On Wed, 24 Mar 2010 19:02:14 -0400, Nate Nagel wrote:

My Dell laptop power supply says that it will work on 100-240V, 50 or 60
Hz. Wikipedia sez

http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets

that Japanese receptacles, despite having 100V, 50Hz power are
essentially identical to a NEMA 1-15. However, both "bricks" that I have
use a 3-wire cord instead of a 2-wire like every other laptop I've
had/used

My Dell laptop PSU uses a 3-wire cord - but dismantling it revealed that
the ground isn't actually connected to anything internally. I've used
mine on US power with and without a ground, and UK power (230V @ 50Hz)
with no problems (but not Japan :-)

cheers

Jules