Earliest and Latest time to light Chanukah Candles
Earliest Time to Light
- According to Ashkenazim, while some poskim hold that one may light Chanukah candles immediately after sunset, many say that one shouldn't light until 10 or 25 minutes after sunset. According to Sephardim, the ideal time to light Chanukah candles is immediately after Tzet HaKochavim, which in Israel can be approximated to be 15 minutes after sunset.
- In general, one should not light earlier than Shekiyah or Tzet Hakochavim, as stated in the previous halacha, except on Friday afternoon of Chanukah because once it becomes Shabbat, it will be forbidden to light.
- But if on a weeknight one will be unable to light after Shekiyah or Tzet Hakochavim and will miss the mitzvah totally, he should light after Plag HaMincha. Many poskim say that one may light with a bracha in this case, while others say that one should light without a bracha. It is preferable to ask someone else to light for you at your house than light yourself before Shekiya after Plag Mincha.
- If someone lit earlier than Shekiah after Plag Hamincha, he should relight at the proper time of the mitzvah without a bracha. If one lit before Plag Hamincha should relight at the proper time with a bracha. 
- A boy, who regularly lights at Shkiah, who is becoming Bar Mitzvah a night of Chanukah, can light at Shkiah as usual. Some say to light at Tzet HaKochavim even if usually lights at Shkiah. 
Latest Time to Light
- One shouldn’t delay lighting the Chanukah candles at the ideal time (see above), but if one didn't light until after the time that people left the marketplace, one should nonetheless light. However, while some say that one may only recite the bracha if some of the household members are awake, others hold that it’s proper to wake up some of the family, but if one can’t, he should still light with a bracha. 
- Someone who came home right before Olot HaShachar can light with a bracha even though it won’t be lit for 30 minutes during the night. Some say one should light without a bracha if there’s not 30 minutes for the candle to be light at night. 
- One who didn’t light at night (before Olot HaShachar) can’t light during the day, but if one wants, one can light without a bracha. 
- Soldiers in the army who can’t light at night for security reasons and want to light while it’s still day and extinguish it before it gets dark can light without a bracha. 
Coming Home Late from Work
- Some poskim hold that one should wait for his wife because of Shalom Bayit even if that means missing lighting precisely at the time for lighting. 
- Sephardic poskim hold that it is preferable to light at the right time by asking your wife to light rather than light yourself after a half hour after Tzet Hakochavim. Ashkenazic poskim debate the matter.  The minhag is for the wife to wait for the husband to come home to light.
Lighting before or after Mariv
- One who came home late and has to pray Mariv and light candles should pray first. 
- Sephardim have the Minhag to pray Mariv at Shkiah and to light individually at Tzet. So too, if the minyan prays at Tzet they should pray and then light individually unless there’s a concern that they won’t be able to light before ‘Tichle Regel’, in which case each individual should light before praying. One should set up the chanukia and candles before Tzet so that after Mariv one can light right away. 
- Ashkenzim who have the Minhag to pray at Tzet, should light at Shkiah before praying Mariv at Tzet. If Tzet came and one didn’t light he should first pray and then light. However some have the Minhag to always light after praying Mariv. One should set up the chanukia and candles before Tzet so that after Mariv one can light right away. 
- If one has an established minyan for Mariv very late, one can light earlier than Mariv at Tzet HaKochavim. 
If one is in middle of something
- If a person is in the middle of a seder of learning, many poskim hold that one should wait until the end of the seder to light Chanukah candles. 
- If a person is in middle of a class one may wait until the end of the class in order to light Chanukah candles so that one will have time to sit by the candles. 
- The Gemara Shabbat 21b states one should light from Mishtishka HaChama (lit. from the setting of the sun) until people leave the marketplace. What does the Mishtishka HaChama mean?
- On the basis of some Rishonim the Gra (Beiur HaGra 672:1) writes that one should light at sunset. See Bei’ur Halacha s.v. lo, who adds that perhaps the Rambam holds one should light at sunset. [Seemingly, Bet Yosef who quotes Rambam and then says that the Tur used the word “the end of the sunset” because the beginning of the sunset is still mostly day, holds that the Rambam and Tur don’t argue. However, the Yad Aharon 672 explains the Rambam as holding one should light at sunset. and Mishna Brurah (Beiur Halacha 672:1) also suggests this possibility.] Additionally, The Rama (Darkei Moshe 672:4) quotes the Maharil's practice of lighting right after sunset. The Darkei Moshe also quotes the Sefer Minhagim (of Rabbi Tirna pg 144) who agrees that the gemara means that one should light at Shekiyah, but adds that one doesn't need to be careful about this.
