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Hi, I bumped into a question regarding number of circuits for a dwelling. Question says "For a dwelling unit of 1,200 square feet, the minimum number of branch circuit required to supply lighting (at 15 Amp), small appliances, laundry, and a gas fired furnace with 1/4 HP motor is:
a. 8
b.7
c. 6
d. 5

I can't seem to come up with answer indicated, which is b, 7 circuits.

What am I missing?
 

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1200 x 3 watts per square foot equals 30 amps ( 1200x3)/120V. Looks like they made that theee 15 amp circuits. Two circuits for small appliance kit circuits one for laundry and one for furnace.
 

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animal lover /rat bastard
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2 small appliance
2 general lighting
1 furnace
1 laundry
1 bath
=7


although I think now you would need one for exter ckt , makes 8 ?

the assumptions here, which beg the question "who builds a home these days withh/without the following items":
no microwave (or tiny one)
no dw
tiny fridge

tests are tests. gonna be some trick questions, and some that are worded very poorly, and some that haven't been researched or updated. that is one of the reasons you don't need a really high score to pass in most places, I believe.
 

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Honestly, I don't know anything about it. I saw that your number was different than cabletie's so I was curious. :biggrin:

I've never done this calculation. As you mentioned earlier, I would install way more circuits and not even consider the minimums.
 

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1200 x 3 sq.ft= 3600watts

15 x120 = 1800

15 amp cir is 1800 watts so you need 2 for 3600 watts
 

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210.11 (C)(3)Bathroom Branch Circuits.
In addition to the number of branch circuits required by other parts of this section, at least one 120-volt, 20-ampere branch circuit shall be provided to supply the bathroom(s) receptacle outlet(s). Such circuits shall have no other outlets.
Exception: Where the 20-ampere circuit supplies a single bathroom, outlets for other equipment within the same bathroom shall be permitted to be supplied in accordance with 210.23(A)(1) and (A)(2).
 

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Also a garage circuit, but it must be an old question?

I don't get why it's seven also, going by the question. By the square foot you only need two fifteen amp circuits. I don't think continuous load plays a part, making the 30 amps needed really 30 x 1.25
 

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No, residential lighting loads are not continuous


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Yup. Plus, IMO the 3w/sqft thing is only for calculations. It's not expected to be actually used and therefore need 80% rules (even if they applied).
That extra "play" is already built into the 3watt number.

@KenanBilge what are you doing this for? Are you studying for your license or in school?
 

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1200*3=3600
15*120=1800

80% loading is coming into play here is my guess.

1800*0.8=1440.

3 general purpose/lighting circuits

No, residential lighting loads are not continuous


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I agree, but when I was studying for my test last year, damned if every question for a load calc treated then that way.
 

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Hi, I bumped into a question regarding number of circuits for a dwelling. Question says "For a dwelling unit of 1,200 square feet, the minimum number of branch circuit required to supply lighting (at 15 Amp), small appliances, laundry, and a gas fired furnace with 1/4 HP motor is:
a. 8
b.7
c. 6
d. 5

I can't seem to come up with answer indicated, which is b, 7 circuits.

What am I missing?
If you read this question then a bathroom should not enter into the answer as the question specifically states what is considered.

We know that a small appliance branch circuit has minimum 2 circuits, laundry has 1 circuit, gas furnace has 1.

Now we are into the 1200 sq.ft which is 3600 watts- 2 - 15 amp circuits. 6 should be the answer but I am guess the person who did the test was thinking continuous load.. That is incorrect as stated by others
 

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animal lover /rat bastard
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If you read this question then a bathroom should not enter into the answer as the question specifically states what is considered.

We know that a small appliance branch circuit has minimum 2 circuits, laundry has 1 circuit, gas furnace has 1.

Now we are into the 1200 sq.ft which is 3600 watts- 2 - 15 amp circuits. 6 should be the answer but I am guess the person who did the test was thinking continuous load.. That is incorrect as stated by others
the first 4 words of the question state " for a dwelling unit".

I'm not gonna dig out my book, but my recollection is that a dwelling unit, as defined by NEC, has a kitchen and a bath and at least one bedroom.

so I believe your answer of 6 is in error.
 

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Hackenschmidt
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the first 4 words of the question state " for a dwelling unit".

I'm not gonna dig out my book, but my recollection is that a dwelling unit, as defined by NEC, has a kitchen and a bath and at least one bedroom.

so I believe your answer of 6 is in error.
But the question doesn't ask how many circuits are needed for the entire dwelling; it asks how many are needed for this list of loads - lighting (2 for 1200 square feet), small appliances (2), laundry (1) and furnace (1).
 
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