In many cities around the world there are communal eruvin in order to allow Jews to carry outside on Shabbat. In order to establish an eruv 4 steps are necessary: (1) First, it is necessary to establish that the city in question is suitable to have an eruv and isn't considered a reshut harabbim. That can be accomplished in several ways such as by ensuring that there is a population less than 600,000 people, the area is surrounded by a majority of walls, or according to some opinions the streets aren't straight. This topic is discussed on the Hotzaah page. (2) Halachic walls need to be erected using a combination of buildings, fences, walls, bushes, and cliffs. The gaps or large areas with no walls need to be closed using tzurot hapetach, with a string over two poles. This is discussed on this page. (3) It is necessary to rent from the municipality or police the public areas for ritual purposes. This is called shechirut reshut and discussed on the Sechirut_Reshut page. (4) A box of bread or matzah needs to be acquired to the Jews of the community and stored in a publicly accessible location. This is called an eruv chatzerot and discussed on the Eruv_Chatzerot page. For a conceptual background to the topic of eruvin see Introduction to the Modern Eruv.
Modern Day Eruv
- Many poskim hold that it is permissible to carry on Shabbat within an eruv. However, some poskim disagree and wouldn't allow carrying in any eruv. Sephardim are initially strict not to carry in an eruv when possible but have what to rely upon to be lenient if there is a serious need to carry within the eruv.
- As long an area can be determined not to be a public domain on a biblical level, an eruv using tzurot hapetach, entranceways made with two polls and a lintel as thin as a string on top, suffice.
- See Rav Hershel Schachter's article on Introduction to the Modern Eruv and the Hotzah page for details about how to create the tzurat hapetach and the definitions of the 4 halachic domains.
- A tzurat hapetach is a doorframe made up of two side posts and a lintel on top. It doesn't need to be possible to actually hang a door in the tzurat hapetach.
- It is permitted to set up four walls of a tzurat hapetach to enclose a residential area. However, for an uninhabited valley it is invalid.
- Four walls made of tzurot hapetach aren't effective for a reshut harabbim because of the issue of ayti rabbim, conceptually "the masses come and knock down the tzurat hapetach."
- Wire should directly over the sideposts without anything separating between the sidepost and the wire.
Doorpost behind a Wall
- Most poskim are stringent not to allow a tzurat hapetach if one side post is inside of a four-walled area.
- If there is only one wall separating between the two poles that is a dispute if it is kosher.
- It is fine for one doorpost to be wider or taller than the other.
Swaying in the Wind
- If the side posts would sway in the wind the tzurat hapetach is invalid.
- Many poskim hold that the wire on top is acceptable even if it sways in the wind as long as it doesn't fall off the top of the side posts.
- If the wire on top of the tzurat hapetach sways in the wind to the sides beyond the two side poles many poskim hold that it is invalid.
- If the wires sag, some poskim invalidate it, others hold it is kosher.
- If two poles have a kosher side post and wire on top, some poskim allow skipping poles even though they have a wire going to the side of the post as long as it is in a straight line.
Tzurat Hapetach Detached from a Wall
- Some poskim hold that if a tzurat hapetach is detached from the wall more than 3 tefachim it is invalid. Others hold that it is valid. A compromise view allows the tzurat hapetach if it is detached from one side but on the other side attached to a wall. Some are strict even in that case.
Tzurat Hapetach on Four Sides
- According to some rishonim, it is impossible to make a tzurat hapetach for the four sides of an eruv if the tzurat hapetach gaps are more than 10 amot. This opinion is not accepted.
Wire Goes into Pole
- If the wire goes straight into the pole (Picture 1 and 2) some poskim hold that it is invalid since it is going into the side of the pole and not over the top. Others hold that it is kosher since the top of the pole is meaningless and can be viewed as though it was removed as long as the wire is still over a pole that is ten tefachim.
- If the wire goes into a pole which is cut out in the middle and there are protrusions on the sides of the slit which extend upward (Picture 3), according to many poskim it is invalid, but if the wire goes into the slit and is flush with the top of the protrusions (Picture 4), according to many poskim it is valid. Some are lenient in both cases.
