Help with subpanel install questions

[ride92]

So I’m going to be installing a 100amp subpanel in my garage. I plan on running several 20amp circuits for outlets all around the garage and a few dedicated 20amp circuits for other things like heater and pressure washer. I need to surface mount my panel because of the way my house was built in 2019. I have 2x4 walls with OSB wall sheathing, 1” foam board over the OSB that is all wrapped in tyvek and the interior walls common with house has 5/8 drywall over that. So finding studs in damn near impossible! The best spot for the panel is just inside and behind the rear service door in the garage.

I have encore wire type SE Style R 2-2-2-4 to use as the main feeder cable from the main panel to the sub. The main panel is just inside and around the corner in the basement from where I’m installing the subpanel. Maybe 6-8 total length needed. I got 1-1/4” EMT and an LB. I am Planning on drilling a 2-1/8” hole thru the sill plate from the basement to the garage to pass this thru.

so question #1: do I need to have conduit going from the NB through the wall and sill plate or can the cable just exit the NB at the threaded 90degree part and pass straight thru the wall?

Question #2: since this surface mounted I need to run the circuit wires up the the attic space but I can’t just run NM-b 12-2 straight out of the box and up the wall. I believe it need to be protected by conduit. I should have enough 1-1/4 EMT to make it into the attic space and I can run THHN thru the 1-1/4 but I don’t know how to add a junction box to the 1-1/4 that I could then run branches or NM out of. Could I just run several 12/2 NM’s down the 1-1/4 EMT? I need 6-8 circuits at least.

Or do I need to just run a couple 3/4 EMT up and connect to a junction box with those

 

[Marc Voorhees]

Okay, so take this for what it is worth, but a few notes as I just did mine.

1) I believe the SER rater 2-2-2-4 does not require conduit as it is service line. I assume you are using it as extra protection? or is there a reason you are using it? you should be able to run it straight through the sill and into the LB, I have done it before and the inspector passed it without much comment.

2) you are correct you need to run conduit up to the attic space. My opinion is to run multiple 1/2 or 3/4. Personally, I run one 1/2 conduit when I do it this way with 1 NM in it for each circuit., I find it a bit neater and easier to organize in the attic. Plus this way I always know exactly where everything is. I BELIEVE if you wanted to run one 1 1/4 up you don't need to put a junction box at the end of it, each wire would then be able to go to its own box separately away from that conduit. Once the NM is in the attic space it can be run along joists etc as needed. You may need a EMT-NM end piece for the conduit to secure the wires, but honestly I don't even know if that is needed if you secure the wire within a certain distance to prevent movement. I know they make these for smaller conduit, not sure about 1 1/4.

I am sure I will be corrected f I am talking too much out of my ***

 

[ride92]

1) I believe the SER rater 2-2-2-4 does not require conduit as it is service line. I assume you are using it as extra protection? or is there a reason you are using it? you should be able to run it straight through the sill and into the LB, I have done it before and the inspector passed it without much comment.
(I’m surface mounting my subpanel so the length it comes out of the wall and goes up to the box I’m running it in emt since it will be exposed. I just didn’t know if coming out of the LB elbow if it has to be sleeved thru the wall.)

As for the 2nd part: I need about 6-8 different circuits and am thinking running THHN up thru the conduit would be less cluttered as I could run multiple circuits in each emt to the ceiling. 8 1/2” emt is going to look cluttered and I’m trying to keep it clean looking. I actually have enough 1-1/4 left over I might just use that but I’d have to find a way to attach a junction box in the attic. Can I enlarge a knockout to fit the 1-1/4”? If I do that can I clamp several NM cables in one larger knock out?

 

[Marc Voorhees]

1) I believe the SER rater 2-2-2-4 does not require conduit as it is service line. I assume you are using it as extra protection? or is there a reason you are using it? you should be able to run it straight through the sill and into the LB, I have done it before and the inspector passed it without much comment.
(I’m surface mounting my subpanel so the length it comes out of the wall and goes up to the box I’m running it in emt since it will be exposed. I just didn’t know if coming out of the LB elbow if it has to be sleeved thru the wall.)

As for the 2nd part: I need about 6-8 different circuits and am thinking running THHN up thru the conduit would be less cluttered as I could run multiple circuits in each emt to the ceiling. 8 1/2” emt is going to look cluttered and I’m trying to keep it clean looking. I actually have enough 1-1/4 left over I might just use that but I’d have to find a way to attach a junction box in the attic. Can I enlarge a knockout to fit the 1-1/4”? If I do that can I clamp several NM cables in one larger knock out?

1) right, but the exposed part doesn't need to be in conduit anyway (unless you want it to be) it is rated as its own conduit since it is service. Same reason when service lines outside are just exposed. If you want it in conduit I believe you can do exactly what you said, I did it before and it passed

2) yeah, I see what you are saying here. If you want to run thhn into a junction box, I would do the 3/4 and then run 2-3 up each this lowers the amount of conduit. I guess in my subpanens I only ever have 4 circuits or so, less messy. You just have to make sure you are labeling everything or you will end up mixed up pretty quick.

I do t think it is possible to modify a standard junction box to accept 1 1/4. Plus, the junction box will be too small by volume to hold 8 circuits and jump offs. I would say this is the least good option.

 

[Bert_]

Yes ser doesn't require conduit but the way you want to do it is good. I would just poke a short ****** through the sill plate. Use as big of an lb as you can. #2 cable doesn't fit in small LB's

I would just sleeve the Romex into the panel also rather than putting a junction box in the Attic. Each wire doesn't need its own conduit.

 

[Terry D]

I agree with Bert. Use as large of conduit as you can out the top of the panel into the attic, and just fish you Romex down to the panel. No need to switch to THWN. I also would sleeve the SER through the sill plate. Use a box connector on the end with a threaded plastic bushing or a bang on plastic bushing.

Plastic EMT Insulating Bushing, 1-1/4 in.

EMT Insul Bushing 1-1/4IN

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