Like this?
(.) (.)
(!)
Uhoh! My outlet is measuring 122 volts right now.... ;-)
It seems like old-timers refer to it as 110, and now it seems to be more
commonly known as 120. At one time I thought the standard was 117 VAC, and
I've also heard 115 and 125. Yet a three phase source with 120 VAC L-N is
always called 208, AFAIK, even though the actual P-P voltage may vary from
200 to 225. Similarly, 480 VAC is sometimes called 440 or 460, but the L-N
is always referred to as 277, which corresponds to 480 / sqrt(3). I have
also heard it explained that the voltage source is described with the
higher number, such as 120, 240, or 480 while the equipment nameplate is a
lower number, such as 110 or 115, 220 or 230, or 440 or 460. Rather
confusing. And the actual voltage can vary by 10-15%.
And the standard common NEMA 5-15 outlet
http://en.wikipedia.org/wiki/NEMA_connector is actually rated 125 VAC
(maximum), and that is also the way fuses and circuit breakers are usually
rated (125, 250, and 600 VAC are most common). These are also referred to
as "Low Voltage", under 600 VAC. Then there is "Medium Voltage" 601-5000
VAC, and above that is "High Voltage", although I think there may be
another class of "Very High Voltage" above 138 kV, used for transmission
(as opposed to distribution).
Probably much more than the OP needed to know...
Paul