# Wire gauge

Discussion in 'Archived Threads 2001-2004' started by Greg*go, Jul 1, 2002.

1. ### Greg*go Supporting Actor

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I've heard that if you use two 16 gauge wires together for the same connection, then it makes a 13 gauge wire. My question is, how does one determine the gauge of a wire? Is there some kind of mathematical equation? If I use two 12 gauge wires, what would I get besides one thick-ass wire? How about one 12 gauge, and one 16 gauge? Surely someone must know some kind of equation that would satisfy my pointless babbling...

2. ### Jason Wilcox Supporting Actor

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i just know that if you combine two of the same gauge wires you drop the total gauge by 3.

3. ### Blake R Stunt Coordinator

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Greg, there is no such wire size(13 Ga.)in the American Standard Wire Gauge. If you run parallel sets of conductors you double the ampacity of the feeder. If you run two sets of #14 AWG copper(15A), the ampacity is 2x15A = 30 amps. The ampacity of #10 Cu is 35 amps so you could run a single set of #10 in lieu of two sets of #14.

4. ### StanT Auditioning

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Gauge basically refers to the size of the conductor.

Nominal
Nominal Cross Section
Gauge Size Cond. Diam. (Circular mils)
18 0.04030" 1624
16 0.05080" 2583
14 0.06410" 4107
12 0.08080" 6530

There are many more, but I'll stop here...

And yes, there are odd numbered gauges whose size falls between the even numbered gauges. If you have a wire which you are unsure of the size, you can take a micrometer and measure the diameter over the conductor and get in the ballpark. If you want to get even more precise, take the micrometer and measure the diameter of each strand. Record each strand size in mils (1 mil = 0.001"). Square each strand size and multiply by the number of strands which are that size. Add all of the strands together and you have circular mils. The same would work when combining to wires.
A Yahoo search will yield several web sites showing the sizes of other gauges.

Hope this helps.

5. ### StanT Auditioning

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My table didn't come out so good.

The numbers show gauge, conductor diameter in inches, and conductor cross sectional area in circular mils.

6. ### Blake R Stunt Coordinator

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I guess I did not emphasize "standard" enough. If you examine manufacturer's wire tables (the stuff they actually make)you will see almost no odd numbered gauges because there is no need to make them. In the signal category you usually find only 15 and 25 manufactured in bulk. In power wiring you will find only #3 and #1 manufactured in bulk. Above #1 the designations are changed entirely. The National Electrical Code has the most comprhensive wire table data but they do not go below 15A(#14)

My mistake.

7. ### Bob McElfresh Producer

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Great info guys.
Some background: the term "gauge" used to describe how many times you ran a rod/wire through a press to squish it. A 20 gauge wire was squished 20 times so it is thinner than a 12 gauge wire which was squished less.
(Why yes, "squish" is a technical term I believe ... )
For speaker wire, several speaker sites recommend the following gauge wire based on the run-length:
1-10 ft: 16 ga
11-20 ft: 14 ga
20+ ft: 12 ga
The reason is NOT power handling or resistance. Its because a long run of speaker wire will reduce the higher frequency sounds a lot more than the lower frequency sounds. It "slants" the sound. A thicker wire reduces the effect, but does not eliminate it.
So if you are trying to use 2 runs of 12 ga wire for a 8 foot distance - it's really not going to help.

8. ### Wayne A. Pflughaupt Moderator Moderator

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9. ### Allan Jayne Cinematographer

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>>> How does this accommodate the diameter differences for solid-core vs. stranded wire?
You need the cross sectional area of the copper. Because stranded wire has air spaces between strands, the overall diameter of the strands all together is greater than a single solid conductor of the same gauge.
If you measure the individual strands you should come up with the same circular mil value for both stranded and solid wire.
Note that if the strands are round, you must compute circular area to obtain the number of circular mils (take half the diameter, square that, and multiply by pi, or 3.1416,) as opposed to square the thickness as measured with a micrometer.
Video hints:
http://members.aol.com/ajaynejr/video.htm