Pole Blocking Tzurat Hapetach
- If there is a tzurat hapetach that is blocked by a horizontal pole or multiple poles (see picture to right), some poskim hold that it is invalid since it isn't the normal way that people make doorways. Others hold it is acceptable since the tzurat hapetach is constructed properly and anything additional can be ignored.
- If there is a partition that blocks the entranceway from side post to side post and covers the entire width of the doorway so that there isn't ten tefachim above the partition, the tzurat hapetach is invalid.
- If one of the poles of the tzurat hapetach is slanted (picture #1) many poskim hold that it is kosher.
- if one of the poles of the tzurat hapetach is slanted and the wire goes over the side of the pole, such that if the pole were to be cut at the point of the wire it would be over a pole that is 10 tefachim tall (picture #2), many poskim hold it is invalid. If there are a notch or groove where the wire is or below the wire and above 10 tefachim, then it is valid.
Angle of the Slope
- A slope that that has a height of 10 tefachim over a distance of 4 amot or less is considered a wall for enclosing a reshut hayachid. According to majority of poskim, this distance is measured along the slope and not the floor (Picture #1), however, a minority of poskim hold it is measured along the ground (Picture #2). A tel hamelaket has the halacha of gud asik.
- A slope that is more gradual than 10 tefachim within 4 amot, such as 10 tefachim over 5 amot, is not considered a wall.
- The slope is considered a wall where it reaches 10 tefachim within 4 amot. The top of the slope is where it is considered to be the wall and not the bottom of the slope.
- Once the slope is 10 tefachim high within 4 amot, the area that slopes above it is considered within the walls of a reshut hayachid. Some argue that it isn't a reshut hayachid until the area flattens out on top.
If Slope Becomes Gradual in Middle
- If the slope becomes more gradual in the middle but altogether over 4 amot it reaches a height of 10 tefachim (Picture #3), many poskim hold it is considered a wall. The main point is that as a whole the area of 4 amot has a slope that rises 10 tefachim but it is irrelevant what the slope is at any point. Other poskim hold that this would not constitute a wall. Any part of the slope which is more gradual than 24.6 degrees is not considered a wall at all is a break in the wall. If the break is larger than 4 tefachim it breaks up the two parts of the slope completely.
Two Slopes Broken Up
- If the slope is broken up with a width of more than 4 tefachim (Picture #4), even though each slope is at least 24.6 degrees, some poskim it doesn't join together, while others hold it can join together.
- If there is a slope that is 5 tefachim within 2 amot or less and a wall of 5 tefachim on top of it, some say that it isn't a wall, but others argue that it is a wall. If there is a slope with less than 3 tefachim of height and a wall of the remaining height to reach 10 tefachim, it is questionable if that is considered a wall.
- If the stairs are less than the width of 3 tefachim and less than 3 tefachim wall they can become a wall if altogether there is a height of 10 tefachim within 4 amot. If they are different dimensions see footnote.
- A separate issue that some poskim raise regarding counting stairs as a wall is that the wall is trampled (nidreset). Many aren't concerned about this issue.
- Chazal forbade carrying in an area not suitable for living that is larger than 5000 square amot even if it is surrounded by walls. Colloquially, this place is called a karpef. Biblically, this area is a reshut hayachid, but the rabbis made a restriction not to carry there more than 4 amot.
- What is considered enclosed for living and not subject to the laws of karpef? A house meant for dwelling or a yard opened to a house and then enclosed. If the yard was enclosed not for living then a house was built there afterwards it still has the status of a karpef.
- A plateau or island that has natural walls of 10 tefachim that is larger than 5000 square amot has the status of a karpef.
- One may not carry in a planted area, such as a garden, that is larger than 5000 square amot and it forbids carrying in the whole eruv. Whether it applies to our cities is a discussion. Some poskim are lenient since relative to the whole city it is insignificant. The lenient view is only lenient if the garden is not enclosed with walls that are 10 tefachim wall. If the garden has walls it is considered its own area and doesn't forbid carrying in the city, but it is forbidden to carry in it.
