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swampwiz 11-16-2007 04:17 PM

How big of a breaker box will I need for my new home?
 
OK, I will be starting to build a new home very soon, and need to figure out what size of breaker box to install. The breaker box will be put in the laundry room, against an interior wall with attic space directly above, if that makes any difference. I live in a jursidiction in which I can pull my own electrical permit, and if I need to save the case, I plan to do all the wiring up to the box (I will get an electrician to tie the breakers up, and then to the main line.) I am an aerospace engineer and have worked on plenty of electrical projects, so I think that I know how to do this, including following codes.

Anyway, everything starts with the breaker box. I will have the standard requirements of a 5 BR home, but also for my gameroom, I will need 7 x 20A circuits. My question is how big of a box (both number of circuits and total capacity.)

As a side question, I have heard that when a breaker box is rated as 200A, that is for 240V, so it is equivalent to 400A at 120V. Is this accurate?

jbfan 11-16-2007 04:31 PM

http://www.electricalknowledge.com/SFDLoadCalc.asp

This will get you started.
I'm already thinking that with the game room, kitchen circuits, laundry circuit, and assuming electric heat and cooling and cooking, you will need a 400 amp service with at least 2 40 circuit 200 amp panels.

The last statement you made is incorrect.
A 200 amp panel is 200 amps per leg.

spebby 11-16-2007 05:00 PM

You should check with your jursidiction and see if there are any limits on where the breaker panel can be located. In my area, you can not have a breaker panel on an interior wall.

chris75 11-16-2007 05:07 PM

Quote:

Originally Posted by spebby (Post 74350)
. In my area, you can not have a breaker panel on an interior wall.

This is a state amendment? I don't see the sense in this requirement?

spebby 11-16-2007 05:23 PM

chris75, I don't have a clue as to where the requirement originated, but it's been in my area (Oklahoma City) for at least 7 years. 7 years ago I went from 200 amp service to 400 amp service and was required to move the breaker panel from an interior wall to an exterior wall, basically to the opposite side of the room. The old panel box is now a large junction box with the door screwed shut. In a current project I am building an attached garage. The meter base would have been in the garage so it had to be moved. I thought I was going to have to move the two breaker panels again, but the head electrical inspector granted a waiver and allowed them to remain in the current location. I quizzed all 3 of the licensed electricians making bids and the only answer I received was it was required by the Fire Department.

Andy in ATL 11-16-2007 07:53 PM

I'm probably gonna get booed for this.:huh: Assuming you have gas heat (Do you?) 200 Amps will be plenty for the house. I wired a 10,000 sq.ft 600A behemoth for a restaranteur up in the north GA mountains a couple of years ago and... try as I might, could not get more than 157A out of that sucker... I REALLY tried, to.

Can you expound a little more on this new house of yours? I assure you that you will not bore us...we eat load calcs for lunch. It excites us.:yes:

Speedy Petey 11-16-2007 08:24 PM

Quote:

Originally Posted by Andy in ATL (Post 74391)
... try as I might, could not get more than 157A out of that sucker... I REALLY tried, to.

Do you mean load calc or actual draw?

Andy in ATL 11-16-2007 08:29 PM

I forget the load calc, Speedy. It was no where near 600A, though. But this guy was filthy rich. I'm surprised we didnt put a 1000A service on it, though.

Actual draw with AC's, electric oven on broil, all the lights, etc., etc., It was an experiment that taught me alot actually.

That being said, I'm all for 400A services...very profitable.

troubleseeker 11-16-2007 09:41 PM

Quote:

Originally Posted by spebby (Post 74350)
You should check with your jursidiction and see if there are any limits on where the breaker panel can be located. In my area, you can not have a breaker panel on an interior wall.

Like every building regulation, there are many local quirks and this may be oone of them in your area, but to my knowledge you can install a breaker panel on any wall you want as long as it is not in a closet and has the required service clearance spaces in front of it, but there must be a panel box outside containing a "main" breaker that can be tripped to shut all power into the house in case of emergency.

Watch the laundry room installation, as many times the placement of the washer/dryer will violate the clear service space required in front of the panel.

Just as a side note, I"m not sure how much luck you are going to have finding an electrician willing to risk his license by making the panel tie ins only on a house wired as a DIY project.

sparky1980 11-16-2007 10:16 PM

Quote:

Originally Posted by troubleseeker (Post 74409)
Like every building regulation, there are many local quirks and this may be oone of them in your area, but to my knowledge you can install a breaker panel on any wall you want as long as it is not in a closet and has the required service clearance spaces in front of it, but there must be a panel box outside containing a "main" breaker that can be tripped to shut all power into the house in case of emergency.

How about a bathroom? I thought it was not permitted. I need to look in a code.

JGarth 11-17-2007 11:42 AM

Quote:

Originally Posted by swampwiz (Post 74343)
I am an aerospace engineer and have worked on plenty of electrical projects, so I think that I know how to do this, including following codes.

Where have I heard this before ....

Andy in ATL 11-17-2007 12:03 PM

Quote:

Originally Posted by JGarth (Post 74458)
Where have I heard this before ....


Where, Mr. Garth??? Where?:huh:

220/221 11-17-2007 05:46 PM

200 amp service is standard unless you have more than 2 AC's.


Quote:

I am an aerospace engineer and have worked on plenty of electrical projects, so I think that I know how to do this,

Heh heh...it's NOT rocket science pal. Hire a contractor.

jbfan 11-18-2007 11:56 AM

My son is an aerospace engineer, and he can wire his house.

Of course he worked with me til he graduated!

LawnGuyLandSparky 11-18-2007 12:18 PM

Quote:

Originally Posted by swampwiz (Post 74343)
OK, I will be starting to build a new home very soon, and need to figure out what size of breaker box to install. The breaker box will be put in the laundry room, against an interior wall with attic space directly above, if that makes any difference. I live in a jursidiction in which I can pull my own electrical permit, and if I need to save the case, I plan to do all the wiring up to the box (I will get an electrician to tie the breakers up, and then to the main line.) I am an aerospace engineer and have worked on plenty of electrical projects, so I think that I know how to do this, including following codes.

Anyway, everything starts with the breaker box. I will have the standard requirements of a 5 BR home, but also for my gameroom, I will need 7 x 20A circuits. My question is how big of a box (both number of circuits and total capacity.)

As a side question, I have heard that when a breaker box is rated as 200A, that is for 240V, so it is equivalent to 400A at 120V. Is this accurate?


I recommend you take a tour of a new home in it's rough stage of wiring before you proceed.


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