Question: What is the proper time for lighting Shabbat candles and is there a difference Jerusalem and other cities in Israel and abroad regarding this law?
Answer: The Gemara (Yoma 81b) derives from expounding certain verses that one must add on some time from the mundane weekday onto the sanctity of Yom Kippur. One must likewise add some of the weekday onto the sanctity of every Shabbat and holiday, both at their onset and their conclusion.
The essence of this addition is taking care to light Shabbat candles and to abstain from any works forbidden on Shabbat even before sunset; one must not wait until the moment of sunset to abstain from forbidden works although until the sun sets, Shabbat has not yet begun and it is still Friday. The same applies on Motza’ei Shabbat in that one may not perform work immediately at nightfall; rather, one must wait a short amount of time before doing so (and this is the time commonly printed in calendars). This is indeed the ruling of most Rishonim, Maran Ha’Shulchan Aruch, and is the prevalent among the Jewish nation.
According to the letter of the law, the minimum amount of time that one must light Shabbat candles before sunset is a short amount of time (meaning there is not set amount of time and even one minute is sufficient) before sunset. Nevertheless, the prevalent custom in most places is to light candles and abstain from performing any more work at twenty minutes before sunset for several reasons. Thus, it is customary to calculate the time of Shabbat candle lighting as twenty minutes before sunset. (Important Note: In the United States, most Jewish calendars calculate candle lighting time as eighteen minutes before sunset. This is because the first calendars printed by Hagaon Harav Yosef Eliyahu Henkin zt”l calculated candle lighting time in this way. Although this is the prevalent Ashkenazi custom today and it is certainly well-founded, nevertheless, the Sephardic custom has always been to light Shabbat candles twenty minutes before sunset and thus, Sephardic Jews should continue with their custom even in the United States. For further reference, see Responsa Igrot Moshe, OC, Volume 1, Chapter 96 where Hagaon Harav Moshe Feinstein zt”l mentions that candle lighting time is twenty minutes before sunset.)
The Mishnah Berura writes that since not everyone is an expert in calculating the precise time of sunset, it is proper to act stringently and light Shabbat candles much before sunset. The basis for his words is the ruling of Maran Ha’Shulchan Aruch who writes that if one is not an expert in calculating this time, one should light Shabbat candles when the sun appears at the top of the trees. Nevertheless, Maran Rabbeinu Ovadia Yosef zt”l points out that nowadays when almost everyone has a watch and sets it based on the radio and the like, one need not be concerned with the above issue and lighting Shabbat candles and beginning to abstain from work at twenty minutes before sunset is perfectly sufficient.
In the holy city of Jerusalem, it is customary to announce the onset of Shabbat forty minutes before sunset and some claim that this is based on an ancient enactment from many years ago. However, this is not the case and this custom was created based on a ruling of the city’s Ashkenazi rabbis; the Sephardic residents of the city in addition to the greatest Sephardic sages never observed this custom whatsoever and they sufficed with lighting Shabbat candles approximately twenty minutes before sunset. Thus, Sephardic and Middle Eastern Jews are not bound by this custom at all and they may continue with any necessary Shabbat preparations until approximately twenty minutes before sunset. Even if one has customarily ushered in Shabbat at forty minutes before sunset based on the “Shabbat Siren” heard in Jerusalem and other cities following its customs (such as Petach Tikvah which was founded by Rabbi Yoel Moshe Solomon, a Jerusalemite, and whose customs are therefore based on those of Jerusalem, as well as Bet Shemesh, and the like) because one was under the assumption that this was indeed dictated by Halacha, one may discontinue this custom and light Shabbat candles at twenty minutes before sunset.
Nevertheless, one must take care wherever possible to enter Shabbat peacefully with advanced planning so as not to enter Shabbat in a panic which can also lead to anger and fighting. Thus, although candle lighting time is at twenty minutes before sunset, one should take all Shabbat preparations into consideration so that one can usher Shabbat in tranquilly and without anger and strife, G-d-forbid.
Summary: The proper time to light Shabbat candles in all locations is approximately twenty minutes before sunset. One should nevertheless take all Shabbat preparation into consideration beforehand so that this does not cause unnecessary anger and stress right before sunset.