What is power-line noise?
Virtually all power-line noise, originating from utility company equipment, is caused by a spark or arcing across some power-line related hardware. A breakdown and ionization of air occurs, and current flows between two conductors in a gap. The gap may be caused by broken or loose hardware such as a cracked insulator. Typical culprits include insufficient and inadequate hardware spacing such as a gap between a ground wire and a staple. Note: The terms “gap” and “conductors” should be interpreted broadly in this case. While not power-line noise, a gap can exist in the commutator of a motor. A gap can also exist between insulator units and other parts of a utility structure. In some cases, the “conductor” can be the wood on the utility pole. Once an ionized path is established in the gap, current flows at all parts of the cycle where the voltage is higher than the breakdown voltage of the gap. This typically occurs only at the positive and negative voltage peaks — the times of highest i
