General Electric Lighting introduced a dimmable compact fluorescent bulb on Thursday that mimics the performance of old incandescent bulbs.

The bulb, with a re-engineered ballast, can be dimmed smoothly to 5 percent of its full power and light, just as the old incandescent bulbs do.

The CFL spiral is available in 14-watt and 26-watt versions, producing the light of 60-watt and 100-watt incandescent bulbs, respectively, and rated to last 10,000 hours.

The bulb is also available as a dimmable reflector flood light in 15-watt and 26-watt versions, rated to last 8,000 hours.

Anthony Serres, led systems engineer for GE Lighting at Nela Park, said the bulb will dim a little differently with every dimmer switch. It will not work well with old-fashioned dimmer systems, which use a device called a rheostat, he said. Installed in homes decades ago, rheostat switches vary the voltage with resistance.

"If the bulb starts turning off and on, it is not the right type of dimmer," he said. "But anything installed within the last 10 years should be OK."