Deep dimming fluorescent ballasts allow lamps to be dimmed below 50% of output. They apply to ballasts that operate T5 and T8 four-foot linear and u-shape fluorescent lamps
Though there are national standards for dimming fluorescent ballasts, there are none for deep-dimming fluorescent ballasts. In 2015, the California Energy Commission (CEC) adopted the following standards for deep-dimming fluorescent ballasts:
(1) Shall not consume more than 1 watt in standby mode;
(2) Shall have a power factor of 0.9 or greater; and
(3) Shall have a weighted ballast luminous efficacy greater than or equal to the threshold described in the following equation:
CEC also modified the national test procedure by adding criteria with which to test ballasts dimmed more than 50%.
The CEC standards are effective July 1, 2016.
CEC estimates lifetime savings of $22 per ballast over the 13-year lifetime. In California, the net present value is estimated at $38 million the first year and $505 million per year once the stock turns over.