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OK, Here is the story, I live in NC and I manage an calibration lab "electric and mechanical... I know, no the same thing as an electrical contractor shop but still some of the same principals apply. I recently moved into a house that has 200 amps on the main and would "like" to add (2) 20A circuits to the garage. A buddy of mine said that you can only have up to amount on the main worth of breakers... if that were the case I would be 5A over already without adding anything... after adding phase A and B, I don't buy it. I would like to, and feel good about doing the job myself with an inspector checking the work after for insu. reasons, but I don't even know where to begin with the code regulations in NC. I would hate to do the job and try to get it inspected and have to rip it out and try again. Is there anyone who knows what to look for or what I need to do to plan this out?
 

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Inspectors? Codes? in NC? Close to a first for me. You must live in the city.
Just kidding! For local codes you are going to have to go to your local bldg. dept. as the codes vary from town to town and county to county, especially in NC.
Everything that I do to my house up there is done to Miami-Dade codes and the inspectors think that I am nuts but I pass everytime and sleep in the security that everything has been done right.
 

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al, a 100 amp panel with 20 15 amp breakers adds up to 300 amps. the code states that the service rating is to be able to handle the load. you can add as many circuits as you need as long as you do not overload the main breaker. for example, non-coincidental loads, a 30 amp a/c breaker and a 30 amp breaker for electric heat. only one will be used for load calc.
 

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The load on a panel is not figured by the number of, or number on the breakers. 20 15 amp breakers does not mean you have a 300 amp load! The load on a panel is figure by doing a load calculation! If that was the case I would have a 620 amp load at my house. Wouldn't the power company love me every month, not that they don't now:)
 

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Ok here goes, I couldn't resist. This doesn't apply to the original post from AL who definitely should contact his local authority to determine what code they follow. (Probably National Electrical Code) Just tell them that you are looking into a project and you want to make sure that it's done properly.

jbfan is right. To determine your load you have to get out your calculator and start adding. Your overall load determines the quantity and the size of your breakers.

I hear a lot of homeowners say "i gotta get a couple of 20 amp circuits to my new workshop" Well to that I say ok what kind of tools do you have? " Aw, man I've got everything, a band saw, table saw, mitersaw, lathe, welder, grinder, planer,router and a vacuum system that would suck a golf ball through a garden hose. Oh yeah and it's all lit up with 300watt metal halide high bay fixtures. and a butt kickin, stereo"

A guy in this situation has two choices. 1) Always work alone and never run more than 1 tool at a time + the vacuum and the lights or 2) Do the right thing and get a sub panel installed. It's easy to do, it's inexpensive materials-wise, and you don't have to trudge down to the main panel to reset a breaker when your miter saw binds up on that petrified piece of wood that you are trying to fashion into a book end.

If you are worried about code the best thing you can do is exceed it. Code is the MINIMUM requirement for a safe installation. You are always free to exceed standards.
If you have a 200 A panel and you have a couple of spaces left, jam a GFCI 50A two-pole breaker in there, run 4 #8 (2hot,1 Neut.,1 Ground) wires to a sub-panel in the garage or workshop and run everything you have off of that. You should have room there for at least 6 circuits to work with depending on your expected load.

If you are confused by that much then you should probably do some research or call in a pro. You'll learn an awful lot in a hurry by asking a pro a few questions.......you may learn that he doesn't like to answer a lot of questions.

I think I've done a good job clouding the issue here now. I'll leave the rest to you.
 
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