The conduits (bus ducts) don't get hot mainly because they have greater
total cross sectional area than the bus itself. They're about a half
inch thick aluminum and maybe three feet in diameter. All joints are
continuously welded.

Some documents I've found suggest 95% shielding efficiency, supposedly
less than 100% due not to skin effect, but to resistivity.

Regarding the other responder's comments on jewelry and so on, here's
my anecdote. Not so long ago I climbed up near the main generator
output bushings to view a cooling air damper through a window in the
housing. This is sort of unusual with the plant at power and it made
me a bit nervous. I stayed about five minutes, but after I climbed
down I discovered that my (analog) watch had gained an hour!

Now I can't find that watch. My theory is that it's off in the future
just an hour out, but I can't catch up to it.

73--Nick, WA5BDU

(... this being the internet, I guess I'd better state that I was only
kidding about the location of my watch.)


Howard Eisenhauer wrote:

I'm no expert on this but it sounds to me like the magnetic fields
around the busses are inducing eddy currents in the scaffolding as
opposed to actual current flowing around the square sections in a
loop. The conduits surrounding the busses will be "thin" skin-depth
wise at 60 Hz so a large amount of field gets through. I'm actually
kinda curious as to why the conduits themselves arn't getting really
hot :?.

I'd suggest posting on sci.electronics.design, I'll bet somebody there
knows about this...

H.