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Electric Outlets - Hot and Neutral Reversed
wrote:
On Thu, 20 Oct 2005 15:20:27 -0400, Phil Munro
wrote:
z wrote:
Joseph Meehan wrote:
Chris Lewis wrote:
According to Joseph Meehan :
It is safe to use any device or lamp that does not have a
polarized plug (one with one prong larger than the other so it will
only fit in the outlet one way). Most devices with polarized plugs
are also safe, but it may not be easy to be sure. I would avoid
using any polarized plug device in those outlets. I would also
suggest contacting the owner and having it fixed.
There is NO difference between a polarized plug fixture and a
non-polarized plug fixture other than the fact that the plug is
polarized.
There may be differences in how well guarded electrically live parts may
be, I just would not count on it.
It is always best to be conservative when it comes to electrical
problems.
The only reason that bulb fixtures are polarized, is that a correctly
wired outlet puts the neutral (less hazardous) on the base shell -
which you might come in contact with while changing a bulb.
If the hot is on the base shell (from a reversed outlet), the base is
hot EVEN IF the light switch is off (because the switch switches the
neutral!).
In other words, with a correctly wired outlet (and non-defective
fixture), a polarized receptacle guarantees you can't electrocute
yourself from accidentally touching the base shell of the bulb or
fixture, switched on or not.
As a corrollary, with unpolarized fixtures, or, polarized fixtures
on an hot-neutral reversed outlet, you will want to consider
unplugging the fixture before changing the bulb. It's not necessary
on a polarized fixture on a correctly wired outlet.
--
Joseph Meehan
Dia duit
Does anyone remember the classical 5 tube AM radio of the 50s, the "all
american 5"? The standard design had the chassis connected to one side
of the AC line, before polarized plugs were common. Directly, no
capacitor or resistor or such. If you were hip, you knew that you could
reduce the AC hum a bit by trying the plug both ways, sometimes when
the chassis was connected to the neutral rather than the hot there
would be an audibly lower hum. Of course, that would keep the chassis
from being electrically hot, too. Just to add to the fun, often the
chassis was attached to the case with screws whose heads were freely
touchable on the underside of the chassis. Oh yeah, those were fun
times.
My memory of those 5-tube jobs is that the chassis was NOT connected
directly to the line. Rather the line connection as ground was a
floating one, and there was a 0.1 uF capacitor between the true ground
and the chassis ground.
But this was not always the case, and some of the no-xfmr TVs of the
time DID have the AC line connected to the chassis, and the volume and
other controls were metal connected to the same chassis, so if the
plastic knob was pulled off, there would be real danger.
Of course 0.1 uF (or were they larger) also gives a significant
connection, too. --Phil
I agree Phil. The All American was the one that didn't have the hot
chassis.
Sheesh. I was being so careful for nuthin.
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