class P ballast

ballast

1. Coarse stone, gravel, slag, etc., used as an underlayer for poured concrete.

2. A device used to provide the required starting voltage and operating current for fluorescent, mercury, or other electric-discharge lamps.

3. Class P: A ballast for a fluorescent lamp which meets the requirements of the Underwriters’ Laboratories, Inc.; includes an automatic resetting thermal protector to remove the ballast from the circuit if its temperature exceeds a specified value.

4. Same as constant-wattage ballast.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.