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Adding Subpanel for Basement - Few Questions

21K views 28 replies 6 participants last post by  mindle 
#1 · (Edited)
First, I know this is my first post, so please be gentle. I've done some searching and have found a lot of posts about adding a panel for external buildings (garages, sheds, etc), but either my queries are wrong or I am just skipping over the ones I need. I realize this is a large job, likely best placed in the hands of a professional. That said, I'd still like to tackle it with proper guidance because I'm a relatively hands on person.

Cliff Notes Version:
200 AMP service panel in attached garage. Want to add 100AMP subpanel in basement, to provide service for finished basement and potentially add a hot tub in rear of house, outside the basement door. I currently only have 3 spots left open in my main panel.

Location: Delaware

About me: Homeowner, and have done some home electrical changes myself. (Re-wired switches to control a ceiling fan instead of 1/2 an outlet, installed the boxes necessary for those jobs, etc.) This will be my largest electrical task to date.

I originally thought about putting in a 50AMP subpanel using 6/3 wire, but figured if I'm going to go through the trouble of installing a panel I mind as well plan for the future just in case.

My research so far is pointing me in the direction of using 2-2-2-4 SER wire to provide a feed to the subpanel. Can someone confirm if this is the correct wire? The main panel will use 2 of the 3 available slots and will have a 100AMP breaker installed there, as well as a 100AMP breaker in the subpanel in the basement. I'm also aware that the I'll need a separate neutral bar and grounding bar in the subpanel.

The main questions I have surround how to get the (2-2-2-4) wire from the main panel to the basement. I've added a diagram (which is unfortunately small(er) than I'd like, but hopefully helps. The main panel is located in my attached garage, front left corner of the house. The subpanel can, at this point, be placed anywhere in the basement as I'm still in the process of framing.

I have a two floor home, with un-used space above the garage. I could go through the attic, and climb down, above the garage, and run the cable through the wall, across the attic, and down another wall to the basement. Alternatively, I was hoping to run the cable through conduit, either along the wall into the basement, or across the basement ceiling and down another wall. (Either works, really.)

I've tried my best to mark the attached diagram to where the main box is located, and the proposed ways to get the cable into the basement. Any and all advice is welcome. (Good or bad, I'm a big boy, I can take it.)

Some notes on the Diagram:

All Sub Locations are in the basement.
Sub A location will be in an unfinished area of the basement.
Sub B location will be in finished section of the basement. That section is an office, and the location of the panel would be in the closet of that office.
Sub C location is underneath the steps, inside a finished closet.

Thanks in advance for either helping, or taking the time to read this rather lengthy post. If I can answer any questions that will help you form a better opinion, please let me know!

-cj
 

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#2 · (Edited)
Just a few things about the diagram:

It's the complete basement layout. The 'grayed' area in the main portion is the section that will eventually be completely finished. (~950 sq ft)

In between 'square' between Sub B and Sub C, that will be a secluded room (4 walls, and a closet) to be used as an Office. I don't mind putting the box there.

Where the label 'MAIN SERVICE PANEL' is, the panel is on the LEFT, inside the garage. Underneath that label is two garage doors. I can run the cable up the wall and over the garages through conduit, or can climb into the attic and run them from there.

Let me know if anything else isn't clear.
 
#4 ·
No, it's not.

The garage on the main floor level. I have a second floor, which for this project is fairly irrelevant (but I can answer any questions if you have them).

Also, the basement is considered a 'walk-out'. I have a 6' sliding glass door out to a patio behind the house. Above the patio is a deck off the main floor. (I believe how much above/below grade has some relevance, but I don't know for sure.)
 
#5 ·
I assume that you are going to use 2/3 w#4 groung Aluminum SER cable to feed the sub panel. Because the NEC allows you to downsize the cable for a service. Instead you can use 3/3 SER Aluminum or 4/3 romex. I would run it through the attic. I do not like the idea of running service feeders above garage doors even though you would sleave it in EMT. Once you get into the basement you can place the panel anywhere except in a closet per NEC.
 
#6 ·
I do not like the idea of running service feeders above garage doors even though you would sleave it in EMT. Once you get into the basement you can place the panel anywhere except in a closet per NEC.
I felt the same way, to be honest. (Especially considering I have two small(er) kids.)

And anywhere BUT a closet. Alrighty.. Can you point me in the right code direction? Aside from wanting to know the rights and wrongs, I actually want to learn this stuff to be self sufficient.

Thanks HIVOLT.
 
#11 ·
100a sub I ran #3 copper approx 27' from my 200a Main, #6 ground
2 black/red hots, white neutral, green ground
Not familiar with SER, I prefer to do copper

Usually hot tubs (or large loads) they prefer you run them from the Main panel
That said both the tubs at the last 2 houses ended up being run from a 100a sub
How much room do you have above the garage doors ?
If tight I probably would not run it there...but chances are if enough room it would be OK
Up to an Inspector if the y might consider it subject to physical damage & need protection

Spot A seems like it would be out of the way, which can be a good thing
But that would mean longer circuit runs

Spot B same main run but some circuit runs would be shorter

Spot C do you have the 30" width required for clearance ?
That area seems like it would be better used for storage...or a dart board
 
#12 ·
100a sub I ran #3 copper approx 27' from my 200a Main, #6 ground
2 black/red hots, white neutral, green ground
Not familiar with SER, I prefer to do copper
The only question I have about this, is I thought 6/3 wire was only rated upto 50a? Perhaps I am confusing 6/3 with different type of wire.

