3 way switch leg colors

[al hildenbrand]

you can not use white as a traveller

That's a common misunderstanding. Travelers supply the next switch, whether a threeway or a fourway. The restriction on the use of a cable's white wire applies to the switch loop return from the last switch to the lighting outlet.

 

[GoldDigger]

That's a common misunderstanding. Travelers supply the next switch, whether a threeway or a fourway. The restriction on the use of a cable's white wire applies to the switch loop return from the last switch to the lighting outlet.

It looks like the Code reads that way (at least under one interpretation).
But if fmtjfw's guess as to the reason for the restriction is valid, the CMP missed the boat by not writing the section to address travelers too. :happyyes:

 

[al hildenbrand]

It looks like the Code reads that way (at least under one interpretation).
But if fmtjfw's guess as to the reason for the restriction is valid, the CMP missed the boat by not writing the section to address travelers too. :happyyes:

With the section "silent" about traveler use or restricted use of a white conductor, it is still a silence. The only language that is enforceable is that of the NEC itself.

When the traveler to the next threeway or fourway switch, in any switch setting, is not energized, that conductor is not in the switch loop. . . which means that the traveler that IS energized is THE supply to the next switch.

To say it another way, at any switch setting in the common threeway switch loop configuration, each switch always and only has a single supply. . . and, according to the rule, when a cable white conductor is so used as the supply it shall be re-identified.

 

[GoldDigger]

With the section "silent" about traveler use or restricted use of a white conductor, it is still a silence. The only language that is enforceable is that of the NEC itself.

When the traveler to the next threeway or fourway switch, in any switch setting, is not energized, that conductor is not in the switch loop. . . which means that the traveler that IS energized is THE supply to the next switch.

To say it another way, at any switch setting in the common threeway switch loop configuration, each switch always and only has a single supply. . . and, according to the rule, when a cable white conductor is so used as the supply it shall be re-identified.

Just pointing out that fmtjfw might want to submit input to some future code cycle based on his reasoning.
I agree that it has no effect on what IS.

 

[kwired]

The purpose in the limitation of a re-identified white wire use in a switch loop to supply only is that, if the circuit is energized, it will be energized and detectable using a non-contact tickey or voltmeter. It can not be the conductor from the switch to the load because this purpose is violated. A "traveller" conductor may or may not be energized depending on the position of the feeding switch(es) (3 and 4 ways).

200.7(C) Use of Insulation of a White or Gray Color or with Three Continuous White or Gray Stripes. Circuits of 50 Volts or More.
(1) If part of a cable assembly that has the insulation permanently reidentified to indicate its use as an ungrounded conductor by marking tape, painting, or other effective means at its termination and at each location where the conductor is visible and accessible.
Identification shall encircle the insulation and shall be a color other than white, gray, or green.
If used for a single-pole, 3-way, or 4-way switch loops, the reidentified conductor with white or gray insulation or three continuous white or gray stripes shall be used only for the supply to the switch, but not as a return conductor from the switch to the outlet.

Notes:
1) The last sentence states shall be used only for the supply to the switch. Travellers are not allowed because a traveller is not the supply to the next switch, is a supply to the next switch.

2) 2-way switches do not have this limitation which would allow the use of 2 conductor cables with white reidentified on the load side of the switch to the outlet.

With a little care you can use 2 conductor cables for the feed/switch loop and 3 conductor cables between 3- and 4-way switches without violating 200.7(C)(1).

Further you can use a 3 conductor cable between the outlet point that also contains the feed -- providing the newly required neutral in switch box.

SO if you can do it with standard cables and meet the requirements of 200.7(C)(1) why would you do it another way?

The only reasons I can think of:

1) We didn't have the rule in the past

2) We don't care about the added safety of the new scheme.

The only rule we didn't have in the past is the requirement to have the grounded conductor run to switch location(s). Nothing else relating to this has really changed for some time.

That's a common misunderstanding. Travelers supply the next switch, whether a threeway or a fourway. The restriction on the use of a cable's white wire applies to the switch loop return from the last switch to the lighting outlet.

Well said, switch "loop" can have hundreds of four way switches in the loop before finally leaving the end switch of the loop.

 

[jap]

You can not use white as a traveller.

See,,,, told ya so.....

Just kidding.

JAP>

 

[mbrooke]

I disagree with you on this... Read what it states here-- if used for switch loops then the white cannot be the return. It does not say it cannot be used elsewhere when reidentified. These are 2 different items. We use the white conductor as a hot all the time for 240V. They just don't want the switch leg to the light being the white wire

I'd say you are correct. I gathering that the only requirement is having black at the light, not how anything will be used as the travelers.

the reidentified conductor with white or gray insulation or three continuous white or gray stripes shall be used only for the supply to the switch, but not as a return conductor from the switch to the outlet.

Correct?

 

[iwire]

I'd say you are correct. I gathering that the only requirement is having black at the light

Sounds like post 2.

 

[mbrooke]

Sounds like post 2.

It does :ashamed1:

Right again!

 

[jap]

On a dead end 3 way, if you use the white and red as travellers to the 2nd 3 way,,, the white and the red are never used as "Return" wires,,, thus they are the input wires "To" the 2nd 3 way switch,,, the Black from the 2nd 3 way is the one and only "Return" wire.

But if someone wanted to get techincal,,, alternating current is always coming and going so it tends to blow the whole idea of "To and From" all to you know where.

JAP>

 

[wwhitney]

The only rule we didn't have in the past is the requirement to have the grounded conductor run to switch location(s). Nothing else relating to this has really changed for some time.

