[community]

Introduction:

My attached, two-car garage in my 1984-built home has one outlet in it, and I would like to install a subpanel so that I can run additional circuits for the purpose of woodworking. The immediate question is can or should I do this myself? Or if not a subpanel, what other, potentially better options are there?

House main panel information:

The existing main panel is a Cutler-Hammer CH7CC, presumably original to the home, with a 100-amp main breaker and two of the 22 slots open. One breaker will have to be moved to install a new, two-pole breaker for a new subpanel in the garage. The breakers are CH, given the 3/4” width and tan handles. Two of the three licensed master electricians I had in this past week to provide estimates for the job ($2,200 - $2,600) said it is a very high-quality panel that will last for many more decades, additionally noting that it will not be a problem to install a few 20-amp circuits in the garage, even given the 2,300 sf home has central air, an electric clothes dryer, and an electric range. For woodworking, only a main tool and a dust collector would run at the same time. There is -- oddly -- spray foam around the panel. This was clearly added more recently, likely to keep out rodents or cold air. One electrician noted this, adding that it is unusual...but not bad for the wiring.

House main panel location and proposed wire run:

The existing main panel is located in a drywalled wall in the finished basement, 16' 8" directly across from the side garage-house wall. The space has a drywalled ceiling, part of which is 6.5" lower due the sunken living room above, and the joists are running perpendicular to a direct wire run. Both the garage and this space are in the front half of the house.

The back half of the basement is all drop ceiling and so is effectively open and accessible. There is actually a >6" wide space running along the center beam (so between the main ductwork and the beam itself) that already has several wires running along it. To get to this beam, one would have to go up the drywalled wall into the ceiling and back (parallel to the joists) 10', and once the wire has been run 30' across the house to the utility room, it's just 5' across the room and a few feet up the back of the garage wall that is shared with the house. The total wire run would be roughly 45' plus going up from panel to ceiling and going up from utility room ceiling / garage floor to subpanel in garage. This is the same path the three electricians said they would take, each saying they would use six-gauge wire.

I have run miles of low-voltage wire in commercial facilities, including through drop ceilings, and I've done enough drywall work to not be concerned about access or patching. So this wire run, so long as it's legal, which I presume it to be given that three licensed master electricians would do the same thing, is not going to be a problem for me. Additionally, I am assuming that involving a city code person and/or an inspector would alleviate any potential problems with legality or safety.

Subpanel placement:

The garage is on the other side of the utility room and one level up. The rear wall of the garage is 22' long. If looking at the back of the garage from the inside, the utility room is on the right side, and the house door is on the left side. I am thinking a subpanel would go about three feet from the house door, meaning the wire would not only have to go up, but over a few feet as well. As I intend to hang a 45,000 BTU gas heater on the ceiling towards the right side of the space, I don't know if I can put a subpanel directly up from the utility room.

Other things:

I see the rest as needing to learn and understand the hookups as well as any potential rules and regulations dictating subpanel placement. It is also my understanding that I might need a torque wrench to torque one or more connections. It is only now that I am starting to read up on these things.

Questions:

Can or should I do this myself? Is there anything wrong with the feeder wire going out the side of the main panel, through a stud, and then up so that I don't have to pull out insulation foam around existing wires? How difficult is it to ensure that everything is done to code so that it passes inspection(s)? Is it odd for the feeder wire to go up into the garage wall and then over a few feet, through studs? Or would it have to either go up into the attic and then back down a few feet over or even in conduit on the surface of the drywall?

Additionally, for punching into the garage from the utility room, would I go out through the top of the block wall and into the garage, or would I try to go up into the studded wall from below? There is a 14” drop from the linoleum or vinyl floor on the main level to the concrete garage floor, and it is 10" from the top of the basement block wall in the utility room to the underside of the main level OSB substrate.

One thing I should probably consider is, with the main panel effectively full with the addition of a two-pole breaker, will this prospective garage subpanel be used to supply future expansion electrical needs for, say, a kitchen remodel or ceiling lights in the living room? If so, how would I get wires from the proposed garage subpanel back into the house? Surely that is a consideration as well?

Maybe I should just run two circuits to the garage instead of installing a subpanel? Or put a subpanel in the utility room and run a few circuits directly up into the garage?

I've tried to be as comprehensive as possible here. I started thinking about this in December, and, as noted, I had three electricians in to provide quotes this past week.

Attached is a diagram and a few photos.

