[AT] Tractor wiring

[Spencer Yost]

Mattias is right, the formula holds true for any type of electrical
circuit.   Be sure to realize resistance, an important additional load on
the circuit that may change your decision on wire size, increases with the
length of the wire.

As for wire sizes, 10 ga. is used for charging circuits on virtually all
vehicles with regular duty alternators and alternators are usually the
highest wattage circuits (400-800 watts) on a vehicle.  So I use 10 ga for
any type of charging circuit, I use 10 ga (and a relay!) for modern
high-intensity lamps and I use 12 ga. for for lower output lights if there
is more than 2 on the circuit.  I use 14 ga. for everything else.  If I am
unsure, I use 10 ga and a separate switching circuit with a relay.  Heavy
duty alternators, if I had ever wired for any, would probably get 6-8 ga
wire.

I have no engineering calculations to back this up but this is what I have
learned to use over the years and seems to match pretty well with what is
used in practice by manufacturers and hold up to a few offhand resistance
and wattage calculations I have done on the back of a tool package label.
I am sure others have some better ideas that maybe are tested or calculated
that may give you a better degree of comfort than "This is Spencer's system
and it works for him because nothing has burned down"  (-;

Spencer Yost
Owner, ATIS
Plow the Net!
http://www.atis.net

*********** REPLY SEPARATOR  ***********

On 11/16/2004 at 10:18 PM Greg Hass wrote:

>After several years of procrastinating I am going to completely rewire my 
>Farmall 856 with a year-a-round cab.  I can rewire a house, a barn or a 
>shop.  However, when it comes to tractor wiring I can't figure the size of

>wire to use when it comes to wiring the various components.  For instance,

>I want to add some halogen lights, some hooked together and some wired 
>singly.  Also, I want to add a heater and possibly get the circulating fan

>running, which has never worked since I've owned the tractor.
>
>I want to use adequate sized wire, but on the other hand no bigger than 
>needed as the heavier wire is harder to work with.  Does anyone know of a 
>chart, or source, or rule of thumb on how to figure such things?  For 
>instance, with house wiring "amps x volts = watts", but I'm not sure the 
>same formula would apply to a 12-volt system.
>
>Greg Hass
>
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