Scuba_Dave said:
How much room do you have above the garage doors ?
Above the garage I have a fair amount. I snuck up in the attic earlier and took some pictures of the room above the garage. You can see a majority of the wiring coming up out of the wall where the main is located, and running above the garages. This should give you a good idea of room, I haven't climbed down there yet but I expect to be able to stand and walk around.

Below is a picture of the 6/3 cable that I have... about 25 feet of it. If I can use it, great, but if I need additional cable I'll just buy whatever is necessary to meet code requirements.

Here is a picture of the currently unfinished spot "C". I also have another picture of spot "B". "C" would be enclosed underneath the steps, so I'm not sure if that would count as a 'closet', in which case it would no longer work. Spot "B" is definitely going to be a closet, so again, I think thats also out.
 
#15 ·
Locations B and C.

For Loc "C", it would be along the inside of the 'right' framing you see. I originally was thinking to put it there, but beginning to think that's a horrible idea the more I look at it. :laughing:

I marked off where I was originally thinking in the pictures. Hope that helps. First two pictures are "C" location (and irony would have it, I have a dart board in the box on the floor). The last picture is location "B"
 

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#18 ·
I thought you would be running the wire over the garage doors IN the garage?
I can do either/or to be honest. I don't mind climbing into the attic. Just trying to make sure things are done as best as I can, adhering to code where applicable. Didn't know if the wire choice would require through conduit, or could be run straight through the attic. The drop down from the second floor to the boards above the garage (attic side) is about 12'.

I'm actually thinking it would be best to just build a wall and put the panel in (or around) the original "A" location. Would require a little extra cable in the basement side, but its probably the best location to have it installed properly but also hidden from the 'finished' area. Thoughts?
 
#20 ·
I was planning to leave it unfinished. Right now its where I keep some boxes and a lot of my workout equipment. I'll snap a pic of the whole area here in a few to give you a better idea. Would it be a better idea to build a wall in that unfinished area and install the sub there, and ultimately finish off that wall. (Thinking a) to cover the cables and make them less accessible to people and b) any requirements they are behind finished walls?)

BTW, thanks for the input SD.
 
#23 ·
110.26​
Spaces About Electrical Equipment. Sufficient
access and working space shall be provided and maintained
about all electrical equipment to permit ready and safe operation

and maintenance of such equipment.
(E) Headroom.​
The minimum headroom of working spaces
about service equipment, switchboards, panelboards, or motor
control centers shall be 2.0 m
(6.1/2 ft). Where the electrical
equipment exceeds 2.0 m
(6.1/2 ft) in height, the minimum

headroom shall not be less than the height of the equipment.
(a)​
Dedicated Electrical Space. The space equal to the
width and depth of the equipment and extending from the
floor to a height of
1.8 m (6 ft) above the equipment or to
the structural ceiling, whichever is lower, shall be dedicated
to the electrical installation. No piping, ducts, leak protection
apparatus, or other equipment foreign to the electrical

installation shall be located in this zone.
 
#25 · (Edited)
Sub panel

The size of your feeder panel over current protection and wiring should be determined by the load on that panel. Lets just assume that with all calculations (including your hot tub) 100 amps is sufficient. The hot tub can be fed from your feeder panel (sub panel) with no problems. The integrity of the feeder panel is the same as your main panel for all intents and purposes.

Location of the panel ultimately should be were it is most convenient to you and to repeat one poster not in a closet and where you can maintain your clearances without obstruction (more clarification as needed). I would recommend that if possible you find a spot where you can keep your feeder runs as short as possible (less costly for wire).

Feeder size for panel is a #3 whatever copper (SER, romex, THHN in conduit). I do not like aluminum, I'm old school. The panel must be treated as a branch circuit and not a service so #4 copper will not fly. Aluminum is cheaper, but in my opinion more maintenance. Your house, do it right.
 
#26 ·
CJ:

You can not mount the sub-panel below the ductwork, as the Code requires dedicated open space below structural ceiling, or 6 feet above the panel whichever is less. Read section 110.26(F)(1) of the Code. If you build a new wall in front of the ducts, which is clear of the ductwork to the structural ceiling, then this would be acceptable.

You indicated you are located in Delaware. Homeowners are prohibited from installing any wiring associated with swimming pools or hot tubs in Delaware.

Click here for Chapter 14 of title 24 and read the first sub-section concerning the issuance of homeowner's permits.

If you still choose to do this job yourself, you will also need to apply for electrical inspection of the work after obtaining the homeowner's permit.

Judging by those pictures, I would guess that you are located in central or northern Delaware, as there are not many houses in lower Sussex with basements such as you have. :whistling2:
 
#27 ·
I would also consider installing your sub-panel conduit outside. You could easily poke thru the outside wall in back of the main panel using an LB, dig a trench around the foundation of the house to anywhere adjacent to the basement, then poke back thru with another LB.

From there, it would be easy to locate the sub-panel virtually anywhere in the unfinished basement.

I've done this type of installation dozens of times.
 
#28 ·
Okay, when I get home I'll snap a picture of the end of the ductwork runs. It doesn't go all the way to the end of that long wall, so perhaps in that corner is the best location for it.

As far as the hot tub, thanks very much for the heads up. Luckily, I'm only planning ahead and can't afford the hot tub yet. If I could, I would hire an electrician. :)
 
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