If necessary, one may fulfill the mitzva by switching on an incandescent light bulb. A bulb is similar to a candle as the glowing metal filament is the equivalent of a wick and the electricity is the equivalent of the oil or paraffin. However, some maintain that one does not fulfill the obligation with an incandescent bulb, because in a candle the fuel is adjacent to the wick, which is not the case with an electric bulb. Nevertheless, the vast majority of poskim maintain that one may fulfill one’s obligation by lighting an incandescent bulb, since there is a halakhic consensus that electric light is considered fire and igniting an electric light on Shabbat violates the Torah prohibition against lighting a fire on Shabbat. Nevertheless, it is preferable to use a candle for the mitzva so that one fulfills the requirement according to all opinions. Additionally, by lighting a candle it is more apparent that this is a special lighting in honor of Shabbat.
It is preferable le-khatĥila to turn off electric lights before lighting the candles and to turn them back on in honor of Shabbat when lighting the candles. In this way, the mitzva is beautified greatly, through the candles and the electric lights. Moreover, if electric lights are on when she lights the candles, it is not apparent that she is lighting candles to fulfill a mitzva, since there was light already. Therefore, it is good to turn off the electric lights several minutes before candle lighting, and when she comes to light the candles, she should first turn on the electric lights and then immediately light the Shabbat candles. When reciting the berakha, she should have the electrical lights in mind as well. All this is ideal, but technically even if the electric lights are on, she may light the candles with a berakha. We are not concerned that this is a berakha in vain, because lighting the additional candles to fulfill the mitzva provides additional light in honor of Shabbat (see the next section for the laws pertaining to one staying in a hotel).