The Proper Time to Light Candles on Rosh Hashanah
On the first day of Rosh Hashanah, we customarily light Yom Tov candles before the onset of Yom Tov similar to how we light them on Erev Shabbat. If the candles were not lit before the onset of Yom Tov, a woman may even light the candles on Yom Tov itself, provided that this is done in a permissible fashion, i.e. by transferring the fire from an existing flame and lighting the candles; it is prohibited to ignite a new flame on Yom Tov, as we have previously explained in the laws of Shavuot.
The Proper Time to Light Candles on the Second Night of Yom Tov
On the second day of Rosh Hashanah as well as any other second day of Yom Tov in the Diaspora (meaning the second day of Yom Tov celebrated outside of Israel for every holiday, just as two days of Rosh Hashanah are celebrated even in Israel), Yom Tov candles are lit as well.
Some have the custom to light candles for the second day of Yom Tov of Rosh Hashanah after nightfall (i.e. approximately twenty minutes after sunset) before reciting Kiddush on a cup of wine.
The reason for the above custom is because it is forbidden to prepare anything on the first day of Yom Tov for the second just as it is forbidden to prepare anything on Shabbat or Yom Tov for weekday use. Based on this, it would seem that it is forbidden to light candles “in honor of the second day of Yom Tov” when it is still during the first day of Yom Tov.
Indeed, it is correct that one may not prepare anything on the first day of Yom Tov for the second and it is therefore prohibited to prepare the wicks, cook, or wash dishes on the first day of Yom Tov for the second, for this is considered “preparing”.
Nevertheless, regarding candle-lighting, Maran Harav Ovadia Yosef Shlit”a writes (in his Chazon Ovadia-Yamim Nora’im, page 182) that, based on the words of the Tosafot and other great Poskim, one need not be concerned about the prohibition of preparing and one may light candles for the second day of Yom Tov even before sunset of the first day of Yom Tov, for this serves a purpose for the first day of Yom Tov as well since the candles add light to the house. He quotes Rabbeinu Yosef Haim (in his Responsa Rav Pe’alim, Orach Chaim, Volume 4, Chapter 23) as ruling likewise.
Summary: One must light candles in honor of Rosh Hashanah just as one would do for any other Yom Tov including Sukkot, Pesach, and Shavuot. One should preferably light the candles before sunset. One may likewise light candles for the second night of Yom Tov before sunset (of the first day of Yom Tov) when transferring the flame from a pre-existing one.
This year, 5774, Rosh Hashanah falls out on Thursday and Friday and we must therefore discuss how to light Shabbat candles on the second day of Yom Tov. This will be explained in the following Halacha.
By Popular Demand: As a response to the many questions we have received regarding the issue of showering during the upcoming holiday of Rosh Hashanah (especially since it will be a three-day holiday since Rosh Hashanah falls out on Thursday and Friday leading directly into Shabbat), we have already discussed some details pertaining to this law in a special Halacha. Regarding the question which arises every year in the United States regarding boiler systems which consist of large tanks always filled with boiling water under which there is always a small flame ignited by means of a pilot; sometimes (when an abundance of cold water enters the tank via the cold water valve and causes the thermostat to turn on and sense the difference in water temperature) the pilot ignites a larger flame and reboils the water, indeed, several great Halachic authorities of our generation have discussed this issue. Recently, however, our Rabbi Meir Gavriel Elbaz Shlit”a (coordinator of the English version of the Halacha Yomit) has written an halachic thesis on this topic and has presented it to the great Rishon Le’Tzion and Sephardic Chief Rabbi of Israel, Hagaon Harav Yitzchak Yosef Shlit”a, whereby the latter responded in a letter dated 21 Elul, 5773, that he too agrees that there is room to rule leniently on this matter and it is thus permissible to take a shower using water coming out of this kind of boiler when the tank was already filled with boiling water before the onset of Yom Tov. This ruling is comprised of several sources for leniency with regards to this matter based on the words of great Poskim and halachic works. This lenient ruling applies to the upcoming holidays of Sukkot and Shemini Atzeret as well which likewise fall out on Thursday and Friday and lead directly into Shabbat. Nevertheless, there is absolutely no room for leniency to do so on Shabbat and obviously, the above applies only to Yom Tov.