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Old 01-02-2008, 03:35 PM   #1
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Populating New 100 AMP Subpanel


How many breakers can I install in a 240v/100amp panel? I am planning a new workshop with welders and lots of lighting. I have a count of 132.5 amps worth of breakers some 120v some 240v on each of the two legs. Is this OK? The two bigest loads are two welder that would not be used at the same time.

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Old 01-02-2008, 03:50 PM   #2
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You question was a great attempt, but we will need more info. "Lots of lighting"...How much and what kind? How many amps is the biggest welder? What other loads? If it is just lights and a welder (or two, not welding at same time, ever ) I bet you would be fine with 60A. The more info, the better. Pictures excite us as well, so break out the digital and snap some photos of this shop.

Andy

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Old 01-02-2008, 05:18 PM   #3
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You question was a great attempt, but we will need more info. "Lots of lighting"...How much and what kind? How many amps is the biggest welder? What other loads? If it is just lights and a welder (or two, not welding at same time, ever ) I bet you would be fine with 60A. The more info, the better. Pictures excite us as well, so break out the digital and snap some photos of this shop.

Andy
Hi Andy, the shop is not even started other than the drawings. Here is the schedule I have so far...See attachment.
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Old 01-02-2008, 06:09 PM   #4
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To answer your question...42 circuits. That goes away in '08. Great attachment.
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Old 01-02-2008, 09:01 PM   #5
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How many breakers can I install in a 240v/100amp panel?
As many as it will hold


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Old 01-02-2008, 10:54 PM   #6
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To answer your question...42 circuits. That goes away in '08. Great attachment.
What goes away with the '08 code?

btw, last I knew, the largest 100 amp panel is, I think, 24 circuit, maybe 32 but I think it is 24. If you want a 42 circuit, you have to use a higher ampacity panel ( can't remember where the 42 circuit panels start) and either backfeed with a 100 amp breaker as a main (will reduce it to a 40 circuit panel), or if in the same building, use an MLO panel and feed it with a 100 amp circuit.
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Old 01-02-2008, 11:14 PM   #7
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Populating New 100 AMP Subpanel


the largest 100 amp panel box [ USA verison ] is 30 space i know both SqD and C-Hammer both carry this size.

The Canaida verison is much larger AFAIK many as 60 space [ 200 amp verison ]

that will be nice with larger homes with that many circuits and what really help is the AFCI requirement that will somehow increase the circuits anyway.

Merci, Marc
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Old 01-02-2008, 11:20 PM   #8
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Ok, maybe I misworded that question. What is the maximum sum of the breakers that could go in a 100amp sub?
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Old 01-02-2008, 11:23 PM   #9
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220, 221, whatever it takes...



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As many as it will hold


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Old 01-03-2008, 09:23 AM   #10
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Ok, maybe I misworded that question. What is the maximum sum of the breakers that could go in a 100amp sub?
The sum of the breakers has nothing to do with it. You need a load calculation for the building the panel will serve.
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Old 01-03-2008, 09:50 AM   #11
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The sum of the breakers has nothing to do with it. You need a load calculation for the building the panel will serve.
So help me out here, I feel like I'm a human landmine detector in old landmine field. I have a load plan attached above with my lighting, conv recp's and special need recepticals. What next?
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Old 01-03-2008, 11:54 PM   #12
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How do I calculate the load of the new building or my existing residence?

Thanks,
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Old 01-04-2008, 12:49 PM   #13
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What they are saying is that if your panel has 42 slots you can install 42 breakers. If it has 32 you can install 32 breakers. This is a combination of single and double pole breakers. Or all single or all double.
If you were to ask "what size service panel do I need" then a load calculation is required.
You see your panel has a main breaker. Regardless of how many breakers are installed, the main breaker is your overcurrent and short circuit device. You could even install a 200 amp breaker in your 100 amp panel, but your protection is 100 amp. Stubbie posted these links today in another thread.

http://ecmweb.com/mag/electric_dwell...feederservice/

http://www.selfhelpandmore.com/homew...calc/index.htm


Last edited by J. V.; 01-04-2008 at 12:52 PM.
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