AAW wire gauge question.

[Mike65 475]

I sent an e mail to AAW asking about the gauge of one of their wires & while I am waiting maybe someone here might know. I am doing my alternator wiring hookups today & I am using a Ford 95 amp 3G alternator in my 69 Coupe, & I am running the wires under the fender to clean up the engine bay & the brown alternator wire in the AAW wiring harness is short by a few inches. Does anyone know the gauge of the brown alternator wirie in the AAW wiring harness so I can purchase some wire to finish my hookup?. Here is what the installed alternator looks like.

 

[danno 128]

Whatever AAW used, it might not be large enough for your alternator.   According to the national electric code, for 95 amps, you need a #2 wire.  Wires will create heat when you have current through them, and from the NEC, if you run 95 amps continuously through a #2 wire, it will get up to 60 degrees C, or 140 degrees F.  As an engine compartment is already quite hot, that might not be enough if run continuously.    So you should probably use a #2 wire with insulation good for high temperature.   You would be much better running the wire direct from  the alternator to the battery and not splicing a heavy wire like that into the AAW harness. 

[Grabber70Mach 107]

I agree with Danno's comment about running a wire directly from the alternator to battery.  I would also suggest that you install a inline circuit breaker or mega fuse. 

[Mike65 475]

I have a wire that is supplied with the AAW wiring harness that goes from the power stud on the back of the alternator through a supplied fuse link to the battery side of the starter solenoid. The Ford 3G alternator I am using also has a 3 wire plug connector that plugs into the regulator on the alternator marked A, S, & I. The A wire has an eyelet on it that goes to the power stud on the back of the alternator, the S wire has a small plug on it that plugs into the alternator, & the I wire gets connected to the ignition switch. See post #-2 in attached link for hookup I am using. https://www.ford-trucks.com/forums/1520526-3g-alternator-question.html   The brown wire I am referring to according to the AAW wiring instructions states "if you are using an alternator that requires an internal voltage regulator this exciter wire must be connected to the switched or 12 volt ignition terminal on your alternator". I am trying to see if anyone knows the gauge of the exciter wire so I can lengthen it. 

[danno 128]

Do you have a caliper ( micrometer)?  You can measure the diameter and then use a chart to determine the size.   Another way is to go to a local hardware store and clip a 1 inch section of wires they have that are close. Compare what you know from the sort sections of wire that you clipped to what you want.  For both methods, check the wire, not the wire with the insulation. 

[mwye0627 44]

Automotive wire gauge requirements are different than what you would find under the NEC, National Electrical Code, which specifies requirements for residential and commercial Alternating Current wiring.

The alternator excitation wire is only used to energize the magnetism of the field windings. It is typically low current, and is nowhere close to the 95 amp output of your alternator.     Just use the same gauge as the excitation wire in your AAW kit to extend it...

AAW Has a White Paper on Alternator Operation:   https://www.americanautowire.com/view-faq/the-workings-of-an-alternator/

 

Choosing the Wire Gauge

To choose an adequate wire gauge, determine the amp draw (amperage) that the wire circuit will carry.  Then measure the distance that the wire will travel (length) including the length of the return to ground (the ground wire running to the chassis or back to a ground block or battery.  Using these two numbers, Amps and length, locate the nearest gauge value in the chart below.  For 6 volt automotive systems typically a wire gauge 2 sizes larger than what is shown should be used.  

Amps  @ 13.8 Volts	LENGTH OF WIRE American Wire Gauge (AWG)
	0-4 ft.	4-7 ft.	7-10 ft.	10-13 ft.	13-16 ft.	16-19 ft.	19-22 ft.
0-10	16-ga.	16-ga.	14-ga.	14-ga.	12-ga.	10-ga.	10-ga.
10–15	14-ga.	14-ga.	14-ga.	12-ga.	10-ga.	8-ga.	8-ga.
15-20	12-ga.	12-ga.	12-ga.	12-ga.	10-ga.	8-ga.	8-ga.
20-35	12-ga.	10-ga.	10-ga.	10-ga.	10-ga.	8-ga.	8-ga.
35-50	10-ga.	10-ga.	10-ga.	8-ga.	8-ga.	8-ga.	6 or 4-ga.
50-65	10-ga.	10-ga.	8-ga.	8-ga.	6 or 4-ga.	6 or 4-ga.	4-ga.
65-85	10-ga.	8-ga.	8-ga.	6 or 4-ga.	6 or 4-ga.	4-ga.	4-ga.
85-105	8-ga.	8-ga.	6 or 4-ga.	4-ga.	4-ga.	4-ga.	4-ga.
105-125	8-ga.	8-ga.	6 or 4-ga.	4-ga.	4-ga.	4-ga.	2-ga.
125-150	8-ga.	6 or 4-ga.	4-ga.	4-ga.	2-ga.	2-ga.	2-ga.
150-200	6 or 4-ga.	4-ga.	4-ga.	2-ga.	2-ga.	1/0-ga.	1/0-ga.
200-250	4-ga.	4-ga.	2-ga.	2-ga.	1/0-ga.	1/0-ga.	1/0-ga.
250-300	4-ga.	2-ga.	2-ga.	1/0-ga.	1/0-ga.	1/0-ga.	2/0-ga.

 

Automotive Wire Gauge Chart.pdf

[Vicfreg 773]

Mike, what wire # in the AAW harness are you referring to?  If it is brown wire 4D, it is the voltage regulator feed for the old style alternator, and you don't use it.  I have my spared

[Mike65 475]

I am running a Ford 3G alternator that has the hot wire that comes from the battery side of the starter solenoid & the 3 wire plug that is connected to the regulator on the back of the alternator. See post #-2 in the link for the diagram. https://www.ford-trucks.com/forums/1520526-3g-alternator-question.html

[Vicfreg 773]

oh, so likely the green wire.  The AAW wires are 14 gauge

 

 

[Mike65 475]

Yes.