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Posted: 11/30/2022 10:31:35 PM EDT
ETA: A couple of photos added further down the page
I made arrangements to have a professional do this but now that the time is here his schedule won’t allow him to make it when I need and I’m not delaying my concrete. I just need to get the conduit in. I need to get a single 12/2 out to my garage which is about 12 feet from the house. There will be a concrete pad between the two that I want to run conduit under (not in the concrete). The area the conduit will run is currently backfilled with 2b gravel awaiting concrete (early next week). I plan to use the grey PVC conduit and put it 6”ish down in the gravel. This conduit will exit the garage floor and probably have two 45s in the gravel, total run length 10-12 feet. Then poke through an 8” retaining wall beside the house. Can I use one of these on the side of the wall the conduit comes though?  Attached FileIs there a such thing as selecting a conduit that is too large? I was going to use 1”. I only need 1 12/2, but who knows what the future will hold. Go bigger? This stuff gets glued right? Any other tips? |
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Posted: 11/30/2022 10:35:53 PM EDT
[#1]
Conduit bending is mostly triangle math with a bit of circle math mixed in, but that doesn't matter right now because your installing PVC...
...bigger doesn't hurt but each end has to terminate (connect) to a box of some sort. You'll be limited by that. Yes, it is to be glued. (6) inches is a bit shallow but its your property, go for it |
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Posted: 11/30/2022 10:36:37 PM EDT
[#2]
+(1) for calling it conduit too...
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Posted: 11/30/2022 10:39:08 PM EDT
[#3]
Too large? No, that's just a matter of cost.
They should be glued. What seems like a super tight fit will still allow for water intrusion. You'd be surprised. That said, that should be a fine configuration. The standard 90 degree (and 45, for that matter) bends are easy to pull through. What you see there is *impossible* to pull through. You will need to remove the cover, pull 100% from one side, and then feed it through the other side and pull again. It is not forgiving. I have used this many times. It works and is sometimes the best (only) thing that will work, but it's not pull-friendly at all (especially not with 12/2). The only tip I can provide is that you can avoid PVC glue if you use RectorSeal putty on the joints. It will still be watertight, but removable. I have used this on permanent installations many times. Glue isn't honestly necessary. |
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Posted: 11/30/2022 10:43:48 PM EDT
[#4]
Code does require the conduit to be 18" deep, if that helps. Use sweeping 90s so it's easier to pull wire.
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Posted: 11/30/2022 10:44:33 PM EDT
[#5]
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Posted: 11/30/2022 10:48:15 PM EDT
[#6]
Quote HistoryQuoted: Too large? No, that's just a matter of cost. They should be glued. What seems like a super tight fit will still allow for water intrusion. You'd be surprised. That said, that should be a fine configuration. The standard 90 degree (and 45, for that matter) bends are easy to pull through. What you see there is *impossible* to pull through. You will need to remove the cover, pull 100% from one side, and then feed it through the other side and pull again. It is not forgiving. I have used this many times. It works and is sometimes the best (only) thing that will work, but it's not pull-friendly at all (especially not with 12/2). The only tip I can provide is that you can avoid PVC glue if you use RectorSeal putty on the joints. It will still be watertight, but removable. I have used this on permanent installations many times. Glue isn't honestly necessary. This conduit will never be seen again, buried under concrete and gravel. I’m not concerned with it being removable and have no issue using glue. I’ve just never done it so I didn’t know what was the norm for it. That body or box or whatever it’s called that I pictured will be forever accessible. It’s where I will access to pull wire through my “underground” conduit run. |
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Posted: 11/30/2022 10:51:01 PM EDT
[#7]
Dupe
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Posted: 11/30/2022 10:51:21 PM EDT
[#8]
Quote HistoryQuoted: Code does require the conduit to be 18" deep, if that helps. Use sweeping 90s so it's easier to pull wire. Now I got this from google so I expect it to be wrong, but I read that 18” under concrete was required on a driveway 4” under in other applications. This will essentially just be a pad, no vehicles driven over this area. |
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Posted: 11/30/2022 10:52:09 PM EDT
[#9]
Run an extra rope or line in case you want to run something else in the future, you can use the rope to pull it through.
