On Tue, 18 Oct 2005 20:21:39 -0400, Bill Coleman wrote:
>Seems to me that 12.3 A and 13.4 A are both less than 15 A. So a #14
>circuit seems adequate for your example.
Yes and no. Remember that ALL electronic loads (that is, anything with a
DC power supply) utilize some form of rectifier and capacitor-input
filter. This includes switching power supplies. Thus current draw will
be concentrated at the peak of the waveform, and will tend to be quite
non-linear. So will the IR drop in the wire. And, because the current is
rich in harmonics, IZ drops can enter the picture.
What does this mean in practical terms? It simply means that the sag
due to loading will be greater than predicted by simple RMS calculations
assuming sinusoidal 60 Hz current flow. Bigger copper will reduce that
drop (but not change the fact that the current will be non-sinusoidal).
The non-sinusoidal current flow causes distortion of the 60 Hz sine
wave, so bigger copper will reduce that distortion and that drop.
Last year I wrote a "white paper" on power systems for audio
professionals. It addresses this issue as well as many others.
http://audiosystemsgroup.com/SurgeXPowerGround.pdf
Jim Brown K9YC
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