- Many poskim hold that flowers that are planted for beauty are not considered a karpef since its purpose is to enhance living nearby. Others disagree and hold that flowers are included in other plants which are considered a karpef.
- A karpef that was enclosed for dwelling which was then filled with plants is no longer considered an area enclosed for dwelling since people don't walk on plants. If it is larger than 5000 square amot it is a karpef and forbidden to carry there. Also, any place adjacent to it and open to it is forbidden. The same applies to plants in a yard that is considered not enclosed for dwelling.
- A karpef that was enclosed for dwelling which was then filled with trees is still considered an area enclosed for dwelling since people like to walk beneath the shade of trees. There is a discussion if a forest within a city is a karpef.
Ponds and Lakes
- A karpef that was enclosed for dwelling which was then filled with water that is 10 tefachim deep is no longer considered an area enclosed for dwelling, unless the water is drinkable.
- Yalkut Yosef 345:4. For background see Introduction to the Modern Eruv.
- Rav Hershel Schacter in "Introduction to the Modern Eruv"
- Shulchan Aruch O.C. 362:11 rules like Rif and Rambam that it isn't necessary to have a heker tzir. Bach 362:10 agrees. Mishkenot Yakov 123 p149 writes that it is proper to be strict to require a heker tzir for a tzurat hapetach. He garners support for this view from Rosh, Maharam, Tur, Ritva, Raavad, Smag, and Smak.
- Pri Megadim MZ 363:1 has an unresolved question whether a tzurat hapetach is valid from the Torah or derabbanan. Biur Halacha 362:10 s.v. kshkol tries to prove that this is a dispute between the Ri and Rabbenu Chananel. Chazon Ish 70:13 holds that the tzurat hapetach is valid m'deoritta (excluding the issue of ayti rabbim).
- Biur Halacha 362:10 s.v.aval is lenient on uninhabited valley if it is only 10 or less. Chazon Ish 70:11 machmir.
- Eruvin 6b, Shulchan Aruch O.C. 364:2
- Taz 363:19 holds that if there's a roof between the lechi and the kaneh on top it is an invalid tzurat hapetach. Tosefet Shabbos 363:64 disagrees and allows it. Mishna Brurah 363:112, Shulchan Aruch Harav 363:32, Chazon Ish 71:13, and Kaf Hachaim 363:189 accept Taz. Rav Dovid Feinstein (Vdibarta Bam v. 2 p. 289) holds that in extenuating circumstances at least for derabbanan purposes it is possible to follow Tosefet Shabbat unlike Taz. Chazon Ish 71:13 implies that if the roof was small and not 4 amot long it isn't a hefsek.
- The Netivot in Tikkun Eruvin writes that you can’t make a tzurat hapetach with one kaneh that is enclosed in an area surrounded by four walls. He presents two reasons. 1) A tzurat hapetach needs to be recognizable and if it is inside another area it isn’t recognizable. 2) The reshut hayachid is considered completely filled up and the kaneh is like it doesn’t count. Shaarei Teshuva 363:7 quotes this. Mishna Brurah 363:113 agrees. Avnei Nezer OC 291 accepts the Tikkun Eruvin’s point for another reason because he disagrees with both reasons of the Tikkun Eruvin. He says that it is like the kaneh that in the reshut hayachid is like it is separated from the other kaneh. Chazon Ish 70:22 writes this idea to explain the Tikkun Eruvin.
- Chazon Ish 70:22 is also machmir even if it is behind one wall. Mishnat Yaakov pp. 115-116 writes that a tzurat hapetach with one wall blocking the tzurat hapetach is kosher according to Mekor Chaim, Chatom Sofer, and Mishna Brurah, but Chazon Ish has a safek about it in 70:18.
