On 27 Mar 2005 05:09:09 -0800, someone wrote:

It seems to me that if the same wire is always
hot (when the current is flowing), the current is acting as direct
current.

Nah. The black (or red!) wire has a sine wave current in it that
alternates back and forth, you might think of it as from plus to
minus. Whereas the white wire is supposed to be at ground potential.
If everything is perfect, in practice you would USUALLY be ok touching
the white - the "stick you finger in the socket" situation, you can
indeed USUALLY get away with it when the black has been switched off.

You get 120/240 because the red and white are at opposite phases, its
240 between them and 120 from each to white neutral.

In theory and code you don't allow anyone to touch the white as their
are possible faults where a potential could develope that would cause
current to flow.


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