200.7 Using white wire as ungrounded conductor

[hurk27]

In my many travels to the Western Sectional IAEI meetings across the country, this very question came up more then once, I'm not sure when the wording was changed because my "99" NEC has the same language, but every time this was asked, the same answer by the panel members was made, in essences it is because they don't want two white conductors at the switch outlet, so the requirement is basically that if a white conductor of a cable is used it must be used for the supply to the switch and not the return from a switch, in 3-ways and 4-ways, white is allowed as the travelers, but can not be used as the final return conductor to the switched outlet.

and the panel members I mention above was made up of CMP's from NFPA

 

[skeshesh]

Why would you re-identify a white or gray conductor? I personally see no reason for this.

Roger

Roger's comment should have ended the discussion. This rule is so a white or gray conductor being used as supply is identified as such. What is the point of reidentifying it.

 

[480sparky]

Why would you re-identify a white or gray conductor? I personally see no reason for this.

Roger

Power taken to light first, then a cable down to the switch.

I must say, however, it's a poor design and one I avoid at almost all costs.

 

[roger]

Power taken to light first, the a cable down to the switch.

I must say, however, it's a poor design and one I avoid at almost all costs.

I have no problem with doing this and with that said, why would you re-identify the white or gray conductor?


Roger

 

[LarryFine]

Power taken to light first, then a cable down to the switch.

I must say, however, it's a poor design and one I avoid at almost all costs.

It wouldn't be an issue with conduit (would it?), and the rules for using the white as ungrounded explain how to use NM the same way, so it's a non-issue to em as well.

While I rarely use the 2-wire switch loop (as it's called) in most NM work, because I like running the feed from switch to switch, I'd use it in attics, sheds, crawls, etc.

 

[LarryFine]

I have no problem with doing this and with that said, why would you re-identify the white or gray conductor?

Interestingly, I rarely recolor the white with 2-wire switch loops, and have never been pinged for it. (I always recolor for 240v hot wires.)

It's painfully obvious when you see a white and black(s) together in the outlet, and moreso when there are only two wires in the switch box.

 

[DARUSA]

My personal opinion

My personal opinion

if you use you withe conductor as the supplie wire to the switch any person that open the light boxe will relase that the withe conductor is spliced with the ungrounded wires and quckly will know that the withe wire is used as an ungrounded conductor

 

[hurk27]

It wouldn't be an issue with conduit (would it?), and the rules for using the white as ungrounded explain how to use NM the same way, so it's a non-issue to em as well.

While I rarely use the 2-wire switch loop (as it's called) in most NM work, because I like running the feed from switch to switch, I'd use it in attics, sheds, crawls, etc.

In the red above, did you mean to say EMF?

a switch loop does not emit EMF because power on the conductor to the switch is 180? out of phase with the power on the conductor leaving the switch which cancels out any EMF.

This is why a grounded conductor is not needed to cancel out the EMF. See 404.2(A) Exception

 

[roger]

Here is a test I wrote a couple of years back.

Note; all scenarios are cable assemblies in normal 120/240 volt single phase residential installations and the white conductor is not re-identified.

Also note that the answers do not not necessarily have to be code compliant, (more than one answer might work too the questions are dealing with whether an electrician would need the white conductor re-identified to know what it is doing per the scenarios.

Scenario #1 You open a box containing a single pole switch and find a white conductor and a black conductor from the same cable connected to the switch, an Electrician will know the white conductor is _______

(A) a hot conductor or switch leg
(B) an EGC
(C) a Grounded Conductor
(D) a High Leg

Scenario #2 You take a panel cover off and see a 2 conductor cable whose white conductor is connected to one pole of a multi-pole breaker and the black conductor of this cable is connected to the other pole, an Electrician will know this white conductor is being used for a _________

(A) Main Bonding Jumper
(B) GEC
(C) Grounded Conductor
(D) Hot Conductor

Scenario #3 You are trouble shooting a set of three-ways and see a white conductor connected to a terminal on the first switch you open, an Electrician would know this conductor would be a ________

(A) colored conductor that lost its pigment
(B) bleached and enriched wheat conductor
(C) skinny Caucasian guy
(D) traveler or hot conductor

Scenario #4 You open a light fixture box and find a 2 conductor cable whose white conductor is wire nutted to the blacks of the other cables in the box, the black conductor of this cable is connected to the fixture, an electrician would know this white conductor is________

(A) not a Bigot
(B) a Data Cable
(C) a hot conductor
(D) a piece of tie wire

Given the scenarios above, it is necessary to re-identify a white conductor used as a hot so that __________ will not be confused and spend the rest of the day scratching his/her head.