 

[Nealtw]

Where is the kitchen and where would you want the outlets in the garage and where is the door in the garage.



@community

 

[community]

Where is the kitchen and where would you want the outlets in the garage and where is the door in the garage.
@community

Kitchen is in middle of back of house, so the center bottom of the above diagram. Garage outlets...I will probably do three circuits, outlets 4' up from floor, and 4' apart. Garage door is at top of diagram. The door from the garage to the house is the small blue rectangle.

My diagram depicts the basement as well as the garage. The garage is ground level and the basement one story lower. The photo of the utility room depicts the block wall upon which the garage-house wall sits.

If a subpanel is mounted in the garage, additional wiring to new locations in the house, fed from below since it's a drop ceiling, will almost definitely require feeding wire back into the house from the garage, meaning down a few feet and back into the utility room.

If this is a matter of how many circuits will have to pass through the house-garage barrier, it may be worth noting that a 220v outlet or two may be added to the garage in the future for a welder, 220v table saw (likely), or even an electric car charger someday. Additionally, I need to redo the lighting, as there's a single incandescent bulb in there with a socket accessory that provides two outlets to adjacent T5 tubes. I will either be installing a set of six LED shop lights (same physical size as T5 tubes...just skinnier, brighter, and virtually weightless) that plug in to an outlet, or, probably a better solution, mounting proper LED lighting and hardwiring it.

 

[Nealtw]

Holes between garage and house, less is better, So I would put it in the basement at A, B or C with one conduit thru the rim joist and run conduit from one outlet to the next with 3 circuits in one conduit.

 

[community]

Holes between garage and house, less is better, So I would put it in the basement at A, B or C with one conduit thru the rim joist and run conduit from one outlet to the next with 3 circuits in one conduit.

I figured as much. So a conduit isn't unusual? I feel like there will be more to do in the garage than in the house. A main panel is expensive (and requires punching into the wall near the panel and the ceiling in two places. I feel like there isn't a good solution here.

 

[mnak]

the king electric garage heater installation is very easy. they are single phase can easily be mounted at wall/ceiling.

 

[seharper]

The existing main panel is a Cutler-Hammer CH7CC... Two of the three licensed master electricians... said it is a very high-quality panel that will last for many more decades...

Yeah, they told you right. Fantastic, industrial quality panel and my first choice, and the breakers are sanely priced. My only regret is Eaton makes some very exotic breakers in the 1" form factor that won't fit in 3/4", but you're fine for regular stuff like AFCI or DFCI. I install CH by default unless I have a reason not to (only QO supports DC; Siemens has a nice cheap generator interlock). So I'd totally go CH on your new panel.

That foam in the panel, you gotta get that crud out. Least, it's a NEC 110.12 violation (workmanship) and probably 110.3(B) (since UL never tested a panel full of foam). No inspector will tolerate that, even though it's not your mistake (foamers don't answer to the NEC).

Your low voltage experience is a boon, especially for this job. Just be aware that "low voltagers overestimating how much their LV experience applies to mains" is pretty much a trope in this business. Mains is different in unexpected ways (example: current going out one cable and back another is forbidden). You will certainly see many NEC rules which seem stupid. They're not; NEC is very well-designed and almost every rule is worth following.

The key to panel location is a working space that must be kept clear 24x7: Floor to 6'6", 30" wide (doesn't need to be centered) and 36" stepback room. Ideally, in a hallway or path nobody would block. Also, not allowed in clothes closets or moist spaces like bathrooms. Standard panel is 14.25" wide (to fit between 16" joists).

Beware of multi-wire branch circuits (MWBC) in that panel. That's a 2-hot, shared-neutral circuit, one cable with red and black hots going to separate breakers. They must be on opposite poles or they will overload neutral. Code now requires they either a) be a 2-pole breaker, or b) have factory handle-ties. CH handle ties are readily available at Eaton dealers for $3. But a 2-pole ($10) is easier for "the next guy" to understand, and you can reuse the two $5 1-poles that you liberate. You must hunt MWBCs down before you start moving breakers around bric-a-brac, because you could disturb the careful placement (if it ever was careful lol, I see so many dangerous mistakes).

Can or should I do this myself? How difficult is it to ensure that everything is done to code so that it passes inspection(s)?

