Cause of Humming Compact Fluorescent Bulbs/Lamps (CFL)

RMissyDog · Joined: 14 Oct 2006 Posts: 2 Location: Minnetonka, Mn

Not to change the subject, but what cause a compact fluorescent bulb to hum, it is not on a dimmer switch. There are two compact flourescents on the same switch, same bulbs, but one maybe both are humming all the time.

handnhammer · Joined: 13 May 2006 Posts: 60 Location: Ann Arbor, MI

Most fluorescent lamps (the older style one would find in a garage, office, or basement) and some older compact fluorescent bulbs have coil ballasts. Ballasts are designed to regulate current through the bulb, and the older magnetic coil ballasts did this at a lower frequency which is sometimes audible and can cause flickering...this can get worse as the bulb ages. Newer electronic ballasts (pictured) control current at a higher frequency without any humming or flicker, and have quicker startup. The lack of these annoyances is what's making CFLs a suitable alternative to incandescent bulbs.

If the CFLs you have are a little older, then they probably have magnetic ballasts instead of electronic. Though I'm sure you could call the manufacturer with a model number to find out for sure. If this is the case, replace the bulb with a newer CFL. Not only is a bad ballast annoying, but it could eventually fail, causing uncontrolled current draw and possibly bulb destruction and fire...or at the very least a popped circuit breaker. (CFLs have negative resistance, and without a ballast, would start drawing current exponentially!)

webmaster · Posted: Sun Oct 15, 2006 2:15 am Post subject: Welcome!

Hi Dave...Welcome to the board!

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