On 2 Feb 2006 19:58:56 -0800, "sparty" wrote:

Yep like I said, since I figure a max of 57 amps, I divided the by 0.8
to make sure I was only running 80% safe capacity. So that's why i'm
chosing 70 amp breaker in my main panel. And yes, like I mentioned I
will be running 4/3 NM-B Wire.

Not sure what you mean by 80 in free air.
What it means is that the wire, with insulation, is exposed to the air
all around, or virtually all around. This keeps the wire cool. The
wire itself can stand to be very hot but the insulation, depending on
type, has varying degrees of temperature resistance. This why the
Romex type of cable is not to be run inside conduit. The insulation
can eventually break down and allow the wires to touch each other or
the conduit and/or the insulation can catch fire. The ratings are
conservative. I believe this is because people tend to push things.
ERS