3 -way switch box location requires a neutral ?

[Electromatic]

You do end up with an extra 'neutral' at the light. It is a compliant way to do a 3-way with only 2-conductor NM. You also end up with an unswitched hot and neutral at the end of the run. You could theoretically keep the circuit going, but it ends up violating parallel conductor rules.

 

[wwhitney]

You could theoretically keep the circuit going, but it ends up violating parallel conductor rules.

Care to elaborate on extending the circuit to more switches? The obvious way to do that would cause the light to be off only when all the switches are in the same position, and on whenever any two switches are in different positions. Which is not the desired control scheme, that flipping any switch will toggle the light state.

As to the parallel conductors rules, I would say that neither the two switch version or a multiple switch version would violate them. In the diagram you drew, if both switches are down, then the center conductor is part of a conductive path parallel to the hot conductor. But as that path also includes both switches, I would not say that the center conductor is "electrically joined at both ends" with the hot conductor--the center conductor ends at the switch terminals.

Cheers, Wayne

 

[Electromatic]

left switch=L, right switch=R, up=U, down=D

LU, RU = OFF
LD, RU = ON
LU, RD = ON
LD, RD = OFF

You end up with unswitched hot and neutral after the second switch. You could put receptacles, etc. downstream without it being affected by the switches. If both switches are down, both conductors between the switches will be sharing the current of whatever is downstream of the second switch. Though the 'center' conductor does terminate at the switches, it is still a path for current, so I would consider that electrically joined. Unless you're wiring 3-ways with 1/0 or larger, it seems to me to violate 310.10(H). [unless the lights are indicating instruments!]

 

[LarryFine]

There is the issue of the hot and neutral taking separate pathways.

 

[wwhitney]

You end up with unswitched hot and neutral after the second switch. You could put receptacles, etc. downstream without it being affected by the switches

Yes, that's obvious. As my response indicated, I was referring to adding more switches.

Though the 'center' conductor does terminate at the switches, it is still a path for current, so I would consider that electrically joined.

As I did until I submitted a PI to change "electrically joined" to "directly joined," citing examples of switching arrangements, and the CMP responded (to paraphrase) that it wasn't necessary as "electrically joined" already means "directly joined."

Cheers, Wayne

 

[wwhitney]

There is the issue of the hot and neutral taking separate pathways.

Which is best handled by just routing all the conductors through the light box.

Cheers, Wayne

 

[Electromatic]

Ah, Wayne, I didn't intend to mean adding more switches, as in 4-ways, just continuing the circuit unswitched. For any load downstream of the switches, yes the hot and neutral take separate paths, but not for the light itself.

 

[LarryFine]

For any load downstream of the switches, yes the hot and neutral take separate paths, but not for the light itself.

It does during LD, RU = ON.

 

[Rock86]

left switch=L, right switch=R, up=U, down=D

LU, RU = OFF
LD, RU = ON
LU, RD = ON
LD, RD = OFF

You end up with unswitched hot and neutral after the second switch. You could put receptacles, etc. downstream without it being affected by the switches. If both switches are down, both conductors between the switches will be sharing the current of whatever is downstream of the second switch. Though the 'center' conductor does terminate at the switches, it is still a path for current, so I would consider that electrically joined. Unless you're wiring 3-ways with 1/0 or larger, it seems to me to violate 310.10(H). [unless the lights are indicating instruments!]

Maybe i didn't read everything... is there 2 hots legs? wouldn't LD/RD = BANG?

 

[LarryFine]

Maybe i didn't read everything... is there 2 hots legs? wouldn't LD/RD = BANG?

Yes and no; the latter simply creates a parallel pathway for any downstream loads.

 

[Electromatic]

It does during LD, RU = ON.

D'oh!

 

[Rock86]

Yes and no; the latter simply creates a parallel pathway for any downstream loads.

Oy, i did miss it. I wasn't seeing the highlighted red line showing the hot wire. I saw two separate hots. thanks.

 

[garbo]

Standard 3ways always end up with a nuetral you don't have to dead end them always but if for some reason you need to dead end some so long as it's the same circuit it will work for smart switching

Believe this is not always the way. I have seen the power go to the luminare box then 14/2 cable from there to first three way then another 14/3 cable between the three way switches. Ends up that neither three way locations have a grounded conductor.

 

[letgomywago]

Believe this is not always the way. I have seen the power go to the luminare box then 14/2 cable from there to first three way then another 14/3 cable between the three way switches. Ends up that neither three way locations have a grounded conductor.

That's how you get messed up nuetrals unless you're carefull

 

[Amps]

I've done it but hate using a 14 2 for travelers incase it throws off a future apprentice.

LOL. Don't have that future apprentice go near knob and tube wiring.

 

[letgomywago]

LOL. Don't have that future apprentice go near knob and tube wiring.

I was tought side by side when learning about that wiring method. I plan to always continue that method of teaching while working whenever working with any obsolete wiring with an apprentice. I also was drawn out examples while working with my jmen and have continued to do the same with my apprentices.

 

[kwired]

I believe it is a violation of 300.3(b) which says all circuit conductors have to be in the same cable

that is the general rule, then there is sub part (3) that follows for non ferrous wiring methods which nullifies the general rule if using NM cable.

230806-2135 EDT

In any circuit you wire there is a source wire and a return wire. These two wires must be in close physical proximity to each other, preferably less than an inch apart for low voltage and current. 120 V and 20 A are low voltage and current for this purpose. None of this current should flow anywhere else. This is to minimize stray magnetic fields that may interfere with sensitive equipment.


.

.

Though this might be good practice, I don't believe it violates NEC as long as non ferrous wiring methods are involved.

 

[James L]

there is sub part (3) that follows for non ferrous wiring methods which nullifies the general rule if using NM cable.

Can you tell us what you see in that section which would nullify the general rule? I don't see anything

 

[kwired]

Can you tell us what you see in that section which would nullify the general rule? I don't see anything View attachment 2566946

It's not in (3) it's in (B) at the end "unless otherwise permitted in in accordance with 300.3(B)(1) through (B)(4). Last time I checked three is between one and four

This rule would even let you run different conductors of same circuit through multiple aluminum raceways or aluminum sheathed cables as those are non ferrous also.

 

[James L]

it's in (B) at the end "unless otherwise permitted in in accordance with 300.3(B)(1) through (B)(4)

So, what do you see in anything between 1 & 4 which negates the mandate? I just don't see any wording there to support the notion. What's there that otherwise permits it?

Can you quote the exact words, and how you come tothe e understanding you have?