> Most commonly circuits are 14ga wire and rated for 15 amps. Some
> specific circuits are rated for 20 amps and use 12ga wire (I believe
> it's 2 in the kitchen by local code) and usually in the utility area
> (garage, basement, outdoor...)

NEC changed in the last 10-20(?) years to specify 2 circuits in the
kitchen, 1 in the laudry area, 1 in each bathroom, 1 in garage, and
a bunch of other residential wiring details.  I'm showing my age...

> But just to make things complicated they fit the same plug. (there
> are differences between 15 and 20 amp rated sockets, but the consumer
> can't tell the difference by looking). It's still safe though, because
> a 15 amp socket is protected by a 15 amp breaker. But it can certainly
> be annoying.

It's easy to tell the difference.  If a device draws 15 amps or less,
the standard plug has 1 round ground prong and 2 vertical blades for
hot & neutral.  If a device will draw between 15 and 20 amps, then the
hot blade is horizontal (neutral blade is vertical & ground is round).

Normal 15 amp duplex wall outlet can be used on either a 15A or 20A
circuit and both blade jacks are vertical.  Dual use duplex outlets
have a T shape hot blade so you can insert either a vertical or a
horizontal blade.  "20 amp only" outlets have vertical neutral and
horizontal hot.

> but we also have a myriad of other plugs for high current devices to
> about 50A.

Once you get above 120V 20A, the number of plug styles seems to
grow exponentially.  And the number of places where you can buy
the more exotic ones approaches one over infinity.  :-)

						Lee Jones

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