Conduit to subpanel inside garage

[Jeff590]

I have a detached garage that I want to run electric to. I did not have a specific plan for the subpanel location when it was being built, so when the foundation/slab was put in the guy doing the work asked if I wanted to put in a conduit run. I bought 1 1/4” schedule 40 conduit and a 90 degree elbow and we put it in. It comes up in the front corner, about 2 inches from each block wall and about 18 inches tall. I am getting a permit, so I want to lay out a plan before I set up a meeting with the county inspector.

Some questions:
- Is this considered "exposed to physical damage"? Should I plan to replace this with schedule 80? (this is inside the structure, very close to the walls) And by replace, I mean to cut it off close to the slab and then put in a section of schedule 80 so that only schedule 80 is exposed.

- Can I use a LB on the top of this and then run a 90 degree elbow and conduit in the wall up to the panel box? Seems ok to me, but I can’t recall seeing something similar.

- Are there “schedule 80” fittings? Like the LB and 90 degree elbow, or is the schedule 80 just straight pipe?

Thanks!

 

[Bert_]

-I would not consider that subject to damage since it is in a corner like that, but your inspector may see it differently.

-No reason you can't the only concern is that the 90 may not fit in the wall. It would have been nicer to place your pipe IN the wall if you wanted a flush mount panel.

-Fittings are all the same.

I've noticed sch 80 will crack almost as easily as sch 40. In an application where you are truly worried about damage the only real solution is a section of rigid steel pipe were it emerges from the concrete.

 

[wyliesdiesels]

What size circuit did u plan on running to the garage?

 

[Jeff590]

50 amp with #8 copper THWN assuming the inspector signs off on it.

 

[Jeff590]

-No reason you can't the only concern is that the 90 may not fit in the wall. It would have been nicer to place your pipe IN the wall if you wanted a flush mount panel.

Yes it would have. What I am proposing would have the elbow partially in the wall and I would drywall around it. Not great, but the best solution I think.

 

[Eriehunter]

Could you just cut the conduit off flush at the slab and patch it? Dig outside the building intercept the conduit in the ground and route it up inside the block wall inside the finished wall?

 

[Ed Devinney]

FWIW, and I'm no expert, but the conduit that goes under my garage slab from the meter and disconnects to the panel is plastic, and is exposed at either end of the slab.

 

[Jeff590]

Ok, so I mocked up what I was planning to do here:



Does this look ok? The vertical going into the bottom of the box will be behind drywall eventually and the LR box and part of the 90 degree sweep will be exposed. Here is a closeup of that run:



Someone asked about just going into the side of the garage, and I could do that, but I think this is cleaner since the pipe is already in the slab. The area in front of the panel needs to be clear anyway, so I’m not concerned about losing that little bit of floor space.

Any concerns before I epoxy the floor this coming weekend?

 

[mm08822]

I know its only a mock-up but you will need at least one strap into horizontal nailer to secure the conduit.

Also if you are finishing the inside of the garage, you will need blocking and another stud for that corner to secure drywall, etc.

How about this alternate conduit routing and eliminate the exposed 90 and LB (double up the 2x4 on the right before drilling holes in stud and add nail plates......I think that is much safer to minimize possible damage.


How old is the floor? What is the minimum cure time needed before applying epoxy? Is your construction work far enough along so you wont damage new floor coating?

 

[wyliesdiesels]

Mms idea is cleaner and less obtrusive.

BTW i dont see a ground bar in that panel. Make sure u put one in and isolate the neutral bar.

U will also need 2 grounding electrodes...

 

[CNGsaves]

+1 that only using conduit size 1 1/4" might be a problem.

What is planned CIRCUIT size ?? What is DISTANCE of the buried wire to main panel ??

What WIRE do you plan on using ??

 

[wyliesdiesels]

+1 that only using conduit size 1 1/4" might be a problem.

What is planned CIRCUIT size ?? What is DISTANCE of the buried wire to main panel ??

What WIRE do you plan on using ??

see #4 above

 

[Jeff590]

I know its only a mock-up but you will need at least one strap into horizontal nailer to secure the conduit.

Also if you are finishing the inside of the garage, you will need blocking and another stud for that corner to secure drywall, etc.

How about this alternate conduit routing and eliminate the exposed 90 and LB (double up the 2x4 on the right before drilling holes in stud and add nail plates......I think that is much safer to minimize possible damage.


