12-2 romex and 12-3 romex on same breaker.

[luvtheheat]

In my new detached garage I want to run romex 12-2 30 feet from the panel in the garage to a set of switches for overhead lighting, 8 lights total. I want to have 4 lights each controlled by 2 switches. Since cost of romex is sky high these days, I want to economize as much as possible. Can I run 12-3 from the switches to the first 4 lights, then 12-2 from light #4 to light #5-8?

My guess is no, due to potential for unbalanced neutrals if something shorts out, but would like the opinions/facts of those who know more than me about home electrical wiring. Facts preferred.

Thanks in advance.

 

[PCustoms]

In my new detached garage I want to run romex 12-2 30 feet from the panel in the garage to a set of switches for overhead lighting, 8 lights total. I want to have 4 lights each controlled by 2 switches. Since cost of romex is sky high these days, I want to economize as much as possible. Can I run 12-3 from the switches to the first 4 lights, then 12-2 from light #4 to light #5-8?

My guess is no, due to potential for unbalanced neutrals if something shorts out, but would like the opinions/facts of those who know more than me about home electrical wiring. Facts preferred.

Thanks in advance.

Why are you running 12/3 to the lights at all?

You want 2 banks of lights each, each bank with a switch?

12/2 to the switches, then 12/2 to bank 1 and 12/2 to bank 2. 12/2 between each fixture in a bank.

If you're doing 3 way switches for each bank I'll have to think for a minute.

 

[mike93lx]

Unless these are some massive lights, just run 14/2 and a use a 15a breaker. You can run 1440 watts of lighting on that circuit which is a ton when using led's.

But what you are proposing is fine. You can't overload the neutral when it is all fed from a single breaker.

 

[edcarey]

That should not be an issue of an unbalanced neutral as you will use a single pole breaker.

 

[sparky 1971]

It doesn't matter if it's 12 or 14 gauge, you aren't going to overload or unbalance the neutral with one circuit. Take the 12/3 or 14/3 to the first light, you don't need to take it through the first four. Jump from light #1 to light #5-8 with 12/2 or 14/2 tied to the black or red from three wire. Wire lights 1-4 with 12/2 or 14/2 using the color from the 12/3 you didn't use for lights 5-8. There's no sense in pulling 12/3 through four boxes and splicing one of the hots just to get to another set of boxes. If you already have the 12/3 go ahead and proceed. If you don't have it, and don't need it for anything else, leave it at the box store and just use two 12/2 or 14/2's. You're not saving much, if anything since what you do save will be offset by the partial roll of 12/3 that's going to sit on a shelf for years.

 

[mike93lx]

You're not saving much, if anything since what you do save will be offset by the partial roll of 12/3 that's going to sit on a shelf for years

I felt that.

I was a ******* and thought I needed 12/3 for a project, so I was a ******* again and bought a 250' coil. Used 75' for that project and have managed to find a good use for 3' of it in the last decade.

I keep trying to come up with excuses to use it, but it feels wasteful. So it sits on the shelf.

 

[dave*99]

12/3 is handy for a MWBC in the garage...... where I seem to use more and more cordless tools.....

 

[theoldwizard1]

Why are you running 12/3 to the lights at all?

I'm not sure when this was add to the NEC, but all branch junction boxes are required to have a "hot at all times" and a neutral in addition to any switched lead.

14 AWG is more than adequate for almost any residential lighting circuit.

 

[PCustoms]

I'm not sure when this was add to the NEC, but all branch junction boxes are required to have a "hot at all times" and a neutral in addition to any switched lead.

14 AWG is more than adequate for almost any residential lighting circuit.

This one is news to me....

I get the neutral, but what is the logic with the always hot?

 

[Zeke]

This one is news to me....

I get the neutral, but what is the logic with the always hot?

So you can use electronics in the box like timers and USB chargers. Used to be that to have a circuit to these devices where a switch leg was present, the electronics were getting the 'neutral' by way of the EGC.

I think with the necessity of so many things/locations requiring GFCI you don't want stray voltage on the grounding conductors.

I may not be answering your question. What box doesn't have a "hot at all times" that would have any device?

 

[PCustoms]

So you can use electronics in the box like timers and USB chargers. Used to be that to have a circuit to these devices where a switch leg was present, the electronics were getting the 'neutral' by way of the EGC.

I think with the necessity of so many things/locations requiring GFCI you don't want stray voltage on the grounding conductors.

I may not be answering your question. What box doesn't have a "hot at all times" that would have any device?

You're not...

I get the neutral, and wired my own house that way. I do not know of a code requirement for an additional got in each junction, now doni understand what it would bring.

Unless I'm missing something the OP could have wired with 14/2 and been all set.

 

[sparky 1971]

I'm not sure when this was add to the NEC, but all branch junction boxes are required to have a "hot at all times" and a neutral in addition to any switched lead.

14 AWG is more than adequate for almost any residential lighting circuit.

No, no, no. Junction boxes are not required to have a constant hot. As far as the neutral goes, it's switch boxes that you are thinking of but it's not always required even though it's not a bad idea. Read NEC 404.2(C) for the requirements.

404.2(C) Switches Controlling Lighting Loads.

