NavList:

My original query of 16 November is close to being answered:

"Can some physicist or power engineer explain how an alternating current can produce a constant magnetic field? "

We postulate leakage currents being rectified at, say, corroded joints and the direct current in the ground or transmission towers setting up a constant magnetic field. Short circuit currents are apparently in the order of thousands of amps, but probably 400 amps is a more usual line current (does anyone know?).
Assuming a 1 percent leakage, a 4 amp ground current could easily occur. We can imagine this concentrated in a water pipe and having an effect on a compass, but at what distance, I wonder?

We have only 33 kV lines near where I live and it has just rained, so I might just take a compass and go in search of one to see if I can detect an effect.

Bill Morris
Pukenui
New Zealand
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