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Discussion Starter · #1 ·
I have the following circuits available to my basement:


(A) 1 - 20A (Currently 12/2 dead-end in blank box)

(B) 1 - 20A (Currently 12/2 to outlets including GFI)

(C) 1 - 15A (Currently 14/2 to 3 standard light bulb fixtures)

(D) 2 - 15A (Currently 14/3 to dead-end in blank box)


What I found odd was that the electricians ran a 14/3 off of two different 15A breakers, non-interlocking...So, I have one romex with 2 hots that share one neutral and one ground wire. I'd seen this done for 220V circuits with interlocking breakers, but not for two 110V circuits...


Anyway.


My plan is as follows:


(A) Equipment Rack + Projector (Panasonic 75u)


(B) Change to Outlets for HT (2 Subs, conv duplex, possible elec screen)


(C) Change to Lights for HT (10 Cans, 5 sconces, Dimmers)


(D1) One leg of 14/3 - Lights for non-HT areas (5 Cans, 2 Utility closet lights, 2 Ceiling Fans, 1 Track Lighting)


(D2) 2nd leg of 14/3 - Outlets for non-HT (1GFI, 8 duplex)


Firstly, does this look like a good arrangement of circuits, and secondly does it meet NEC load requirements.



EDIT:


I was doing some more research and ran across this post by Brucer:


max wire feet @ 120 volts, 1 phase, 2% max voltage drop:


15 amp #14=30' #12=47' #10=75' #8=120'

20 amp #14=.... #12=36' #10=57' #8=90'

30 amp #14=.... #12=.... #10=38' #8=60'


Is this a code requirement, or more of a performance guideline for not dropping your voltage to your AV equipment. My Basement is 30' long, and the breaker panel is on one end. The electrician's ran all #14 for 15 amp circuits. Now, the 15A circuits are only destined for general duty use (outlets and lights), but the entire circuit would certainly exceed 30 feet.


Lastly, what is the rule for splitting runs? Do you have to start at one device and end at the last one? For example, my services come into one corner of the basement...I have lights down both walls perpendicular to this corner...Do I have to go down one wall, loop back up and then down the other, or can I go to the first device, and split two feeds (#1 and #2) from there going back with #1 to service the other wall, and continue down with #2 on the existing wall?
 

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Hey Robert-


The wire size vs. Voltage drop chart came out of my 'Pocket Reference' by Thomas J. Glover, which is an extract of many sources - but most all the electrical comes from the National Electrical Code, and National Fire Protection Association.


BTW, this little book is jam packed full of all kinds of great stuff, and is generally available at better hardware stores, etc. It's about 500 pages packed into a 5-1/2" X 3" little book, I highly, highly recommend it. Virtually everything you ever wanted to know is in this little book.


By following these recommendations, relative to length of runs, you will avoid putting undue stress. Here's a quote:


" If the (voltage) drop is greater than 2%, the efficiency of the equipment in the circuit is severely decreased and life of the equipment will be decreased. "


it gives this example: "...if the voltage drop on an incandesent light bulb is 10%, the light output of the bulb decreases over 30%!"


If you think about it, it is easy to understand how H.D. and other building supply stores, make so much money selling portable power tools to the contractors. These guys are generally running hundred(s) of feet of light weight extension cord, and are plugging everything under the sun into it, thereby wearing the tools out quickly. (due to voltage drop).


For your example, If you are pulling 15 amps @ 30 feet on #14 wire, then you are right at the 2% recommended tolerance level. But say you were really only pulling 10 amps on that circuit, then that would be good up to 45 feet. Follow?


Anyway glad you found it and hope it helps,


Regards, Bruce


P.S. - Your last assumption of splitting, can be done as you asked (at the first device) or even ahead of that, if it's more convient. What is frowned upon is running two circuits, that double up at the breaker, (although, some people do it, probably not legally though).
 

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Discussion Starter · #4 ·
Can somebody please comment on the (D) to (D1) and (D2) circuits...Right now, this 14/3 comes to a box and dead ends...It was installed by the electricians when the house was built as a future use to the basement. It's connected to two different 15A breakers back at the main panel.


Can I use this box as a junction point, and run two romexs out, one for one 15A circuit, and one for a second 15A circuit. In other words, I would have one 14/3 coming in, and two 14/2's going out. The two 14/2's would be sharing the single neutral and ground in the 14/3, and then the two hots from each 14/2 would be nutted to each hot in the 14/3....


