15 Ballast noise rating
Aaron Lee
Q: Why do Ballasts “hum”?
A: Because they don’t know the words!
Ballasts are given a noise rating, from “A” being the quietest in operation, to “F” being the loudest. In noisy environments it might be acceptable to have louder ballasts in operation, but for general office and institution lighting the constant “hum” of a noisy ballast can be distracting and annoying for people nearby.
The noise is produced by tiny expansions and contractions of the ferrous metal that is affected by the constantly changing magnetic field produced in core and coil ballasts, in a process call magnetostriction. This noise is the conversion of electrical energy into sound and represents a loss of energy.
Modern electronic ballasts have a very quiet operation as there is no oscillating magnetic circuit to vibrate the metal housing.
