From FB comment
There were 4 main breaker panels in the electrical room inside, 3 rated at 1200 amps and one rated at 3000 amps. My shop was on the other side of the wall, and I could put a CRT type monitor against the wall and the 60 Hz magnetic field caused the monitor to display a wavey picture, enough to make one nauseated after awhile.
I measured the field with a ELF gauss/tesla meter, and it went offscale!
