On Fri, 29 Aug 2008 15:47:33 -0700, David Nebenzahl
wrote:

On 8/29/2008 12:53 PM Mark spake thus:

On Aug 29, 12:14 pm, "Steve Barker DLT"
wrote:

that's because it doesn't matter.

"Mark" wrote in message
...

I find it funny that the NEC seems to cover every detail you could
think of, but not this one.

well it does matter in the sense that many cords and wall warts seem
to hang better with the ground pin down....but many commercial
buildings seem to have the ground pin up...

Except that, as someone else pointed out, almost all wall warts have
2 prongs and no ground pin.

However, some (for no apparent reason) have POLARIZED plugs. That has
the same effect as having a ground pin, for limiting the ways they can
be turned.

The "invisible" reason would be the type of cktry in the warts types.
To some styles, as it used to be with TV sets, the polarity of
hot/neutral was important. But if an item is fully Class II designed,
then it doesn't need polarization. They can also use polarity to meet
certain safety ratings, such as having to cover more than one receptable
position.
You don't find many polarized wall warts anymore though.