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neutral wire requirement and three ways #196049
09/07/10 03:00 AM
09/07/10 03:00 AM
S
sparkyinak  Offline OP
Member
Joined: Jul 2007
Posts: 1,328
Alaska
I wonder if they are going to make 12-4 NM-B more readily available for the upcoming code change to prevent generating induced voltage by someone trying to mickey mouse a three or four way.


"Live Awesome!" - Kevin Carosa
2017 / 2014 NEC & Related Books and Study Guides
Re: neutral wire requirement and three ways [Re: sparkyinak] #196051
09/07/10 12:08 PM
09/07/10 12:08 PM
renosteinke  Offline
Cat Servant
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Joined: Jan 2005
Posts: 5,316
Blue Collar Country
I have not encountered any problems obtaining NM with the necessary conductors. As I see it, all you need is a black, a red, a white, and a ground.

I will admit that you will need to run two cables to each switch - one 'in' and one 'out.' Again, I don't really see that as an issue with 3-way and 4-way switches; it really affects the ordinary switch, though.

Let's face it - we're going to have to get out of the practice of making the box above the fixture our "main" box. That's what the proposal changes. No more running a single cable from the fixture to the switch, and re-labeling the white wire as a switch leg. They want the feed to enter the switch, then go on to the fixture.

Good practice? Probably. Warrant becoming part of the code? I don't think so.

Re: neutral wire requirement and three ways [Re: renosteinke] #196058
09/08/10 10:49 AM
09/08/10 10:49 AM
S
sabrown  Offline
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Joined: Dec 2002
Posts: 302
Ogden, Utah, USA
You already know this so to clarify, you can run to the fixture and then run a 3 conductor with ground to the switch. So this does make the switch first more likely and the likely way to run 3 and 4-ways and ending with the run to the light, otherwise the requirement for 4 conductor with ground. Just a bit more planning if you are not in a habit that already includes the neutral.

Shane

Re: neutral wire requirement and three ways [Re: sabrown] #196116
09/14/10 03:49 AM
09/14/10 03:49 AM
S
sparkyinak  Offline OP
Member
Joined: Jul 2007
Posts: 1,328
Alaska
If I understand it right, a grounded conductor will be required to be pulled to eash switch. In a 3 and 4 way swith loop, three wires are required to run between the switches just to switch the hot leg. How to you get your a grounded conductor to the other switches without violating 300.3(B)? Violate 300.3(B) could likey generate some CEMF and FUBAR the electronics in the switches the new rule call for.

Not only the NEC is a safety manual. Its becoming a designing manual. By bringing a grounded conductor to each switch in no way makes the wiring any safer. It's a design issue. If shhh-poopheads are using the grounding conductor as a grounded conductor, the shhh-poophead will still do what he/she is doing til someone holds him/her to their actions.


"Live Awesome!" - Kevin Carosa
Re: neutral wire requirement and three ways [Re: sparkyinak] #196120
09/14/10 10:39 AM
09/14/10 10:39 AM
renosteinke  Offline
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Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Here's how you can do it:

Ordinary B/W/G Romex brings power to the first 3-way switch, then B/R/W/G continues to the 4-way(s), B/R/W/G to the last 3-way, then B/W/G to the lights. Between the 3-ways. you use the black and red as your 'travelers.'

What the rule eliminates - or at least makes impractical - is running simple switch legs to a junction box above the light. In effect, every switch box will need two cables to it - one 'in' and one 'out.'

I like the idea, but I don't like the rule.

Re: neutral wire requirement and three ways [Re: renosteinke] #196122
09/14/10 11:13 AM
09/14/10 11:13 AM
G
gfretwell  Online Content

Member
Joined: Jul 2004
Posts: 9,166
Estero,Fl,usa
Another option, if you want to keep doing the "big J box at the light" method is to drop smurf tube to the switching locations.
It is not the cheapest way to go but it does give you the most flexibility later.

Down the road, I wonder how many of these "neutrals" will be hijacked as current carrying conductors for additional switches or added 3 ways.


Greg Fretwell
Re: neutral wire requirement and three ways [Re: gfretwell] #196128
09/14/10 05:27 PM
09/14/10 05:27 PM
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Someone once told me: Don't speak of it ... if it's good it runs away, if it's bad it shows up!

I just encountered a remodeling job - the guy wants to add a third switch to several 3-way light circuits. My first thought was to simply interrupt the travelers, then run a single 14-2-2 from that new j-box to the new new switch location (re-tagging the neutrals).

Well, under the 'run a neutral' rule, that short-cut is out; looks like I'll be running some more wire. Oh, Well!

Edit to add ... Since each room (for this project) has two levels of lighting, that means there will be two 4-ways at each location. Adding the neutrals and grounds means I need room in the box for 16 wires (plus pigtails, etc.) Let's face it; "switch" boxes and "stack" switches are now restricted as to your use of them.

Just run a single neutral and ground? If I was coming from a single j-box in pipe, I could do it. Since I'm using Romex, that's out - there's no form of Romex with 4 'hots,' 1 'neutral,' and 1 'ground.'

The "Law of unintended consequences" just kicked in.

Last edited by renosteinke; 09/14/10 05:37 PM.
Re: neutral wire requirement and three ways [Re: renosteinke] #196130
09/14/10 11:48 PM
09/14/10 11:48 PM
G
gfretwell  Online Content

Member
Joined: Jul 2004
Posts: 9,166
Estero,Fl,usa
Push a 1/2" smurf tube down there wink


Greg Fretwell
Re: neutral wire requirement and three ways [Re: renosteinke] #196131
09/15/10 03:13 AM
09/15/10 03:13 AM
S
sparkyinak  Offline OP
Member
Joined: Jul 2007
Posts: 1,328
Alaska
Originally Posted by renosteinke
Here's how you can do it:

Ordinary B/W/G Romex brings power to the first 3-way switch, then B/R/W/G continues to the 4-way(s), B/R/W/G to the last 3-way, then B/W/G to the lights. Between the 3-ways. you use the black and red as your 'travelers.'
One of is missing something. I understand that 2011 NEC will require a grounded (neutral) wire to be pulled to every switch. 300.3(B) requires that all the wires of a circuit be ran in the same conduit, raceway, or jacket. This is to prevent CEMF. doesn't matter how you slice it, you would need a minimum of 4 wires to run a 3 and 4 way between the switches. Running 2 NM-b is a violation of 300.3(B)


"Live Awesome!" - Kevin Carosa
Re: neutral wire requirement and three ways [Re: sparkyinak] #196135
09/15/10 10:24 AM
09/15/10 10:24 AM
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
B/R/W/G ... Black, red, white, ground ... that' four wires. Two travelers, your neutral and your ground. That's all you need between the 3-way switches.





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