- The Rashba (21b s.v. Ha DeAmrinan) seems to understand the term Mishtishka HaChama to mean Shkiyat HaChama. The Ran (on the Rif 9a s.v. Mitzvata) and Meiri (21b s.v. Achar) also imply this understanding. The Beiur HaGra 672:1 understands the Rashba and Ran as discussing the Shekiya Sheniya (the second sunset, a term that will hopefully be clarified later).
- However, the Mordechai (Hagahot Mordechai 455) writes that one should light Chanukah candles at Tzeit HaKochavim, because a candle isn’t noticeable during the day. Similarly, Rabbenu Tam (Sefer HaYashar 221, Tosfot Menachot 20b s.v. Nifsal) holds that one should not chanuka candles until the end of the second shekiyah, which is equivalent to Tzet Hakochavim. The Hagahot Mordechai (Shabbat 455), Ritva 21b, Sh”t Trumat HaDeshen 102 in name of Mordechai, Sedah LeDerech 4:7(2), and Bach 672:1 based on the Rosh (Shabbat 2:3) concur with the opinion of Rabbenu Tam. The Tur and S”A 672:1 rule like the Mordechai.
- Most achronim hold like S”A to light at Tzet Hakochavim including the Shaarei Knesset HaGedolah 672:1, Magen Avraham 672:1, Eliyah Raba 672:1, Maamer Mordechai 672:1, Chaye Adam 154:18, Derech HaChaim 672:2, Ben Ish Chai Vayeshev 7, Shulchan lechem Hapanim 672, and Kaf Hachaim 672:2.
- Thus, Yalkut Yosef 672:1 writes that one should light at tzet hachochavim which is 15 minutes after sunset. [The time of 15 minutes is built off the Geonim's opinion that 13.5 minutes after sunset is Tzet Hakochavim unlike the tzet hachochavim of Rabbenu Tam, which is 72 minutes after sunset because Chanukah is only derabanan and one can rely on the Minhag Eretz Yisrael for derabanan mitzvoth (Sh”t Yabia Omer 2:21). Additionally, by not lighting until the Tzet Hakochavim of Rabbenu Tam will lead one to light after the latest time for which one doesn’t fulfill the mitzvah according to many poskim (Sefer Chanukah of Rav Kanievsky pg 13 note 8).] Halacha yomit writes that the time is extrapolated to each place based on 13.5 minutes Sha'ot Zmaniot.
- However Pri Chadash 672 and Buir HaGra O”C 672:1 (see also Beiur HaGra O"C 261 and Y”D 266:17, and Maaseh Rav 235) hold that one should light at sunset. Mishna Brurah 672:1 quotes both the opinion of the Shulchan Aruch and Gra and then writes that if one davens at Tzet Hakochavim one may follow the opinion of the Gra even initially. See also Sh”t Az Nidabru 7:70. Rav Moshe Feinstein in Igrot Moshe O”C 4:101:6 and Rav Chaim Kanievsky in Yemeh Hallel VeHodah 12:8, say to light 10 minutes after sunset and have it last for a half hour before tzet hachovim and a half hour after tzet hachoavim. Torat HaMoadim 4:1 rules to light 15 minutes after shekiah [15 minutes is based on the geonim’s tzet hachochavim (3/4 mil) with the Rav Amram Goan’s lengh of a mil being 18 minutes, the fact that in the winter the shaot Zmaniot are shorter, and we add on a few minutes to be strict for Rabbi Yose’s opinion of Ben Hashemashot which only happens after Rabbi Yehuda’s finishes.]
- Igrot Moshe 4:101:6 writes that one should light 10 minutes after sunset with enough oil to last an hour. Shemaytata DeMoshe 672 explains that Rav Moshe held that 10 minutes was sufficient time to be considered the Tzet Hakochavim of the Geonim and it is still within a half hour of sunset. Halachos of Chanukah by Rabbi Eider p. 20 cites Rav Moshe Feinstein's practice was to light between 13 and 18 minutes after shekiya. He cites that Rav Aharon Kotler would light 25 minutes after sunset. Az Nidbaru 7:70 agrees.
