Has anyone ever figured out why they put one wide and one narrow on a
plug that does not have a ground?
OK, I understand that on a lamp it's a good idea, or the socket shell
and bulb threads will be live if the hot side of the power line is
connected to that part of the socket.
But, lets say I have a all plastic cased electric power tool. (Like
all of them made in the last decade or more). I'm holding plastic,
which does not conduct electricity. It dont matter which side of the
power line goes to which side of the motor on AC. What's the point of
having that wide terminal? Is the only reason to piss off the user,
particularly those of us who are older and dont have the best eyesight
anymore. I cant see any other reason.....
My grinder does a quick job of narrowing that wide prong though !!!
I actually own an older Dremel tool that has a plastic coupling to
isolate the output shaft. The motor has a pair of bearings, and the
output shaft has another pair of bearings. The two shafts are in line
but don't touch, and a splined plastic coupling connects them.
It works fine for transmitting rotation, but it makes the tool almost
unusable for routing and some grinding and milling operations. The
output shaft is just a short stub, and the bearings that hold it are
only half an inch apart. So any side load on the cutting tool has
plenty of leverage in applying force to those bearings, which are only
held by the plastic housing. The result is lots of chatter.
I notice that all of the more recent Dremel tools I've looked inside
have a single shaft from chuck all the way back to the rear end of the
motor. So there are only 2 bearings, and the chuck is better at
withstanding side loads.
But the newer Dremels are *still* double insulated. I think they do it
with insulation between the steel stampings that make up the armature
magnetics and the motor shaft. So if the insulation on the armature
wire wears through and touches the steel, the armature could become
"hot" but the shaft would still be isolated.
The wide blade is the neutral, the narrow blade
is the hot. Some appliances may have the neutral
attached to the metal chassis parts inside. Did
I hear "shock hazard"? I used to work with an
idiot who would cut the ground pin off plugs.
The hot wire is switched. If you grind down the
neutral and plug it into the hot side, the item
will be energized when the switch is off.
A famous man once wrote something to the effect:
"Experience is a fools best teacher." My father
taught us how to do electrical wiring when we
were kids on the farm. I have experienced shock
therapy many times over the years. I would hope
others could learn from my experience.
On Sun, 26 Oct 2008 21:39:27 -0700, marlboroman wrote:
Short Answer: Lawyers and (product) Insurance.
Too Much Information (TMI) answer:
NEMA, National Electrical Manufacturing Association sets the standards
for all US Electrical plugs and receptacles. Search for a Wikipedia
write ups on NEMA standards. There are links at the bottom of the
Wikipedia to NEMA configuration charts. Your plugs are NEMA 1-15 type
The National Fire Protection Association publishes the National
Electrical Code. The NFPA has adapted the NEMA standard as part of its
new building code for Electrical Safety. Many states adopt the NFPA
electrical code standards in their building code and statutes for
enforcement of such building codes.
Underwriters Laboratories, inc, the testing agency for Insurance
companies that issue policies against product liability, adopts the
National Electrical Code (which includes the NEMA standards) as part of
its product safety testing and check list.
Thus, in order to purchase product liability insurance a maker of
consumer products, like a homeowner's hand drill, needs to submit the
product to UL for safety testing. UL will give its blessing only
provided ...... (yada, yada, yada)
Thus the products you buy will have a narrow (hot or black wire) and a
wide blade (neutral or White wire indicated by the "W" on the NEMA 1-15
standard.) Even if the general public safety intent and need for the
narrow / wide blade makes no difference in a specific manufacturer's
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