This standard describes the procedures to be followed and the precautions to be observed in obtaining uniform and reproducible measurements of the electrical characteristics of fluorescent lamps under standard conditions when operated on alternating current (ac) circuits. These methods are applicable both to lamps having hot cathodes??either switch-start (preheat-start)@ rapid-start (continuously heated cathodes)@ or instant-start??and to lamps of the coldcathode variety. The electrical characteristics usually measured are lamp current@ lamp voltage@ and lamp power. In the case of rapid-start lamps@ the power measurements may include both the arc watts1 and the cathode watts. Total lamp power is the sum of arc watts and cathode watts. The methods noted in this standard apply to fluorescent lamps operated at common power-line frequencies (50 and 60 Hz). Other methods may be needed for operation of lamps at high frequencies@ and these are under consideration. 1 Arc watts is the term used for the power consumed by the discharge only and does not refer to any power that may be supplied to the lamp cathodes from a separate voltage source.