On Sat, 29 Aug 2009 15:07:40 -0700, David Nebenzahl
wrote:

On 8/29/2009 2:49 PM EXT spake thus:

Also, just as a long wire needs to be a thicker gauge, compared to a normal
length of wire, to carry a fixed amount of amperages,

Saying "a fixed amount of *amps*" would do.

a very short length of wire can be rated to carry a larger amperage
at a smaller gauge than normally used.

That's not true. Conductors are rated at a certain current regardless of
their length.

No, the ampacity of cables varies with length, becuase the resistance
per foot causes more voltage drop on a long cord than on a short one.

This is the rational used on appliance cords, and the internal wiring
in appliances. I have seen a formula somewhere that will determine
the exact gauge needed for a given length at a specific amperage.

I was going to bring up the aspect of cords too, as our 20-amp circuits
have cords plugged into them that are rated at far less than that,
creating another potential source of fire.