>>below.
>
>
> You've just chosen definitions that suit your denials.
See ANSI Standard C1, where the nomenclature of US electrical systems is
defined. This is not a matter of opinion.
>
>>>- the angles must add up to 360 degrees) would
>>>create a rotating field, but it is not easy to derive such a supply from
>>>the public electricity system.
>>
>>It's trivial, using a standard device called a Scott-connected
>>transformer. It consists of two transformers, one connected between
>>phases A and B, and the other connected between the center tap of the
>>first one and phase C. If you choose the ratios of the two transformers
>>correctly, the other windings of the two transformers are 90 degrees out
>>of phase, giving you two-phase power. How you make the connections on
>>the two-phase side determines whether you're dealing with two-phase
>>three-wire, two-phase four-wire, or two-phase five-wire. Being a
>>transformer, this can pass power either from the three-phase system to
>>the two-phase system, or vice versa.
>
>
> That is TRIVIAL?
Another poster addressed this.
73,
JohnW
No Spam
>
> I read in sci.engr.electrical.compliance that s <sim....@cwcom.net>
> wrote (in <AOOeb.13$kC5....@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.
>
> 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??
>
> 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
> 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.
John Woodgate
<no....@hotmail.com> wrote (in <3F7F33BF...@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.
John Wilson
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
John Woodgate
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.
Rowbotth
John Wilson <johnw...@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.
Michael Moroney
>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
John Wilson
> I read in sci.engr.electrical.compliance that John Wilson
> <johnw...@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
Trevor Barton
> 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
Spehro Pefhany
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 $1000 cash after tax to put a carpet down (less
expenses) goes right into the pocket of some guy with a pickup and a
free weekend. Not everyone does it, but enough that it's a factor.
Paul A
"AC/DCdude17" <Je...@prontoREMOVETHISmail.com> wrote in message
news:3F8A507E...@prontoREMOVETHISmail.com...
> X-No-Archive: Yes
>
> Someone here mentioned main entry wires for multi-thousand ampere service
uses
> paralleled wires. If this is ok, why not in smaller scale?
>
Short answer:Because the NEC dose not allow it for wires smaller than 1/0.
Longer answer: Because if one wire was damaged, opened up, etc, the entire
load would be carried by the other wire, which is greatly over the rating of
the other wire and is a fire waiting to happen.
Spudley
"Paul A" <nos...@nospam.com> wrote in message
news:Nixib.6383$fv4...@nwrdny02.gnilink.net...
Then use 4 wires in parallel and solder them together at the ends to
ensure this doesn't happen.
>
Ben Miller
news:5LgGb.64183$aT.5...@news-server.bigpond.net.au...
> Then use 4 wires in parallel and solder them together at the ends to
> ensure this doesn't happen.
In the US, parallel conductors are not allowed in the smaller sizes, and
connections that depend on solder are not allowed for service conductors.
Also, if this was allowed, wouldn't it be a lot more material and labor than
just using a single wire of the correct size?
Ben Miller
--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com
PJx
<benm...@worldnet.att.net> wrote:
>"Spudley" <anti...@bigpond.net.au> wrote in message
>news:5LgGb.64183$aT.5...@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
Texan
<benm...@worldnet.att.net> wrote:
>"Spudley" <anti...@bigpond.net.au> wrote in message
>news:5LgGb.64183$aT.5...@news-server.bigpond.net.au...
>> Then use 4 wires in parallel and solder them together at the ends to
>> ensure this doesn't happen.
>
>In the US, parallel conductors are not allowed in the smaller sizes, and
>connections that depend on solder are not allowed for service conductors.
>Also, if this was allowed, wouldn't it be a lot more material and labor than
>just using a single wire of the correct size?
>
>Ben Miller
Just for the techs who wonder why solder isn't allowed. When a
connection gets hot the solder would melt and create all kinds of
problems.. Solder has a much lower melt temp than copper. That's why
in higher load carrying circuits we use crimp or compression type
connectors.
John Woodgate
(in <stkjuvgm2prd272b7...@4ax.com>) about '30A wiring
advice', on Wed, 24 Dec 2003:
>On Wed, 24 Dec 2003 15:17:23 GMT, "Ben Miller"
><benm...@worldnet.att.net> wrote:
>
>>"Spudley" <anti...@bigpond.net.au> wrote in message
>>news:5LgGb.64183$aT.5...@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.
Ben Miller
news:stkjuvgm2prd272b7...@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).
Andrew Gabriel
John Woodgate <j...@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
Doug 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.
>
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?
John Woodgate
<spam...@milmac.com> wrote (in <WEVHb.19442$P%1.180...@newssvr28.news
.prodigy.com>) about '30A wiring advice', on Mon, 29 Dec 2003:
>How come we choose from just two people to run for president and 50 for Miss
>America?
Almost all the people with the necessary qualities to be President have
too much sense to want the job. (;-)
Doug Miller
>I read in sci.engr.electrical.compliance that Doug Miller
><spam...@milmac.com> wrote (in <WEVHb.19442$P%1.180...@newssvr28.news
>
>>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. (;-)
Friend of mine is fond of saying that the mere fact that anyone wants the job
should be regarded as conclusive evidence of his lack of fitness for it.
--
Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
Frank Warner
Yes Minister Series
Quotes from the dialogue
"The argument that we must do everything a Minister demands because he
has been 'democratically chosen' does not stand up to close inspection.
MPs are not chosen by 'the people' - they are chosen by their local
constituency parties: thirty-five men in grubby raincoats or thirty-five
women in silly hats. The further 'selection' process is equally a
nonsense: there are only 630 MPs and a party with just over 300 MPs
forms a government and of these 300, 100 are too old and too silly to be
ministers and 100 too young and too callow. Therefore there are about
100 MPs to fill 100 government posts. Effectively no choice at all."
Don Phillips
news:WEVHb.19442$P%1.180...@newssvr28.news.prodigy.com...
If you vote in the primary, you get to vote for more than two people.
Sincerely,
Donald L. Phillips, Jr., P.E.
Worthington Engineering, Inc.
145 Greenglade Avenue
Worthington, OH 43085-2264
dphi...@worthingtonNSengineering.com
(remove NS to use the address)
614.937.0463 voice
208.975.1011 fax
http://worthingtonengineering.com
Spudley
"Frank Warner" <fwarn...@yahoo.com.au> wrote in message
news:3FF1F402...@yahoo.com.au...
Albert
John, THANK you for yr Comments.
can you tell me when cable ratings are calulaged for say 10mm2 twin and earth
do they apply to the WHOLE cable, or just per single Conductor? If at all poss
please Emil your reply.
Many many thanks.
albert
--
for full context, visit https://www.homeownershub.com/maintenance/30a-wiring-advice-478049-.htm