Mailing List lml@lancaironline.net Message #2559
From: Brent Regan <brent@regandesigns.com>
Subject: Re: circular mils
Date: Thu, 10 Jun 1999 07:34:23 -0700
To: <lancair.list@olsusa.com>
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John's post stirred an ancient memory that sent me diving for the books.

John wrote:

<<A mil is 0.001 inch.

A circular mil is the area of a circle 1 mil [.001] in diameter, which is
pi x .0005^2. or .0000007854 square inches or 7.854 x 10^-07 sq. in.>>

Oh if it were only so. Eons ago some wire gage bureaucrat decided that
it would make more sense if a circular mil wasn't the actual area in
millionths of a square inch but rather the diameter of the wire in
thousandths of an inch (mils) squared. From Marks Standard Handbook "To
obtain the cir mills of a solid cylindrical conductor, square its
diameter expressed in mils." Reminds me of the urban legend of Congress
attempting to legislate the value of Pi to 3.00.

John, however, did use the published area in square inches so his answer
is correct :)

A word of caution to Angier, copper work hardens very quickly and may
crack if subjected to flexing due to vibration so be sure the components
that are connected by this strap are otherwise mounted solidly.

Brent



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