Sub Panel Feed Wire Question

[ProjectX]

Hi New member to this forum here. I discovered this forum from searching for info on installing a sub panel in my attached garage. I'd like to do this correctly since I don't like to cut corners especially where bad things can happen if not done correctly. Anyway, I'm sure I will have a few more questions but my main question at the moment is finding out if I can run the feed wire from my main panel to my sub panel through conduit and above ground. My main panel is on the outside of my house and I would like to install a sub panel on the same side of the house about 20 feet away inside my attached garage. I'm would like to know if I can run this in conduit along the outside wall, maybe 10 inches above the ground, then up about 5 feet, though the brick and inside my garage where I would install the sub panel using the appropriate conduit connectors ect. Also, what type of wire would be appropriate for this type of run? I'm hoping this would not need to be buried since that would be somewhat difficult since I have 2 ac units/pads that would be between the main panel and where I want to enter the garage plus who knows what other things are buried and running along the side of the house.

Thanks in advance!

 

[wyliesdiesels]

yes you can run conduit for this. as for wire type, use THWN

what size feeder do you want? that will dictate the conduit size you will need.

remember you will need 4-wire: 2 hots, 1 neutral, 1 ground. the neutral buss(es) need to be isolated.

check the electrical FAQ sticky for diagrams...

 

[ProjectX]

Thanks for the response. Thats a relief on the conduit .

I was planning on going with a 100A sub panel. I'm needing this to run a 220v welder 30A and a 80 gallon compressor which should be 30 A, but I need to verify that. The welder and the compressor should be used separately. I would be using the compressor and a plasma cutter which is 220v 20a at the same time. I will have a look at the FAQ section.

 

[The Cobbler]

most home shops don't require 100 amp services since you're normally only using 1 machine at a time. figure out what you'll be using and that will help determine your amperage needs . do you plan to heat it? with gas or electricity? Air condition? etc

 

[ProjectX]

No heating, it's basically my 2 car attached garage and Im in Texas. It gets hot but I don't ever see me running ac either. Based on how it was at my previous house you are right, the only 2 things usually running at the same time would be the compressor and my plasma cutter. The welder and the plasma cutter last time shared the same 220v plug (one at a time) and the compressor would be the other 220. I dont really need any 110v circuits since the garage has plenty of 110 plugs. What service size would you recommend?

 

[wyliesdiesels]

Well 60a might be plenty. You could use #6 THWN and if you dont want 120v out of that panel it would be 6-6-10 meaning 2 runs of black #6 and 1 run of green #10.

Or you could go with #2 AL which is probably cheaper than the copper and that will give you 90a...

 

[mike93lx]

I'd do #2 aluminum xhhw and any breaker size between 60 and 90. Lots of supply issues with breakers, so you may find a 90 is very expensive or not available.

I'd run the 4th wire and have 120v out at the sub too. The run is short, so the money saved won't be massive and it won't restrict you later

Three #2's and a #4

 

[75gmck25]

You can run 2-2-2-4 AL Mobile Home Feeder in conduit and it will handle up to 90 amps. You can use a 90 amp breaker at the main panel, or even downsize to a smaller 60 amp breaker (easier to find at the home store). I would recommend a 100 amp, 24 space panel at the garage, since it gives you more flexibility than saving a few bucks by using a smaller panel.

Aluminum MHF is used a lot and stocked almost everywhere, so its relatively cheap compared to the choices in copper wire. I would recommend using 2" conduit and making sure all bends are long sweeps. Using an LB as a pull box when changing directions with the wire also makes it a lot easier.

 

[ProjectX]

Thanks Guys for all the help and advice so far, this site has been a great welth of knowledge in the few hours I've been a member. I've been reading through different post on this topic and started venturing out to the different formun lists. Looks like a great site for the DYI type person.