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Posted: 11/30/2022 10:53:15 PM EDT
[#10]
Quote HistoryQuoted: @denverdan Ours is generally about 5’-6’ deep because it’s in a substation yard. Anything inside the apprentices end up doing. Under my close supervision of course Everything outside is hydro trenched. |
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Posted: 11/30/2022 10:55:52 PM EDT
[#11]
Bow and go. No need for factory bends in the dirt if you can help it.
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Posted: 11/30/2022 10:56:04 PM EDT
[#12]
I could be wrong but I’m pretty sure 12/2 NM cable should not be put in conduit.
You need THWN.(THHN rated for wet) |
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Posted: 11/30/2022 10:58:31 PM EDT
[#13]
Quote HistoryQuoted: Conduit bending is mostly triangle math with a bit of circle math mixed in, but that doesn't matter right now because your installing PVC... ...bigger doesn't hurt but each end has to terminate (connect) to a box of some sort. You'll be limited by that. Yes, it is to be glued. (6) inches is a bit shallow but its your property, go for it 1" of concrete equates to 3" of soil depth per the code I've always been around in the commercial world. I'm guessing his concrete will be 3.5' thick (depth of a 2x4 form board). if he's round about 6-8 inches below that, he'll be fine. OP, you keep saying 12/2. You'll want 12awg pulled, not a pvc pipe stuffed with romex. |
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Posted: 11/30/2022 11:00:05 PM EDT
[#14]
Quote HistoryQuoted: I could be wrong but I’m pretty sure 12/2 NM cable should not be put in conduit. You need THWN.(THHN rated for wet) That’s fine, I’ll cross that bridge when I get there, thanks for the heads up. For right now I just have to get some conduit down. Wires ran at a later date. |
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Posted: 11/30/2022 11:01:06 PM EDT
[#15]
PVC needs at least 18" of cover.
Romex is not listed for wet/damp location which underground conduit is. |
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Posted: 11/30/2022 11:03:57 PM EDT
[#16]
Don't forget your slip/expansion joint where that LB ties into the structure, they are $$$$ for larger sizes.
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Posted: 11/30/2022 11:04:05 PM EDT
[#17]
Couple of things
yes no romex in conduit under ground, either use uf or thwn ( most thhn is duel rated ) If in dirt it needs to 18 inches unless gfi protected and 20 amps or less, then its 12 inches. 2 inches of concrete used to count for 6 inches of depth, not sure if it still does. In commercial work the conduit can not be in the slab but it can be directly under it.( when dirt under the slab ) Always go bigger, but you want at least 3/4. 1/2 will fit UF but it will be very tight, thwn would be easy. Lube will make your life a lot easier when you go to pull the cable. |
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Posted: 11/30/2022 11:04:56 PM EDT
[#18]
Quote HistoryQuoted: 1" of concrete equates to 3" of soil depth per the code I've always been around in the commercial world. I'm guessing his concrete will be 3.5' thick (depth of a 2x4 form board). if he's round about 6-8 inches below that, he'll be fine. OP, you keep saying 12/2. You'll want 12awg pulled, not a pvc pipe stuffed with romex. The concrete is probably going to be more like 6” thick in this area but no thinner than 4”. But yeah, I’m no electrical pro. One will be actually doing that work. I’m just in a time crunch to put in conduit. |
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Posted: 11/30/2022 11:06:55 PM EDT
[#19]
4" under a 4" thick slab with no vehicular traffic
edit: Saw your post above. under 6" of concrete you'll have your 18" depth equivalent. |
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Posted: 11/30/2022 11:07:46 PM EDT
[#20]
Quote HistoryQuoted: Don't forget your slip/expansion joint where that LB ties into the structure, they are $$$$ for larger sizes. Can you link me to an example of this? |
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Posted: 11/30/2022 11:10:43 PM EDT
[#21]
Quote HistoryQuoted: Can you link me to an example of this? On phone but Google PVC Conduit Expansion Coupling |