- Mayim Amukim 2:26, Magen Avraham 362:18, Tosefet Shabbat 362:26
- Magen Avraham 362:18, Mishna Brurah 362:20, Netivot Shabbat 19:14
- Machasit Hashekel 362:18 writes that the wire on top can sway in the wind and although is part of a wall, doesn't have all the stringencies of a wall which cannot sway in the wind at all. Mishna Brurah and Aruch Hashulchan agree. Pri Megadim E"A 362:18 argues that every mechitza must be strong enough not to fall down in the wind but it doesn't matter if it would sway in the wind. For the wire on top he writes that it is kosher if it sways as well as it doesn't fall off the side posts. Chazon Ish agrees. However, unlike the above poskim, Mishna Brurah cites Mishkenot Yakov who holds that the wire is completely invalid if it sways in the wind at all. Kaf Hachaim 362:97 cites Mishkenot Yakov, but in 362:112 he seems to accept Machasit Hashekel. Igrot Moshe 5:40:2 agrees with Pri Megadim and Chazon Ish.
- Mishkenot Yakov 123 writes that the wire sways to the side beyond the two poles, it is invalid because the lintel on top is not functioning as a lintel on top of where it should be a wall. Also, he writes that it is a kal vchomer from min hasad that it is pasul. Chazon Ish 71:7 writes that if the wire sways to the side beyond the width of the posts, it is invalid. In Chazon Ish 71:8, he rejects his proof for that point but doesn’t reject his main point. In 71:10, he reiterates his stringent view. Shoneh Halachot 362:59 quotes Chazon Ish as being strict in the case where the wire extends to the sides of the poles. Netivot Shabbat 19:42 agrees that it is invalid. Binat Simcha (cited by Bikurei Elazar p. 498) quotes the Griz who was strict to make very wide side posts so that the wire doesn't sway beyond them. Bikrei Elazar p. 499 quotes the Shaarei Tzion 3, Maharam Brisk 68, Imrei Yosher 2:133, and Har Tzvi as being lenient on a wire that sways beyond the side posts.
- Mishkenot Yakov 123 invalidates a wire that is sagging for three reasons. Ritva Eruvin 11b writes that the lintel on top of a tzurat hapetach must be flat. Also, if it sags it is like a tzurat hapetach min hasad. Lastly, if it sags then it'll move in the wind. Chazon Ish 71:10 isn't sure and seems to be strict on sagging wires.
- Shaarei Tzion 3 argues that a wire that’s sagging is kosher because the wire of a tzurat hapetach can be curved. His primary argument is based on an inference from Rashi Eruvin 11a and then defends his position in light of Eruvin 11b which implies otherwise. Even though Ritva Eruvin 11b is explicit that the wire must be flat, he argues that this is only relevant to mezuzah and not eruvin, as Tikkun Eruvin argued. He also writes that it is kosher if it sways to the side but he isn’t clear how much it is allowed to sway to the side, particularly if he’d allow swaying beyond the width of the side posts.
- Har Tzvi 2:18:12
- Tevuot Shor 11b learns from Tosfot Eruvin 11a that a tzurat hapetach needs to have the halacha's of a lechi. Since a lechi is invalid if it is more than 3 tefachim away from the wall (Eruvin 12b), so too a tzurat hapetach in such a fashion is invalid.
- This seems to be a dispute between the rishonim. Raavad (quoted by Rashba 10b s.v. shmat and Meiri Eruvin 11b s.v. zeh) holds that tzurat hapetach which isn’t connected to the walls on the side are invalid since a tzurat hapetach is not considered like omed. Tosfot Rabbenu Peretz Eruvin 11a explicitly is lenient if a tzurat hapetch is not attached to a wall. Ritva (Eruvin 10b s.v. shmat) disagrees with Raavad and hold that tzurat hapetach is like omed. Rashba Eruvin 10b isn't clear about his conclusion.
- Magen Avraham 363:5 quotes a dispute between Riaz, Rabbenu Yonatan, and Tosfot whether a lechi that’s 3 tefachim away from the wall and is itself 3 tefachim wide is kosher. According to Riaz and Rabbenu Yonatan that the lechi is kosher, a tzurat hapetach should also be kosher even if it is more than 3 tefachim away from the wall. Tosfot who holds that the lechi which is more than 3 tefachim away from the wall is always invalid might also invalidate a tzurat hapetach that is more than 3 tefachim from the wall.