EMT Conduit IMO is the best way for a newbie to get it right and look pro. I had the good fortune of my very first electrical work being conduit work, and I look back at that novice work and it's tip top. It's hard to put in initially, but you get to do the job in digestable chunks. Get the first segment in, close up the service panel, and continue onward at convenience. No fat cable draping everywhere, no need to do the job in one big bite. And then, running the wires is a piece of cake. So is changing or adding more. Also, you can get the conduit inspected/approved *before* you buy wire

Harper's Rule: buy the wire last. (always, not just in conduit). You use THHN individual wires. Much more flexible than stiff cable. Cable in conduit is legal, but requires larger conduit and is a hellish pull, and typically requires more pulling tools than a DIYer has or wants to buy. Note too, you are allowed more ampacity on THHN wires in conduit: #8 -> 50A, #6 -> 70A breaker (65A design max). But conduit is hard to install, so there's the balance.

I would run 1" EMT, but if you ran 3/4" EMT that would support 3x #6 wires (THHN by the way). I like 1" because it gives you the option to a) run #4 Al to save some coin, or b) run #3 Cu to support 100A. In large feeders, aluminum is just fine, especially since it'll be the new AA-8000 alloy, and fair chance the lugs are aluminum anyway. However with 1" EMT you would probably need to buy prefab 90 degree sweep bends; with 3/4" or 1/2" you can bend your own to fit.

Is there anything wrong with the feeder wire going out the side of the main panel, through a stud, and then up so that I don't have to pull out insulation foam around existing wires?

Sure that's fine if you don't mind busting out the drywall. You just have to line up the hole in the stud with the knockout, and still fit proper hardware entering the box (cable clamp for cable, straight connector for EMT). I see you have a 1/2" gap on either side giving you room to squeeze a finger or pliers in there to place a conduit nut. A cable clamp, install it inside-out (conduit nut on the outside). With Rigid pipe you can go "conduit nut on the outside, pipe through the knockout, then conduit nut on the inside and tighten against each other". So the hole doesn't need to be any larger than the diameter of Rigid pipe. Use a short pipe and immediately on the other side of the stud have a Rigid coupler, straight EMT connector and onward with EMT.

One thing I should probably consider is, with the main panel effectively full with the addition of a two-pole breaker, will this prospective garage subpanel be used to supply future expansion electrical needs for, say, a kitchen remodel or ceiling lights in the living room? If so, how would I get wires from the proposed garage subpanel back into the house? Surely that is a consideration as well?

Very wise thoughts, yes! 24 spaces is too cramped for any house. I recommend for a new house a 40 or 42-space panel (42 is a multiple of 3; matters to industrial tier panels). Larger than that are too expensive. For a legacy house adding a subpanel I recommend aiming for 48-ish total spaces.

As far as carrying power back to other areas of the house, again, conduit. If you are going back to a junction box (where you could then transition to Romex), you can use THHN wires: You're allowed 4 circuits per conduit for the <=30A stuff. With 1/2" conduit you also must check conduit fill limits; with 3/4" you'll hit 4 circuits before you ever fill. 3/4" is better for pulling anyway.

If you just want to pull Romex into a conduit that just arbitrarily ends somewhere, you can do that. But oval cable is treated as a round wire of the wide dimension (because it twists). So you must calculate conduit fill accordingly and that requires fat conduit. 1-1/4" EMT is a good choice for up to four #12 Romex.

Maybe I should just run two circuits to the garage instead of installing a subpanel? Or put a subpanel in the utility room and run a few circuits directly up into the garage?

The ruling factor there is subpanel placement. Put the panel in the best location where the work space is likely to be kept clear. You can always run conduit to the other location; junction boxes don't require work space.

 

[community]

seharper, I clearly missed the notification for your reply. THANK YOU for all the information! I have just a couple of followup questions at this time:

The key to panel location is a working space that must be kept clear 24x7: Floor to 6'6", 30" wide (doesn't need to be centered) and 36" stepback room. Ideally, in a hallway or path nobody would block. Also, not allowed in clothes closets or moist spaces like bathrooms. Standard panel is 14.25" wide (to fit between 16" joists).

Does working space and clearance matter as it relates to where a car may park in the garage? As it turns out, I will instead be placing the subpanel in the lower right corner of the garage portion of my diagram, which is effectively immediately beside the front driver side part of the car. The reason for the change is it is a shorter feeder run, and I would rather put a subpanel there than on the back wall of the garage anyway due to the back wall being more useful for other purposes (shelves, machinery, etc).

