What is “low frequency hum?
All power frequency overhead lines produce a low level 120 Hz sound due to the mechanical vibrations caused by the changing voltage on the wires. The voltage changes direction twice each cycle. There can also be a higher frequency popping, crackling or hissing sound. This noise may be more noticeable under rainy or foggy conditions, although noise from wind or rain may mask the noise generated by the line. High voltage transmission lines are designed to comply with the Alberta Utilities Commission (AUC) noise guidelines, and measurements will be taken to ensure compliance with the AUC 012 Noise Rule.
