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From: jroth@allvax.dec.com (Jim Roth)
Newsgroups: sci.electronics
Subject: A conundrum about the AWG (wire gauge) table
Summary: How was the AWG table created?
Message-ID: <2588@ryn.esg.dec.com>
Date: 29 Aug 90 03:13:20 GMT
Sender: guest@ryn.esg.dec.com
Organization: Digital Equipment Corporation
Lines: 28


Many of the standard values in electronics and elsewhere follow an
approximate log/exp scale to accomodate a wide range of values.

Examples are resistors, ISO 3'rd octave audio frequencies, etc.

Wire gauges are no exception, but here's an odd thing - virtually
none of the diameters or areas in circular mills are "round numbers".

Yet when we take logs, we find that each jump of 10 wire gauges
increases the cross sectional area of the wire not by a nice round
number like 10, but by about 10**1.007!

Examples:

      gauge	  area	   log(ratio)
      -----     ------     ----------
	 0	105500	   1.007055
	10	 10380	   1.006747
	20	  1022	   1.007285
	30	 100.5	   1.007058
	40	 9.888

Why the brain-damaged exponent?

How on earth was that table created in the first place?

- Jim