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Posted: 11/30/2022 11:22:19 PM EDT
[#22]
Quote HistoryQuoted: On phone but Google PVC Conduit Expansion Coupling Thanks, I’ll use one. I’m not sure my short run will see that much expansion but I suppose it can’t hurt, we do have all 4 seasons here. |
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Posted: 11/30/2022 11:24:54 PM EDT
[#23]
Quote HistoryQuoted: Thanks, I’ll use one. I’m not sure my short run will see that much expansion but I suppose it can’t hurt, we do have all 4 seasons here.  I've had to fix tilted LBs or adapters torn/broke off boxes where the ground settles before, a little give can be a good thing sometimes |
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Posted: 12/1/2022 12:01:14 AM EDT
[#24]
Quote HistoryQuoted: Conduit bending is mostly triangle math with a bit of circle math mixed in, but that doesn't matter right now because your installing PVC... ...bigger doesn't hurt but each end has to terminate (connect) to a box of some sort. You'll be limited by that. Yes, it is to be glued. (6) inches is a bit shallow but its your property, go for it Yep, 1.41 Times the marked spot......... you know. easier to bend 30's |
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Posted: 12/1/2022 12:04:31 AM EDT
[#25]
When you pull your wire through ...Go ahead and add an extra pull string just in case you ever want to add a second Circuit.
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Posted: 12/1/2022 1:08:40 AM EDT
[#26]
Quoted: I made arrangements to have a professional do this but now that the time is here his schedule won’t allow him to make it when I need and I’m not delaying my concrete. I just need to get the conduit in. I need to get a single 12/2 out to my garage which is about 12 feet from the house. There will be a concrete pad between the two that I want to run conduit under (not in the concrete). The area the conduit will run is currently backfilled with 2b gravel awaiting concrete (early next week). I plan to use the grey PVC conduit and put it 6”ish down in the gravel. This conduit will exit the garage floor and probably have two 45s in the gravel, total run length 10-12 feet. Then poke through an 8” retaining wall beside the house. Can I use one of these on the side of the wall the conduit comes though? https://www.ar15.com/media/mediaFiles/190718/80D09BD9-DB44-4995-816C-B8CC4F8CA10F_jpe-2619450.JPG Is there a such thing as selecting a conduit that is too large? I was going to use 1”. I only need 1 12/2, but who knows what the future will hold. Go bigger? This stuff gets glued right? Any other tips? All that effort for 12/2? How far? No welder? No kiln? EV? No data, POE? Antenna? |
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Posted: 12/1/2022 1:24:18 AM EDT
[#27]
Quote HistoryQuoted: Now I got this from google so I expect it to be wrong, but I read that 18” under concrete was required on a driveway 4” under in other applications. This will essentially just be a pad, no vehicles driven over this area. I think there's a table in NEC 300.5 |
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Posted: 12/1/2022 2:27:12 AM EDT
[#28]
Quote HistoryQuoted: All that effort for 12/2? How far? No welder? No kiln? EV? No data, POE? Antenna? Quote HistoryQuoted: Quoted: I made arrangements to have a professional do this but now that the time is here his schedule won’t allow him to make it when I need and I’m not delaying my concrete. I just need to get the conduit in. I need to get a single 12/2 out to my garage which is about 12 feet from the house. There will be a concrete pad between the two that I want to run conduit under (not in the concrete). The area the conduit will run is currently backfilled with 2b gravel awaiting concrete (early next week). I plan to use the grey PVC conduit and put it 6”ish down in the gravel. This conduit will exit the garage floor and probably have two 45s in the gravel, total run length 10-12 feet. Then poke through an 8” retaining wall beside the house. Can I use one of these on the side of the wall the conduit comes though? https://www.ar15.com/media/mediaFiles/190718/80D09BD9-DB44-4995-816C-B8CC4F8CA10F_jpe-2619450.JPG Is there a such thing as selecting a conduit that is too large? I was going to use 1”. I only need 1 12/2, but who knows what the future will hold. Go bigger? This stuff gets glued right? Any other tips? All that effort for 12/2? How far? No welder? No kiln? EV? No data, POE? Antenna? Might as well run two so you can get low voltage too... That 12/2 might turn in to 6/3 if you want a small garage panel with 240 for things or even an EV charger, plan accordingly now with appropriate sized PVC. (As already stated thwn not NM, can be bought as "tri-wire" or individually) |