How old is the floor? What is the minimum cure time needed before applying epoxy? Is your construction work far enough along so you wont damage new floor coating?

Strap - yes, understood. That's that 5/4 board in the picture on the lower left. This will be screwed to the sheathing and then the conduit strapped to it, assuming this is the routing.

I like the alternate routing, but I am concerned about pulling the wire without that LB in place. I am thinking about stepping up to #6 wire and there will (3) 90s underground already. I assume what you are proposing is to use (2) 45s and then another 90? Will I be able to pull the #6 wire through all that? (run is probably 40 feet in total)

On the floor, it is 2 months old, and with me doing some of the stuff myself on evenings and weekends, I want to get the floor down while the weather is decent. I know it's a risk.

Thanks for the feedback.

 

[Jeff590]

BTW i dont see a ground bar in that panel. Make sure u put one in and isolate the neutral bar.

U will also need 2 grounding electrodes...

Thanks - I have the ground bar also, just didn't install it yet.

 

[mm08822]

Strap - yes, understood. That's that 5/4 board in the picture on the lower left. This will be screwed to the sheathing and then the conduit strapped to it, assuming this is the routing.

I like the alternate routing, but I am concerned about pulling the wire without that LB in place. I am thinking about stepping up to #6 wire and there will (3) 90s underground already. I assume what you are proposing is to use (2) 45s and then another 90? Will I be able to pull the #6 wire through all that? (run is probably 40 feet in total)

On the floor, it is 2 months old, and with me doing some of the stuff myself on evenings and weekends, I want to get the floor down while the weather is decent. I know it's a risk.

Thanks for the feedback.

You should have no problem with 6's in 1-1/4". Instead of a coupling on the conduit coming out of the floor, use a "C". then you can go into the offset and last 90. Code is max 360 degrees of bends between outlets. Maybe 45's can do it for you. Without being there to measure hard to say, but you can always trim 45's to get the correct offset, just don't trim down into oval areas of the 45's.

Or you can use a heated blanket to soften the pvc to get the offset needed w/o any 45 pieces.

You would want 2 straps in this routing to have a secure conduit run inside.

screw nailers to the studs.

 

[sberry]

Or can come up outside the building to LB

 

[pattenp]

Jeff590, do you understand mm08822 is saying to use a "C" type conduit body in place of the "LB" type.

 

[Jeff590]

Jeff590, do you understand mm08822 is saying to use a "C" type conduit body in place of the "LB" type.

Yes - but I had to Google it

I'll talk with the inspector and see if he has any preference or concerns on the approaches.

 

[Norcal]

With that conduit stub where it is could be defined as not protected against physical damage, it would not take much to snap it off flush with the slab, have seen it before.

 

[sberry]

That looks like a fuccup. Do it outside and as a benefit it makes it obvious where the power enters the building which can be a good thing.

 

[Jeff590]

That looks like a fuccup.

Possibly. I guess it is just a guy building his first garage and not knowing the best approach for everything. But thanks.

 

[Marctrees]

Jeff - No bigee.

I would put in the "C" condulet if you are concerned about the pulling.

Frankly, if your total # of bends is clearly within code allowance, I would skip the "C".

Or just make the pull, then finish the pipe to panel.

Some will have problems w that idea, whatever.

In any case, Use the path MM suggested probably.

Only advantage of the LB and 90, is no need for the torch hot kick.

Get that pipe kicked over to the wall.

Just check Youtube videos for using a propane torch for bending PVC.

Very easy, just go SLOW to not char the pipe.

The heat blankets mentioned above are very nice for often done work, but totally unnecessary for home hobbyist, and like surprisingly expensive.

In any case, put a couple of 2x4's at 45 across that corner, maybe faced w ply, to protect that stub exiting the floor, up till the just above height of above the hot kick you will make.

Stuff happens, no big deal. Marc

 

[mm08822]

Yes - but I had to Google it

I'll talk with the inspector and see if he has any preference or concerns on the approaches.

Run both by him. Bring the pics. The conduit at floor level can always be protected. Just more to look at. Find out the minimum what he wants for protection.

In your original mockup, inspector might not like the conduit as a hinderance to the required working space.

Last resort, get your shovel out.

