Discover Lighting!

Ballasts are the Rodney Dangerfield of the lighting industry – they don’t get no respect. Ballasts have many nicknames – black brick, F-can, core and coil, Buffy – derived from their appearance or physical configuration. Buried deep within a luminaire, they silently (usually) go about their business as caretaker and partner of all types of discharge lamps (remember – that’s fluorescent and HID). If lamps are the engines of lighting, then ballasts are like the carburetor – oops, I’m dating myself – make that the fuel injection system. They insure the lamp receives the correct amount of fuel (electricity in this case) for starting and then the correct amount once it is operating.

There are two basic categories of ballasts – electromagnetic and electronic. Within each of these categories, there are many hundreds of different types, sizes, shapes, and configurations to fit the myriad of luminaires and applications out there in the lighting world. The electromagnetic ballast was the original type introduced along with the first fluorescent lamp. More recently, electronic versions were developed to replace and improve upon the older technology. Electronic ballasts, while more costly than their electromagnetic ancestors, bring additional benefits that usually justify their higher price. This is not to say that electromagnetic ballasts are no longer around. Quite the contrary – they are still quite popular for many outdoor fluorescent applications like sign lighting and for most HID lamps (there are electronic ballasts for some low wattage – 150W and below – HID lamps).

So, tell me again - why do I need one of these things? Well, as we discovered in the lamp section, fluorescent and HID lamps produce light using an arc (not an “ark” – that was the Noah thing). Electric arcs will allow gobs of current to flow if one lets them. The ballast acts to control and limit the amount of current flow to that which is not too much, not too little, but just right! For those of you out there that brave the briny deep in a sailboat (Motto: “The trip is what matters, not the destination.” Yeah, right.), what is all that heavy stuff in the keel that keeps the boat from leaning over so far that you have to look down to see the sky? Correct! It’s the ballast. Same principle. The ballast also knows how to start the lamp quickly and cleanly.

Fluorescent electromagnetic ballasts for general lighting use are designed to operate either one lamp or two lamps. One ballast doesn’t handle both cases – there are one-lamp ballasts and two-lamp ballasts and each is designed for a specific length or wattage lamp. Electronic ballasts are much more flexible. For example, fluorescent electronic ballasts for T8 lamps are available in 1-, 2-, 3-, and 4-lamp versions. Any one of those can operate multiple lamp lengths from 2-foot through 5-foot types. You can even mix lengths on the same ballast. Woo-hoo!