The narrow blade goes into the "hot" slot. The wide one goes
into the neutral.

with a polarized plug, you turn the switch off at the
appliance, and there is "hot" power up the cord, and to the
switch. The rest of the appliance is safe to touch.

With a same size plug, the switch might turn off the power
in the appliance, or it might turn off the neutral, leaving
the appliance energized all the time. Energized, as "can
shock you". Not energized as in "costing your electricity".

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Aloysius Q Roger-YoMama" wrote
in message
...

I live in a little house built in 1954. It has a certain
number of
ungrounded receptacles.

In the context of DC power, I have some notion of the
importance of
polarity.

For years, all small electrical devices/accessories (i.e.
extension cords)
with 2-prong male plugs that I've seen have 1 wide and 1
thinner blade.
To facilitate connections and minimize hassle, I've been
grinding the
wider to the width of the thinner blade.

This'll likely qualify as a "naive question". In the context
of single-phase
power and small ~120v 60 hz AC ("Alternating Current")
household devices,
what purpose does having 1 blade wider than the other serve?

Thanks,
AQ