(A) an Electrician
(B) a fellow Electrician
(C) an Electrician working in FL
(D) a person that should not have their paws in these boxes in the first place.

IMO there is no reason for the requirement. :wink:


Roger

 

[hurk27]

I agree with you Roger, and sometimes I think the NEC is being more and more written for DYS

even with the areas that do need a little clearing up to stop inspectors from wrong calls, but at the same time should not be dumbed down to the level it has been done in some areas, a qualified electrician should not have a problem with your post above.

 

[Power Tech]

I'm currently debating whether or not the white wire, as part of a cable assembly (more specifically 12/2 NM) can be used to switch a light fixture where power is brought into the fixture junction box and fed down the 12/2 cable to the switch and back up to the fixture on the white. I understand the the white must be reidentified with black. The debate is over whether or not the white insulated conductor can be used for the switch leg period. Can anyone clear this up?

Regards,
Mike

Basically you have it backwards.

The white is the power leg down to the switch, back up to the light with the black.

Switch to switch is the industry standard now.

I do make exceptions.

 

[mikepett]

I didn't wire this particular setup. Personally I don't use this method but I also have no problem with people who do. When I have installed the light fixture where another electrician wired to this method I have always used the white as the switch leg as it made more sense to me logically. Black is always power, I use any other color as switch leg. Seems simpler that way.. at least we can have one sure thing - black is always hot.

I understand the logic for not using it too however and I will do this the other way from now on but think the code needs to be reworded here. For those making comments along the lines of "any qualified electrician should know this" or similar comments, get a grip and grow up. If you honestly say this isn't the least bit unclear, you are severely undermining everything you say from this point on. There are a ton of very smart people that agree with me, and while they may be wrong as I am, we are not idiots for seeing things this way. So lets not dumn down the entire forum here.

 

[jaylectricity]

Given the scenarios above, it is necessary to re-identify a white conductor used as a hot so that __________ will not be confused and spend the rest of the day scratching his/her head.

(A) an Electrician
(B) a fellow Electrician
(C) an Electrician working in FL
(D) a person that should not have their paws in these boxes in the first place.

IMO there is no reason for the requirement. :wink:


Roger

I completely agree.

 

[roger]

I understand the logic for not using it too however and I will do this the other way from now on but think the code needs to be reworded here. For those making comments along the lines of "any qualified electrician should know this" or similar comments, get a grip and grow up. If you honestly say this isn't the least bit unclear, you are severely undermining everything you say from this point on. There are a ton of very smart people that agree with me, and while they may be wrong as I am, we are not idiots for seeing things this way. So lets not dumn down the entire forum here.

I honestly say it is not "the least bit unclear" and I am grown up. :roll:

It is obvious that you have had a belief that has been busted and it is hard to swallow, stick around and there will probably be more. :grin:

Roger

 

[480sparky]

I have no problem with doing this and with that said, why would you re-identify the white or gray conductor?


Roger

'Cause 200.7(C) says you so, at least since 1999.

 

[roger]

'Cause 200.7(C) says you so, at least since 1999.

And that is the answer I was hoping you would give, you passed.

Roger

 

[electricmanscott]

So lets not dumn down the entire forum here.

Sorry, I couldn't help myself.

 

[Electron_Sam78]

When I have installed the light fixture where another electrician wired to this method I have always used the white as the switch leg as it made more sense to me logically. Black is always power, I use any other color as switch leg. Seems simpler that way.. at least we can have one sure thing - black is always hot.

Yeah but then there's 2 white wires connected to the light fixture and if no one re-identified the one that is hot it might take an additional 1 minute or so to figure out which one's hot - that is if the circuit is dead and it's not painfully obvious due to other clues.

 

[480sparky]

It wouldn't be an issue with conduit (would it?), and the rules for using the white as ungrounded explain how to use NM the same way, so it's a non-issue to em as well.

While I rarely use the 2-wire switch loop (as it's called) in most NM work, because I like running the feed from switch to switch, I'd use it in attics, sheds, crawls, etc.

I just hate switch loops from a service standpoint. If you have a problem with a switch loop, you've gotta pull the light fix...... errr.... luminaire..... down.

Feeding the switch first makes troubleshooting much easier. If I know the only splices in the ceiling are from the switch leg to the light fixt..... sorry..... luminaire...... then chances are, it's easier to troubleshoot and fix.

 

[mikepett]

I honestly say it is not "the least bit unclear" and I am grown up. :roll:

It is obvious that you have had a belief that has been busted and it is hard to swallow, stick around and there will probably be more. :grin:

Roger

Has nothing to do with a belief and everything to do with what I believe to be the english language, but good theory though.

Good luck with your future endeavors Rogie... glad I had the pleasure of finding out what this forum is all about before spending too much time here.