On Wed, 2007-06-06 at 18:13 -0500, Stuart Rohre wrote:
> OF course a manufacturer is going to use the least cost option to keep a
> good profit margin. For short runs, you can skimp on gauge.
>
> But, the ampacity rating of your wire should be generous in case you run a
> long distance from power supply location to the rig. In the electrical
> trade, no. 12 is considered good for any length of usual house wiring runs
> at 20 amps. Your radio will have full voltage for high duty cycle modes
> like PSK, or RTTY. Things will run cooler from less voltage drop. Your
> radio will not have to visit the service department as often.
>
> In some cases of long runs, you can use larger cable, and splice to a
> smaller cable that fits the DC connector pins, close to the radio.
>
> -Stuart
> K5KVH
However, at 12 volts, voltage drop from wire resistance is ten times as
important as at 120 volts so you can't run 20 amps through 12 gauge
copper the length of the house.
I found 12 gauge circuits 80 feet long were not good enough to run a 120
volt radial arm saw in my barn. I ended up tapping a local box into a 50
amp 240 volt circuit to run the saw using a short run of a 10 gauge
extenssion cord and a relay to put the shop vac on the opposite phase
from the saw, else starting voltage droped under 80 volts which made for
a slow atart and poor cutting.
73, Jerry, K0CQ
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