I would like the option for 110v there if I needed it in the future. What size conduit would you recommend for for this run? Can I use metal conduit or does it have to be the pvc type, also if PVC what type would be recommended. I saw different "schedule" types when I looked it up online at one of the big box stores so some advice on that would be great.

 

[Max]

I have a 60A sub panel in my one man shop and it works fine for me. I do woodworking, so for me the maximum load is table saw plus dust collector with both the mini split and air filter running. I also have a bunch of 120V outlets but they are either not used or running low loads when I run the big tools. I have never popped a breaker, but I do think that 90A would have been more future proof. In your case it’s only 20’ so I‘d go 90 or 100 as the added cost will be small.

Use a good sized sub panel and you’ll be able to add all of the 120V lines you want. I am not sure about your question, but you do not need to run separate 120V lines to your panel. When you run the wires to the sub panel you run two different hot phases, one neutral, and one ground. You get 240V by using both hot phases, and you get 120V by using one hot and a neutral.

Note that depending on where you live and which version of the NEC is being used, you’ll almost certainly have to use anti-tamper outlets and GFCIs (either breaker or outlet) for your 120V outlets. If your area is using the 2020 NEC you’ll need GFCI breakers for the 240 as well. I don’t know if you’ll need arc fault breakers or not - someone more familiar with the NEC will have to answer that. This all presupposes that you live in the US…

 

[ProjectX]

Ok, yes I think for the minimal cost increase more amp panel maybe better for future needs. I'm not sure which question you were confussed about but I was asking about the type of PVC conduit since when I looked it up on HD website I saw something about schedule 40 and maybe 80 or something like that. I thought that was more for water pipes, but it was last last night so maybe I miss read something lol. The other question was regarding what conduit size I needed to use? I need to get my profile filled out which I will do today but I am down in Houston Texas.

 

[Innovate1]

Sch 40 PVC is easy to work with and readily available. In most cases that is fine but some places require schedule 80 outside where it may get hit with vehicles, mowers, etc. I lived near one place that required Sch 80 for the inlet to the meter base because of possible damage. Best to check with local authorities. For my recent detached garage I had to use GFCI on all recepticles but they didn't require tamper proof.

Sounds like 60A is more than enough but that's something you have to figure out for your uses. Best to do more than the minimum immediate requirement for future expansion (electric car?). But also know that you will get a number of people here telling you to grossly oversize things (Tim Taylor, more power theme...)

Size of conduit is not something to scrimp on. I pulled one run at my house at near max fill (there are tables for how many conductors are allowed in different sizes of conduit) and it made the pull difficult. You only have a few bends so it won't be bad but upsize at least 1 size and maybe two. Long sweeps help but are more difficult to find in under 2". I used 1.5" for the run to my shop and it was an easy pull for two #1, one #2, and one #4 with a much longer run. I bent the long sweeps to 24" radius with some steam heat and then bent them around a large tire. Sounds like you may only have one bend and a LB so a regular bend will likely be fine if it's a bit larger than minimum.

 

[mike93lx]

Schedule 80 is heavier wall and you would want to use it where it would be subject to damage.

2" would make for an easy pull

 

[Innovate1]

Here's a fill calculator.

Conduit Fill Calculator | Southwire

Get accurate conduit fill percentages with Southwire's Conduit Fill Calculator. Perfect for electricians, engineers, and contractors.

www.southwire.com

1.5" can take up to 7 #2 AL conductors. No way I would want that many but for 3 with a #4 ground I think it would be fine and you might have that big of hole in the main panel already. If you go 2" you may need to punch the hole for it.

 

[Innovate1]

Wireandcableyourway.com is a place many of us have used to get wire. They will put it on multiple reels if you buy single conductor so it's easy to feed from the spools for you run. With your short run that isn't as big of issue.

