power lines and radio signals
The EMF generated by a 12KV line is not a problem for our receivers beyond 6 feet. 60KV increases that to 11 feet.
A cracked insulator, dirty insulator or loose or dirty hardware generates a broadband RF signal, not a harmonic, that will cover all frequencies, not just multiples of 60Hz. Do a search on "Spark-Gap Transmitters" and you'll see the mechanics of this signal.
Close proximity to clean power lines generally do not affect our receivers, but bad hardware on the pole does. Up to many thousands of feet.