Why would I not put the outlets in the walls if I plan ahead? For the unfinished, 22' side wall, I am thinking four outlet boxes roughly four or five feet apart, four to five feet off the ground, and maybe three 230v outlets as well.

I just got my first 230v tool, a 2HP dust collector, and there is a possibility I will upgrade the motor on my table saw from 1.75HP to 3HP in the future and/or add a 2HP or 3HP bandsaw. I have no intentions to add a welder or a large air compressor or anything like that. I am just thinking 'many outlets, equally spaced, and three circuits' to account for various possibilities. There will never be more than one machine and the dust collector running at the same time.

The back wall (bottom of garage portion of diagram) and shared portion of other side wall are drywalled, and they have this firewall or fire stop product behind the drywall. How do I deal with this? The side wall (right side of garage portion of diagram) is where I now intend to put the panel.

Should I surface mount the panel, or is it okay to cut the drywall and firewall material between the studs so the panel can sit flush with the wall? The 6/3 feeder will come from below (up from the basement, through the sill plate sitting on the basement joists, right?), and the wires for the circuits will go out the top, up into the garage attic, and down the appropriate walls. Does this sound right?

How on earth can I add outlets to the back wall, which, again, has the firewall product behind the drywall, then the attic also has the same material on the same side of the 2x4s, thus preventing me from fishing a wire down into the wall from above?

 

[seharper]

Does working space and clearance matter as it relates to where a car may park in the garage? As it turns out, I will instead be placing the subpanel in the lower right corner of the garage portion of my diagram, which is effectively immediately beside the front driver side part of the car. The reason for the change is it is a shorter feeder run, and I would rather put a subpanel there than on the back wall of the garage anyway due to the back wall being more useful for other purposes (shelves, machinery, etc).

Technically, that 30x36" space can't be fouled by anything, for any longer than it takes to open and shut a door. So an excellent location would be that deadspace you can't stack boxes in, because the car door has to be able to open into that space. But imagine painting the 30x36" zone on the floor in yellow and black zebra stripe, and never putting anything there, ever. Is that going to disrupt the garage space in some serious way? Or will it be easy to keep that space clear? I would say don't set yourself up to cheat. Don't place the panel where you will *inevitably* block it with a bunch of stuff, because that's just how humans use garage space.

Why would I not put the outlets in the walls if I plan ahead? For the unfinished, 22' side wall, I am thinking four outlet boxes roughly four or five feet apart, four to five feet off the ground, and maybe three 230v outlets as well.

Sure, inset 'em in the walls for a clean look. Myself I'm a huge fan of EMT conduit (at least for a few sites) because it lets me fit blank plates and throw "whatevs" in the pipe at a future point, but it depends how practicable that is.

I just got my first 230v tool, a 2HP dust collector, and there is a possibility I will upgrade the motor on my table saw from 1.75HP to 3HP in the future and/or add a 2HP or 3HP bandsaw. I have no intentions to add a welder or a large air compressor or anything like that. I am just thinking 'many outlets, equally spaced, and three circuits' to account for various possibilities. There will never be more than one machine and the dust collector running at the same time.

Except different machines will have different breaker requirements. For that reason I'd throw nice fat wire/cable in the wall so you can swap breakers/receps as needed. No big deal to swap a $10 breaker. However you have NEC 2020 breathing down your neck; *that* will require $80 GFCI breakers. So get permitted before then

The back wall (bottom of garage portion of diagram) and shared portion of other side wall are drywalled, and they have this firewall or fire stop product behind the drywall. How do I deal with this? The side wall (right side of garage portion of diagram) is where I now intend to put the panel.

Well, I'm biased because I don't care what *your* garage back wall looks like Also, I'm kinda into the steel box/EMT conduit look. But my reco is exactly that, or the more attractive (erm, less unattracitve) Legrand Wiremold surface conduit system. The huge advantage is it satisfies the "protection from physical damage" requirement. It's also a ground path so 1 less wire. You use THHN in it.

Should I surface mount the panel, or is it okay to cut the drywall and firewall material between the studs so the panel can sit flush with the wall? The 6/3 feeder will come from below (up from the basement, through the sill plate sitting on the basement joists, right?), and the wires for the circuits will go out the top, up into the garage attic, and down the appropriate walls. Does this sound right?

I would check with your AHJ about their firewalling requirements. Other than that, surface vs flush is an aesthetic choice. I for one VASTLY prefer surface mount for accessibility for upgrades. But your option of "throw a lot of wire in the wall, then bury it" works too.