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Posted: 12/1/2022 2:31:33 AM EDT
[#29]
Quote HistoryQuoted: I think there's a table in NEC 300.5 Quote HistoryQuoted: Quoted: Now I got this from google so I expect it to be wrong, but I read that 18” under concrete was required on a driveway 4” under in other applications. This will essentially just be a pad, no vehicles driven over this area. I think there's a table in NEC 300.5  I read that as 4" so long as it stays under the pad ymmv, not an electrician. |
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Posted: 12/1/2022 3:11:40 AM EDT
[#30]
I ran 1-1/2 out to mine for a 100a sub from the house. But in addition too it, I ran 2 - 1" out as well to use for anything that may come up in the future. If your pouring concrete a second one may not be a bad idea in case you decide you want to run a line for a PoE camera or a WAP or something since those would have to be in their own conduit even if you just stub it up and put a cap on it . A 1" will support feeders for a 60amp** sub panel if you needed in the future. (( **Yes, I know there are instances where you can go a little bigger, I'm keeping it simple
 )) |
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Posted: 12/1/2022 3:22:31 AM EDT
[#31]
Running PVC conduit in #2 gravel is asking for trouble.
It will act as a grinder and tear up the PVC. I’d trench that in. |
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Posted: 12/1/2022 3:30:34 AM EDT
[#32]
Don’t pull NM (Romex) or UF cable though an underground conduit. UF will be a nightmare (too stiff and technically the large dimension of the flat cable must be used as the diameter of a theoretical round cable for fill rate calculations, ditto for NM. Besides NM isn’t rated for wet locations. Use THHN/THHNW rated wires. You may want to terminate the conduit in junction boxes or extend the conduit to junction boxes accessible from inside the structure. This allows you to change wiring methods e.g. to splice from THHN to NM. Use 1000lb rated nylon pull string. I’d personally just install 1-1/4” conduit instead of 3/4” or 1” it will be much easier to pull the wires. Also, I’d install two conduits instead of one. You could easily develop the need to pull Ethernet, fiber or coax later.
ETA bury a “caution buried electrical line” marker tape over the conduit, bury it deeper than you think you need (concrete guys can and do break shallow stuff) and wrap a yellow tracer wire around the conduit. Leave each end of the tracer wire zip tied up along the side of the conduit on the ends. ETA2: As the poster above pointed out gravel is hard on PVC, burry it in sand under the gravel. |
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Posted: 12/1/2022 7:23:40 AM EDT
[#33]
Quoted: Running PVC conduit in #2 gravel is asking for trouble. It will act as a grinder and tear up the PVC. I’d trench that in. Quoted: ETA2: As the poster above pointed out gravel is hard on PVC, burry it in sand under the gravel. I don’t have that option. The gravel is 8-9 feet deep in this area. Is there a better choice? A different route isn’t an option. |
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Posted: 12/1/2022 7:36:20 AM EDT
[#34]
Quote HistoryQuoted: I don’t have that option. The gravel is 8-9 feet deep in this area. Is there a better choice? A different route isn’t an option. As short as your run is, have you thought about aerial? |
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Posted: 12/1/2022 8:04:37 AM EDT
[#35]
Second on running a second pipe. It can be smaller. Use sweep bends. Low voltage. Security, network, etc. Put a TV antenna atop the garage. Outdoor WAP to cover the yard. Etc.