- Tikkun Eruvin p. 2 makes a compromise that it is valid if it is attached on one side, but invalid if it is detached on both sides. Bet Efraim OC 28, Har Tzvi 2:18:5, and Chazon Ish 70:14 agree. Bet Efraim explains the reason for Tevuot Shor is that the tzurat hapetach needs to connect to the existing walls which come to permit the area. Chazon Ish seems to be leaning to the lenient view about if it is detached on both sides in 70:14, but in 70:21 he seems to be strict.
- Avnei Nezer OC 287 and Geon Yakov 11a agree with Tevuot Shor for another reason. He holds that the tzurat hapetach is not considered like it is standing. Therefore, if it is detached from the walls, there could be more airspace than wall (parutz merubeh al haomed).
- Halacha: Mishna Brurah 363:23 is strict except in extenuating circumstances. Rabbi Akiva Eiger OC 18 holds that it is kosher in extenuating circumstances.
- Shulchan Aruch 362:10 quotes Rambam who is strict unlike Tosfot and Rosh who are lenient. The primary opinion in Shulchan Aruch is Tosfot and Rosh. Avnei Nezer 287 writes that the halacha follows Rosh. Chazon Ish 70:11 agrees.
- Mishkenot Yakov 123 p. 156 s.v. v’ha’rif writes that according to Rambam we can’t make a tzurat hapetach in the four corners. It is a kal v’chomer from what he writes regarding keren zavit. Mishna Brurah 361:8, Kaf Hachayim 361:18, and Chazon Ish 72:1 all rule like Rashi that keren zavit means two corners. It even seems like Shulchan Aruch paskens like that because in 362:10 he quotes the gemara 11a according to Rashi and Tosfot, which isn't true according to Rabbenu Chananel and Rambam or Rif as Rashba and Ritva explain for Rambam and Rif.
- Mishna Brurah 362:64 quoting Pri Megadim isn't sure if it is valid if the side protrusions go above the wire. When the wire goes through the pole there are side protrusions above the wire as well as part of the pole above the wire. Tosefet Shabbat 362:29 and Kaf Hachaim 362:106 agree. Chatom Sofer OC 1:90 s.v. v'ani based on Hagahot Ashri (Eruvin 1:11) is explicitly strict about a wire that goes through a pole.
- Chazon Ish 71:9, Ha'elef Lecha Shlomo OC 1:164, Divrei Malkiel 3:16 s.v. v'b'emet, Har Tzvi 2:18:3. The Aruch Hashulchan 362:32 who is lenient even if the side protrusions extend above the wire isn't clear about this case since part of the pole is above the wire.
- Mishna Brurah 362:64 quotes Pri Megadim (MZ 362:4, 363:19:4) who isn't sure about this case if it is valid and suggests being strict about this case. Tosefet Shabbat 362:29 and Kaf Hachaim 362:106 agree to be strict. The Netivot in Tikkun Eruvin p. 3 isn't clear about this case. Shaar Hatzion 362:52 suggests that he is strict about this case, while Chazon Ish 71:9 explains that he would be lenient.
- Mishna Brurah 362:64 quotes Pri Megadim (MZ 362:4, 363:19:4) who is lenient about this case. Aruch Hashulchan 362:32 agrees. The Netivot in Tikkun Eruvin p. 3 is lenient about this case.
- Aruch Hashulchan 362:32, Chazon Ish 71:9
- Teshurat Shay 327
- Maharil (Likutim n. 15), Avnei Nezer 295
- Chazon Ish 70:19
- Chazon Ish 71:11, Avnei Nezer 291:12-16
- Chazon Ish 71:12. Avnei Nezer 291:15, however, holds that there is gud asik on a tel hamelaket even on the slope once it is above ten tefachim.
