Why the wide prong on a plug?

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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 !!! .
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On Sun, 26 Oct 2008 21:39:27 -0700 (PDT), marlboroman

You don't have much to do. Do you? :)
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On Sun, 26 Oct 2008 21:39:27 -0700 (PDT), marlboroman wrote:

Maybe they want the hot and neutral to be determinate just to protect against lawsuits?
Or, maybe it's a UL standard even for plastic-housed appliances?
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On Sun, 26 Oct 2008 21:48:21 -0700, Donna Ohl

What do they mean by double insulated?
One insulation is the plastic case. Maybe the other one is figurative, that they do the rest of the wiring as if it were a metal case?
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On Sun, 26 Oct 2008 21:48:21 -0700, Donna Ohl

Or maybe the exposed metal chuck and drill bit are somehow connected to the motor within? Ya think?
Sheesh
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snipped-for-privacy@dog.com wrote:

Here's a patent describing an insulated coupling that electrically isolates the chuck from the motor in a double insulated (class 2) power tool.
http://www.freepatentsonline.com/3873863.html
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wrote:

How well does it work submerged?
You bet your life!
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Submerged, it isn't going to make one bit of difference which way the plug is inserted in the outlet.
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On Tue, 28 Oct 2008 00:44:32 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Wet, okay Mr. Picky?
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If you meant "wet" why did you write "submerged"?
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Doug Miller wrote:

Snip
"Submerged" is so much more dramatic than "wet".
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On Tue, 28 Oct 2008 01:56:55 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Just to upset your delicate balance.
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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.
    Dave
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Dave Martindale wrote:

I suppose that's why we end up buying the new improved model!
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marlboroman wrote:

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.
TDD
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Some people learn by reading. Some people learn by being taught. Others just have to go piss on the electric fence themselves.
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Stormin Mormon wrote:

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.
TDD
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The companies use it in case you need an extension cord. Then you'll be forced to buy an extension cord with the wide blade.
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TD wrote:

I'm not going to call you names but that's the silliest thing I've seen posted in a while.
TDD
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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 plugs.
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 product.
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