Ever going to want an electric car charger out there? |
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Posted: 12/1/2022 8:17:05 AM EDT
[#36]
Quote HistoryQuoted: I don't have that option. The gravel is 8-9 feet deep in this area. Is there a better choice? A different route isn't an option. Quote HistoryQuoted: Quoted: Running PVC conduit in #2 gravel is asking for trouble. It will act as a grinder and tear up the PVC. I'd trench that in. Quoted: ETA2: As the poster above pointed out gravel is hard on PVC, burry it in sand under the gravel. I don't have that option. The gravel is 8-9 feet deep in this area. Is there a better choice? A different route isn't an option. Pvc in gravel is fine. It's done every day in commercial construction. As long as you are under the concrete you are fine. Has the garage concrete been poured yet? 1" pvc is fine. Plenty of room for 12-2 UF (not romex). Also gives you room to pull larger single conductors later if you want a sub panel. LB conduit bodies (like you pictured) are also fine. Make sure it's exposed and accessible for future wiring/service. Do NOT bury it below grade or in a wall. You can also core a hole through the foundation if you have a basement or whatever, and can skip the LB. Limit bends and fittings where possible. PVC is pretty flexible, so you can gently bend it in the trench to make up some of the angle and it will be easier to pull through then a 45 degree fitting. Use glue. Apply glue to both the pipe and the fitting. Hold it together for 5-10 seconds and make sure the pipe is fully seated in the fitting. |
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Posted: 12/1/2022 8:25:50 AM EDT
[#37]
Deburr / chamfer the edges (inside & outside) of the pipe prior to gluing. Helps to mark the end of the conduit so you know how far into a fitting it should go when glued up.
You can use a heat gun to bend the conduit verses buying 90's & 45's. |
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Posted: 12/1/2022 8:49:14 AM EDT
[#38]
An easy way to get your pull string through the conduit is tie a bit of plastic bag on one end and put your shop vac on the other end.
Works like a charm. As mentioned, on long pulls use a wire lube such as Wire-Aid. Pulls vastly easier. |
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Posted: 12/1/2022 8:56:16 AM EDT
[#39]
On long runs I also put a little pull lube in every other fitting before I glue them together.
It really keeps things moving along nicely when it comes time to pull wires. |
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Posted: 12/1/2022 9:05:24 AM EDT
[#40]
Quote HistoryQuoted: Code does require the conduit to be 18" deep, if that helps. Use sweeping 90s so it's easier to pull wire. Not under a slab. |
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Posted: 12/1/2022 9:23:25 AM EDT
[#41]
Quote HistoryQuoted: I could be wrong but I’m pretty sure 12/2 NM cable should not be put in conduit. You need THWN.(THHN rated for wet) Yes Also OP you don’t need to go 18 under a concrete pad. Your plan is fine as long as you don’t use regular Romex. Get 4” under the gravel and you will be good to go. |
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Posted: 12/1/2022 9:46:31 AM EDT
[#42]
Quote HistoryQuoted: This conduit will never be seen again, buried under concrete and gravel. I’m not concerned with it being removable and have no issue using glue. I’ve just never done it so I didn’t know what was the norm for it. That body or box or whatever it’s called that I pictured will be forever accessible. It’s where I will access to pull wire through my “underground” conduit run. called an LB, L - right angle B- back |
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Posted: 12/1/2022 9:48:11 AM EDT
[#43]
Quote HistoryQuoted: Don't forget your slip/expansion joint where that LB ties into the structure, they are $$$$ for larger sizes. I was fricken shocked when I bought a 2” expansion. All the other fittings were reasonable. |
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Posted: 12/1/2022 9:51:07 AM EDT
[#44]
I don't know why this myth persists, but you can absolutely put NM cable in conduit. The only caveat is that it needs to be derated because of potential heat dissipation issues. Mind you, that in and of itself is illogical, but whatever. UF cable is used for direct burial, and it makes no sense to use conduit if you're using UF cable because it's redundant and a hell of a lot harder to work with.
