Educate me on sub panels

[zippyslug31]

Not looking for specific answers or advice related to code, but I need some basic info for a sub panel before I make a fool out of myself asking electricians for quotes. We're all fools here so I can hide in larger group.

Here's my setup: I have a pole building already plumbed with a 200A service. It has a full-sized panel (as you'd see in a house, for example) with quite a few open breaker bays. In other words, I don't use anything close to this 200A service. I will do the math on my usage if needed, but I'd guess no more than 100 amps max at any given moment (i.e. running a heater, while welding, with all the lights, and the stereo/TV blasting, maybe the compressor kicks on too?). This is not an industrial operation, just a hobby shop.

I'm currently constructing an additional 30x30 building for the wife (craft studio) about 150' away from the barn. This building would have some form of a mini-split (not sure the exact spec yet), a couple sewing machines, clothes iron, lighting (likely LED, so low draw), TV. I could imagine other things might be thrown in there - Keurig, glue gun, desk lamp... not sure every last item at this point.

So, a couple of questions:
Is this enough detail for me to make a plan on power needs?
Generally speaking, is it "allowed" to run a 100amp sub (effectively splitting the 200A in half) to power the new building by tapping into the barn?

I'll admit that I'm pretty green with a lot of this, so am I missing something obvious here?
Any input or links to reading material would be appreciated.

 

[zippyslug31]

One more quick detail, I should have added that I'd like to put a limited-use tankless water heater in the new building. Probably one of the smallest they have on the market... just for non-cold water for a sink.

 

[exranger06]

100A should be plenty for the craft studio, probably even overkill. But yes, you can run a feeder from the pole barn to the studio. You wouldn't be "splitting" the 200A service per se. You would still have 200A service to the pole barn. Think of the studio as just another load on the pole barn's panel. If your wife was pulling around 50A in the studio for example, you'd still have 150A available to you in the pole barn. If she was using 30A, you'd still have 170A and so on. IF she was actually using 100A and maxing out her electrical service (very unlikely) you'd still have 100A to run your stuff. And if nobody is in the studio and it's pulling basically 0A, then you'll have all 200A available in the barn.

 

[u2slow]

#2 aluminum is a very high sales-volume cable size, so that's probably your best value. Gets you 90A typically, derating as needed for longer distances.

 

[wyliesdiesels]

you asked to be educated on subpanels. head on over to the electrical FAQs sticky. plenty of info there

 

[dcg9381]

Yes, you can split off that 200A panel. Splitting 100A with your power needs (way under that) not a problem.

IMHO, a 30x30 in Oregon would get by fine with 60A. The sweet spot, if you want more power, is typically 90A in terms of wire cost, etc.

A Daikin 24k ductless pulls less than 12A continuous (at least here in Texas). Your main need might likely be heat - I'd go propane/NG if you can. If you are doing ductless for heat, get one designed for cold - Mitsu Hyper-heat or similar. My Daikin functions like **** under 30 degrees for heating.

 

[02vito]

Yes, you can split the 200-amp service with a 100-amp branch circuit to a sub-panel. Keep in mind that a 100-amp, 2-pole breaker takes up a lot of space. In my Square-D QO panel, the 100-amp breaker took up the 4 bottom positions [2 each side].

 

[theoldwizard1]

The physical SIZE of a sub panel does not matter much. It is the size of the breaker and wire feeding it.

If you need a lot of circuits install a large panel, maybe ≥ 100A. You can still feed it from a 60A breaker and wire sized for 60A and the distance between the 2 panels.

(My SWAG. 60A feed is plenty !)

 

[dcg9381]

Keep in mind that a 100-amp, 2-pole breaker takes up a lot of space. In my Square-D QO panel, the 100-amp breaker took up the 4 bottom positions [2 each side].

And you can get a 90A breaker that only takes up 2 spaces. And the wire is more than 10% less expensive than wire required to do 100A.