 

[ProjectX]

From what you guys are saying sounds like 1.5" schedule 40 may work especially since it's a really short run and not subject to damage since it will be on the side of my house. Another question is seems like sub panels are out of stock in my local home stores in the smaller sizes. I was looking at 100A or 60A with 10 or 12 spaces which should be more than enough for my purposes. If I had to get a 125A panel could I down size that with the feeder breaker (sorry not sure about the correct term) like say a 60A breaker to feed the sub panel or does it have to match the actual panel amperage or does it matter if the sub panel is 100A as well? Sorry about all the questions, I think for now after this round I should have a pretty decent handle on things and you guys have been tremendous wealth of help and knowledge.

Innovate1, thanks for the wire website, those are some great prices per foot. Hopefully the shipping isn't too bad. Also, according to that fill calculator I should be good to go with 1.5 PVC.

 

[Innovate1]

The main breaker in the subpanel can be bigger. No issue as it is only serving as a main shutoff. The feeding breaker provides overcurrent protection. The 100A panels are a good size. I went with a 24 slot one but it was for a detached 30 x 40 space. Only thing to watch for is the range of cable size the lugs are rated for and there are ways to work around that and you have to get quite a difference to run into that. I used XHHW aluminum. The single strands are a little easier to pull than the twisted MHF and you have more choices of wire size.

 

[Innovate1]

1.5 is almost two sizes bigger than what the fill calculator says is needed - 3 x #2 + #4 is barely over allowed in 1". I wouldn't go smaller than 1.5" because in my experience you want at least 1 size bigger for ease of pull on short runs without many bends (your case) and + 2 sizes (or more) for longer runs and more bends. I had to add mine to the top of a nearly full main panel at the house and I was able to get 1.5" in without too much trouble and even had an available large knockout. 2" would have been a lot more work.

 

[Innovate1]

Not sure what brand you are looking at but I checked locally and both Menards and Lowes had several Homeline 100A 24 slot panels in stock. You might want to use the same brand as your main panel so the breakers are interchangeable. Not required but that's what I have done.

 

[dcg9381]

No heating, it's basically my 2 car attached garage and Im in Texas. It gets hot but I don't ever see me running ac either. Based on how it was at my previous house you are right, the only 2 things usually running at the same time would be the compressor and my plasma cutter. The welder and the plasma cutter last time shared the same 220v plug (one at a time) and the compressor would be the other 220. I dont really need any 110v circuits since the garage has plenty of 110 plugs. What service size would you recommend?

Welcome.. This is a great place for electrical advice.

Having built a separate 2-car garage before, I'd agree that 60A is more than enough.
If you're wanting "100A service" - the sweet spot for wire price per foot is actually 90A using MHF. I'd use 2" conduit. If you're going to need to get anything else to that garage (like internet), you may want to run a parallel 3/4" conduit. It's cheap and easy to do once trenched.

I'm surprised that you don't see a need for AC. a 2-ton ductless split unit can be had DIY installed for about $1500 last time I checked and will pull less than 15A continuous (Daikin). It's more than enough for a marginally insulated 2-car garage, but that's OK because you're not cooling it all the time and ductless systems are less sensitive to this "short cycle" business that you need to be careful with when sizing residential AC.

For what you're doing, where you need a relatively small number of breakers, have less than 100A feed, I like the Siemens Talon panel - it comes with 3 breakers and 3 outlets already installed on the panel (50A@240V, 30A@120V, and 20A GFCI). It's my "go-to" for garages/small shops. I think it has 5 breaker slots that are open and costs <$200. It surface mounts and can be mounted outdoors.

Make sure you install 20A outlets. Trust me. They cost a little more.

 

[mike93lx]

Make sure you install 20A outlets. Trust me. They cost a little more.

Why? Most shops have no 20a equipment and the guts are the same as 15a on good quality stuff

 

[dcg9381]

Why? Most shops have no 20a equipment and the guts are the same as 15a on good quality stuff

I have one or two "**** tools".

The bad thing about this forum is tend to get in the weeds a bit. Just wait until you mention "220V power".