Also, I would say that the *vast* majority of "old work" low voltage wiring is buried all of about two inches deep. Burial requirements are rarely followed. |
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Posted: 12/1/2022 9:54:47 AM EDT
[#45]
Quote HistoryQuoted: Code does require the conduit to be 18" deep, if that helps. Use sweeping 90s so it's easier to pull wire. Some states call for greater depths. And in some states, it has to be a given distance from water or gas. Electrician used his line puller/machine to run a new main from the garage to the house and get rid of our overhead wires coming from the pole. We dug by hand and buried our channel for conduit to 12"+ to run low-voltage network/antenna cables (2x RG6U and 2x Cat6) through 3/4" PVC from our garage to the house. Inspector needed visual confirmation that we were no AC voltage lines in the way or being run in the same conduit before he would sign off on the inspection for the other work. (I just took a photo with my phone and he was happy) In MN, nearly every electrician I talked to has said they are trying to bury the power lines more than 18" (when possible). |
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Posted: 12/1/2022 9:56:11 AM EDT
[#46]
Two main things to check and be sure of.
1. Make sure your burial depth is at least what is required by code. I think 18" under concrete, but make sure you don't have a local addendum. 2. Make sure the PVC thickness meets or exceeds code. They may require sch 80, which you're not likely to get at home depot. Oversizing the conduit is no big deal. It just means a little more expense up front in fitting and terminating the conduit. |
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Posted: 12/1/2022 10:01:59 AM EDT
[#47]
Not an electrician.
But, run 2 conduits, one for electrical and one for communication. My electrical run would be pretty big (for your future EV thread). Don’t use Romex in conduit. Don’t use the 90 corner you posted. Use the sweeps (to allow pulling; be aware that you can only do a max amount of degrees) Your depth sounds ok (look up your code requirements), but deeper is better and glue it well. Good luck. |
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Posted: 12/1/2022 10:04:03 AM EDT
[#48]
Quote HistoryQuoted: Two main things to check and be sure of. 1. Make sure your burial depth is at least what is required by code. I think 18" under concrete, but make sure you don't have a local addendum. 2. Make sure the PVC thickness meets or exceeds code. They may require sch 80, which you're not likely to get at home depot. Oversizing the conduit is no big deal. It just means a little more expense up front in fitting and terminating the conduit. Yes they do... Both 3/4" and 1" schedule 80 is something they stock on-hand Even though I ran low voltage, this is what my electrician friend told me to use in MN and avoid future fuck-around-and-find-out shit from building codes. |
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Posted: 12/1/2022 10:04:55 AM EDT
[#49]
You need to install the conduit at least 18” below grade. Installing it in the gravel will be problematic if the concrete slab shifts. I personally don’t install anything less than 1” conduit below grade. Transition to IMC or Rigid conduit where the conduit stubs out. Wrap the stub outs with insulating tape to prevent corrosion below grade extending above grade. You can use an LB to turn in but I prefer a pull box. If you think you might ever need an additional conduit, now it the time to install it.
Don’t sweat the gravel already being installed. Use a flat nose shovel to remove it and stock pile it near by. Then use a sharp shooter shovel to dig your trench. Back fill the trench with sand and reinstall the gravel. |
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Posted: 12/1/2022 10:54:27 AM EDT
[#50]
A couple of photos.. would it make more sense to just go through the house foundation (green line) and into the basement instead of through my retaining wall and under the porch as shown below in red? I have some electrical under the porch that was all on the garage circuit but I’m thinking it would make more sense to get the garage by itself.
Red line is where I planned to run. 6 or so inches down in the gravel I obviously have to move the gravel that’s placed there for the steps and penetrate through the wall behind it.  Attached FileThis is the back side of that wall where the conduit will penetrate, approximate area circled. This is where I plan to use the LB.  Attached File |
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