[rescue] I'm not an EE Q - clarification

[Greg A. Woods]

My guess is that it means "no thinner than."  Remember AWG numbers get
larger as the wire gets thinner, so the _maximum_ AWG number in this
case is #12.

The question of course can easily be answered by knowing how much
current the machine might draw (i.e. what rating the fuse has -- a
machine can draw as much power as the fuse will pass under failure
conditions!), and then looking up that value in the appropriate
electrical engineering tables.

Here is a portion of a current & AWG table from the Amateur Radio Relay
Handbook, 1985, probably for stranded wire, though I'm not 100% sure.

AWG  dia    circ  open   cable  ft/lb   ohms/
     mils   mils  air A  Amp    bare    1000'

10   101.9 10380    55    33    31.82   1.018
12    80.8  6530    41    23    50.59   1.619
14    64.1  4107    32    17    80.44   2.575

and here's another table giving recommendations by length of run for
low-voltage power (probably stranded) wire from the rec.audio.car FAQ:

                              Length of run (in feet)
    Current     0-4  4-7 7-10  10-13  13-16  16-19  19-22  22-28

      0-20A     14   12   12     10     10      8      8      8
     20-35A     12   10    8      8      6      6      6      4
     35-50A     10    8    8      6      6      4      4      4
     50-65A      8    8    6      4      4      4      4      2
     65-85A      6    6    4      4      2      2      2      0
    85-105A      6    6    4      2      2      2      2      0
   105-125A      4    4    4      2      2      0      0      0
   125-150A      2    2    2      2      0      0      0     00


I note that Cisco recommends 12 AWG or even 10 AWG for 20 Amps.....

IIRC 12AWG stranded wire carrying 20 Amps will actually run up to 75F.

(you probably don't want a lot of voltage drop, so 10 AWG will be
guarantee good power if you've got more than 10 feet or so to run)

-- 
								Greg A. Woods

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