Capiche?
 

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I would not use the common neutral. This is a common practice on three phase lighting circuits where the load is known and can be balanced. In order for it to work both would have to be from opposite "sides" of the breaker panel and the attached loads would need to be balanced. The neutral carries any unbalance in the branch circuit currents plus non canceling harmonics, this can lead to overloading and overheating of the single neutral.


I'd pull another circuit if you can, or just use one of the circuits.
 

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I would venture a guess that the electrician ran the 14-3 for the convenience of the homeowner who might wish to put a 220V receptacle for a shop, etc. In most (i.e, new in the last 30 years) residences, the power company supplies single phase 110/220V service. This is a 3-wire service which delivers 2 sets of 110 (one for each "side" of your panel) with respect to neutral, and 220V with respect to each other. So, if the two non-interlocked breakers are on the same physical side of the box (i.e, opposite 110 power feeds), they could be replaced with interlocking breakers to obtain 220V service.


What is strange is that he would run 14 ga for such a circuit, when 12 ga would be more practical (220V @ 20A) and cost about the same.
 

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Discussion Starter · #7 ·
Well, don't that just bite....


I'll have to rip out three panels of drywall to get to the elec panel. The service panel is in the garage, which is drywalled. I know the services come out of the bottom of the panel, then run horizontal, parallel to the floor through holes drilled in the studs (I remember during construction). They then run under some framing for the water heater, then through a header board into the the ceiling of the basement.


To get more romex from the panel to the basement, I'll have to cut out the drywall in the garage. Not a huge deal, as the garage is unfinished, but still a royal pain.


No way to use the 14/3 for two circuits? Yes, I understand ssabin's post, but normally, a 220v circuit would have had interlocking breakers. These breakers are not only on different legs of the 220 service, but the breakers are even on different sides of the panel. Strange :(
 

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I wouldn't rip out all that rock. Too much work for a few wires IMO. I would try to fish new lines through the panel wall into/above the ceiling. OR you CAN use that 14-3 for 2 circuits like you plan. I would of course make sure the 14 guage wire can handle the load and consult an electrician to be sure. But yes, my electrician friend suggested I do this in my own theater. Since I already had 1000 ft of 12-2 sitting around and was running new lines anyway, I didn't do it. You are just using it for lighting and non-HT equipment. If you wanted, you could put the side for the plugs on the same "side" as the rest of the circuits of the theater and then the other for the lights. So IMO, your idea for 2 circuits on the 14-3 can work. But, just be sure to consult an electrician first.
 

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Discussion Starter · #9 ·
Just as a follow up, I spoke with a couple of electricians, and this is not uncommon and not an NEC violation. In fact, after their suggestions it makes perfect sense, as it is no different than a regular sub-panel feed. To avoid confusion with Inspectors I'm going to replace the two non-interlocking breakers at the main panel with a double pole 15A breaker. At the other end, I'm going to install a small load center (sub-panel), and install two single 15A breakers and go out from there with my two 14/2 circuits.


Thanks everyone for the input.
 

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Quote:
Originally posted by mysphyt

I would not use the common neutral. This is a common practice on three phase lighting circuits where the load is known and can be balanced. In order for it to work both would have to be from opposite "sides" of the breaker panel and the attached loads would need to be balanced. The neutral carries any unbalance in the branch circuit currents plus non canceling harmonics, this can lead to overloading and overheating of the single neutral.


I'd pull another circuit if you can, or just use one of the circuits.
Yea, but this is a Single Phase circuit. Using a common neutral in this case is done all the time and is perfectly OK. Since the two hots are 180 degrees out of phase, the neutral can never carry more than 15 amps. The advantage of doing this is, when both circuits are equally loaded, the current cancels in the neutral and you get no voltage drop in the neutral.


BTW, you can install the little load ceneter if you want to, but you don't have to -- just splitting it out to two 14-2's would be OK.
 

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Discussion Starter · #11 ·
BarryO,


Thanks for the confirmation....I went ahead and bought the little 2 circuit load center, but I can take it back...It may end up presenting more problems anyway, as I'm having a hard time placing it somewhere. What are the rules for location of a load center and/or junction box. I know it can't be hidden behind rock, but does it have to be recessed into a stud. I have some unfinished space that will be the back part of my equipment rack underneath the stairs. Can it be mounted here (Box or Load Center)? Does it have to be a certain height? If I mount it above my equipment area, it will be about 7' off the ground. Is this permissible?


Thanks
 
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