- The Rambam (Chanukah 4:5) and Bahag (Chanuka p. 25b) hold that one does not fulfill one’s obligation if one lights Chanukah candles prior to sunset. The Rashba (Shabbat 21b), however, writes that after the fact, if one lit them before sunset, one still fulfills one’s obligation. This is also the opinion of the Ran, Ritva, and Orchot Chaim (Chanukah #15). The Mishna Brurah 672:3 (Shaar HaTziyun 672:5) explains that the Shulchan Aruch 672:1 rules like the Rashba and one may light before sunset with a bracha. This is also the opinion of the Pri Chadash 672:1 s.v. VeYesh Mi SheOmer and Chaye Adam 154:18. Kaf HaChaim 672:10 however, holds that one shouldn’t make a bracha in such a case. See also the Levush, Bach, Kiseh Rachamim 63a, Siddur Bet Ovad 159b, Moed Kol Chai 27:26, Tefilah Ledavid, Pri Megadim M”Z 673:9, Sefer Yeraim 274, Shaarei Kneset HaGedolah 672:1, and Pri Megadim A”A 672:1.
- Halachos of Chanukah p. 35 n. 20
- Torat HaMoadim 4:3 writes that if one lit before Shekiyah, one should relit at night because some Rishonim hold that one doesn't fulfill the mitzvah to light after Plag HaMincha (such as the Rambam and Bahag). However, he adds that one should relight without a bracha in deference to the opinions (Rashba, Ran, Ritva, and Orchot Chaim) who hold that one fulfills his mitzvah then. Torat HaMoadim concludes that if one lit before Plag Hamincha one should relight with a bracha because no one holds that one fulfill the mitzvah at that time.
- Sefer Chanukah of Rav Kenievsky 13:16, Sh”t Teshuvot Vehanhagot 2:337 against Rav Vosner in Kovetz Mebet Levi kislev 5757 says not to light until Tzet. Mikrei Kodesh (Chanukah 11:3) leaves it as a question.
- The Gemara Shabbat 21b has two explanations of the Briatta's language of ‘Tichleh Regel Min HaShuk’ (once people leave the market). The first explanation is ‘if one didn’t light, one can still light’ and the other explanation is that one must put in enough oil to last until the time people leave the market. The Rambam (Chanukah 4:5) rules that one who didn’t light at the beginning of the night, one can still light until ‘Tichleh Regel’. The Bach 672 explains that the Rambam understood that the two answers of the gemara are complementary and so he rules based on the first answer that one may only light until the time people leave the market. Magid Mishna, Bahag (Chanukah pg 25d), Sh”t HaGoanim Sharei Teshuva 233, Riaz, Rid, Shiltei Giborim, Smak 280, Mordechai (Shabbat 2:265), Ran, Sefer HaTrumah 228, Rosh (Shabbat 2:3), Tur 672, Pri Chadash, Maamer Mordechai 672:4, Sh”t Sadeh Aretz O”C 35 s.v. VaAni, hold like the Rambam that after ‘Tichle Regel there’s no mitzvah to light. Therefore, Meiri, Ritva, and Orchot Chaim (Chanukah 15) say to light after then without a bracha.
- However, Tosfot (Shabbat 21b s.v. Deiy Lo Adlik) writes that according to the second answer of the gemara one may light all night. However, in deference to the first answer if people have already left the market one should only light without a bracha. The Gra (Maaseh Rav n. 236) seems to side with this opinion of Tosfot. However, the Ri (Tosfot Shabbat 21b s.v. Deiy Lo Adlik) raises the point that since nowadays we light indoors and there is pirsumei nisa for the family members, one may light even after the time that people have left the marketplace.
- Additionally, the Rashba (Shabbat 21b) understands that if one didn’t light by ‘Tichleh Regel’ can still light all night and the Briatta is only telling us what is preferable. The Rashba bases his idea on the Mishna Megillah (20b) that states any nighttime mitzvah may be performed anytime during the night. The Ravyah 3:843, Hagahot Maimon (Chanukah 4:2), Machsor Vitri (236 pg 199), Rabbenu Yerucham 9:1, Siddur Rashi 316 pg 151, Teshuvat Rashi 52, Pardes HaGadol 199, Sh”t Maseh HaGoanim 52 pg 43, Tosfot (Shabbat 21b s.v. Deiy Lo Adlik) in name of the Ri, Sefer Trumah 228 in name of Ri, Shibolei HaLeket 185 in name of Sefer Hatrumah, Ohel Moed (Chanukah 4), Teshuvat Ravyah 972, Rosh 2:3, Smak, Rabbene Yerucham 9:1, Meiri, Smag, Orchot Chaim in name of some Geonim and Sefer Hatrumah, and Ran hold that one may light later in the night based on the opinion of the Ri and Rashba. Rabben Peretz (on Smak 280) says to light while household members are awake. Ritva says nowadays when we light inside we can light after ‘Tichle Regel’ against the Tur who says this time applies even nowadays. [Darkei Moshe and Bach write that the Tur also agrees to the Tosfot but just was writing according to the Minhag of his place.]