 

[sberry]

Yes, I would abandon that and do it up the outside.

 

[Jeff590]

How about this alternate conduit routing and eliminate the exposed 90 and LB (double up the 2x4 on the right before drilling holes in stud and add nail plates......I think that is much safer to minimize possible damage.

I took down the original configuration and was playing around with this new approach tonight, but now have a question. If I keep the 1 1/4 conduit up to the side of the panel, I assume I will need the same male terminal adapter to attach to the box with a locknut. I'm measuring the OD of the terminal adapter to be a little over 2 inches, so I would probably drill a 2 1/4 inch hole for it to fit through. Even doubling up the studs to allow for a 60% hole size, I think I'm allowed only 2.1 inches, so that is going to be really tight. Also the knockout on the box is towards the rear, so that 2.1 inches won't be in the center, which I read as not compliant.

Seems like I can't do this unless I drop down in conduit size. Is there some other approach I could take here?

Thanks!

 

[wyliesdiesels]

Possibly. I guess it is just a guy building his first garage and not knowing the best approach for everything. But thanks.

Best place is to bring the stub up through the bottom plate right below the panel...

 

[mm08822]

I took down the original configuration and was playing around with this new approach tonight, but now have a question. If I keep the 1 1/4 conduit up to the side of the panel, I assume I will need the same male terminal adapter to attach to the box with a locknut. I'm measuring the OD of the terminal adapter to be a little over 2 inches, so I would probably drill a 2 1/4 inch hole for it to fit through. Even doubling up the studs to allow for a 60% hole size, I think I'm allowed only 2.1 inches, so that is going to be really tight. Also the knockout on the box is towards the rear, so that 2.1 inches won't be in the center, which I read as not compliant.

Seems like I can't do this unless I drop down in conduit size. Is there some other approach I could take here?

Thanks!

Sometimes the hole just gets deeper and deeper!
There are a few options:
You can holesaw your own ko in the box on centerline where you need it. I say hole saw b/c i doubt you have access to a ko punch. (1-1/2" from memory? Doublecheck me).
Always allow room for locknut and bushing.

Then drill the 2.25" hole through both studs. You could always scab on a steel plate to the studs with the same hole diameter/location to get more strength back into the studs.

Safest way to do this is drill your pilot hole squarely through all and then take down panel to drill it and the studs seperately with respective hole sizes.

PVC does not require nail plates but i would reccomend it. You could probably flatten two plates and work them in between stud and sheathing with a little persuading.

You could also use an emt 90 through the studs for a slightly smaller hole but now you need to knotch for the set screws at 6:00 or 12:00.
You could skip the nail plates here.

Next option.....shovel.

Nothing a lot of time cant fix!

 

[cort]

The best advice here is to excavate outside and route the conduit up the ouside wall of the building into the back of the subpanel. Rather than waste anymore of your time researching conduit fittings and plotting awkward paths, bite the bullet and start digging.

 

[sberry]

The best advice here is to excavate outside and route the conduit up the ouside wall of the building into the back of the subpanel. Rather than waste anymore of your time researching conduit fittings and plotting awkward paths, bite the bullet and start digging.

This is worth repeating.

 

[Marctrees]

Jeff - One more last opinion - Do the LB and 90 EXACTLY as you mocked up in post #8.

I would strap pipe at 2 places.

Build an enclosure over that top of LB level w lift off lid, like a little corner 45 deg bench.

Put a potted plant on it.

Quickest and simplest , best of all ....Done. Marc

 

[Marctrees]

Jeff - Can't tell for sure from your photos if you have an LR there (best choice) or an LB turned toward camera just to show??

Anyway, LB is ok, LR more professional, but little tougher to get. Marc

 

[Marctrees]

FYI just in case...... Post # 104 in this thread... Marc

http://www.garagejournal.com/forum/showthread.php?t=285957&page=6

 

[carotene]

If it were me I'd run new conduit in from the outside to an external LB to the exact spot you need to align with the subpanel knockout. Keep your existing stub-up around if you want to run some low-voltage wiring sometime in the future. When you trench, run both conduit together. And when you run your new external conduit use 2" in case you want to upgrade to 100A in the future.

Build an enclosure with lid in the corner as Marc suggested above to protect the existing stub-up, but at least with LV wiring you don't have to worry about funky runs and elbows to the subpanel.