power outlet shapes

If you look closely at the thrid prong, USA style, you will see that it looks like a bannana plug ( round connecter split in 4) this provides a stiffness during connection. Most US products don't even come with the third prong. Usually styles are chosen based on which organization best lobbyed their system.

I meant which company had their system lobbied to the corps which handle the safety rules/sets.

Hi, Joe. Not a silly question at all. Looking at the standard United States 120VAC plug, you noticed that one of the flat blades is wider than the other. For wiring, the narrower blade is at line voltage potential (Hot), and the slightly wider blade is Neutral. This standard wiring scheme is made so the manufacturer of electrical equipment can know which side is which.

Cheers Chris

I forgot to mention that the sole purpose of the third prong is not for a stiff connection, but for a ground path. But due to GFI (Ground Fault Interrupters) most corps decide not to use it in their product, unless it is handline large loads.

I myself always wonderd what the holes on the blades were for. I always thought they were for a spring loaded metal ball, to fasten the mating, but that doesnt seem to be the case. Maybe you can answer this?

"Chris" wrote in news:1155357759.605108.162820 @m79g2000cwm.googlegroups.com:

So the manufacturer can wire the Hot side to the on/off switch. That way, when you turn the applicance off, the hot side is disconnected. This is for safety. You touch the applicance, and you are completely safe.

Decades ago, both prongs were the same width and this safety feature wasn't available. So you had only a 50% chance of disconnecting the Hot side. (c:)

Its a holdover from very early US AC outlets and plugs. The metallurgy wasn't as good, so there was a dimple pressed into the contacts in the AC outlet. They were turned so the raised spot was against the blades of the AC plug to help hold it tighter. It created a detent lock that made it harder to plug and unplug a cord into the outlet.

This was in the early 1900s. Later designs use springy alloys that hold the blade without the detent. The holes are still there, just in case something is plugged into a really old outlet.

Actually, they are designated by NEMA in the US. It has to pass their safety standards before you can sell it, but who in their right mind would try to push a non compatible outlet or plug for consumer equipment? Look at the Hubbell or Leviton sites for information on the standard connectors. If you use a non certified design, you generally have no insurance coverage if it starts a fire. The NEC handbook details US wiring regulations, and is the end results of the insurance industry setting minimum standards.

On 11 Aug 2006 21:48:40 -0700, in message , snipped-for-privacy@gmail.com scribed:

It probably would have been best for you to continue to forget to mention that. The third prong is a safety feature that provides a path for current from the metal case of an electrical device. That way, if somehow a fault current is induced into the case, the return path is through the low-resistance wiring instead of through the operator of the device. Its use has nothing to do with the magnitude of the load.

Manufacturers do not omit the ground prong because of GFI. If a device comes without the third prong, it indicates that there is no metal case that presents a possible shock hazard. A "wall wart" transformer, for instance, or a lamp (note that a "wall wart" typically does not even have polarized plugs, as the hot and neutral leads will not normally come in contact with the user of the device).

GFI is an additional protection against fault currents, and is mandated only where the possibility of standing water as a normal condition exists (bathrooms, garages, etc). If you use a drill with a metal case in your bedroom, and have hacked off the third prong because you have GFI in the bathroom, you have compromised your safety.

And they make it really handy to solder to them to build a suicide cord. ;-)

Cheers! Rich