- Based on the opinion of the Ri, the Rama 672:2 rules nowadays one doesn’t need light by Tichleh Regel but one should be careful to light by then. Similarly, S”A 672:2 rules that if one did not light before people left the marketplace, he nevertheless should do so later on until Olot HaShachar. The Magen Avraham 672:6 explains that one is allowed to light after people left the marketplace with a bracha only as long as the family members are awake. Eliyah Raba, 672:3, Chaye Adam 154:19, Derech Hachaim 672:2, Ben Ish Chai Vayeshev 7, Aruch HaShulchan 672:7, and Kaf Hachaim 672:26 agree with the Magen Avraham. Thus, Mishna Brurah 672:11 says that if one is lighting after the time that people have left the marketplace, it is proper to awaken family members so that one may light with a bracha. Similarly, Rav Dovid Yosef (Torat HaMoadim 4:4) rules that one shouldn’t make a bracha but shouldn’t stop someone who wants to make the bracha as he has what to rely on.
- However, Igrot Moshe 4:105:7 argues that even if all family members are sleeping, one may recite the bracha, because pirsumei nisa isn’t an absolutely essential part of the mitzvah. The Chemed Moshe (quoted by Shaat Tziyun 672:17), Erech Hashulchan 672:4, and Moed Kol Chai 27:27 agree. One of the proofs of the Chemed Moshe is the Riaz (quoted by Shulchan Aruch 677:3) who says that if a person is alone in a town that is completely filled with non-Jews one should light there with a bracha, even if there is someone lighting for him at home. The Igrot Moshe writes that the same would be true even if a person is all alone and there aren't even non-Jews around, one should light there with a bracha.
- Similarly, Rav Ovadyah in Chazon Ovadyah (Chanukah pg 64-7; published 5767) writes it in this language: if one comes home late and everyone is sleeping if one can wake up one or two house members that's great, however, if one can’t wake anyone up then one can still make a bracha. [It seems that Rav Ovadyah Yosef retracted from his ruling in Kol Sinai 5725.] Rav Shlomo Zalman Auerbach (cited by Beyomin DeChanukah 242 and Shalmei Moed pg 218) agrees.
- See also the Magen Avraham quotes Maharshal who says to make a bracha only up to Chatzot. The Gra (Maaseh Rav 236) agrees with the Maharshal.
- The Rif (9b), Rambam (Chanuka 4:5), and Rosh (2:3) all write that the time that people leave the marketplace is one half-hour after the time for lighting begins. Tur and S”A 672:2 codify this as halacha. However, the Ritva 21b s.v. Ad points out that this amount of time is not an objective time period, but rather is dependent on the time and place. Therefore, Rabbi Mordechai Willig (Hilchos Chanukah and Purim #1, min 19-20) rules that although the minhag of some yeshivot is to light about 20 minutes after sunset (see note 1), one may light as long as people are walking in the streets, which in a yeshiva could be very late indeed.
- Sh”t Shevet Halevi 8:156 writes that one can light with a bracha even if there’s not 30 minutes for the candles to burn before Olot Hashachar. He proves this from the simple language of S”A, Magen Avraham and Mishna Brurah (and all other poskim) that one can light all night until Olot HaShachar. So writes Sh”t Rivovot Efraim 5:582 in name of Sh”t Shem MeShimon 3 pg 120. Chazon Ovadiah (Chanukah pg 67) seems to agree because he quotes the Shevet HaLevi and no one who argues. Yalkut Yosef Kitzur Shulchan Aruch 672:2. However, Rav Elyashiv in Sefer Chanukah 13:13 and Torat HaYoledet 54:7 say not to light with a bracha unless there’s 30 minutes before Olot HaShachar.
