ECN Forum Forums Technical Discussion Electrical Theory and Applications wiring a three way switch

Hi again electrical,

The weather has been great here, however because of all of these lakes, the mosquitoes have been hell! LOL I know what you mean about strong coffee being good coffee.

Well I guess I can only add that it seems clear to me that the evolution of 200.7 into requiring the reidentification of the white conductor was an attempt to further eliminate confusion, and was in addition to the long standing requirement that it only be used as the supply to the switch.

To the untrained person, white wire = neutral = safer to touch. When a trained person sees a white wire connected to the terminal of a switch, he knows that it is probably not a neutral, whereas the untrained person still may see a neutral. I believe that this is the reason that CMP #5 added the requirement to reidentify.

It is obvious to me why they wanted the return conductor to be black. You have a choice of two conductors, a black and a white. Since one conductor is no more or less difficult to use than the other, why not use the black as the return so that at that outlet you have a black hot, and a white neutral? If the white wire were truly reidentified along its entire exposed length at all splice locations it may not be a problem, but a small strip of tape could be overlooked or may not mean anything to an untrained person. A mixup here would reverse the polarity on a lampholder or receptacle, whereas from a safety standpoint it doesn't matter if the wires are reversed on a switch. Matt

[This message has been edited by Matt M (edited 08-01-2002).]

reason they are more partial (I think) to using a white wire for a feeder to the switch rather than to the fixture is because the fixture will more likely be replaced/upgraded etc.
Taping the switched hot (white) with red or black is acceptable here in the south.
Note that you have to refer to your local jurisdictions as well.

I believe that 200.7(C) (1) and (3) are connected with OR not AND.

This allows either the white (re-identified) or black to be used as the ungrounded conductor to the switch. And either to be ungrounded as the power returns from the switch.

I guess that the NEC has a process to resolve these questions.

“In my opinion the intent of the code is that the white only be used as the supply to the switch, when part of a cable used for switch loops.”

I do not think that is the intent.

C2 is saying WHERE the white is used for the supply…
I remember way back when being told that if you use the white for a supply to a switch, you don’t need to re-identify it because it is spliced to a black (or red) conductor. I think C2 just specifically addresses this mindset.

C1 will allow you to use the white as a traveler if re-identified.

Welcome, Engy!

What about using a re-identified white conductor as a switched leg back to the luminaire?

Al

yes, welcome engy !


in reference to this 'permanent' deal,

there are some who would insist on running 14-3, 12-3 switch legs, with the white unused.

Perhaps the NEC has assessed DYI confusion in viewing two wires in a box with switch?


other than that i cannot see any safety relation this code controversy would address.....

Mark (and anyone else needing Schematics for 3 and 4 way Switchloops), I have recently included Schematics to the ECN Technical Reference area, which should be of help to you.

These Schematics can be accessed by either:
Using this Hyperlink:
3 way and 4 way Switchloop Schematics

Or one of the following methods:

<OL TYPE=1>

[*]Going to the Tech. Reference area and using the "Menu",

[*]Selecting the topic from the Tech. Reference area's main page.
</OL>

Scott S.E.T.