[AT] Tractor wiring

ken knierim wild1 at cpe-66-1-196-61.az.sprintbbd.net
Wed Nov 17 08:32:54 PST 2004


Greg, Spencer,
       As noted, Ohms Law applies to most of the wiring. And I'm sure
you're aware that using solid core wire on an automotive or tractor
application isn't the best idea.

Here are some general ratings I use on wire (useful for the short runs
you're going to see on a tractor or automotive application. longer runs
might have you going to the next bigger size of wire)

14 gage for 15 amps or less
12 gage for 20 amps or less
10 gage for 30 amps or less
8 gage for 40 amps or less
6 gage for 65 amps or less

     I believe those are rated for in-wall usage and are very
conservative for that. When we were rewiring aircraft the chart was a
lot closer to the actual wire limits (many times easily doubling the
amount of current for the wire sizes listed above). So it'll depend, but
if the wire starts getting warm, you're loosing power. Copper isn't very
expensive and I hate to wire things twice. 
     Solder connections are preferred on the wiring but if you use GOOD
QUALITY crimp connectors with a good crimping tool, it usually works OK
(this means avoiding some of the cheapo stuff at the Auto Parts store).
Tractors have been known to have a little vibration so where possible I
try to solder the terminals to the wire. Makes a much more reliable
connection.
     The wildest one I saw was the starter on a German Focke-Wulf FW-190
we rewired... it used 6 gage wire to start an inverted V-12 Junkers
engine (BIG). I found out that the starter is actually an inertia-based
unit; it builds up a large rotating mass and dumps it into the gear
train to spin the engine past compression. Saves a lot of weight that
way, I guess. And it was an American designed starter (built in France)
on a German fighter plane... 

On Wed, 2004-11-17 at 07:32, Spencer Yost wrote:
> 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
> >
> >_______________________________________________
> >AT mailing list
> >http://www.antique-tractor.com/mailman/listinfo/at
> 
> 
> 
> _______________________________________________
> AT mailing list
> http://www.antique-tractor.com/mailman/listinfo/at
> 




More information about the AT mailing list