The audible noise you hear from high-voltage cables occurs because of the energy that is being discharged. This discharge happens when the conductor surface's electric field surpasses the breakdown strength of the surrounding air, resulting in a discharge. So, what's the reason for this seemingly random, grating noise? In short, this noise is due to a phenomenon called corona discharge, an energy discharge within the power lines themselves. When. When near high tension power lines, particularly after a good rain, the lines themselves emit a buzzing noise. I've heard before that this is supposedly from the 60Hz AC current that's running through the lines. Electric hum, mains hum, or power line hum are all terms used to describe the sounds produced by transformers or power lines due to the alternating current passing at the mains electricity frequency. TLDR: The buzzing is from corona discharge, where the. Distribution boxes are the unsung heroes of our electrical systems, quietly managing power until something goes wrong. When they start tripping, overheating, or making strange noises, it's more than just an inconvenience - it's your home's cry for help. In this guide, we'll walk through these.