The grounded circuit conductor for the controlled lighting circuit shall be installed at the location where switches control lighting loads that are supplied by a grounded general-purpose branch circuit serving bathrooms, hallways, stairways, or rooms suitable for human habitation or occupancy as defined in the applicable building code. Where multiple switch locations control the same lighting load such that the entire floor area of the room or space is visible from the single or combined switch locations, the grounded circuit conductor shall only be required at one location. A grounded conductor shall not be required to be installed at lighting switch locations under any of the following conditions:

(1) Where conductors enter the box enclosing the switch through a raceway, provided that the raceway is large enough for all contained conductors, including a grounded conductor

(2) Where the box enclosing the switch is accessible for the installation of an additional or replacement cable without removing finish materials

(3) Where snap switches with integral enclosures comply with 300.15(E)

(4) Where lighting in the area is controlled by automatic means

(5) Where a switch controls a receptacle load.

The grounded conductor shall be extended to any switch location as necessary and shall be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and shall meet the requirements of 404.22.

Exception: The connection requirement shall become effective on January 1, 2020. It shall not apply to replacement or retrofit switches installed in locations prior to local adoption of 404.2(C) and where the grounded conductor cannot be extended without removing finish materials. The number of electronic lighting control switches on a branch circuit shall not exceed five, and the number connected to any feeder on the load side of a system or main bonding jumper shall not exceed 25. For the purpose of this exception, a neutral busbar, in compliance with 200.2(B) and to which a main or system bonding jumper is connected shall not be limited as to the number of electronic lighting control switches connected.

 

[wyliesdiesels]

I'm not sure when this was add to the NEC, but all branch junction boxes are required to have a "hot at all times" and a neutral in addition to any switched lead.

14 AWG is more than adequate for almost any residential lighting circuit.

Huh? What code is that?

 

[wyliesdiesels]

So you can use electronics in the box like timers and USB chargers. Used to be that to have a circuit to these devices where a switch leg was present, the electronics were getting the 'neutral' by way of the EGC.

I think with the necessity of so many things/locations requiring GFCI you don't want stray voltage on the grounding conductors.

I may not be answering your question. What box doesn't have a "hot at all times" that would have any device?

There is no requirement to have a constant hot in every box... the neutral on the other hand is required at all switch boxes...

 

[dave*99]

Huh? What code is that?

Maybe here, I'll send you my copy after I'm done reading it.

 

[PCustoms]

Maybe here, I'll send you my copy after I'm done reading it.

Thanks for confirming I haven't list my mind!

 

[alfredeneuman]

the neutral on the other hand is required at all switch boxes...

Not so.
Sparky 1971 posted the rule in post #12, with the exceptions>>>

(1) Where conductors enter the box enclosing the switch through a raceway, provided that the raceway is large enough for all contained conductors, including a grounded conductor

(2) Where the box enclosing the switch is accessible for the installation of an additional or replacement cable without removing finish materials

(3) Where snap switches with integral enclosures comply with 300.15(E)

(4) Where lighting in the area is controlled by automatic means

(5) Where a switch controls a receptacle load.

 

[Zeke]

There is no requirement to have a constant hot in every box... the neutral on the other hand is required at all switch boxes...

You always get me on the technicalities. I wasn't thinking of a ceiling box meant for a light that might only have a switched leg.

At least I got part of it right. Now excuse me while I go sit in the dog house.

 

[dave*99]

You always get me on the technicalities. I wasn't thinking of a ceiling box meant for a light that might only have a switched leg.

At least I got part of it right. Now excuse me while I go sit in the dog house.

And a receptacle box with only a switched leg might not have an unswitched hot leg.

 

[dcg9381]

Since cost of romex is sky high these days, I want to economize as much as possible. Can I run 12-3 from the switches to the first 4 lights, then 12-2 from light #4 to light #5-8?

I think what you want to do is run 12/3 to a double pole breaker and share the neutral. That works, everything is out of phase, and you save yourself 2 additional wires over a duplicate run of 12/2.

 

[dave*99]

I think what you want to do is run 12/3 to a double pole breaker and share the neutral. That works, everything is out of phase, and you save yourself 2 additional wires over a duplicate run of 12/2.

No need for a 2 pole breaker. 1 breaker, 1 neutral is all that is needed.

 

[dcg9381]

No need for a 2 pole breaker. 1 breaker, 1 neutral is all that is needed.

We must be talking about two different things. To get "two circuits" out of 12/3, you need a dual pole to make sure they are out of phase. What am I missing?

 

[dave*99]

We must be talking about two different things. To get "two circuits" out of 12/3, you need a dual pole to make sure they are out of phase. What am I missing?

The OP has 1 switch box. He wants to put 2 switches in it. Switch A controls 4 lights and switch B controls 4 lights.
So he needs 2 switched legs and 1 neutral with 12/3. Or he can use (2) runs of 12/2
As best I can tell, the 8 lights are all in a line (row) and he wants to conserve wire. He proposed to run 12/3 along the first 4 lights and exit #4 with 12/2 to hit lights 5-8.

 

[luvtheheat]

The OP has 1 switch box. He wants to put 2 switches in it. Switch A controls 4 lights and switch B controls 4 lights.
So he needs 2 switched legs and 1 neutral with 12/3. Or he can use (2) runs of 12/2
As best I can tell, the 8 lights are all in a line (row) and he wants to conserve wire. He proposed to run 12/3 along the first 4 lights and exit #4 with 12/2 to hit lights 5-8.

Dave*99^^^, exactly.

Sorry if I was less than clear in my OP. I have one single pole breaker. Original Q was can I run 12-2 from breaker to switch box. Then 12-3 from switch box to two banks of lights.

Since my OP, I've read some of the replies and thought more about this, and came to the conclusion that I can do what I proposed and not get into "unbalanced neutral" territory.

Thanks