- S”A 672:2. Siddur Rashi 116 pg 151 (quoting Teshuvat Rabbenu Yitzchak Bar Yehuda) says if one didn’t light during the night one can’t light during the day. Sh”t Maaseh Goenim 55 pg 43, Teshuvat Rashi 52, Machsor Vitri 237 pg 201, Sh”t Maharam MeRotenberg 634, Pardes HaGadol 199, Tur 672, Shibolei HaLeket 185, and Roke’ach 226 quote this as well. Ravyah 3:843 in name of Rabbenu Tam says one can light in the day if one didn’t light at night. Sh”t Hitorerut Teshuva 1:119 writes that since we light nowadays indoors one should light as long as the candle gives off light (before HaNetz, when the sun’s light overwhelms the candles light). However, Rav Ovadyah in Kol Sinai (kislev 5725) and Torat HaMoadim 4:5 argue that even though one should light to satisfy all opinions one isn’t allowed to make a bracha.
- Yalkut Yosef (Moadim pg 210)
- Emet LeYacov 677 in the footnote, Kovetz MeBet Levi kislev 5757, Halachos of Chanukah by Rabbi Eider p. 34 n. 8 citing Rav Moshe Feinstein, Rav Mordechai Willig (oral communication, Halachipedia Chanuka Packet 5775).
- Rav Ovadia Yosef (Yechave Daat 3:51) writes that it is preferable to ask one’s wife to light for him at Tzeit HaKochavim, rather than light later at home by oneself. The idea of Mitzvah Bo Yoter Mbshelucho is only if you can fulfill it in an equally ideal fashion, however, since if you light later that is not ideal it is better to fulfill the mitzvah yourself now. Yalkut Yosef Chanuka p. 382 rules exactly the same thing for someone at work late he should ask his wife to light on time. Torat Hamoadim Chanuka 4:6 and Or Letzion 4:43:4 agree. He even extends it to the case where neither the husband or wife is home and he says that you should ask a neighbor to light for you. Mayan Omer v. 3 p. 343 also quotes Rav Ovadia as saying that you should ask your wife to light for you on time instead of later. However, he also quotes Rav Ovadia from personal communication that if the whole family is away until very late Rav Ovadia said it is better to light later when you get back rather than ask a neighbor to light for you as a shaliach. Mayan Omer distinguishes between the two cases because the wife is more shayach to your house to be yotzei there than a neighbor. Also, he says that since everyone is coming home later there's a mitzvah for them to see the candles so that's a reason to have them light later but if the wife can light earlier then at least she can see the candles. Mayan Omer quotes Ben Ish Chai in Rav Poalim YD 2:35 that is similar to Rav Ovadia's approach. (As a contradictory piece of evidence, Rav Eliyahu Shtarit in Rabbenu p. 30 quotes Rav Ovadia Yosef as having allowed him to light later than tzet hakoachim himself rather than have his wife light for him on time. Also, he quotes Rav Dovid Yosef as saying that Rav Ovadia Yosef did that himself. To clarify, Rav Yitzchak Yosef in a Motzei Shabbat Shiur Vayeshev 5779 min 29 explained that his father used to give shiurim until very late like 11pm and then come home and light. His mother didn't want to light herself despite the fact that he asked her to.)
- Rav Shternbuch (Teshuvot V’hanhagot 4:170) agrees, but adds that the husband should still light when he gets home. He may even recite the bracha if he had in mind not to fulfill his obligation earlier with his wife and some people in the house are still awake. Rav Vosner (Shevet Halevi 4:66) raises a doubt as to which is preferable, and concludes that it is probably preferable for the husband to light later that night by himself.
- Halachos of Chanukah by Rabbi Eider p. 34 n. 3 writes that if someone can't be home at the proper time but will get home before it is too late to light, that is while someone will still be a awake inside he shouldn't ask his his wife to light for him but to light himself when he gets home, especially if he's generally not careful to light at the earliest time. He concludes that such is the minhag. On p. 35 fnt. 22 he quotes that Rav Moshe Feinstein (Moadei Yeshurun n. 28) agreed that it is better to light yourself later than have someone else light for you on time.
