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How to determine wire gauge.

T

Tibur Waltson

Jan 1, 1970
0
I salvage electrical wires from dishwashers, cars, and
heaters. I keep only the ones that can power large motors,
fans or anything that demand high current and power.
The wires look and feel the same but actually are not.
They, except a few, cannot drive a car radiator fan
longer than a couple minutes without heating up or
sometimes melting.

I don't have fancy gadgets to determine which wires
are which but I like to know which ones can handle a
simple load as a radiator fan. How do I determine the
wire gauge when they look the same?

TIA, Tibur
 
M

Michael A. Terrell

Jan 1, 1970
0
Tibur said:
I salvage electrical wires from dishwashers, cars, and
heaters. I keep only the ones that can power large motors,
fans or anything that demand high current and power.
The wires look and feel the same but actually are not.
They, except a few, cannot drive a car radiator fan
longer than a couple minutes without heating up or
sometimes melting.

I don't have fancy gadgets to determine which wires
are which but I like to know which ones can handle a
simple load as a radiator fan. How do I determine the
wire gauge when they look the same?

TIA, Tibur

Pick up a cheap micrometer or a dial caliper to measure the diameter
of the wire, and look it up on a wire chart..
 
B

Bob Masta

Jan 1, 1970
0
Pick up a cheap micrometer or a dial caliper to measure the diameter
of the wire, and look it up on a wire chart..
--

Even cheaper, you can close-wind a number of turns on a
pencil or something, and measure the packed total length
with an ordinary ruler. Divide by the number of turns and
you've got the wire diameter, then look it up on the chart.


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
B

Bill Vajk

Jan 1, 1970
0
Tibur said:
I salvage electrical wires from dishwashers, cars, and
heaters. I keep only the ones that can power large motors,
fans or anything that demand high current and power.
The wires look and feel the same but actually are not.
They, except a few, cannot drive a car radiator fan
longer than a couple minutes without heating up or
sometimes melting.
I don't have fancy gadgets to determine which wires
are which but I like to know which ones can handle a
simple load as a radiator fan. How do I determine the
wire gauge when they look the same?

It is the cross sectional area of the conductor itself
that matters, not the overall diameter including the
insulation.

Herer's a quick fix for your problem. Hook up your wire to
the load and try running it. If it starts to get warm, add
a second in parallel and try again. Keep adding parallel
conductors till they do not heat up.

The wire is free, after all, so you can use as many as you
would like.

Here's a chart about wire gages. You might find a friendly
soul someplace who might cut you some sample pieces which
you could label and mount so you have something to use for
comparison.

http://www.techfest.com/networking/cabling/gage.htm

As you can see the larger the number the smaller the wire.
 
B

Bill Vajk

Jan 1, 1970
0
Bob said:
Even cheaper, you can close-wind a number of turns on a
pencil or something, and measure the packed total length
with an ordinary ruler. Divide by the number of turns and
you've got the wire diameter, then look it up on the chart.


Modern appliances sometimes use small wire with a thick
insulation, and he's slavaging the stuff out of
everywhere.
 
M

Michael A. Terrell

Jan 1, 1970
0
Bob said:
Even cheaper, you can close-wind a number of turns on a
pencil or something, and measure the packed total length
with an ordinary ruler. Divide by the number of turns and
you've got the wire diameter, then look it up on the chart.

Bob Masta
dqatechATdaqartaDOTcom

I have carried a micrometer in my toolbox for over 30 years to check
wire and sheet metal gauges. I also have a 6" dial micrometer to measure
larger parts. The pair cost less that $20 these days, and are handy for
other jobs. You only need to strip a 1/4" of the insulation to measure
the wire with either of these tools.
 
T

Tibur Waltson

Jan 1, 1970
0
Bill Vajk said:
It is the cross sectional area of the conductor itself
that matters,

The problem is that the cross sectional area look
the same after I strip a 1/4" of the insulation.
Herer's a quick fix for your problem. Hook up your wire to
the load and try running it. If it starts to get warm, add
a second in parallel and try again. Keep adding parallel
conductors till they do not heat up.

The problem is that it takes a long time to heat up (five
minutes.) I have 100 wires, so that'll take 500 minutes.
What if I remove a single strand and test how long it
burns up with a 600-cranking amps battery?

Good link, good advice, thanks to all.

Tibur
 
T

Tibur Waltson

Jan 1, 1970
0
Here, take a look at some wires I scanned.

http://tinyurl.com/2erh8

Actually, what I wanted to say this bare wire measures 2.2 cm in
diameter will not heat up. But when I use two 1.5 cm
diameter bare wire (not shown in the pic) they heat up
compared to a single 2.2 cm wire. What is happening?
The problem is you're a fucking idiot.

Nice use of a discriptive verb. I had the belief that the diversity of the
wires that I collect from would be made up of various
materials. Some withstand heat, some won't. Some come with
poor conductivity, which generates heat. Or is that a myth.
But if what you're saying is true, that all wires are made the same
material, then I'll just get a micrometer, which I'll eventually do.