There was a subtle change in 2011. In the 2008 (and earlier?) NEC, 200.7(C) had two subsections dealing with reidentifying a conductor with white insulation in a cable assembly. 200.7(C)(1) was a blanket allowance, while 200.7(C)(2) was specific to switch loops and included the requirement not to use the white conductor as the return from the switch to the switched outlet.

200.7(C) wasn't clear on whether the allowances in 200.7(C)(1) and 200.7(C)(2) should be read as separate (logical OR) or whether 200.7(C)(2) applied to all switch loops (logical AND). So if you took them as separate allowances, then you could use a white conductor as the return from the switch to the switched outlet under 200.7(C)(1) and ignore 200.7(C)(2).

The 2011 NEC fixed this by combining the two into a single allowance which is now 200.7(C)(1) and includes the prohibition on using the white conductor as the return from the switch to the switched outlet.

Cheers, Wayne

 

[al hildenbrand]

But if someone wanted to get techincal,,, alternating current is always coming and going so it tends to blow the whole idea of "To and From" all to you know where.

In my mind, the absolute value of potential, falling around a circuit, is the easiest way to think of idea of "supply" and "To and From".

Otherwise, the debate over conventions and basic definition gets cumbersome with differing paradigms.

 

[jap]

In my mind, the absolute value of potential, falling around a circuit, is the easiest way to think of idea of "supply" and "To and From".

Otherwise, the debate over conventions and basic definition gets cumbersome with differing paradigms.

I'm with ya Al....


Jap>

 

[GoldDigger]

In my mind, the absolute value of potential, falling around a circuit, is the easiest way to think of idea of "supply" and "To and From".

Otherwise, the debate over conventions and basic definition gets cumbersome with differing paradigms.

And if you have a line to line load on 120/240 supply the absolute value of the potential stops falling halfway around.
I guess there is no return in that circuit, just two opposite polarity supplies. :angel:

 

[al hildenbrand]

I guess there is no return in that circuit, just two opposite polarity supplies.

For the purposes in this thread, of re-identifying the white used as the supply, the "return" from the Load, to the source, isn't part of the discussion. So the absence of voltage across the length of neutral in the multiwire portion of a balanced load circuit doesn't obfuscate the "supply" idea in "fall of absolute value of potential."

 

[fmtjfw]

With the section "silent" about traveler use or restricted use of a white conductor, it is still a silence. The only language that is enforceable is that of the NEC itself.

When the traveler to the next threeway or fourway switch, in any switch setting, is not energized, that conductor is not in the switch loop. . . which means that the traveler that IS energized is THE supply to the next switch.

To say it another way, at any switch setting in the common threeway switch loop configuration, each switch always and only has a single supply. . . and, according to the rule, when a cable white conductor is so used as the supply it shall be re-identified.

I claim that a traveller is "A" supply, not "THE" supply, since the other traveller can be "A" supply as well. The Code says "THE" not "A". But on the other hand the distinction between the definite and indefinite article appears not to have gotten in the way of a discussion.

Further I still posit the idea that the wiring is safer if the reidentified white is always energized if the circuit is energized. Anyone want to take that part up?

 

[kwired]

On a dead end 3 way, if you use the white and red as travellers to the 2nd 3 way,,, the white and the red are never used as "Return" wires,,, thus they are the input wires "To" the 2nd 3 way switch,,, the Black from the 2nd 3 way is the one and only "Return" wire.

But if someone wanted to get techincal,,, alternating current is always coming and going so it tends to blow the whole idea of "To and From" all to you know where.

JAP>

I was taught by my first boss to use the red on the common terminal (when you have that as an option with a three wire cable) and it kind of always stuck with me since that is how I learned. Main rule I remember being taught is you can not have a white conductor as the final segment to the load, but anything goes within the switching scheme otherwise - if a white happens to be part of the switching scheme it must be re-identified though we didn't do that when I first started in this trade, and I still think it is mostly a rule to protect those that don't know what they are doing from what they don't understand anyway but not going to dwell on that either.

There was a subtle change in 2011. In the 2008 (and earlier?) NEC, 200.7(C) had two subsections dealing with reidentifying a conductor with white insulation in a cable assembly. 200.7(C)(1) was a blanket allowance, while 200.7(C)(2) was specific to switch loops and included the requirement not to use the white conductor as the return from the switch to the switched outlet.

200.7(C) wasn't clear on whether the allowances in 200.7(C)(1) and 200.7(C)(2) should be read as separate (logical OR) or whether 200.7(C)(2) applied to all switch loops (logical AND). So if you took them as separate allowances, then you could use a white conductor as the return from the switch to the switched outlet under 200.7(C)(1) and ignore 200.7(C)(2).

The 2011 NEC fixed this by combining the two into a single allowance which is now 200.7(C)(1) and includes the prohibition on using the white conductor as the return from the switch to the switched outlet.

Cheers, Wayne

Kind of mentioned it above but not entirely, but I remember being taught about 30ish years ago that it was code requirement to not use the white as the return to the switched outlet. Maybe it wasn't in the code, but I know that is what I was taught long ago, am not planning to look in older codes anytime soon to verify though.

 

[iwire]

I claim that a traveller is "A" supply, not "THE" supply, since the other traveller can be "A" supply as well. The Code says "THE" not "A". But on the other hand the distinction between the definite and indefinite article appears not to have gotten in the way of a discussion.

Further I still posit the idea that the wiring is safer if the reidentified white is always energized if the circuit is energized. Anyone want to take that part up?

I think the NEC is silent on this.

Personally I do it like you suggest strictly because I see no reason to do otherwise.

 

[mbrooke]

I think the NEC is silent on this.

Personally I do it like you suggest strictly because I see no reason to do otherwise.

There are some (though I do agree with you) that claim white must tie to the hot in the first 3 way switch box.