- Chazon Ovadyah (Chanukah pg 71) and Mishna Brurah (explained in Beiur Halacha) 672:1 brings two proofs :1)Tosfot (Shabbat 23b s.v. Hadar) says Tadir VeShEno Tadir, Tadir Kodem (the more common mitzvah comes first) overrides the mitzvah of Pirsume Nisa (publicizing the miracle. This is also the opinion of Meiri (Shabbat 23b) in name of Gedolei Dorot, Ran (Shabbat 23b), Ramban (Shabbat 22b), Rosh (Shabbat 2:13), Rashba (Shabbat 22b), Teshuvat Rashba 1:1070, Rabbenu Yerucham (p. 61d 2). Also, Kriyat Shema is Deoritta and lighting candles is Derabanan and Peni Yehoshua Brachot 51b, Nodeh BeYehuda Kama O”C 39,41e, and Sh”t Rama MePano 14 hold Deorittas precede a Derabanan. Even though the Shagat Aryeh argues that Deorittas don’t have any precedence over Derabanan’s, most of the achronim agree with the Peni Yehoshua including: Sh”t Imrei Esh O”C 53, Mispeh Eitan (Brachot 51b), Chatom Sofer (Pesachim 102b), and Sh”t Shev Yacov O”C 22. However Magen Avraham 672:5 rules one should light before praying Mariv. Because of Tadir and Shema is Deoritta, Sh”t Shevut Yacov 2:40, Sh”t Shev Yacov 22 quoted by Sh”t Orach LeChaim O”C 1, implied from Sh”t Lechem Seirim 21, Shoel UMeishiv (Riviah 2:219) and Chaim VeChesed Mosefia pg 90d:11 in name of Mahari MeTaril disagree with the Magen Avraham. Chidushei Maharsa 8b says that everyone agrees that if it’s close to Chatzot one should pray before lighting because preferably one should pray before Chatzot. [Bear Hetev 672:2 quotes Magen Avraham and then says so holds Knesset Hagedolah. However Shaarei Teshuva 672:1 says that the Bear Hetev made a mistake about the Knesset Hagedolah as appears from Sh”t Shevut Yacov. Sh”t Shevut Yacov quotes the Shaarei Knesset Hagedolah (Hagahot Hatur 672:1) who writes that he retracted from his opinion that one should light before praying. ]
- Torat HaMoadim 4:8 and Kaf Hachaim 672:5 say that because of Tadir we pray and then light. Chida in Machzik Bracha 672:3, Sh”t Mahari Halevi 1:182, says if there’s a concern of missing ‘Tichle Regel’ one could light first. One should set it up beforehand as per Mishna Brurah 672:1 and Kaf Hachaim 672:6.
- Mishna Brurah 672:1 in name of Mor Ukesiah and the Minhag of the Gra to light before they prayed at Tzet, if one didn’t light until Tzet one prays first because of Tadir and that Shema is Deoritta. He also records the practice of some who would always light after Mariv. Torat HaMoadim 4:8 agrees. One should set it up beforehand as per Mishna Brurah 672:1 and Kaf Hachaim 672:6.
- Yeshuot Yacov 681:1, Sh”t Az Nidabru 9:47, Sh”t Teshuvot VeHanhagot 2:338, Mitzvah Ner Ish Ubeto (6 footnote 4), and Rav Elyashiv (quoted in Halichot Yosef p. 239) say that the reason of Tadir (and that Shema is Deoritta) only applies if the two mitzvot (mariv and Chanukah candles) are both available at the same time, but if one mitzvah is later, such as if one goes to a Maariv minyan later, one can light earlier at the appropriate time. See, however, Igrot Moshe 4:99:1 who seems to disagree with this point (See the Sefirat HaOmer#When to count Sefira page about this).
- Meiri (Shabbat 21b) writes that in France, the minhag of the bnei yeshiva was to wait to light Chanukah candles until after they finished learning in the beit midrash. Rav Hershel Schachter (MPeninei HaRav pp. 188-9; Halachipedia Article 5773 #9) quoted Rav Soloveitchik as having ruled that if someone is in middle of a seder of learning, such as the kollel’s afternoon seder, one should wait until the end of the seder in order to light Chanukah candles.
- Halichot Shlomo p. 296 cites Rav Shlomo Zalman Auerbach as ruling that kollel members should go home to light at the right time even at the expense of interrupting a seder. Chazon Ovadia Chanuka p. 76 agrees. See Yalkut Yosef p. 267 who writes that in Yeshivat Chazon Ovadia he said that they should continue to learn through the seder and ask their wives to light or light themselves afterwards. He said Rav Ovadia agreed but added that for a kollel member who will learn properly and come back right away it is preferable to go home to light and come back. Yalkut Yosef also quotes that Rav Chaim Pinchas Sheinberg in his yeshiva ruled that the boys shouldn't go home in the middle of the seder to light.
- Rav Hershel Schachter (Halachipedia Article 5773 #9) said that if one is in middle of a class, he need not leave in order to light. Rather, one should wait until afterwards so that he will be able to sit by the candles for a short while.