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So, would the first method posted by Roger be legal if supplying, say, a linear halogen lamp, which has the same kind of contact on each end? It this case, there is no "shell" that has to be at neutral potential.

(Edited to fix speling.)

[This message has been edited by SolarPowered (edited 10-18-2005).]

200.11 Polarity of Connections.
No grounded conductor shall be attached to any terminal or lead so as to reverse the designated polarity.

I think what Solar is saying is there is equipment without any clearly defined polarity. A double insulated tool without a polarized plug would be another example. Anything with a transformer, ballast or switching power supply would be another example.
The real problem is the white wire, only because it is white and switched.
In the case of the power tool the disconnecting means, the plug, disconnects both wires simultanously.
At the equipment end there is no difference

It does beg the question, what if both of the switched wires to the non-polarizerd equipment were run in a color other than white?

[This message has been edited by gfretwell (edited 10-18-2005).]

See Article 404, in particular 404.2. You are simply not allowed to switch the neutral. It doesn't matter if the load is polarity sensitive or not.

Also see 300.20 (A) requiring all conductors to be grouped together in metal enclosures and raceways.

Now I suppose that if this load was fed with 2 ungrounded conductors, and was in a non-metallic wiring method, then I think that it would be allowed...

-Jon

Very nice Roger!
ten points to you.

There are many more names for that kind of setup... Hamburg three way, thunder-and-lightning three way (a reference to the fact that an arcing switch will cause a dead short in this arrangement),...
The problem is, the lights are off and you still might have a live wire up there. And it doesn't work with most modern switches. The old rotary snap switches and toggles were big and had a wide contact spacing. New decora style switches have the internal contacts much closer together, making them much more prone to arcing and shorts.
In Germany that was a way to install a grounded socket and three-way switch using only a 3 wire cable w/o ground... combined ground and neutral, hot and lamp return wire was all that was needed. In Austria it seems to have been used but I've never seen it done.