- Sfat Emet (Shababt 100a s.v. amar rav)
- Gemara Shabbat 100a, Rambam Shabbat 14:16, Shulchan Aruch and Rama O.C. 363:36, Shulchan Aruch O.C. 362:2
- Rabbenu Chananel (Shabbat 100b), Ritva (Shabbat 100a s.v. tel, Eruvin 19b s.v. tel), and Riaz (Eruvin 2:1:7) hold that 4 amot is measured along the slope, while Tosfot Zevachim (63a s.v kol) holds that 4 amot is measured along the ground. Goan Yakov (Eruvin 19b), Mishna Brurah 345:5, 363:154, Aruch Hashulchan 345:28, Maharalbach 19, and Netivot Shabbat 16:6 hold like Rabbenu Chananel. Mahalbach explains that this is also the view of Rashi Eruvin 19b and Rambam Shabbat 14:16. Markevet Hamishna explains Rambam like Tosfot. Sfat Emet Shabbat 100a says Rashi agrees with Rabbenu Chananel. (There Tosfot write that a slope of a triangle with height 9 and floor 20 is steeper than a tel hamelaket. According to Rabbenu Chananel it isn’t true.) if 4 amot is measured on the floor then the angle of the slope is arctan(10/24)=22.6 degrees. If 4 amot is measured on the slope then the angle of the slope is arcsin(10/24)=24.6 degrees.
- Rashi Eruvin 15a s.v. gevoha, Machaneh Yisrael (12:16:5 p.293), Netivot Shabbat ch. 16 fnt. 19. See Rav Chaim Halevi on Rambam Sukkah 11:4 who suggests that Rambam doesn't hold of gud asik but, nonetheless, the top of the tel hamelaket is a reshut hayachid that extends upward. Chazon Ish 108:9 implies that there is no gud asik for the slope of the tel hamelaket.
- Rashi Shabbat 100a s.v. tel writes that if the slope is more gradual than 10 tefachim within 4 amot it is like the ground of the reshut harabbim since people can walk over it easily. Taz 363:28 and Mishna Brurah 363:154 quote Rashi. Chazon Ish (65:70 s.v. achrei) suggests that an area that is raised up or lower 10 tefachim than the area next to it, it could be a reshut hayachid, since it is set off from the reshut harabbim even though the slope is more gradual than 10 amot within 4 amot. This is true on condition that people don't walk over the walls. For example, if there is a house with walls that are sloped more gradually than 10 amot within 4 amot, it is a reshut hayachid inside since people don't walk over the walls. His proof is Sukkah 19a. Netivot Shabbat ch. 6 fnt. 17 notes that the implication of the poskim is unlike this Chazon Ish.
- Rashi Shabbat 100a s.v. tel and s.v. otto. Machaneh Yisrael (12:18 p. 294) writes that only the top of the slope where it reaches 10 tefachim within 4 amot is considered a wall and not the bottom of the slope.
- Maharshal (Shabbat 100a s.v. bdibur hamatchil tel) explains that Rashi holds that even the slope is also considered a reshut hayachid once the slope reaches 10 tefachim high within 4 amot of distance. Avnei Nezer OC 291:15 explains that there is gud asik on a tel hamelaket even on the slope once it is ten tefachim.
- Chazon Ish 108:9. Tosfot Shabbat 5b s.v. kotel writes that a slanted wall which is less than 10 tefachim from the ground is considered like a reshut harabbim only if people place items on top of it. Tosfot implies that people didn't use the slanted wall, it would be considered a karmelit according to its dimensions. Ramban disagrees and argues that a slanted wall is like a straight wall and the side of it is considered airspace of the reshut harabbim. Rashba defends Tosfot by saying that the side of a wall is the airspace of a reshut harabbim, but a slanted wall is considered a new domain since there is a place upon it to place items. Chazon Ish applies this discussion to a slope of a tel hamelaket above 10 tefachim. According to Ramban, since it is like a wall, the surface is considered the airspace of the domain below. In practice, it would be a makom patur since it is 10 tefachim above a reshut harabbim. Even though according to Tosfot it seems that the slope is considered a new domain and should be a reshut hayachid, Chazon Ish explains that isn't the case. Tosfot fundamentally agrees with Ramban, though he considers the sloped wall to be a new domain since no one can walk below it and can't be called airspace. However, above ten tefachim where walking below it is irrelevant Tosfot agrees with Ramban. Machaneh Yisrael (12:16:5 p. 293) rejects Chazon Ish's conclusion because it is against the Rashba and also Ritva Eruvin 90a. Machaneh Yisrael holds like Maharshal. Netivot Shabbat (ch. 16 fnt. 19) quotes the dispute between Maharshal and Chazon Ish.
