Im not an electrician but I believe it depends on what your installing it for. For instance, electric ranges often have outlets installed at floor level. But you may want to check with your local building codes, as they differ from state to state.

You can put the outlet as low as you like.

Unless specifically required by code, you can pretty much place the outlet where you want it. We just wired a basement with 6 20AMp outlets. Customer wanted them 48" off the ground for easy reach for plugs. Consider not placing it too low since dust, dirt and water are more likely to enter the outlet. Most wall outlets are 14-16" center of the box.

CA Code is 12" off the floor and not more than 72"

CA Code is 12" off the floor and not more than 72"Is this in writing somewhere, or is it some inspector's whim?

What do you do if you want a clock outlet at 78"?

Many down here and myself(myself anyway) use 18" to the center for recepticles, 48" to the center on switches, 80" for Bath lights/outside lights, maybe 42" to the center for kitchen and bath recepticles.
Larger Homes with high ceilings may have higher lighting.
Tile Design may affect the height of recepticles.
Shorter and Taller People may require a different height for recepticles and lighting?
Floor recepticles I install at 0". You can also have recepticles in the ceiling?
Flood Level down here can also determine the lowest they can be installed?

Keep in mind, the OP asked about a "220" outlet.
Maybe he is talking about a 240v range line? This would typically be installed right at the floor.