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Clutchcargo 05-25-2007 11:03 AM

Circuit configuration???
 
I'm working on the configuration of the circuits in my house. I'll be doing the second floor electrical shortly and I wanted to run my ideas by you guys.

I have a small 2 story 3-bed house (renovation). The second level is where all the beds are and a full bath. I'm trying to figure out how many circuits I need.

My thoughts are:
1 circuit each for the receptacles in the bedrooms (3-AFCI 15A circuits). The hall outlets would also share the circuit with the smallest bedroom.
1 circuit for the entire second floor lighting/ceiling fans and CO/smoke detectors (1-AFCI 15A circuit). Can I also put the bath lighting and exhaust fan on this circuit?
2 circuits for the bath receptacles (2-20A circuits with GFCI outlets).

That's a total of 6 circuits for the 2nd floor. Does this sound reasonable?

TIA

joed 05-25-2007 04:36 PM

You can put the bath lights and fans on any circuit you wish.
Have enough circuits to meet all the code requirements. Most bathrooms only have one 20 map but there is no rule against two.

jwhite 05-26-2007 09:11 AM

Could be a bit overkill, but if this is your dream home, then I would say not too far overkill, just overly practicle.

Dont forget that all the CO/Smokes in the house must interconnet, so the ones on the first floor must also be on this same AFCI protected circuit. You should run a 14-3 from smoke to smoke, and a 14-2 from the first smoke to a good place where you can split the circuit to the lights.

Clutchcargo 05-29-2007 02:21 PM

Thanks,
No not my dream home, but since the walls are open anyway, why not.
What is a typical configuration in new construction?

Good point about the interconnected smokes, I forgot I needed to connect basement, 1st floor, and 2nd floor together. Is there a code that specs where in the basement the smoke detector goes?

Also, I'm going to create a chase next to the chimney. The chase is going to contain 2 - 1" EMT and hydronic heating pipe. The conduit will be run from a large junction box in the basement to another one in the attic. The other conduit is for data/phone/TV. Do you see any issues going this route?

Since this will be metal conduit and j-boxes, do I need to run a ground from the panel or can I just pigtail all the grounds in the attic j-box and screw to the junction box in the attic?

TIA

keyser soze 05-29-2007 03:42 PM

For the low voltage you could use plastic (EMT?) conduit if its cheaper. Great idea about separate pipes for the high and low volt. You will be happy you did that later.

Code here (for new construction) says that each rooms recepticles' have to have their own breaker (one home run per room) so I don't think you are going too far overboard. I am jealous of your open walls. I've been trying to fish through plaster and rough cut heart (sp?) pine for months now. :mad:

You're on the right track I think. My motto is more wire is better (which works 99% of the time unless you just can't cram it all into the box). :)

jwhite 05-29-2007 05:45 PM

keyser, where in NC are you. I am a licenced master in NC and know of no such code as the one you stated above.

Typical number of recs on one circuit for new construction is 9-12 on one circuit. The code tells us to use a sq foot rule. measure the sq foot of the rooms, and insure that you have 3 va of electric or each sq foot. This is a bogus rule, cause you could have one 15 amp circuit with all the recs on it, and add one circuit with one rec on it and meet the rule.

as for the pipe chase you have issues with bundled cables that are a bit complex. we need to know if you are going to run romex in the conduit, or THHN. We need to know how many.

It does sound like a good idea for future. Grounding depends on the type of wiring you use, either way you should put at least one ground wire in the pipe at the time you put any circuit wiring in it.

In the mean time be sure to fire stop both conduits

Clutchcargo 05-29-2007 06:55 PM

I'll be running THHN between the panel and the junction box in the attic. At the junction box I'll switch over to NM to run down into the bedroom walls.

I was thinking 4 AFCI circuits = 8-14G wires.
2 20AMP circuits = 3-12g wires. If I don't need individual grounds, that's only 11 conductors. Using 2005 NEC Annex C, 1" EMT should be able to handle 35-14AWG or 26-12AWG THHN conductors before derating is needed.

Would the junction box at both ends of the EMT qualify as a firestop or do I need to stuff some insulation at each end of the EMT?

Do you have any idea if there is a code for minimum chimney clearance to the conduit?

JohnJ0906 05-29-2007 08:18 PM

Derating begins at 4 current carrying conductor. NEC 310.15(B)(2)(a)

JohnJ0906 05-29-2007 08:21 PM

To run the circuits as you have said, the 15 amp circuits (in the conduit) will need to be #12 AWG, and #10 AWG for the 20 amp circuits

keyser soze 05-29-2007 08:24 PM

Quote:

keyser, where in NC are you. I am a licenced master in NC and know of no such code as the one you stated above.
I'm near Asheville and I stand corrected.

I'll stop trying to tell others what code is. Everything I know is from electricians (and I only trust one that I know, now that I think about it).

Thanks for straightening me out there.

Clutchcargo 05-29-2007 11:37 PM

Quote:

Originally Posted by JohnJ0906 (Post 46824)
Derating begins at 4 current carrying conductor. NEC 310.15(B)(2)(a)

Wow, thanks John. Because of the AFCI breakers, I've got 10 current carrying conductors, which means I have to derate by 50%. I might have to rethink this.

jwhite 05-30-2007 09:01 AM

now start your de-rating calcs from the 90 deg C columb. 30 amps for 12 wire and 25 amps for 14 wire.

12 wire at 90 c is 30 amps x .5 is 15 amps, and 15 is a common size breaker. so the 12 wire needs to be increased.

14 wire at 90 c is 25 amps x .5 is 12.5 amps. the next common size breaker is 15 amps. So the 14 wires can go on a 15 amp breaker.


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