This may be a long and stupid question but....

[Prodigus]

but I just don't know so I'm gonna ask.

I just built a house (ok, I payed a builder). Said house came with a detached large 2 story garage.

I want to turn the upstairs into an apartment/poker room.

The house came with 200 amp service (I verified this by staring at the 200 amp breaker that's at the top of the outside (and only) breaker box (which by the way is on the total oposite side of the house from the garage).

To the garage (through some series somewhere I'm sure) is ran

Power for 2 duplex outlets (1 is on the ceiling to power the garage door opener) and and a light are wired to the downstairs.

Probably the same run also provides the 2 lights and 2 duplex outlets upstairs.

There is a seperate 30 amp wire ran to a box in the garage that's supposed to provide me with 1, 220 outlet that I wanted out there "just in case I need a 220 outlet".. (hmm, now that I think about that, shouldn't they have wired an outlet for that....)

Now that I want to do so much with the upstairs plus have a woodshop downstairs I think I should have a sub-panel in the garage to make it easier to run the wiring for it. (Remember, apartment/poker room upstairs, wood shop downstairs, pool equipment right outside it).

I'm going to assume that I'd be making a good choice of action there.

Here's where I get REAL murky.

First of all my theory of how an electrical panel works was blown out of the water when I realized that the total of ALL of the other breakers in the box would total less than or equal the size of the service breaker.

I had a 200 amp main breaker but when I add up the other smaller ones it all adds up to like 485 (perhaps not exact but real close).

This blew my mind because I'm figuring if a 20 amp breaker starts getting pulled for 30 amps that it would like pop or get hot or something bad like that...

Yet I can have (what looks like) a big 200 amp breaker gettin pulled for 485....
Now, I'm not saying tht all of those breakers are pulling what it says on them all the time but theoretically that possibility is there????

Anyway, what would be the best and easiest way to put a subpanel out in the garage and how much power do ya think I would need for what I described I want to do?

Confused? I am too. I wont be too surprised if I get no responses to this babble.. If I do.... THANKS!! I really appreciate it.

[Wgoodrich]

YOu mentioned one thing that hit a concern for me. YOu said an apartment on second story of same building.

First you must be zoned [plan commission approval] allowing a second dwelling on that property. Be sure to confirm this concern with your planning commission before you get in trouble.

Then be aware that an apartment must be served by a minmum of 100 amps and that is only if your demand load calculation says you pull less than 100 amps. If your demand load calculation [calculation telling you minimum service size required for that apartment] answers more than 100 amps then the apartment service must be with a service size meeting or exceeding that demand load calculation.

Also an apartment in the same building must have a 1 hour fire wall between the two dwellings as well as a 2 hour fire protection between the garage ceiling and the apartment upstairs.

Then again you must have all main breakers grouped together [probably outside] so that either tenant of either dwelling has continuous access to their breakers. Then a sub panel would need to be installed in that apartment.

Then again you have a requirment of smoke detectors warning all who live there at the same time if a fire occurs.

Any apartment is required a kitchen, living room, bedroom and a bathroom serving that certain apartment exclusively.

Your shop needs to have a demand load calculated for what you have in that shop in your garage. First you would have to decide how many people would be working at the same time in that shop. If only one person then find the largest amp load rated manually operated machine. Increase the amp rating of that machine 25% higher then add the full load amp rating of all auto operated machines in that shop.

Now you must perform a demand load calculation of your original home sizing the minimum service for that original dwelling.

Then add the answer to these three demand load calculations together to find the total service demand load minimum service size.

Look abuve for "demand load calc". Perform a demand load calculation of each dwelling in that building. Then calculate the demand load of the shop as discibed above. Add them together and this will be the minimum service size required.

Your subpanel and feeder in teh apartment must be equal to or larger than the answer of minimum size required to serve each area.

You do not add branch circuit breakers together. You perform a demand load calculation format as discribed in teh green and yellow boxes above. This allows for diversification of intermittent load in charicter of a dwelling unit being used.

Hope this helps

Wg