- Tosefet Shabbat 345:2, Sfat Emet (Shabbat 100a s.v. amar rav). Mishna Brurah (Biur Halacha 358:2 s.v. v'im) seems to also be other this opinion as he compares two vertical walls split by some horizontal distance to be a wall if altogether it is 10 tefachim tall over 4 amot.
- Chazon Ish 65:62 and 111:4 writes that if at any point if the slope it becomes more gradual than 24.6 degrees that part is not considered part of the slope and would break it up if it is wider than 3 tefachim. That is true even if altogether the slope is 10 tefachim tall within 4 amot. However, in 65:70 he prefers the logic that it would be a wall unless it is broken up with an area of 4 tefachim. In 111:4 he also uses the width of 4 tefachim. Netivot Shabbat 16:8 codifies the Chazon Ish, though in footnote he notes Tosefet Shabbat and Biur Halacha's view.
- Chazon Ish 65:62 and 70
- Gra 358:2, Biur Halacha 358:2 s.v. v'im. Trumat Hadeshen cited by Rama 358:2 writes that a 9.5 tefach wall of dirt of a width of 4 tefachim next to a 19 tefach stone wall is considered as though the dirt wall is a new ground and the stone wall is broken since it isn't 10 tefachim above the dirt wall. Gra 358:2 argues that the two walls should combine, even though there is a flat ground of 4 tefachim on top of the dirt wall between them. Biur Halacha 358:2 s.v. v'im writes that everyone should agree that the walls can combine as long as altogether there is a height of 10 tefachim within 4 amot. Chazon Ish notes that his argument is against Gra. Biur Halacha 362:2 s.v. sh'asa suggests that this is the dispute between Trumat Hadeshen and Gra.
- Biur Halacha 362:2 s.v. tel isn't sure about this case because perhaps only a slope that altogether with 10 tefachim tall constitutes a wall. On the other hand, it the slope of 5 tefachim could be a partial wall and joins together with the vertical wall of 5 tefachim.
- Biur Halacha 362:2 s.v. tel isn't sure if this type of slope can join together with a wall, since the slope is less than 3 tefachim tall it is like part of the ground of the reshut harabbim. If so, the wall on top is ineffective unless it itself is 10 tefachim tall.
- Netivot Shabbat 16:9 writes that stairs which are 3 tefachim or less wide and 3 tefachim or less tall are considered a wall. He compares this to a tel hamelaket since it rises 10 tefachim within 4 amot and even though it isn’t a flat slope since each aberration is less than lavud and it is like a flat slope. According to the analysis of Kovetz Teshuvot 4:33 the following emerges:
- If the stairs are a width of 4 tefachim according to Trumat Hadeshen (cited by Rama 358:2) and Chazon Ish 65:70 it isn't considered a wall, but according to the Gra it is considered a wall.
- If the stairs aren't 4 tefachim wide, it is considered a wall according to Chazon Ish, but possibly not a wall according to Rav Elyashiv.
- If the stairs are less than the width of 3 tefachim, according to Trumat Hadeshen, Chazon Ish, and Rav Elyashiv it is a wall.
- Rav Elyashiv writes that an eruv should not be lenient on this question. See Chashukei Chemed Shabbat 100a where he writes that stairs can count as a wall as long as it is 10 tefachim within 4 amot, but does not specify any of the above conditions.
