In article , Ignoramus26750 wrote:
On Thu, 10 Nov 2005 09:36:44 -0800, Esther & Fester Bestertester
wrote:
NEC reference says that 12ga THHN wire can carry 30A max
current. Motor load is currently drawing constant 20A (230v
1ph circuit). Breaker is 30A.

It is my understanding that wire must be matched to the breaker. So,
if the breaker is 30A, the wire should be rated for 30A as well. That
means 10 gauge.

It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

greg


(A bit of history: Previous motor (running from 208v) was
drawing less (15A?) current until machine broke. New
machine's motor (running from 230v via boost
autotransformer) is drawing 20A (measured at breaker).
Motor spec plate says 16A.)

Is 12ga wire sufficient, or should I bump it up to 10ga?

Would the autotransformer account for the increased current
draw?

FBt

"Ignoramus26750" wrote in message
...
On Thu, 10 Nov 2005 19:10:05 GMT, GregS wrote:
In article , Ignoramus26750
wrote:
On Thu, 10 Nov 2005 09:36:44 -0800, Esther & Fester Bestertester
wrote:
NEC reference says that 12ga THHN wire can carry 30A max
current. Motor load is currently drawing constant 20A (230v
1ph circuit). Breaker is 30A.

It is my understanding that wire must be matched to the breaker. So,
if the breaker is 30A, the wire should be rated for 30A as well. That
means 10 gauge.

It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

I agree.

i

The breaker should be greater than the cable capacity so that the cable
doesn't burn out to protect the breaker.

Cheers.

Ken

On Fri, 11 Nov 2005 08:44:44 +1300, "Ken Taylor"
wrote:

"Ignoramus26750" wrote in message
.. .
On Thu, 10 Nov 2005 19:10:05 GMT, GregS wrote:
In article , Ignoramus26750
wrote:
On Thu, 10 Nov 2005 09:36:44 -0800, Esther & Fester Bestertester
wrote:
NEC reference says that 12ga THHN wire can carry 30A max
current. Motor load is currently drawing constant 20A (230v
1ph circuit). Breaker is 30A.

It is my understanding that wire must be matched to the breaker. So,
if the breaker is 30A, the wire should be rated for 30A as well. That
means 10 gauge.

It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

I agree.

i

The breaker should be greater than the cable capacity so that the cable
doesn't burn out to protect the breaker.

Cheers.

Ken


Eh? The breaker trip rating should be _lower_ than the current
capacity rating of the wire.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

GregS wrote:



It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

Nonsense- if you hook say 40A 6ga to a 20A breaker, that 40A will trip
the breaker almost immediately...

Fred Bloggs wrote:



GregS wrote:



It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.


Nonsense- if you hook say 40A 6ga to a 20A breaker, that 40A will trip
the breaker almost immediately...

Even without a load?

:-)

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

"Jim Thompson" wrote in
message ...
On Fri, 11 Nov 2005 08:44:44 +1300, "Ken Taylor"
wrote:

"Ignoramus26750" wrote in message
. ..
On Thu, 10 Nov 2005 19:10:05 GMT, GregS wrote:
In article , Ignoramus26750
wrote:
On Thu, 10 Nov 2005 09:36:44 -0800, Esther & Fester Bestertester
wrote:
NEC reference says that 12ga THHN wire can carry 30A max
current. Motor load is currently drawing constant 20A (230v
1ph circuit). Breaker is 30A.

It is my understanding that wire must be matched to the breaker. So,
if the breaker is 30A, the wire should be rated for 30A as well. That
means 10 gauge.

It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

I agree.

i

The breaker should be greater than the cable capacity so that the cable
doesn't burn out to protect the breaker.

Cheers.

Ken


Eh? The breaker trip rating should be _lower_ than the current
capacity rating of the wire.

...Jim Thompson
--
Damn! That was what I meant! Thanks Jim.

Ken

"Fred Bloggs" bravely wrote to "All" (11 Nov 05 00:24:42)
--- on the heady topic of " Commercial mains wiring: 12ga wire for 30 amp load?"

FB From: Fred Bloggs
FB Xref: core-easynews sci.electronics.design:522117
FB sci.electronics.misc:132449 sci.electronics.repair:348125
FB alt.engineering.electrical:142556

FB GregS wrote:
It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

FB Nonsense- if you hook say 40A 6ga to a 20A breaker, that 40A will trip
FB the breaker almost immediately...


And perhaps permanently...

A*s*i*m*o*v

.... A fail-safe circuit will destroy others.

On 11/10/05 4:24 PM, in article , "Fred Bloggs"
wrote:



GregS wrote:



It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

Nonsense- if you hook say 40A 6ga to a 20A breaker, that 40A will trip
the breaker almost immediately...


Where did the poster to whom you are commenting, say he would put a 40A load
on a 20A breaker?

He said, "The wire can be bigger than the breakers rating.

In article , "Asimov" wrote:
"Fred Bloggs" bravely wrote to "All" (11 Nov 05 00:24:42)
--- on the heady topic of " Commercial mains wiring: 12ga wire for 30 amp =
load?"

FB From: Fred Bloggs
FB Xref: core-easynews sci.electronics.design:522117
FB sci.electronics.misc:132449 sci.electronics.repair:348125
FB alt.engineering.electrical:142556

FB GregS wrote:
It does not have to be matched. Only on how big the breaker can be.
The wire can be bigger than the breakers rating.

FB Nonsense- if you hook say 40A 6ga to a 20A breaker, that 40A will trip
FB the breaker almost immediately...


And perhaps permanently...

A*s*i*m*o*v

.... A fail-safe circuit will destroy others.


Let me try another approach. If you attach a 10 guage wire to a 20 amp breaker, a 10 amp load will
opperate more effeciently and have more voltage, and the wire will run cooler. The ground will also
have a better connection to the main box.

greg

On Fri, 11 Nov 2005 15:44:53 +1300, Ken Taylor wrote:
"Jim Thompson" wrote in
On Fri, 11 Nov 2005 08:44:44 +1300, "Ken Taylor"
....
The breaker should be greater than the cable capacity so that the cable
doesn't burn out to protect the breaker.

Eh? The breaker trip rating should be _lower_ than the current
capacity rating of the wire.

Damn! That was what I meant! Thanks Jim.


What does Homer Simpson use to bake bread?

v



v



v



v



v




v




v



v



Doh!

;-)
Rich

On Sat, 12 Nov 2005 22:06:47 +0000, Rich, Under the Affluence wrote:

On Fri, 11 Nov 2005 15:44:53 +1300, Ken Taylor wrote:
"Jim Thompson" wrote in
On Fri, 11 Nov 2005 08:44:44 +1300, "Ken Taylor"
...
The breaker should be greater than the cable capacity so that the cable
doesn't burn out to protect the breaker.

Eh? The breaker trip rating should be _lower_ than the current
capacity rating of the wire.

Damn! That was what I meant! Thanks Jim.


What does Homer Simpson use to bake bread?

Marge.

--
Keith

v



v



v



v



v




v




v



v



Doh!

;-)
Rich