If you are close to buried or overhead power lines they could certainly cause some EMI,
mostly in the near field (aka: magnetic field) which would absolutely have an effect on the
performance of your machine. A powerful 60hz field would pretty much obliterate the
7-15hz low power radiation emitting from your coil.
The coil is a very sensitive transmitter/receiver, and it's going to send whatever it receives
to the processor in the control box. You really can't shield against it, as to attenuate those
low freq. magnetic fields requires dense/heavy shielding materials such as plate steel, as those
low frequencies will pass right through most RF absorbing materials, including copper and ferrite.
Ferrite, which can attenuate (absorb) RF signals down to approx. 14 kHz, but reducing interference
from a 60hz. line can be a real PITA.
My father and I had the honor or working with Dr. Robert Olsen at Washington State Univ.
for over 25 years, and he has been doing research in overhead and underground power transmission
lines for over 30 years. No question he is one of the leading physicists performing this type of research,
and is frequently sought out for his opinions on the safety and dangers associated with high-power
transmission lines.
Here is a list of his publications, and odds are high that you will find something there that will help explain
the details of why the problem was happening. You may not understand all the technical jargon, but for
the most part Dr. Bob speaks in plain English so those of us that are not Ph.D's can comprehend what
he's saying.
Publications of Robert G Olsen - WSU Scholars - SciVal Experts v4.1
Simple explanation is you'll likely need to move away from those lines far enough to escape the
powerful magnetic fields they are creating. Also, you can contact your local power company and
discuss the issue with them, as they may have a line radiating that they're not aware of.
Little to -0- safety risk for you
based on the research, however I still would not feel
comfortable hanging around in that radiating EM field, nor would I want my children (OK,
grandchildren..lol) paying underneath those lines.
Hope that's of some help!