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

can i get a schematic to wire a three way switch?

Sparky,

Re-identifying the white wire with black tape such as in the last diagram does not satisfy the requirement of article 200.7c2 does it? I believe the white wire must be re-identified, but it must be used as one of the travelers, and not as a return conductor from the switch to the light. Even though you've re-identified the wire with black tape, you still end up with both wires feeding the light being white. When the tape falls off sometime in the future, there will be no way to visually identify which wire is which.

Also, because the NEC requires the white wire to be "permentantly" re-identified, does taping it qualify as a permenant means? I know that many do it this way, but does it technically satisfy the NEC? I use a permenant tip magic marker to color the exposed ends. Matt

Good catch Matt. The white wire is not allowed to be used as the switch leg even though it is reidentified, just for the reason you stated. The white wire would be reidentified and used as one of the travellers. It is perfectely okay however to reidentify with tape.

LOL!, well Matt, you've caught me bettween an old link & the 02', very good.....

so, i would recommend that one end get fed, one gets switched, and the white remain neutral throughout...


probably cut the gauss down too!

The 1996 language said the unreidentified white shall feed the switch in 200-7 Ex. 2.

But doesn't 2002 200.7(C)(1) allow the use of the reidentified "white" wire as a ungrounded conductor anyway? This would allow the use of the reidentified white as the switch leg to the fixture or as the traveller.

As I read 200.7(C)(2) I see a positive language statement reversing the 1996 and earlier exception that allowed the use of a cable's unreidentified white as the hot. (C)(2) says "where" the white is used to feed a switch loop. . .I don't pick up the "shall" pointing at anything but reidentification.

Help me see how I'm confusing myself.

Inquiringly,

Al

Al,
it is not worded well, and has been the source of much ado.

there has been much on this, i believe it was addressed in the 'Code Q of the Day' e-mailings, as well as Mike Holt's code updates in the trade mags.....

my personal feeling is that the NEC should not cater to dummies. this 're-identification' thing has flip-flopped through a number of code cycles.

if in fact there is some 'safety' aspect, i do not see it, as true trades(persons) would all know which is the 'hot' in a compliant installation of B & W to a s.p. switch...

besides, if you look at the HB illustration of 200.6(E) EX#1 you'll see white tape being applied to a black conductor in armored cable, no problem! , so i would not expect that 14-3,12-3 etc be run to all switch legs and pop up the box fill, make for an unused conductor, and create more confusion.....i haven't seen anyone wire in such a manner as yet......

methinks that this is somehow related to the colored NM marketing of late, and will continue being lobbied ( read the latest NEC digest lead article) for nothing but NM variations , totally profit driven.....

the 20.7 HB commentary here supplies some rationale ;


desends saop box....

For anybody who cares, over here we usually use the black (normally neutral) as the return from switch to light and the red as the feed to the switch. Yes, it results in two black wires at the lamp (code requires the hot black to be reidentified red).

It is possible to buy NM-type cable with two red wires, but very rare to see it used.

which you do with tape Paul?

BTW...
someone here previously suggested drilling a small hole in the tip of a 'permanent' marker , thus compling with 'permanence'......

said dedication to the NEC is admirable, yet the NEC intent seems hazy.....

Scott (electure) mentioned in another thread of the same ilk, that the chemicals is said marker may not be proven to be safe for thermoplastics or any other insulation type...

So is it better for the tape to fall off, or the ink to attack the insulation?

On side note:

I've had Scotch-kote soften the jacket on SOW cord that we were using for water fountain lights... I had put some Scotch-kote on where the SOW meets the WP connector gasket, and is softened the jacket rather badly.

Who'd a-thunk it?