One caveat to remember, that chart is for SOLID single strand
wire.
Yes... it's a fact...electron flow theory has never been ...proven.
It's all based on 'cause and effect. BUT...
It's a commonly accepted fact that current only flows on the surface
of the wire. Hence, the design of multi-stranded wire.
Now a starter can easily draw 150+ amps. That's 1800 watts (V*A=W)
So with these numbers we'll say the starter has a 0.08 ohm resistance.
These calc's bypass any wiring/connection resistances. Add just 0.05
ohms into the wiring before the load and you get a voltage drop across
that resistance. You are limiting the ckt. to 92 amps (12V/(0.05R+0.08R)passing
through it. You've now limited the starter power to 1104 watts. (V*A=W)
Where does the power go... HEAT!
Now the 92amps passing through the 0.05 ohms = a 4.6V drop across
the 0.05 ohm resistance. (A*0=V)
That 0.05 ohm resistance now becomes a 424 watt heater. (V*A=W)
(remember... even a 20 watt soldering iron will melt solder in just seconds)
The starter is now only getting 680 watts delivered ( (12V-4.6V)*92A )
delivered to it.
So to put of all this detail in perspective... any extra resistance can quickly
bypass the power needed to turn the starter properly. And as we all know....
heat (excessive) will kill just about anything.
Paul Tegler ptegler@gouldfo.com www.teglerizer.com
----- Original Message -----
From: "Terry Thompson" <epharisto@yahoo.com>
To: <spitfires@autox.team.net>
Sent: Tuesday, January 16, 2001 12:55 PM
Subject: Amperage/Gauge list
I don't know if I made it clear, but that list is for
DIRECT CURRENT only and is a very short (6 foot run).
For household (AC) currents, you have current
traveling at greater distances (you must calculate
the hot and neutral wires as distance e.g. double the
distance to the outlet), and is a 120 volt circuit
compared to a 12 volt circuit.
There are charts on the web for more definative
calculations:
All kinds of wire and electronic equations:
http://www.hut.fi/Misc/Electronics/docs/wiring/wire_resistance.html
DC wiring chart (where I got the DC amps):
http://www.off-road.com/jeep/swb/articles/electrical2.htm
-Terry
'76 spit 1500 (w/TSI Sport starter. Works fantastic!
And it's less expensive than buying a starter every 6
months.)
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