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# Right size circuit breaker

#1
11-25-07, 05:05 PM
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Join Date: Nov 2007
Posts: 3
Right size circuit breaker

The main circuit breaker box in my house is 200 Amp. There are two Sub-boxes. A 100 amp breaker in the main box feeds the sub-box for the detached garage. a 50 amp breaker in the main box feeds the second sub-box. Circuits on the sencond sub-box include an electric range and eight other 15 amp circuits.
The 50 Amp in the main box seems to small to me. What is the right size?

#2
11-25-07, 05:12 PM
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Location: Central New York State
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You have not provided enough information to answer the question.

What size is the wire feeding this sub panel? What are those 8 other 15 amp circuits for? What size is the breaker for the electric range?

#3
11-25-07, 05:12 PM
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Join Date: Mar 2007
Location: Bras D'Or, Nova Scotia ,Canada
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Breaker size is not determined by the sum of the breakers in the box... but by demand load, which is to say the amount of power you will be using at most times.

As long as the wire size is large enough to accomodate 50 A then you should be fine.

#4
11-25-07, 05:31 PM
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It is not uncommon for one range to be put on a 50 amp circuit. If the range is 8750 watts or more the minimum is 40 amps.
So 8.... 15 amp circuits plus a range in IMO is strectching that 50 amp breaker. I believe there is a section of code that requires a minimum of 60 amps for any panel that has more than two 2 wire branch circuits installed in it. Nec 225 something or 215 I don't have the book at this time. It really just depends on what the loads are and the diversity of those loads. If the range under normal cooking load is say 8500 watts thats 35 amps roughly so that only leaves 15 amps for loads on the 8 15 amp breakers. That isn't very good design.

Has the breaker been tripping?

Do you happen to know what the name plate wattage of the range?

#5
11-27-07, 08:30 PM
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Join Date: Nov 2007
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more into

the wire from the main box to the sub-box is 3/G 6awg. the breaker in the sub box for the stove is 50amp the same size as the breaker in the main box for the whole sub box. the other eight 15 amp breaker are for various lights and outlets through out the upstairs. The stove is rated at 10.4 kilowatts at 208 vac. I hope that provides enough info. This site has been very helpful.

#6
11-28-07, 07:16 PM
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Location: United States
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The #6 feeder is fine for a 50 amp breaker. If you are not having problems tripping the 50 amp breaker that I would say you have no issues.

#7
11-29-07, 07:45 AM
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I agree that it's a poor design, but doesn't require any action unless the 50A breaker has been tripping.