- In terms of nidreset, Chatom Sofer OC 1:89 holds that it isn’t an issue because we pasken like rabbanan in Eruvin 22a. Chazon Ish 108:13 holds that nidreset is never an issue with a real wall and a borrowed phrase out of context. Imrei Yosher 1:2 holds that nidreset is an issue to mevatel walls completely. Dirshu 358:20 applies his opinion to stairs to be machmir. Netivot Shabbat (ch. 16 fnt. 24) regarding stairs quotes Rav Yechezkel Roth that we’re concerned for mechitza nidreset and we cannot count stairs as a wall. However, Rav Friedman argued with him based on the Chatom Sofer and Chazon Ish. Kovetz Elyashiv (Kovetz Teshuvot 4:33) writes that it is an issue if the stairs are 3 or 4 tefachim wide because we should be concerned for the opinion of the Trumat Hadeshen. He doesn’t raise the issue of mechitza nidreset.
- The halacha follows Rabbi Akiva in Eruvin 23a that an area that is the size of a bet saatayim, 50 amot by 100 amot, is always permitted and if it is larger than that size it is permitted if is enclosed for living purposes. One of the types of areas that fit this description of not being suitable for living is a karpef. Rashi (Eruvin 18a s.v. l'gina) explains that technically karpef refers specifically to a storage area of wood. However, colloquially, this place is called a karpef such as in Gemara Shabbat 7a and Shulchan Aruch O.C. 358:3.
- In Eruvin 67b, Rabbi Yochanan explains that a karpef is a reshut hayachid, but the rabbis forbade carrying in it more than 4 amot. Rambam (Shabbat 16:1) rules like Rabbi Yochanan. Levush 358:1 and Mishna Brurah 358:5 agree. Rashi in several places (Shabbat 80a s.v. v'hu and 99b s.v. mukaf) indicates that a karpef is a karmelit on a Torah level.
- Shulchan Aruch O.C. 358:1
- Shulchan Aruch O.C. 358:3
- Dvar Shmuel 259 writes that a garden in a city is not considered a karpef to forbid carrying in the city. He has 3 reasons: 1) Plants only make the area where they're planted forbidden if they're planted in a karpef, storage area for wood, but not in a city. A city which has a lot of people dwelling there, isn't nullified by a relatively small area of plants. 2) The plants which are made for temporary purposes isn't a karpef. Also, an area set aside for protection of the city isn't a karpef since it is meant to function as part of the city. 3) Making an eruv chatzerot permits a karpef. Chacham Tzvi 59 writes that although originally he disagreed with the Dvar Shmuel, later he defended it based on Rosh (Eruvin 2:2). Rosh isn't sure if the concept that plants nullify area of dirah, dwelling, is only true in a karpef or even in a chetzer. Also, perhaps even plants nullify dirah in a chetzer it wouldn't in a city. Biur Halacha 358:9 s.v. aval has difficulty with this Dvar Shmuel, though he seems like he agrees that it is an opinion to rely on in extenuating circumstance. Kaf Hachaim 358:84 quotes Maamer Mordechai who is strict, but also infers from Chida (Machzik Bracha 358:2) that he is lenient. See, however, Chida in Shiurei Bracha 358:1 who seems to have retracted and is strict. Chazon Ish OC 88:25 is strict. See Minchat Yitzchak 6:33:1 where he implies that he's strict.
- Petach Hakarpef p. 48 quotes Dovev Meisharim who suggests that the Dvar Shmuel is only relevant to plants planted after the city was enclosed, similar to Rosh's discussion. However, Petach Hakarpef rejects this because the Dvar Shmuel himself didn't connect his nuance with the Rosh.
- Bear Sarim 16:38 p. 20-21 proves from Rambam against Dvar Shmuel. He quotes that Rav Iser Zalman Meltzer made this point as well. See Yaskil Avdi 2:111:6 s.v. vlinyan ikar.
- Bet Meir 358, Biur Halacha 358:9 s.v. aval
- Minchat Yitzchak 5:108, Chelkat Yakov OC 181:4
- Divrei Chaim 2:28, Shoel Umeishiv 1:3:131
- Shulchan Aruch O.C. 358:9
- Shulchan Aruch O.C. 358:10
- Shulchan Aruch O.C. 358:9
- Meishvat Regel p. 21 writes that a forest is a karpef. Peni Aryeh (Eruvin siman 8 p. 79) permits a forest based on Dvar Shmuel since it is within the city.
- Shulchan Aruch O.C. 358:11