Heavy Duty Ext. Chord Deal at HF

Hi all,
There have been a few discussions lately about making chords for 240V machines by changing the connectors on a heavy gauge 120V chord that can be purchased.
Harbor Freight has a 50' 12AWG chord on sale for about $11 this week. Similar SJ cable is at least $0.60/ft at the Borg so this is a steal for the raw cable alone.
If you need to go this route, be sure to do the math to determine your maximum length for the current requirement. Failure to do so could result in motor damage or fire hazard. Don't forget the length of wire in the wall.
Tom
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they had the 25' flavor for $6 awhile back
sold out; so had to get raincheck
220 will use 1/2 the amperage; so interesting you can get away with a smaller guage than if you used 110. but i figure 12ga. is the way to go.
i think my delta contractor ts was wired with 14ga; so i had to do some "adjusting" to use the same switch as the internal connectors were designed for 14 (or maybe even 16) guage...
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a side note..
when i was wiring my ts to 220v i talked to a guy at lowes
he said with all that "power" i should use at least 10 guage
as with a medical diagnosis - it's wise to get a 2nd opinion
220v cuts the amperage in half.. thus there's no reason to wire with a heavier gauge when converting to 220. in fact, you could go smaller.
but use the largest possible (12ga is so common.. and as the OP stated.. can be had cheaply) to reduce loss and allow longer runs
but i find having coiled up cords is annoying.. better to just cut it to size..
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10 ga is rated for 30A, regardless of voltage. 12 ga is rates for 20+.
it's never a "bad idea" to use a larger size wire,
going up _three_ wire guages e.g. 14 to 11, _doubles_ the cross-sectional are of the wire, and, thus cuts the resistance _in_the_wire_, by 75%. and the 'losses' in the wiring are 1/16th the size.
Going up two wire guages (e.g., from 12 to 10) reduces the power loss in the wiring by more than 84%. Regardless of whether the wire is loaded to near capacity, or not.

Yup. shifting from 120V to 240(V cuts the current load in half, so you could, in theory, go _three_ wire guages smaller, while maintaining the same 'current density' in the conductor. However, by doing so, you _increase_ the "I2R" losses in the wiring, which is -not- a good thing. At two wire sizes smaller, the wiring losses are essentially the same as the original secnario.
Leaving the wire guage unchanged, and doubling the voltqe, results -- for a given load -- in 1/4 the 'in the wiring' losses.

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Robert Bonomi wrote:

Double the cross section area cuts the resistance in half. NOT by "75%. ...lew...
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He's right, your calcs are off. You're thinking one dimension whereas you need to work with two.
Example: a diameter of 25
Diameter = 2*Radius 25=2*Radius Radius.5 Area=3.14*12.5*12.5 AreaI0.625
Example: a diameter of 50 Diameter = 2*Radius 50=2*Radius Radius% Area=3.14*25*25 Area62.5
Thus the area (capacity) of the double sized circle (cable) is 4 times the size of the original (or 3 times larger) The resistance in the doubled circle (cable) is 1/4 that of the smaller circle, hence the 75% reduction in resistance
Not picking or insulting, it just got my math working! LOL

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Sorry, you're wrong. Lewis was correct when he said _I_ was in error.
I was already talking about cross-sectional _area_ of the wire, not diameter.
It's a real simple situation, Two like-sized resistors in parallel have 1/2 the resistance of either resistor, singly. And, a wire of '2X' _cross- sectional_area_ *is* identical to 2 parallel wires of '1X` cross-section.
No excuses. I had 'sense organ cluster all jammed up ventral orifice' -- as it was once put, in one of my favorite science-fiction stories. :)

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Who was wrong, you or Lewis, I was affirming what Lewis said. His calc's seem right to me.
"And, a wire of '2X' _cross-sectional_area_ *is* identical to 2 parallel wires of '1X` cross-section."
That statement doesn't seem right with basic geometry. You can put two 5" pizzas in a 10" pizza with area left over in the 10".
Now I'm confusing myself! LOL

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*I* was wrong. when I said 'doubling the cross-sectional *area*' cuts the resistance to 1/4". It's only 1/2, as Lewis _correctly_ stated.
Your math was also accurate, but doubling the _area_ is not the same as doubling the _diameter_.    

Again, "area", not 'diameter'. A pizza with an _area_ of, say 100 sq. in., will serve up exactly as many 10 sq. in. pieces as will 2 pizzas each with an area of 50. sq. in.

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On Thu, 29 Jan 2004 23:05:59 +0000, snipped-for-privacy@host122.r-bonomi.com (Robert Bonomi) brought forth from the murky depths:

I'm glad you got it straightened out.
Now, having researched your quote there, I find that Keith Laumer is no Heinlein/Asimov/Clarke/Niven. Methinks it's time for another Niven book. I haven't finished his array yet.
http://www.baen.com/library/0671318578/0671318578__c_.htm Retief!
--------------------------------------------------------------------------------
ONLY HUMANITY'S TWO-FISTED DIPLOMAT CAN SAVE U5 NOW ! "... into the chaotic Galactic political scene, the CDT emerged to carry forward the ancient diplomatic tradition . . : Corps diplomats displayed an encyclopedic grasp of the nuances of Extra-Terrestrial mores asset against the labyrinthine socio-politico-economic Galactic context..."
Official History of the Corps Diplomatique, AD 2940 NOT! What they really had was Retief! Ignore the official versionin these pages is the real story of how Retief tied the bad guys' eye-stalks in knots, and made the Galaxy safe for humanity.
---------------------------------------------- CAUTION: Driver Legally B l o n d (e) http://www.diversify.com Web Database Development ======================================================
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True. But to one with exposure to politics and/or diplomatic circles, this particular set of stories is *excruciatingly* funny. The fact that Laumer was _in_ the diplomatic corps, and many of his characters are supposedly modeled on various 'real people' may well have something to do with it.

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On Fri, 30 Jan 2004 18:56:06 +0000, snipped-for-privacy@host122.r-bonomi.com (Robert Bonomi) brought forth from the murky depths:

This confirms my penchant for all that is hermitlike.
Well, enjoy your books.
---------------------------------------------- CAUTION: Driver Legally B l o n d (e) http://www.diversify.com Web Database Development ======================================================
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Once upon a time, I heard this joke about a guy who played music on his firewood delivery.
Something about it "struck a cord".
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(Tom) says:

to say "12 AW-G MAJOR chord". If it was 16 gauge, it would be a MINOR chord. <G>
Tom (trumpet player & guitar hack)
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"T." wrote:

But, but ........ His spell checker said it was correct!!!!
ARM
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