Direct-wire adapters also are available. When the lamps burn out, the ballast must also be replaced. Circline lamps are fluorescent tubes formed into a circle and designed as direct replacements for incandescents. The following table shows a few typical incandescent lamps and the appropriate fluorescent replacements. Fluorescent Facts Screw-in fluorescents, which are somewhat larger than incandescents, come in a variety of sizes and shapes including globe, tube, and circle styles.
Some fluorescents are heavier than traditional bulbs because they require a ballast.
Measure a fixture before buying compact fluorescent bulbs. Fluorescents are larger and don't always fit traditional fixtures. Harp adapters can often remedy this problem. Most fluorescent lamps cannot be dimmed and are not recommended for enclosed fixtures. Fluorescents also require a special ballast for operation in outdoor settings because of sensitivity to low temperatures.