A 15A circuit is rated for 12A continuous use. I agree that as long as you're working with devices that pull less than 12A continuous and you only have one on that circuit, 15A is fine. Or you can do it like me and install 20A circuits with 20A outlets only. Both are fine, depending on what you're using on that circuit.

 

[mike93lx]

I have one or two "**** tools".

The bad thing about this forum is tend to get in the weeds a bit. Just wait until you mention "220V power".

A 15A circuit is rated for 12A continuous use. I agree that as long as you're working with devices that pull less than 12A continuous and you only have one on that circuit, 15A is fine. Or you can do it like me and install 20A circuits with 20A outlets only. Both are fine, depending on what you're using on that circuit.

Or just do the normal thing and run 20a circuits with 15a receptacles.

 

[ProjectX]

Thanks Guys, this has been very informative and nice to come to one group and get all the answers. I'm going to start getting things together to get this project started over the next couple of weeks. I will definitely come back and give an update and I'm sure I'll have a few more questions. I checked and my current panel only has 2 slots left so I guess that will go to feed the new sub panel. I'm actually surprised that it's out of slots and nothing has been added since the house was built.

 

[mike93lx]

Thanks Guys, this has been very informative and nice to come to one group and get all the answers. I'm going to start getting things together to get this project started over the next couple of weeks. I will definitely come back and give an update and I'm sure I'll have a few more questions. I checked and my current panel only has 2 slots left so I guess that will go to feed the new sub panel. I'm actually surprised that it's out of slots and nothing has been added since the house was built.

Most panels can accept some amount of tandem breakers, which you can use to gain spots if you do need future capacity

 

[TractorJeff]

Technically he only needs those 2 available slots for his current project.........

 

[mike93lx]

Technically he only needs those 2 available slots for his current project.........

Yup.

And then tandems in the future if more space is needed, as I said

 

[Innovate1]

If tandems don't work for whatever reason and you need more spaces in the future a subpanel beside the current one isn't a huge project.

 

[starquestMM]

For what you're doing, where you need a relatively small number of breakers, have less than 100A feed, I like the Siemens Talon panel - it comes with 3 breakers and 3 outlets already installed on the panel (50A@240V, 30A@120V, and 20A GFCI). It's my "go-to" for garages/small shops. I think it has 5 breaker slots that are open and costs <$200. It surface mounts and can be mounted outdoors.

Hmmm, I like that panel, seems like a good ev charger base

 

[ProjectX]

Well I'm back sooner than expected. I was looking at where the run would be and I am planning to come down from the main panel and then. hang a 90* (left) going towards the garage but the meter box has as 1.5" or 2" pipe coming from the ground up into the meter which I would have to go around to continue towards the garage. I took some pics of the planned run area. How would you get around this pipe? It's kind o the same problem with the sprinkler pipes about 12' further up which you can see in the pictures.

Ok, in looking at the pictures while posting this, I'm not sure but if there is a knock out on the upper left of the panel could I come out of there and do a 90* down on the other side of the meter box missing that whole large pipe and then continue on. Not sure if the box has side knock outs but I'll check tomorrow. What do you guys think?

 

[mike93lx]

An electrician would probably use a heat blanket to soften the conduit and move around those obstacles no problem. I just had all the electrical done for my pool and it was pretty neat to see them do some wild bends without a single prebent fitting. All just pipe.

Problem is, I was told the blanket cost $750...

Edit: here is an example https://www.ktool.net/current-tools...-3-dimensions-13-1-2-x-30-800-watts-6-7-amps/

Looking at all that, I would probably go into the ground a few feet from the house and run it there. Getting around all that will be a real PIA

 

[Norcal]

Not code approved but a heat gun, weed burner, or propane torch, works to bend PVC, heat gun offers the most control because scorch marks are a no no.

