Turning on the outside christmas lights (I have alot of them), the 20A breaker for the circuit that some of them are on, buzzes briefly before quieting down. Circuit in question is a dedicated 20A line for this purpose, one of two installed. The other one does not buzz. Perhaps a worn breaker needing replacement soon?
I have heard Buzzing emitted from correctly installed and functioning MCCBs. Always figured the sound is Generated from the Spring in the Reset Assembly.
Would be nice to know exactly which entity is vibrating, and what factors determine it to be Audible.
-- Scott
Scott " 35 " Thompson Just Say NO To Green Eggs And Ham!