Whole house plan(Main and sub-panels)

av8rMay 26, 2010

We are building a new house in Louisiana. I am doing much of the work myself. It will be inspected and I have talked with the inspector. I will run this plan by him but I wanted to get feedback here first. House is 4100s.f. heated and 7000s.f. total. Heat/Water Heaters/Range are gas. The side of the house where service will enter is opposite side from garage and utility room. My plan, Outside: 200 amp meter pan and 200 amp 30 circuit panel with a 200 amp main breaker. This panel will include breakers for 3 ton a/c, a 4 ton a/c, a 100 amp breaker for sub panel, and many of the branch circuits(20?)for that side of the house and kitchen. Inside: I plan to locate a second 30 circuit main lug panel about 125 feet away on the opposite side of the house in the garage or the utility room. This panel will feed a 3 ton a/c and the branch circuits for that side of the house. What size wire should I use for the sub panel? Should I go with copper or Al? Is the main panel being located outside typical for my area of the country. I don't think there is really anywhere inside on that side of the house I can locate it. Also, should I wire the entire house with #12 or is that a waste of time and money? Thanks in advance.

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Ron Natalie

Even with gas heat, that's a lot of A/C you've got there, almost 110A worth on it's own. Did you do a proper load analysis?

I've heard of outside panels in warm places, but the rather "tropical" nature of Louisiana makes me nervous.

I won't screw with 30 circuit panels. What's the point. THe delta for 42 is small and you always have issues with spaces.

There's tons of special circuits that need to be addressed. I recommend you get someone who has a clue about things draw up your electrical plans at least.

You size breakers for the wire, NOT the other way around.

WIre sizes depend on the type of wire, the ampacity required, and the length of the run.

Larger feeders tend to be done with aluminum just for cost practicality. There's no problem with aluminum of feeders/services provided they are installed PROPERLY.

You can wire everything with 12 G (that doesn't need more than 20A) if you like. Makes things more convenient, especially if you've got longer runs.

    Bookmark   May 27, 2010 at 8:43AM
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I did follow up with a licensed electrician in my area that has been nice enough to help me. He agreed with the layout and also said to use the 42 circuit panels as well and pull all of the a/c's out of the first panel even though 2 were in excess of 100' away. He did a load calc. and said 200 amp was fine. He told me to use #1/3 AL SER cable and a 100 amp breaker to feed the subpanel 125' away. Is this adequate or should I up size?

    Bookmark   May 27, 2010 at 9:16PM
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Ron Natalie

1-1-1-3 AL SER will be fine here (as long as it's three #1 conductors plus the ground).

    Bookmark   May 28, 2010 at 7:54AM
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