 

[ProjectX]

I really don't like the idea of digging because I just did some minor digging around a tree a few weeks ago and I thought I was going to pass out, damn that was rough lol. ***** to be in your 50's. Would it be possible to run it like the picture below? I haven't checked the panel yet but I would assume it has knockouts on the side, but not sure if this run would be a code violation, if so I'm going to have to get really good at headting and bending PVC

 

[mike93lx]

I really don't like the idea of digging because I just did some minor digging around a tree a few weeks ago and I thought I was going to pass out, damn that was rough lol. ***** to be in your 50's. Would it be possible to run it like the picture below? I haven't checked the panel yet but I would assume it has knockouts on the side, but not sure if this run would be a code violation, if so I'm going to have to get really good at headting and bending PVC

Absolutely possible. You just can't exceed 360 degrees of bends between pull points.

Digging *****, but you can rent a 1 ton mini ex for under $300 a day at home depot. Just need to hand dig around the utilities

 

[Innovate1]

I really don't like the idea of digging because I just did some minor digging around a tree a few weeks ago and I thought I was going to pass out, damn that was rough lol. ***** to be in your 50's. Would it be possible to run it like the picture below? I haven't checked the panel yet but I would assume it has knockouts on the side, but not sure if this run would be a code violation, if so I'm going to have to get really good at headting and bending PVC

Exactly what I was going to suggest before I saw the picture. If the panel doesn't have a knock out in the side or one not big enough you can use a Greenlee punch to make a bigger hole - Kind of expensive and probably hard to find to rent. Need to find a friend to borrow from. Others will correct me if I am wrong but I don't believe there is any code issues with adding/enlarging holes. You can buy PVC 90s so you may not have to bend it yourself if have enough oversize to make the pull not too difficult. If you want longer sweeps you may have to bend yourself. I used steam for several minutes through a larger pipe so it gets heated evenly. I found 2" large sweeps were available locally but smaller were much harder to find. It looks like you could run just below the window and avoid the sprinkler pipes but not as aesthetically pleasing.

 

[Norcal]

A KO as shown in the drawing that high on the side of the panel will require a sealing locknut, or a Myers hub, because the opening is above live parts, factory KO's are always on the bottom for that reason.

 

[ProjectX]

Innovate1, I don't have any electrician friends, unfortunately, and I definitely dont want to sink money into a took I probably won't use again. Lord knows I have a few one time tools that I had to buy and won't use them again. The difficulty factor is definitely going up, this started out as just running two 220v circuits to the garage to sub panels and bending 1.5" conduit lol.

Norcal, you are right there is no knock out that high, but on the right bottom side there is a knockout, also a bunch on the bottom, so I would just go with one of those. I think I will attempt to bend the PVC to go around the PVC feeding the meeter and then from there should be a straight run. The sprinkler lines if I go high enough I should be able to go behind it after unscrewing the strap that attaches it to the wall. I watched some YouTube vids on bending the conduit, some had some very slick ways to do it, so the plan it to give it a try with a practice piece to see if I can bend it successfully, keep things safe and not look like a 3rd grader did it.

 

[Innovate1]

Sounds like a good plan. If the bending doesn't go well you can always use four 45 bends to go over things. It probably will give more room than needed for the conduits you are going over but you can rotate the bends to be closer to the wall.

 

[mike93lx]

$65 for a one day rental feels like money well spent.

1/2" - 4" 110V PVC Heater Greenlee 851 | Sunbelt Rentals

This PVC heater heats 1/2'’ to 4’’ diameter PVC pipe, making it easy to form and bend PVC to the job requirements. Machine provides heavy-duty, insulated walls to effectively heat pipe up to 50’’ long. Easy operation with full door to open and close, and wheels for mobility. Operates on 110V.

www.sunbeltrentals.com

Make sure you have gloves... You'll need to support the pipe until it cools

Heat guns take a lot of time and patience and you will scorch the pipe using a torch

 

[Innovate1]

My local sunbelt only charges the one day rate for the weekend too. Pick it up Friday and return first thing Monday.