On Mon, 28 Dec 2009 02:12:10 -0600, bud--
wrote:

wrote:

My US built 4 year old Tempstar furnace says for 115 volts AC
operation.. One of my (2 way) radio power supplies says 117 volt AC
in..
My compressor motor says 115/230 volts AC. (it is a year old).
My Beam central vaccum says 115 volts.
My stereo pre-amp says 117 volts AC.
Heck, my model train transformer says 117 volts. Then most of my
computer stuff says 84 - 240 volts AC or 100-240 VAC.

My experience is that 20 years ago, average voltage around here was
much higher than it is today. 117 was low, and 123 was not uncommon.
For the last 5-10 years if I see 120, it is high. 117 is common, and
as low as 114 is certainly not unheard of.

My central air unit says 230 VAC.

But its that funny Canadian stuff.

Made in the "good old USA" back in the day when USA still HAD
industry.

The explanation I have heard is 120/240V is the nominal supply voltage
(at the service). And 115/230V is the nominal voltage at equipment
(after voltage drop). (Would be interesting where 117V comes from.)

The NEC says to use 120/240 for calculations. The values for current in
the NEC motor tables are for 115/230V.

IMHO arguments about what is "correct" are useless.