power
Hugh, there is a thread on here somewhere where power standards were discussed in detail. I'm not sure if it's still current or in the archives, but the shortened version is:
Most US homes, with the exception of very old ones that haven't beenupgraded, have 120 and 220 volts 60 AC available. 220V (or 208V in some areas) is generally used only for high load appliances such as
electric ranges that plug into a special dedicated 50 amp outlet
full-size electric dryers that plug into a special dedicated 30 amp outlet (compact portable units run on 120V)
room A/C units with a capacity over 12,000 BTU
electric heat of any kind (baseboard, ceiling or floor radiant, electric furnace) except for portable units, which run on 120V up to 1500 watts.
Central A/C or heat pumps
electric water heaters over 5 gallons
Some things (well pumps, swimming pool pump motors) can be wired to run on either voltage, depending on size of motor and voltage availability at point of use.
Manufacturers adhere to a Worst Case Scenario power draw of 15 amps at 120 volts, since that's the standard even very old homes used. Newer homes are wired to 120 Volt 20 amp standard, and some neweer 120volt appliances can utilize this, but they have a different type plug and outlet. Otherwise, everything else runs on 120 volts. For quite a while now we've been getting a lot of appliances that are dual voltage and 50/60Hz, you just move a switch and put an adaptor on the plug to fit where you are at. Some of the newer appliances are even self-sensing (my IBM laptop power supply is like this) and automatically knows which voltage/frequency is in use.