Just as the Sages ordained candle lighting for Shabbat, so they ordained candle lighting for Yom Tov. Lighting candles honors the festival and adds joy to the meal. Since this is a mitzva, a berakha is recited: “Barukh ata Hashem Elokeinu Melekh ha-olam, asher kideshanu be-mitzvotav ve-tzivanu lehadlik ner shel Yom Tov” (“Blessed are You, Lord our God, King of the universe, Who sanctified us with His mitzvot and commanded us to light Yom Tov candles”). When Yom Tov falls out on Shabbat, the berakha concludes with “lehadlik ner shel Shabbat ve-shel Yom Tov” (“to light Shabbat and Yom Tov candles”; SA 263:5; 514:11; MB ad loc. 48).
As is the case for Shabbat, common practice is to light at least two candles, corresponding to husband and wife. One who wishes may light additional candles. Nevertheless, the wording of the Hebrew berakha remains in the singular (ner), because one candle is sufficient to fulfill the mitzva.
The ideal time to light is before shki’a, at the time listed on Jewish calendars for the beginning of that Yom Tov. Because women accept Yom Tov when they light, in practice this is when Yom Tov begins for them (and not at shki’a). Some light the candles later, before the meal. Those who wish to may do so. They must be careful to use a pre-existing flame and not light a new fire (below 5:1 and 5:3). On the second day of Rosh Ha-shana and on Yom Tov Sheni in the Diaspora (see ch. 9 below), candles must be lit after tzeit, as one may not prepare on the first day of Yom Tov for the second day (below 9:5; see section 12 below regarding when Yom Tov starts on Saturday night).
On Shabbat, the practice of Ashkenazim and some Sephardim is to light the candles first and recite the berakha afterward. This is to avoid doing the melakha of lighting after Shabbat has already been mentioned in the berakha (Peninei Halakha: Shabbat 4:4). In contrast, on Yom Tov when lighting candles is permissible, according to all customs one should first recite the berakha and then light the candles (MB 263:27). One must be careful not to blow out the match; it should be put down where it can burn out by itself.
The Sages ordained the recitation of the berakha of She-heḥeyanu over each festival, to thank God for keeping us alive, sustaining us, and allowing us to reach this special and sacred occasion. The best time to recite this berakha is during kiddush, which invokes the sanctity of the day. However, many women recite She-heḥeyanu as they light the candles, because they wish to recite this berakha with their special mitzva in honor of the festival. Those who wish to do so may (see She’elat Ya’avetz 1:107; MB 263:23).
When planning to light the candles after Yom Tov has begun – for instance, if this is one’s custom on the second day of Rosh Ha-shana, on Yom Tov Sheni, or when Yom Tov starts on Saturday night – it is preferable to have the candles prepared on a weekday before Yom Tov begins. If they were not prepared (and wax is left from the previous night’s candles), one may force the candles into the candlesticks even though this may shave off a bit of the candles. There is no prohibition of Meḥatekh (cutting), because the shaving is done with a shinui (in an irregular manner). It is also permitted to use a knife to remove wax left in the candlestick, if it is getting in the way of putting in the new candles. Similarly, if one uses tea lights or votive candles, he may pry the little metal discs left over from the previous night out of the glass cup. If one uses floating wicks, they may be inserted into the cork disks that hold them (SSK 13:24, 49-50; n. 151 in the name of R. Shlomo Zalman Auerbach). However, one using candles may not melt the bottoms to make them stay in the candlestick, as this is a derivative of Memaḥek (smoothing). Similarly, it is forbidden to cut the bottoms or sand them in order to stick the candles into the candlesticks, because this is a violation of Meḥatekh (Ḥayei Adam 92:2; Be’er Heitev 314:10; SSK 13:48; see Peninei Halakha: Shabbat 18:6; 15:10).
The rest of the laws of lighting candles are the same for Shabbat and Yom Tov, and they are explained in Peninei Halakha: Shabbat (ch. 4).