Currently the impact of high efficient lighting devices such as compact fluorescent lamps (CFL) and light emitting diodes (LED) is an important concern for the electrotechnical community. This paper makes a contribution towards determining the impact of these devices on electric grid power quality and efficiency, proposed by means of applying FBD-power theory to the currents absorbed by CFLs and LEDs. An analysis of the waveform distortion regarding the standard IEEE 519 and efficiency detriment quantification are presented.