I am finishing out my basement, and will be putting in a sub panel in the office. The basement will essentially be a true live in suite with a full kitchen, washer/ dryer, full bath, sauna, an office and a bedroom. It is roughly 1700 square feet.

I will eventually add heat and AC, and have framed in vents, returns, etc already. My main panel uses eaton, and I have already put in the outlet boxes, and begun running 12-2 for all lighting, and 14-2 for all outlets.

I expect to use mini split heat exchangers to heat and cool the space. In January, the coldest it got was 47 and so far we have had a week of 90+ days, and the hottest it has gotten is 79.

I have not run the kitchen (oven) or dryer outlet.

My question is what size box do I need? I know I will ultimately need at least 14 slots, broken down as follows:
2- bath
2- Washer/ dryer
1- oven
2- kitchen
1- office
1- bedroom
1- storage
2- future HVAC
2- game room

My dad said to get a 125 and call it a day, but a 200 is like $50 more. Worth it or not?

Given your plans, I'm going to agree with dear old dad, just grab and install a 200amp box and call it a day. Its always better to have extra slots available for the future than to have too few.

More info please.
Is this a separate service with its' own meter or are you going to feed it from your main panel?
Amperage and number of free slots in main panel?
Size of house and some idea of normal load on main panel if this is what you are planning.
Another water heater?
Will permits or inspection be needed?
Code would be to put arc fault breaker for bedroom, hard wired a/c for smoke detectors, GFI outlets for kitchen and bathroom.
I would suggest 12/2 for outlets and 14/2 for lighting. Some locations only allow the use of 12/2 for houses for all wiring.
Hopefully skins 2881 will come along and help with load calculations.

This sub panel will be an offshoot of the main panel. It will be inspected. House is 5 years old and 3700 sq feet, 5 bed, 5 bath, no additional Water heater - plumbed and tied to main. Main kitchen has gas cooktop and ovens. AC is a 25 seer system, single unit, dual zone. ALL lighting is LED.

How big is the main panel? 200A as a sub off a 200A main might be questionable as far as inspection goes.

I would run 12/2 for everything, certainly all the outlets as a minimum. 14/2 for ceiling fixtures.

You’re fine with the 125amp. But I would run 12/2 to all outlets and use 20amp outlets. I’ve never been a fan of 14/2 for outlets even though code says it is ok. Main reason is if someone runs an electric heater or some other high load device. 14/2 will get pretty toasty when it has a continuous load of 12 or 13 amps.

You can't add 200a sub fed from 200a. Dilemma solved. 125a is standard subpanel size, they are all 125a unless it's got a breaker installed in it. Then it can either be the breaker size or 125a. You can get a 150a Main Lug Only panel and use that as a sub if you wanted to.

Also how do you run the ducting/venting or linesets for mini splits? It appears you are going to have eight different rooms/areas down there. I wonder how a system that large works? How many compressors will it require? I would definitely look into installing a conventional HVAC system instead.

I believe the max size breaker that will fit in your main panel is a 125 amp 2 pole. This will feed your main lug only sub panel in the basement. In your case I would use a panel that had at least 20 - 1 inch circuit spaces, usually called a 20/30, where the total number of breakers could be 30, by mixing in some 1/2 size breakers.
You only need a 125 amp main lug panel to match the feeder breaker, but you can use either 125 or 200, which ever is the best buy. Lowes usually has an Eaton 30/40 space 200 amp main lug combo pack with some breakers included.
I like to use full size breakers when I can as they seem a little more reliable.

If Skins 2881 chimes in please listen to him.

quote:

Originally posted by Skins2881:
You can't add 200a sub fed from 200a. Dilemma solved. 125a is standard subpanel size, they are all 125a unless it's got a breaker installed in it. Then it can either be the breaker size or 125a. You can get a 150a Main Lug Only panel and use that as a sub if you wanted to.

Also how do you run the ducting/venting or linesets for mini splits? It appears you are going to have eight different rooms/areas down there. I wonder how a system that large works? How many compressors will it require? I would definitely look into installing a conventional HVAC system instead.

One mini split will be in a bedroom, with a single vent duct to the bathroom and office. That totals about 420 square feet. The storage area will not be temperature controlled (3 sides are 12" which concrete), and that space it 460 square feet.

