Simple 120v switch question.

[Allan Speers]

I'm about to wire up a simple wall-mounted on-off switch, which will control a multi-outlet 120v box in the ceiling. (my two air cleaners)
The source of the electricity is also on the ceiling, so it would be cumbersome to simply put the switch "in line." To do that, I'd have to run romex all the way down to the switch, then another run all the way back up to the outlet box.

I'm not sure exactly what method is to code, so I did a little Googling, and now I'm confused.

I've done it a few times in the past, as shown here. Just one 14g romex going to the switch, (the switch grounded, of course) and the white and black wires in that romex simply interrupting the hot lead to the outlet box:

408962

But today I read something about the codes changing in 2011, and that now you need a separate neutral wire at the switch. - But it wasn't clear if that was for every situation. So, is that true? In other words, do I have to run two lengths of Romex, to and from the switch, after all?


Two other questions that always bugged me:

1: In this particular diagram, they used a separate junction box for the romex feed to the switch. Isn't it OK to simply run it from the outlet box? (Or the box for a light, if that was what you were switching?)
I know there's some code about maximum number of wires in one box, but this doesn't seem excessive.

2: Are you supposed to wire the return white wire, which is of course hot, red? I've never seen this done, but it seems reasonable given it's always red in the diagrams. Would you use red heat shrink? Or not bother?


Thanks.

[Bill Space]

Alan,

I am not up to date on the current NEC, but basically all you should need to do is run one romex (two conductor with ground) wire from the ceiling box to the switch box. The white wire in that Romex would be taped (or painted) black at both ends. This tells anyone who happens on that wiring that the wire taped or painted black is being used as a hot conductor. The Bare ground wire would be connected to the switch at the green screw. The black wire and the taped black wire (formally white) would be connected to the switch terminals. The wire with the black tape on it would be connected to the hot side (brass color) of the receptacle powering the air cleaners.

To meet code the box that holds the receptacle powering the air cleaners (the source of the voltage going to the new switch) must meet NEC requirements for wire fill. Larger boxes can have more wires than smaller boxes.

This is is a start anyway. Perhaps others will wish to expand on it.

[Mike Cutler]

Alan

Each situation is different, becuase you never know what is, and isn't allowable, in each geographic location. What may a modification to an existing circuit will be covered by the prevailing applicable code at the time, may be treated as a new installation and have to meet the most recent code in another location.

Basically, with rare exception, you always want to "switch" hot, so in the case you have you could run two conductor Romex and "make white black", or you could run 3 conductor Romex, using the red and black conductors, and dropping the white conductor.
I'm assuming from that diagram that the switch and outlets are mounted to the boxes. If so the first box with the switch has a penalty of "6" . Four 14AWG conductors, ground wire and the yoke of the switch. the second box has a penalty of "5" Two neutral conductors, a hot conductor, ground wire and the yoke of the outlet. Just make sure your stuffing requirements don't exceed the box sq/in limit. Using 14AWG, it's unlikely you will exceed the fill requirements.
I'm assuming that this is in a garage type setting? if so, even though there is a wall switch, that duplex receptacle may need to have GFCI protection depending on code interpretation requirements in your area. I GFCI protected every 120 circuit in my garage at the breaker box, even though I only have to meet the code that was in effect in 1978. It was more expensive, but easier.
As I stated earlier though, code compliance in each area could be different. What may applicable and allowable for me, may not be for you.

[Rod Sheridan]

Hi, the code requirement for a neutral in a switch box is so that devices such as occupancy sensors or timers can be installed at a later date.

Use 3 conductor romex to the switch box, connect the neutral at the source end and leave it with a wire nut on in the new switch box........Rod.

[Charlie Velasquez]

The NEC did change in 2011.

Here is the language from the 2017 NEC, Article 404.2(c)
409002

I have circled the areas that I think are of import in your scenario, defining the applicable locations and exceptions, but I offer no advice.

As an aside, the NFPA now offers free online access to the NEC. Registration is required, but that is free, also.
The document is neither searchable, nor downloadable as far as I could tell (I had to do a screen shot as I could not copy the text).
But it does have a table of contents that is clickable. If you gain familiarity with the structure you can locate stuff.

I posted the url in the sticky of the 2014 NEC above.

MODERATOR, could you consider changing the title of the sticky to reflect its access to the current code, or delete that sticky and initiate a new sticky?

[Don Jarvie]

I’ve done a similar thing and the power goes into the switch and then run a line to the outlet. It would be just like running a light switch instead of a light it’s an outlet. Only draw back is I need to turn on the the air cleaner with the remote but shut it off with the switch.

I dont know what what your local code is so this may not be compliant in your area.

