<< I <was> noticed at HD the other day that many of the 220v plugs were 4 wire.
The only kind of plugin device I can think of that might need 4 wire would be
a dryer. Any others come to mind? >>
Lets turn this around: few 220V appliances, tools, or whatever these days
operate on solely 220V. The majority of things these days have 110V controls,
lamps, whatever, and therefore require a neutral wire. This trend has been
ongoing for some time, so 3-wire plugs will likely be the uncommon type in a
few years just like 2-prong outlets. $0.05 worth...
Electric dryer and electric range come to mind for residental
applications. As far as the 110v clocks and timers go most ranges and
dryers have always had them.
The difference between the old three wire and the new for wire is that
in the old set up the ground was being used as the neutral for the 110v
part of the appliance. This setup used the ground as a current carrying
conductor which could cause a problem if the frame of the unit wasn't
This is no longer allowed under code for new installations. On the 4
wire set ups you have a seperate ground and neural.
BTW the 30amp 4 wire is for clothes dryers and the 50 anmp is for
Different configurations for different uses. The UEC doesn't want the wrong
appliance plugged into the wrong circuit. Thus different plugs for
different applications. A 220v four prong (different sizes for different
amperage) 2 legs are hot, one leg is safety ground no-load carrying, and
one leg is load carrying neutral.
"Doug Miller" < firstname.lastname@example.org> wrote in message
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