Wiring Q; Amperage v. Gauge

[dan at angband.org (Dan)]

On Sun, May 18, 2003 at 08:51:17PM -0400, Cmr446@cs.com wrote:

>   I was out looking for some heavier ga. wire to increase what my car's 
> wiring system can handle (going for slight overkill for potential capacity) 
> and found 8ga. rope strand. The spool this came off of said it can handle up 
> to 60amps. How is it that my alternator lead and the lead from the battery to 
> the fusebox is only 10ga. and seems to deal with the 90amps from the alt. to 
> battery to fusebox without any problem (no smoke)? Is it the difference in 
> the construction or type of strand? That is to say, "stranded", the usual 
> stiff multi-strand 10ga. can handle more amperage because of the thicker 
> strands, compared to the finer "rope strand" 8ga.?
>   I thought the thicker guage is supposed to handle higher amps. A search 
> online for "8 gauge" and "wire guage" turned up very little in answers, lots 
> of  stereo instalation kits for sale, shotguns, and spokes. The only useful 
> chart I found was here:

First, be aware that there is more than one kind of wire gauge.  The two
most comman gauges are AWG and SAE.  SAE wire, which you usually find in
Wall-Mart and most auto supply stores, is 10% smaller than AWG.  I usually
buy my wire at the boat supply store, it is 100% pretinned for corrosion
resistance, measured in AWG, very flexible, and comes in a rainbow of
colors.  

As for sizing,  you need to know:

How long the run is
How many amps it will carry
What your acceptable voltage drop is.  
(Standard is to allow 3% voltage drop.)

After that , just follow the directions at the bottom of this page to
select the correct gauge.


http://www.anzus-technology.com/kp44/Electrical_Specs.htm

Dan


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