Wire size chart for automotive

[wxmn6]

I am an electrician major and I do residential, commercial and industry wiring, but that is different than automotive. I got a bit confused about selecting wire size for automotive because it seems that some wires in automotive are actually smaller for the same amount of current that a household wire is rated for as per National Electric Code. I found a source that use the same chart for household wiring, while other is different. I would like to know if there is a REAL automotive chart that I can use for selecting wire size. Maybe a manufacturer such as GM have a wire size chart that I could use as a reference? Thanks.

[mackin]

wxmn6

This should help you out ......There is a few references here.....Three quarters the way down the page.....
=>http://www.chuckschevytruckpages.com/reference.html

MAC :D

[GBurton]

wxmn6

I have noticed the same thing. What I have found is in non automotive wiring, 110/220/440 ac power wiring, is the NEC is more concerned about the heating effect rather than voltage drop. 1 volt of drop is less that 1 percent in a 110-volt household circuit. While in a 12 vdc automotive circuit a 1-volt drop is almost a 10 percent drop in voltage. What the automobile designers are doing is a good balancing act between how much voltage drop can the circuit stand and still work correctly and the cost of the wire. If they can save weight and cost in the vehicle wiring, they are ahead. I understand those are the driving forces behind the upcoming change to the standard voltage in vehicles, 12 to 36(?) vdc.
One example is the wire that is used in the headlight circuit. Every truck that is sold meets the national lighting requirements but we all know that if the engine is running and the alternator is putting out 14.0 vdc you will not measure 14.0 volts at the headlight bulb.

I work in the telecom field and we use 12, 24 & 48 vdc power systems. The proper wire size is determined by how much voltage drop we will accept. I complained for years when the installation people used the 48vdc wire standards when the installed a 12 vdc system. They just did not understand that at 12 vdc a 1-volt drop was not acceptable. Here is a link that has a simple but usable wire size calculator: http://www.currentsolutions.com/knowledge/vdrop.htm

I know this is not exactly what you were asking for but it is usable information.

George

[wxmn6]

Calculator could be a help but it does not tell how much voltage drop they allowed.

What would be the maximum allowable voltage drop that you would allow in automotive?