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  #1  
Old 12-18-2007, 11:30 AM
smooth72 smooth72 is offline
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Default Help on Breaker Box

This is my second breaker box next to my 200 amp box. It is a 125 amp box. My question is next to the main breaker can I install a 220 breaker. I have seen some boxes that say leave blank but I need to add a 220 breaker for an AC unit and this is the last double breaker place I have remaining. Thanks for any input.
http://i11.photobucket.com/albums/a1...Breakerbox.jpg
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Last edited by smooth72; 12-18-2007 at 01:43 PM.
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Old 12-18-2007, 11:49 AM
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Sberry Sberry is offline
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Yes, if there are contacts and more tabs to remove to make the cover fit go for it.
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Old 12-18-2007, 12:23 PM
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There should actually be a drawing in the cover. I think I would shut that down, unsnap the breaker and work on the wires, pre-fold a little to align and relax them so the breaker relaxes squarely. Some require a main breaker holdown clamp. You may actually have 2 more slots, if this is a sub next to the main there is no breaker needed, hook the feeds to the main lugs and toss the breaker as long as there is correct over current protection feeding it.
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Old 12-18-2007, 02:51 PM
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Default check the codes

I am not sure what the electrical codes are in your area, but in my part of the world, you can not have anything in the top portion of the panel next to the service breaker.
there is a cover plate that will go over the service breaker that will also cover the other side of the bus bar. (If I am reading that photo correctly) to isolate the usage breakers from the service area of the panel. I would check into the codes before setting that up, just to be sure (and safe.)
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Old 12-18-2007, 03:24 PM
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Do you have any idea of the amp draw now .Yes the box is full but the draw through the 200 amp panel is ? You could pull and place a breaker in the 200 to feed the 125 if total draw is ok. otherwise back to meter and seperate feed or to the external disconnect if you have one. If service is 200 the electrcal company may require a upgrad before allowing to pull for the 125.They did allow it for me 200 amp service ,200 amp box for house and pulled a 125 for garage.
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Old 12-18-2007, 06:05 PM
smooth72 smooth72 is offline
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Thanks for the info. The box has normal tabs with no restriction. I think both breaker boxes goes out to the meter. I have a 1300 square garage and when I built the house the electrician said with a garage this big he put in extra service. (maybe). I was wondering how you count the load on the box. If you just count up the breaker amps? I have a 50 amp welder breaker in the 200 box plus lots of other amp breaker that could add up fast. Since you never use every thing at once is there a formula that you use?
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Old 12-18-2007, 07:43 PM
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The only sure way I would know would be turn everything on and clamp a amp probe on the legs to see amp flow . Things like dryer ,range ,welder , heat and air if total electric home are all high draw
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  #8  
Old 12-18-2007, 09:00 PM
russ69coupe russ69coupe is offline
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Quote:
Originally Posted by smooth72 View Post
Since you never use every thing at once is there a formula that you use?
There is a formula electricians use. I read alot on a professional electrician forum(can't post there though, I am not an electrician, and they forbid do it yourself questions). You don't add up the breakers.

http://forums.mikeholt.com/

This has been covered there, I don't remember the details. You can search on it I think.
but remember, don't post there.

Russ
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Old 12-18-2007, 10:02 PM
R Funk R Funk is offline
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There are 3 issues that come to play in a situation like this:

1) What does the manufacturer say. In other words does the UL listing of the panel include a breaker in that position? Read the info on the inside of the panel/panel cover or go out on the web. The information should be there on the manufacurer's site.

2) You need to go through the National Electric Code (NEC) calculations for the connected load and application. This is carefully laid out in the NEC. These calculated values are usually well under 50% of the connected load (sum of all loads conected)

3) The actual measured load on the panel. It will most likely be well below the capacity of the main breaker and probably below the NEC calcualtions.

Editorial Note: It is amazing how low the total typical electrical load on panel is due to diversity of the load. Most of us will not be running a welder, drill press, plasma burner etc at the same time. Go to to Harbor Freight and buy their amp meter (I paid $10.00 or $12.00 for mine if I remember correctly but is now superceded by a $100 meter I purchased later) and measure the typical amp draw. Of course I should recomend a Fluke or other major US company but you will spend almost 10 times more. However I found the HF meter's performance suprisingly acceptable.

Buy the way to pass UL listing the breaker must trip at no more than 120% of rated load after 30 minutes. I doubt if you will continously load the main at full load for more than 5 minutes at a time or so....

Unofficial Comment: Is the electrical inspector going to be involved? If not install it (if allowed by the panel manufacturer) and let her rip. Most panels are so lightly loaded in typical non industrial applications the main will never trip. If it does what does it hurt as long as you don't have your mother in law on life suport equipment in the house or your wife is in a bad mood, if this panel feeds your house also? However make certain that you still follow the NEC for the materials and workmanship.

Trust this helps
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  #10  
Old 12-19-2007, 09:21 AM
smooth72 smooth72 is offline
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Thanks for spending the time on this great information.
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