[Lee Schierer]

Alan,

I am not up to date on the current NEC, but basically all you should need to do is run one romex (two conductor with ground) wire from the ceiling box to the switch box. The white wire in that Romex would be taped (or painted) black at both ends. This tells anyone who happens on that wiring that the wire taped or painted black is being used as a hot conductor. The Bare ground wire would be connected to the switch at the green screw. The black wire and the taped black wire (formally white) would be connected to the switch terminals. The wire with the black tape on it would be connected to the hot side (brass color) of the receptacle powering the air cleaners.

To meet code the box that holds the receptacle powering the air cleaners (the source of the voltage going to the new switch) must meet NEC requirements for wire fill. Larger boxes can have more wires than smaller boxes.

This is is a start anyway. Perhaps others will wish to expand on it.

In the ceiling box the current black wire should be wire nutted to the new black wire leading to the switch. The painted/taped black wire should be connected to the hot side of the receptacles. While you are working it doesn't hurt to write the circuit breaker number on the cover plates of the switch and the receptacles for future reference.

[Mike Henderson]

Hi, the code requirement for a neutral in a switch box is so that devices such as occupancy sensors or timers can be installed at a later date.

Use 3 conductor romex to the switch box, connect the neutral at the source end and leave it with a wire nut on in the new switch box........Rod.

I agree with Rod. It's cheap insurance for the time when you need a neutral in the switch box.

Mike

[John K Jordan]

I don't bother with wire-nutting the white common wire in the switch box but simply leave a long enough loop that I can cut into it if ever needed.

I wired switched outlets in four places in my shop, all to turn on task lights, 3 or more at each location: bandsaw, lathe, etc.

JKJ

[Charlie Velasquez]

In the ceiling box the current black wire should be wire nutted to the new black wire leading to the switch. The painted/taped black wire should be connected to the hot side of the receptacles.

Lee, I was taught the opposite. The black from the switch always went to the load.

[Ole Anderson]

Yep. I wired my son's basement (6 circuits) and the inspector caught me on not having a neutral in two switch boxes. Which you then also need a ground. Times change. Also he told me that all ground wires need to be long enough to wire to a device, can't just leave one long one by using a crimp sleeve. Fortunately he didn't make me fix that as he knew I would have a massive rewire job.

[Allan Speers]

Thanks, guys.

Well, I'm hoping to add a delayed timer at some point, anyway, if I can find a good one. I had forgotten about that. So, two full runs it is.

=========================================

- But then, what about the size of the switch box, and maximum number of wires?

Mike wrote:

"If so the first box with the switch has a penalty of "6" . Four 14AWG conductors, ground wire and the yoke of the switch. the second box has a penalty of "5" Two neutral conductors, a hot conductor, ground wire and the yoke of the outlet."

But two full lines of Romex into that tiny little switchbox would be Four 14AWG conductors, TWO ground wires, and the yoke of the switch. Is that seven?

[Lee Schierer]

Lee, I was taught the opposite. The black from the switch always went to the load.

That is what you are doing by recoloring the white wire between the switch and the ceiling box. That makes the blackened white wire a hot from the switch. Your original hot lead which you wire nut to the black going to the switch will be broken by the switch.

By the way black shrink tubing works well for this color change.

[Charlie Velasquez]

Thanks, guys.

Well, I'm hoping to add a delayed timer at some point, anyway, if I can find such a good one. I had forgotten about that. So, two full runs it is.

=========================================

- But then, what about the size of the switch box, and maximum number of wires?

Mike wrote:

"If so the first box with the switch has a penalty of "6" . Four 14AWG conductors, ground wire and the yoke of the switch. the second box has a penalty of "5" Two neutral conductors, a hot conductor, ground wire and the yoke of the outlet."

But two full lines of Romex into that tiny little switchbox would be Four 14AWG conductors, TWO ground wires, and the yoke of the switch. Is that seven?

Why two runs? 14/3 with ground gets your two current switch loop conductors, your neutral, and your equipment ground.

edit: wrt the size of the box, for new or exposed work I almost always use a deep 4” box, then add the appropriate device ring . If it is a retrofit, I would remove the old box, put in a deep double gang box, then add a duplex or something so there is no patch work.

[Allan Speers]

Why two runs? 14/3 with ground gets your two current switch loop conductors, your neutral, and your equipment ground.

edit: wrt the size of the box, for new or exposed work I almost always use a deep 4” box, then add the appropriate device ring . If it is a retrofit, I would remove the old box, put in a deep double gang box, then add a duplex or something so there is no patch work.

Thanks, Charlie.

I didn't even think of using 14/3.

Simple.

[Marshall Harrison]

... While you are working it doesn't hurt to write the circuit breaker number on the cover plates of the switch and the receptacles for future reference.

Good tip. Thanks.

[roger wiegand]

Just a note that in addition to local differences to the NEC/NRC, "current" is also different in different jurisdictions. You need to check with your local building authority to find out what version of the code is in force in your area. (In MA right now it is the 2017 version; Indiana, Illinois and Kansas use the 2008 code, others are in between.)