Definition: Ballast is a transformer that changes the voltage from your house current to the voltage needed to power lights such as fluorescents and metal halide bulbs. There are several varieties of ballast, such as tar, transformer, and electronic, which must be properly matched to the type of bulb being used.
ballast
By Shirlie Sharpe, About.com
Suggested Reading
Explore Freshwater Aquariums
Must Reads
About.com Special Features
Home Allergy Center
Banish mess, reduce allergens, and maintain a clean, healthy home. More >
Home Improvements Made Easy
Inspirational ideas and expert tips to help you pull off your next DIY project. More >
©2009 About.com, a part of The New York Times Company.
All rights reserved.