Tibur
 
B

Bill Vajk

Jan 1, 1970
0
Tibur said:
Here, take a look at some wires I scanned.

Actually, what I wanted to say this bare wire measures 2.2 cm in
diameter will not heat up.

Let's get the units right. 2.2cm = 1 inch.
But when I use two 1.5 cm
diameter bare wire (not shown in the pic) they heat up
compared to a single 2.2 cm wire. What is happening?

How about a guess of copper vs. aluminum?
 
R

Robert C Monsen

Jan 1, 1970
0
Bill Vajk said:
Let's get the units right. 2.2cm = 1 inch.

1 inch is defined as 2.54cm
How about a guess of copper vs. aluminum?

The resistance of wire is inversely proportional to its diameter. As gauge
decreases, diameter goes up, so resistance goes down. Resistance = heat
given the same current.

Here are some fun wire facts for solid wire.

Here is the formula for the diameter of a wire, given the gauge G:

( 83690 )
D = sqrt(-------------)
(1.26096^(G-1))

D is in mils (which are 1/1000 inch)

The resistivity of solid wire depends on the temperature, and the specific
resistance (rho) of the material the wire is made from. Here is a list of
specific resistances and tempcos (alpha) for various common wire materials:

(View with fixed width font, such as courier)

rho alpha
Aluminum 17 0.004
Copper 10.4 0.004
Gold 14 0.004
Nickel 52 0.005
Silver 9.8 0.004
Tungsten 33.8 0.005

The resistance of a length of wire can be computed from the following

R(T,G,rho,alpha,l) = rho * l * 1.26096^(G-1) * (1 + (T - 20) * alpha)
--------------------------------------------------
83690
rho at 20C, l in feet, T in C.

Regards,
Bob Monsen
 
T

Tibur Waltson

Jan 1, 1970
0
Bill Vajk said:
I swear I pressed the ~, sorry.

Here's the correct units.

2.200 millimeters [mm] or, 0.08661 inch [in] or ~ 12-11 AWG

1.500 millimeters [mm] or, 0.05906 inch [in] or ~ 15 AWG

What will (15 AWG)2 be equal to? My guess is 11 AWG?

If anyone knows how to calculate diameters correctly, (please help).
If the 15 AWG is found to be an inferior conductor, I will throw them
out. Or has Robert and Bill already provided the answer. . . ?
Tibur
 
B

Bill Vajk

Jan 1, 1970
0
Here's the correct units.
2.200 millimeters [mm] or, 0.08661 inch [in] or ~ 12-11 AWG
1.500 millimeters [mm] or, 0.05906 inch [in] or ~ 15 AWG
What will (15 AWG)2 be equal to? My guess is 11 AWG?
If anyone knows how to calculate diameters correctly, (please help).
If the 15 AWG is found to be an inferior conductor, I will throw them
out. Or has Robert and Bill already provided the answer. . . ?
Tibur

When the wire is free, parallel as many as you need to.

As far as equivalent diameters go I don't think you need to
work it out doing the math if you don't want to bother. Use
tables like

http://www.ibiblio.org/obp/electricCircuits/Ref/REF_3.html

Simple multiplication yields two #15 wires equate to about
one #12 so long as they're the same material.
 
S

Steve Dunbar

Jan 1, 1970
0
Tibur said:
What will (15 AWG)2 be equal to? My guess is 11 AWG?

The rule of thumb to find the equivalent of two wires of the same gage is to
subtract three from the gage number: 15 - 3 = 12 AWG.
 
T

Tibur Waltson

Jan 1, 1970
0
Steve Dunbar said:
The rule of thumb to find the equivalent of two wires of the same gage is to
subtract three from the gage number: 15 - 3 = 12 AWG.
Simple multiplication yields two #15 wires equate to about
one #12 so long as they're the same material.

The problem is now SOLVED. :) I can now conclude that I
actually have an inferior conductor. The #12 came from a
BMW while the #15 came from a Honda. A micrometer
will be useful in this case.

I was tossing and turning in bed thinking I wouldn't find a
solution. Now I can sleep. THANKS to all.

Tibur
 
T

Tibur Waltson

Jan 1, 1970
0
The problem is now solved. :)

Thanks once more. I want to apologize to Mr. Fields. I didn't
meant to say that his verb is too descriptive. Because my parents
and teachers are teaching us not to talk about sex and swear, I
admit I'm a little naive and unfamiliar with American English or
newsgroup posting schemes.

Anyway, more happy news, I acquire a digital caliper
which measures in increment of 0.0005, 0.0010, 0.0015", etc.
So, mswire.com/barecu1 is useful, including the Copper wire gauge table.

I also borrowed a book from a friend, "Electronic Fundamental
textbook, from Prentince Hall." and will read 90% and will understand
70% .

Now that I have these off my guilt list, I can relax..... Thank you
everybody being patient, for reading, and for being extremely
helpful and knowledgeable.

Best of luck,
Tibur
 
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