 

[csp]

Keep in mind that a 100-amp, 2-pole breaker takes up a lot of space. In my Square-D QO panel, the 100-amp breaker took up the 4 bottom positions [2 each side].

That's going to depend entirely on the type of panel it is. Mine is a Square-D Homeline (wish it was QO) and the 100amp breaker only uses two spaces. It's no larger than the 30 amp next to it.

 

[wyliesdiesels]

Yes, you can split the 200-amp service with a 100-amp branch circuit to a sub-panel. Keep in mind that a 100-amp, 2-pole breaker takes up a lot of space. In my Square-D QO panel, the 100-amp breaker took up the 4 bottom positions [2 each side].

Are you sure? SQ D QO 100a double pole breaker only takes 2 spaces

 

[AP514]

you asked to be educated on subpanels. head on over to the electrical FAQs sticky. plenty of info there

+1 a Great Sticky

 

[Knight511]

you asked to be educated on subpanels. head on over to the electrical FAQs sticky. plenty of info there

That thread is good, but it really needs to have all post that are not truly FAQs removed. It is full of great info, but too many people with info-less posts at the same time.

Speaking as someone who read that post before anything else on the forum to learn as much as possible before wiring his new workshop.

 

[HamAndEggs]

My main 200a panel has feed through lugs to a second 200a panel, as well as going to my garage 125a sub panel

No problems with what you are doing

Feed through lugs are hidden, they don't have a breaker

 

[wyliesdiesels]

That thread is good, but it really needs to have all post that are not truly FAQs removed. It is full of great info, but too many people with info-less posts at the same time.

Speaking as someone who read that post before anything else on the forum to learn as much as possible before wiring his new workshop.

I agree. And ive asked mods to scrub certain posts from the thread in the past. they didnt understand why i wanted them removed AND it was a real chore for them because i listed the posts i wanted removed by number. yet every time they removed one, the numbers obviously changed, so they kept having to refer back to a cached version of the thread so they could remove the right ones.

since it was so much work for them, i decided not to ask again.

If i could remove the non-relevant posts, it would be a breeze for me as i know what content needs to be removed and dont need to rely on numbering. but alas, i am not a moderator...

 

[Knight511]

I agree... i am not a moderator...

As a former mod to a forum, that is a lame excuse on their part. It only takes 5 minutes to skim the thread to eliminate the posts needed. That indicates a need for a true subforum moderator who cares enough to take the little time to keep things useful.

And, thank you for your work in the thread. I am mostly silent here (some what out of fear of just getting the **** kicked out of me for making a non-pro mistake), but the info here in general has been great for me.

 

[Stuff]

I agree. And ive asked mods to scrub certain posts from the thread in the past. they didnt understand why i wanted them removed AND it was a real chore for them because i listed the posts i wanted removed by number. yet every time they removed one, the numbers obviously changed, so they kept having to refer back to a cached version of the thread so they could remove the right ones.

This is a common problem with those that don't know a simple trick. Give them the post numbers in descending order. You also might need to tell them to not sort the list if they don't get it.

 

[AP514]

if i could remove the non-relevant posts, it would be a breeze for me as i know what content needs to be removed and dont need to rely on numbering. But alas, i am not a moderator...

Well, you have enough post to be considered

 

[AP514]

if i could remove the non-relevant posts, it would be a breeze for me as i know what content needs to be removed and dont need to rely on numbering. But alas, i am not a moderator...

well, you have eough post to be considered imho

 

[alfredeneuman]

As a former mod to a forum, that is a lame excuse on their part. It only takes 5 minutes to skim the thread to eliminate the posts needed. That indicates a need for a true subforum moderator who cares enough to take the little time to keep things useful.

I'm a current mod at a different Electrical BB with multiple subforums and 12 mods.
There any mod can relocate posts, delete posts, and edit posts, in any of the subforums. We also can ban users if need be.
Because of our cross-moderation capabilities almost nothing gets by for more than a couple of hours.