Wire Size,ie,2pieces 22GA=12GA?

[Fuzz]

I can find charts on the size of wire to use for the amps it carries and the length,but can you use ,for instance, 2 strands of 22GA and what is the Amps it will carry. Is it correct to assume that these two wires together would give more capacity than just the single strand of 22GA. Wondering if there is a chart somewhere.



Seems I always end up with a lot of wire in 12 GA when I need a 10GA.

Just wondering. . Thnx

Fuzz

 

[Don M]

"Is it correct to assume that these two wires together would give more capacity than just the single strand of 22GA. "





NO, the resistance will just go up. You will be pushing the current down more wire length and hence, more resistance.

How much current are you trying to get and what is the distance.

Amps multiplied by resistance minus starting voltage gives you the total voltage loss at the end of the wire or device you are powering. #14awg has about 3. 1 ohms per 1000 ft. Remember to figure the length of the wire to the device and back to the source.

So, 20 ft is really 40ft.



Don~

 

[illflem]

No Don, the resistance will be half with two wires vs. one since only half the load will be traveling in each wire. It's still better to use one wire of the correct size than two small ones since an open in one wire can go unnoticed until a melt down occurs in the remaining wire.

 

[Un-Hemi]

If the two equal wires are connected in parallel, their resistance will be halved. Only if they are connected in series will the resistance double.



It appears from my resource book, the 'Aeroelectric Connection' by Bob Nuckolls, that if you go down three wire sizes, you double the circular mils, and half the resistance. For example, a number 18 wire has a circular mil area of 1624 and a resistance of 6. 39 ohms/1000ft. A number 15 wire (if available) would have a circular mil area of 3257 and a resistance of 3. 18ohms/1000ft. A number 14 wire would be a bit better than the #15 wire.



If you parallel two #22 wires (642 c. mils), you get the equivilant of a #19 wire (1288 c. mils)



Two #12s in parallel will be better than one #10.



According to my reference, #12 wire has a resistance of 1. 59 ohms/1000ft. If one uses the frame or body as the ground return , there is less return voltage drop than if you use a ground return wire all the way back to the source.



Clear?

 

[Fuzz]

Thanks

Thanks all.

I see your point Illflem... about running two parallel and one shorting out.



Don. . I shudda said run 'em parallel. I was thinking that but didn't type it.



Tommy T. . Thanks that what I was wondering.

Thanks again guys.

Fuzz

 

[Don M]

My resistance for the #14awg was from the NEC handbook, but it is at a higher temperature (167 degrees F). I figure all wire gauges with the higher resistance values for survivability reasons.

If the cable goes under hood or in a high heat area I figure it high too.

If you have a device, (say a pump for instance) that draws 5 amps at 12 volts and the wire length is 20 feet to the device with #14awg the formula is as follows:



Total amp load__5A____



Wire Gauge__14AWG___



Total length of wire there and back___40_____



Ohms per foot__. 0031_____



Total resistance of wire___. 12ohms____



Starting Voltage__12VDC_____



Total voltage loss_. 60_____



Voltage left at device___11. 4VDC_____





The formula is calcualted by multiplying the total resistance of the cable or wire in ohms by the total amp load.

IMO, the 11. 4 is kinda low and I would go for a larger conductor.

Of course the starting voltage is higher than 12 VDC too.



Circular mill calcs are not generally used for DC conductors. The NEC tables are better. AC conductors are always figured with circular mills in my work though.



Don~

 

[HillCountrykid]

Dang Don, sounds like I'm sitting in school. NEC, circular mils, amps, voltage, AC, DC. I'm four years through a five year program. Taking my journeyman's licence test tomorow morning. Hope I pass. Should have done more studying.



Fuzz, the chart you are looking for is in the National Electrical Code (NEC).



Brian

 

[JWhitcomb]

The mls you guys are talking about, is a ml the same as . 001 inch?

 

[Don M]

Originally posted by JWhitcomb

The mls you guys are talking about, is a ml the same as . 001 inch?

Yep, sure is,



A mil is : . 001 inches.



Don~

 

[JWhitcomb]

What is the term for . 0001 of an inch?

 

[Don M]

2. 54 microns



Don~

 

[JWhitcomb]

Damm, no wonder machinists and engineers butt heads, the engineers keep making up secret terms for things that already have very good names.

 

[Un-Hemi]

Mils are 1/1000th of an inch. Diameters of wires are expressed in mils.



Circular mil area is the square of the diameter value in mils. Somebody decided a long time ago that just squaring the diameter of the wire would yield a number that was PROPORTIONAL to the real area. That was adequate for those who speak "wire-ese" and confuses the daylights out of the rest of the world.



AWG (American Wire Gauge) numbers apply to a solid, single strand of wire. For stranded wire to be rated as 12AWG, for example, it must have the same electrical characteristics as 12AWG solid wire. The total cross sectional area of the strands must have a circular mil area (CMA) of 6530 or more. This means that the resistance and weight of the stranded wire will be the same as for solid wire. Physically, a stranded wire will be slightly larger in diameter than its solid counterpart.



Respectfully plaigerized from the 'Aeroelectric Connection' by Bob Nuckolls.



Just thought you would like to know.



Tom

 

[Chipstien]

Run some 2000 MCM copper and you won't have to worry about VD (voltage drop).

Hillcountrykid... . Hope ya passed. Don't worry if you don't though. I didn't study one bit before I took mine and failed by one question. #@$%! Oh well, Knew what I had to brush up on and passed with a high 80's.

 

[Don M]

Originally posted by JWhitcomb

Damm, no wonder machinists and engineers butt heads, the engineers keep making up secret terms for things that already have very good names.

I thought you were Canadian J.



Don~