This steady, quiet hum is typically caused by the magnetic fields generated within the main transformer or when the panel is under a heavy electrical load. For testing you can connect only the amplifier and just 1 source and put one of them in a wall socket/distributor that has no PE. If the hum is gone you had a ground loop. Does it happen in several different. Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity. But signs you should take seriously: When those occur, you should act. • Loose bolts, current transformer mounting, doors, covers and similar parts can resonate with the normal 60-cycle hum and. Ask Your Local Electrician — Ever noticed a humming sound coming from your electrical panel? Is that normal, or is it a sign of danger? In this video, Brandon from Electrical Specialists explains:.
[PDF Version]