30A wiring advice

[Joe 90]

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.

 

[Wade Lippman]

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.

 

[Wade Lippman]

"Wade Lippman" <toller@frontiernetnospam.net> wrote in message
news:5Tmeb.7273$N57.3589@news01.roc.ny...

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.

Actually, it is okay to thing about it; just don't think about it. (fingers

faster than brain, sorry.)

 

[Andrew Gabriel]

In article <5Tmeb.7273$N57.3589@news01.roc.ny>,
"Wade Lippman" <toller@frontiernetnospam.net> writes:

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.

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

 

[Zathera]

"Joe 90" <donot@usethisaddress.com> wrote in message
news:3f79f827$1_4@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.

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.

 

[Robert Calvert]

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.

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" <donot@usethisaddress.com> wrote in message
news:3f79f827$1_4@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.

 

[Don Phillips]

"Robert Calvert" <Hercules1@pcstarnet.com> wrote in message
news:vnk1teaid4j0e9@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

dphillips@worthingtonNSengineering.com
(remove NS to use the address)
614.937.0463 voice
208.975.1011 fax

http://worthingtonengineering.com

 

[Robert A. Barr]

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.

Sorry, can't help it: Why can't you get #10, when you can get #12?

 

[Tony Hwang]

Hi,
No #8 either?
Tony

Robert A. Barr wrote:

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.


Sorry, can't help it: Why can't you get #10, when you can get #12?

 

[Brian]

Do you have a death wish?!? Let me guess you live at the South Pole and supplies are limited.
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" <donot@usethisaddress.com> wrote in message news:3f79f827$1_4@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.

 

[Joe 90]

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.

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" <spamthis@mail.com> wrote in message
news:meoeb.1358$Gb.1232@news2.central.cox.net...

Do you have a death wish?!? Let me guess you live at the South Pole and
supplies are limited.
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" <donot@usethisaddress.com> wrote in message
news:3f79f827$1_4@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.

 

[John McGaw]

"Joe 90" <donot@usethisaddress.com> wrote in message
news:3f79f827$1_4@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.

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]

"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?

 

[Robert Calvert]

"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

<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]

I read in sci.engr.electrical.compliance that Joe 90
<donot@usethisaddress.com> wrote (in <3f7a16db$1_1@news.bluewin.ch&gt
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]

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.

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" <jmw@jmwa.demon.contraspam.yuk> wrote in message news:h0rdLp
AAtme$EwyT@jmwa.demon.co.uk...

I read in sci.engr.electrical.compliance that Joe 90
donot@usethisaddress.com> wrote (in <3f7a16db$1_1@news.bluewin.ch&gt
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!

 

[Isaac]

On Wed, 1 Oct 2003 10:43:11 +0200, Joe 90 <donot@usethisaddress.com> wrote:

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

 

[s]

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!

 

[C What I Mean]

"Joe 90" <donot@usethisaddress.com> wrote in message
news:3f79f827$1_4@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.

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]

I read in sci.engr.electrical.compliance that Joe 90
<donot@usethisaddress.com> wrote (in <3f7a93a6_2@news.bluewin.ch&gt about
'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.
--
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!