Planning for new subpanel for basement

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  #1  
Old 09-20-05, 10:45 AM
GhostD
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Planning for new subpanel for basement

Hi Everybody!

I am finishing my basement as a DIY project. At the pre-wiring stage for electrical. I have four rooms in the basement not including the new bathroom and the existing HVAC closet. Its about 1100-1200 SqFt and I need just general wiring in all rooms but the one room being designated for a DIY home theater.

*Obviously, the new bathroom will also have special needs for the exhaust fans, ejector pump, and GFCI.
*I am not adding any additional HVAC in terms of heating or cooling, but considering seom room-to-room air exchange fans.

My existing electrical service has the main panel in the basement, with sparce real-estate. I have room for four single-pole circuits. Not enough for what I'm trying to achieve. I'm thinking of using a 2/3-pole 40/50A breaker to feed a subpanel, which would be installed in the next stud-cavity.

I figure that each room would need enough circuits to accomodate wall outlets and ceiling lighting. Bathroom needs 2-3 circuits for GFCI outlets, exhaust fan, and ejector pump. And the DIY home theater will need one circuit for general purpose outlets and a single light-box (not to be used), plus a couple of additional 15A circuits for all of the special lighting and audi-video equipment.

My concern is determineing the amount of current I'll need to provide from the main panel to the subpanel and include some overage. I figure the DIY home theater will need four 15A circuits, but wondered if I could get away with using dual-circuit breakers that fit into one slot. I also was wondering if those dual-breakers could be used for general purpose service for the other three rooms, and then two dedicated (separate breakers) for the new bathroom.

Not really sure at this moment as this is just a preliminary brainstorming endeavor.
 
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  #2  
Old 09-20-05, 10:53 AM
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The cost-difference between a 100 amp Feeder, and a Feeder of less ampacity, does not justify a Feeder with an ampacity of less then 100.

Good Luck & Learn & Enjoy from the Experience!!!!!!!!
 
  #3  
Old 09-20-05, 11:00 AM
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Do not waste your time with 15 amp circuits. Install all 20 amp circuits. You'll be glad you did.
 
  #4  
Old 09-20-05, 11:45 AM
GhostD
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Originally Posted by PATTBAA
The cost-difference between a 100 amp Feeder, and a Feeder of less ampacity, does not justify a Feeder with an ampacity of less then 100. Good Luck & Learn & Enjoy from the Experience!!!!!!!!
Thanks for the best wishes. BTW, I am not sure what you mean about '100 amp feeder'. Not trying to pinch money and more than willing to go with a 100A feeder, but what is a 'feeder'. Lol
Originally Posted by racraft
Do not waste your time with 15 amp circuits. Install all 20 amp circuits. You'll be glad you did.
I hear that! I had run a couple of 20A temp circuits off the pre-existing panel for running the compressor for the nailer, and also the miter, recip, and circular and table saws.
 
  #5  
Old 09-20-05, 12:12 PM
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One other comment. Make sure that if any of these rooms are to bedrooms that you meet the applicable building codes regarding a second means of egress for bedrooms in addition to all applicable electrical codes for bedrooms.
 
  #6  
Old 09-20-05, 12:17 PM
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A feeder is the wiring between panels.
 
  #7  
Old 09-21-05, 06:10 AM
GhostD
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racraft, no new bedrooms in this endeavor, but the designated DIY home theater happens to have a paired window already installed if future plans call for it (like the next homeowner).

John, thanks for that clarification. I'll be seeking a 100A feeder solution.

All, a quick and curious question:

The pre-existing main panel is rated at 225A, but the main breaker (outside, on my side of the meter) is only 150A-rated. I'm betting if I go identifying the main feed (that fat aluminum conductor from the street/meter) its also rated for 'not more than 150A.

While I have access, what should the main conductor be (0000?) for 225A that the main panel is rated for, or is the main panel's rated including a 50% overage of the main breaker?
 
  #8  
Old 09-21-05, 08:52 AM
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The 225 is just a maximum. You can use it at anything up to that. There's no reason to wire it for more than you need.
 
  #9  
Old 09-21-05, 09:33 AM
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The purpose of the "Main-breaker" is to limit the current to a value equal to the ampacity of the Service Conductors.

The rating of the panel can exceed, but cannot be less then, the rating of the circuit-breaker that protects the "supply" conductors to the panel.

For a 150 amp Service , NEC Table 310.15 permitts a #1 copper conductor, or a #00 aluminum conductor.
 
  #10  
Old 09-25-05, 08:02 AM
GhostD
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I guess I'm not reading the main conductor's PVC jacket correctly. It says, AL Type, 1 AWG. I interpret this as being Aluminum, AWG being 1, not 00. I am pretty sure its Aluminum, because the EMC's down here in Georgia love that stuff.

If I am reading the PVC jacket correctly, this would imply its not even rated for the 150-A main breaker service.
 
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