The other mini split will control the game room (520 sq feet) and kitchen (160 sq feet). The rest of the space is a hallway, a sauna and the laundry, which are between the kitchen and storage. The Kitchen and game room are connected through a 12' wide bar

I laser measured the basement this AM, and the whole basement is 1610 square feet. I am looking to buy two mini split systems that are both rated at 1000 sq feet for heating and cooling. Each system controls 2 rooms independently, so there will be 2 compressors.

I am not doing the HVAC work. All three people who came out said that a traditional gas furnace and AC system would be overkill, and cost twice as much as two mini splits.

Your basement is 15 sq ft larger than my house. Before I upgraded panel my entire house was on a 125a panel.

Seems like a lot of space to me for the mini splits. If three people, who are presumably HVAC experts and you trust them go with whatever they say. Personally I rather have a conventional system just for the filtration and circulation. I also leave my furnace fan motor on 24/7 or on circulation setting.

quote:

Originally posted by 280nosler:
and begun running 12-2 for all lighting, and 14-2 for all outlets.

I hope you're doing the opposite of this.

14-2? Arc is right! I have been doing home improvement electrical work , new additions, old work, new work, etc. and have never even encountered 14 gauge wire.

quote:

Originally posted by arcwelder76:

quote:

Originally posted by 280nosler:
and begun running 12-2 for all lighting, and 14-2 for all outlets.

I hope you're doing the opposite of this.

I do too, especially in the age of LED lighting.

quote:

Originally posted by Skins2881:
You can't add 200a sub fed from 200a. Dilemma solved.

Oops, I misread his initial post as he was going to install new service for the basement given its size. 100% right, 200a is a no go.

quote:

Originally posted by stoic-one:

quote:

Originally posted by arcwelder76:

quote:

Originally posted by 280nosler:
and begun running 12-2 for all lighting, and 14-2 for all outlets.

I hope you're doing the opposite of this.

I do too, especially in the age of LED lighting.

Interesting. I lucked into a purchase of some left over electrical stuff that came with what seems to be a couple miles of 12-2 wire. At this point, everything I wire up gets 12-2.

quote:

Originally posted by Gutpile Charlie:
14-2? Arc is right! I have been doing home improvement electrical work , new additions, old work, new work, etc. and have never even encountered 14 gauge wire.

Uh, what? What am I right about? How have you never encountered 14ga wire? Not only has it been commonly in use for decades, but it is still widely used and probably will remain so.

quote:

Originally posted by bigdeal:

quote:

Originally posted by stoic-one:

quote:

Originally posted by arcwelder76:

quote:

Originally posted by 280nosler:
and begun running 12-2 for all lighting, and 14-2 for all outlets.

I hope you're doing the opposite of this.

I do too, especially in the age of LED lighting.

Interesting. I lucked into a purchase of some left over electrical stuff that came with what seems to be a couple miles of 12-2 wire. At this point, everything I wire up gets 12-2.

Finding it for some cheap deal is one thing, go ahead and put everything on 12ga. Typical construction though, most people only use 12 where they need it specifically. Particularly with modern residential lighting, one circuit of 14 can accommodate a lot of lighting.

quote:

Originally posted by 280nosler:
This sub panel will be an offshoot of the main panel. It will be inspected. House is 5 years old and 3700 sq feet, 5 bed, 5 bath, no additional Water heater - plumbed and tied to main. Main kitchen has gas cooktop and ovens. AC is a 25 seer system, single unit, dual zone. ALL lighting is LED.

How many panels do you currently have in your house and how many amps each. Around here larger houses will have multiple panels every 200 amps.

Most basements do not need much to keep them cool/warm, assuming a large part of the basement is below grade.

quote:

Originally posted by Gutpile Charlie:
14-2? Arc is right! I have been doing home improvement electrical work , new additions, old work, new work, etc. and have never even encountered 14 gauge wire.

???

You have never come across 14 gauge wire. I see it all the time. We use it almost exclusively for dedicated lighting circuits. With today's low watt light bulbs, you can run a lot of lighting off a 15amp circuit.

14 and 12 gauge wire is in every house I have ever worked on. Commercial buildings not so much because of code but it's still out there.

Of course I've "seen" 14 gauge wire. I've just hav never encountered it ain any remodels I have done . I just use 12 for al
outlets, switches and lights.