3000W Chinese Gensets Info.

tvman44 wrote:
I didn't say it worked, just that it was comon belief and practice.

toprudder wrote:

tvman44 wrote:
Years ago a lot of the old 2 way technicians used to tie a couple of knots in the A/C power cord because they believed it cut down on lightning damage thru the power line.

Hmmm, don't have ANY data to dispute that, but my gut reaction is that it will have very little effect on lightning induced surges. That is a relatively low frequency phenomenon and a simple knot in a cable will not have very much inductance. But, I may be wrong. :)

It is basically sort of a bootleg choke. Inductive reactance slows the rise of a power surge, making it less damaging.

If you study the "left hand rule", and (to a lesser degree) the "right hand rule", you will get an idea of the science behind it.

Think of it as a "sort-of" toroid.

I know that winding the power cord around a wooden paint stick cleans up the noise in my stereo system. I can hear the difference with electrostatic headphones, but not dynamic. I have also seen it on a scope.

Years ago, my grandfather (an engineer) had an early electric shaver (Sunbeam) that introduced a lot of line noise into the house. I think it had a vibrator type motor with points. This disturbed my grandmother's radio listening. vHe put caps across the points, which helped a little. He wound the cord around a stick and killed most of the noise. Don't know if he tried knots or not, but the principle seems similar. I have also noticed that using a commercial cord shortener does a similar thing.

All of what I said above relates to line noise and transients. The power and rise time of a lightning strike are all over the map. I suspect a close hit would ignore any knots, but a more distant hit might be mitigated by a knot.

Or knot. (had to say it)