Re: winding my own transformer

• To: tesla-at-pupman-dot-com
• Subject: Re: winding my own transformer
• From: "Jim Lux" <jimlux-at-jpl.nasa.gov> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Sat, 25 Sep 1999 13:10:58 -0600
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

> Check the 1999 National Electric Code (NEC) for info in regards to
> wire ampacity versus use.  Most transformer design articles and text
> I've read suggests for conservative design no more then 700mA / CM
> (circular mil - 0.001").

Circular mils aren't 0.001" in diameter. A circular mil is the area of
0.001" diameter circle... = .7854 mil^2

and, the usual recommendation is 700 CM per Amp

Quick table:

2 ga	.2576" diam 66360 CM
10 ga    .1019"         10380 CM
14 ga    .0641"          4110  CM
16 ga    .0508"          2580   CM

20 ga     .0320"         1020   CM

30 ga     .0100"           100   CM

more digits of accuracy are spurious (I've even pushed it here with 4
digits...)

Note quick relations: 20 gauges is 1/10 the diameter, 10 gauges is 1/10 the
area (and 1/10 the current, eh?)
6 gauges is a doubling or halving of the diameter, 3 gauges is doubling or
halving the area...

at 700 CM/amp, you need 21.5 gauge...

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