Neutral at switch location question

JJWalecka

JJWalecka

Senior Member
Location
New England
I have s four gang box. Two switches are on one circuit. The other two switches are B and C phase. If I have say A phase neutral in the Junction box and I put a breaker lock on B phase and C phase does A phase neutral meet the requirements for the neutral at switch location or does each switch need it's own separate neutral
 
JJWalecka said:
I have s four gang box. Two switches are on one circuit. The other two switches are B and C phase. If I have say A phase neutral in the Junction box and I put a breaker lock on B phase and C phase does A phase neutral meet the requirements for the neutral at switch location or does each switch need it's own separate neutral
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Imo, if a neutral is needed for the switch then the neutral would need to be from the same circuit as the conductors on the switch
 
404.2(C) starts off "Switches Controlling Lighting Loads. The grounded circuit conductor for the controlled lighting circuit shall be installed at the location . . ."

So the grounded circuit conductor needs to be from the same circuit as supplies the switch. If you have 3 separate 2-wire circuits A-N, B-N, and C-N, then you'd need 3 separate grounded circuit conductors. If you have a single 4-wire MWBC, then obviously there's only one grounded circuit conductor.

Cheers, Wayne
 
Everything is going back to a junction box next to the panel. I have two A, B,C phase switch locations. I have a 12/4 for A,B,C going to one switch location and a 12/3 for A,B,C going to the other switch location. I need two switches to control one load.

I don't see how I can have two locations feeding one load without having to add the neutrals which is a bummer.
 
More details? You mention A, B and C phase, the A phase neutral then later mention 12/4 and 12/3 going to other ABC switch locations. You need more conductors than that to other switch locations if you have switches in each of the three phases

If you have a "full boat" MWBC then the one neutral that goes with it is the one that can go to any switch location anywhere in this MWBC. If it is three separate two wire circuits then each neutral needs to accompany it's corresponding ungrounded conductor wherever it is needed/required. It would physically work to use one neutral conductor but is not a good practice and doesn't comply with code.

Keep in mind you don't necessarily need the grounded conductor at every switch location when there is multiple switches for the same lighting and each switch location is visible throughout the entire floor area of the space being illuminated. You do need the grounded conductor at one of the locations in that situation though, or if raceway wiring methods you must have enough space in raceway for pulling the grounded conductor if it is ever needed.
 
kwired said:
More details? You mention A, B and C phase, the A phase neutral then later mention 12/4 and 12/3 going to other ABC switch locations. You need more conductors than that to other switch locations if you have switches in each of the three phases

If you have a "full boat" MWBC then the one neutral that goes with it is the one that can go to any switch location anywhere in this MWBC. If it is three separate two wire circuits then each neutral needs to accompany it's corresponding ungrounded conductor wherever it is needed/required. It would physically work to use one neutral conductor but is not a good practice and doesn't comply with code.

Keep in mind you don't necessarily need the grounded conductor at every switch location when there is multiple switches for the same lighting and each switch location is visible throughout the entire floor area of the space being illuminated. You do need the grounded conductor at one of the locations in that situation though, or if raceway wiring methods you must have enough space in raceway for pulling the grounded conductor if it is ever needed.
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Thanks so much for the incite regrettably I cannot use a breaker tie and will have to pull 12/2 to the 12/3 location to have the neutrals for B and C phase switches
 
JJWalecka said:
Thanks so much for the incite regrettably I cannot use a breaker tie and will have to pull 12/2 to the 12/3 location to have the neutrals for B and C phase switches
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The breaker tie is unrelated... If, as stated, you have 3 hots and a neutral and they are all on separate phases then one neutral will do it.
 
Dennis Alwon said:
The breaker tie is unrelated... If, as stated, you have 3 hots and a neutral and they are all on separate phases then one neutral will do it.
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The MWBC itself still needs handle tie or common trip breaker at the branch circuit origin though, just a detail not so directly associated with the required grounded conductor at switch locations.
 
kwired said:
The MWBC itself still needs handle tie or common trip breaker at the branch circuit origin though, just a detail not so directly associated with the required grounded conductor at switch locations.
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Yes I know that but as I stated it will not effect the need for the neutrals.
 
Dennis Alwon said:
I believe if the other switches control the same lights then the neutral is only needed at one location.
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If the entire illuminated space by said switches has visibility of said switch with the grounded conductor then the other switch locations do not require a grounded conductor
 
Dennis Alwon said:
Yes I know that but as I stated it will not effect the need for the neutrals.
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I think maybe you mean it won't require a separate neutral for A, B and C? Which I agree with that.

If it is not a MWBC then you must have separate neutrals for A B and C. Even though the occupancy sensor or other electronic switch would only put a load in the mA ranges on it.
 
If conduit is used, or accessible means to reach the switch box (basement or attic, open space behind wall), then no grounded conductor required. Just a means to get one there if needed.
 
That's why I put my "Public Input" in. You have to keep track of the neutrals, with a stripe, whether it's a GFCI/AFCI, MWBC or not.
 

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mtnelect said:
That's why I put my "Public Input" in. You have to keep track of the neutrals, with a stripe, whether it's a GFCI/AFCI, MWBC or not.
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A requirement that you identify them to distinguish between GFCI protected and non GFCI protected may be ok, though I think it pushes NEC being a design manual to some degree as well. If there is such requirement I don't think it is necessary to word it in a way that restricts that identification to just one method - the stripe. For one thing that would mean we need to stock cable (NM, MC etc) with stripe on white and it's use be limited to load side of GFCI. Field markings should be allowable here IMO. Also grey is an acceptable color for a grounded conductor. Yes it is customary to use it as a 277 volt neutral, but I use gray all the time in facilities that don't have multiple voltage systems. Two circuits in same raceway? I often will use white for one and gray for the other. If striped conductors were something readily available to me I might use white with same color stripe as it's ungrounded when there is multiple circuits though. But that means stocking more conductor choices as well. Field marking is still the way to go on most smaller projects after looking at all the details and costs.

Your wording also would kind of limit conductors with a stripe to load side of GFCI's when there possibly already is people using them in raceways with multiple conductors simply to identify which ungrounded conductor they go with whether GFCI protected or not.

That said if you are going to require identify a GFCI protected grounded conductor I think it only makes sense to identify GFCI protected ungrounded conductors as well.
 
mtnelect said:
That's why I put my "Public Input" in. You have to keep track of the neutrals, with a stripe, whether it's a GFCI/AFCI, MWBC or not.
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A stripe is unnecessary when there are other methods readily available to identify which neutral goes with which circuit. Wire markers are one such option.
 
My "Public Input" is designed for residential work. since it is mostly done on commercial work already. On residential work, I have never seen wire markers on grounded wiring. The installer just grabs any neutral that is convenient and moves on.

As an example, had a service call on a GFCI receptacle in a bathroom that would trip randomly. Discovered that the installer crossed a neutral on a hall lighting circuit. With out fail, the bathroom GFCI receptacle would trip every time, when the hall light was switched on. Finding that crossed neutral required me to go through every junction box in the house to find it.
 
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