John McCoy wrote:

" wrote in
:

Not being an officially trained electrician, I've never looked into
the 220-230-240 volt or 120-115-110 volt issue. I'm pretty sure those
are all identical and interchangeable, but why are all the numbers
used interchangeably? Why don't we pick one number and use it? Why
does everyone talk about 120 volt outlets in their house, but the
outlet says 115 volts.

It's a variety of historical reasons. 110V is what Edison
originally used for his first DC systems (for reasons no
longer understood, that was considered "safe"). When Tesla
and General Electric developed AC systems, they picked 120V
as the "household" voltage, but because 110 was already in
the public conciousness, people continued to call it 110V.

115V comes about because the utility is allowed 5% tolerance
for line loss, and 115 just sounds better than 114 (which is
what 120 less 5% would be).

110V is a legacy term left over from the war of currents that
Tesla/Westinghouse won.

115V comes from the 'design side', equipment is normally designed to
run on 115V ±10%

120V comes from the 'supply side', under standard conditions electrical
utilities deliver electricity at 120V ±5%

http://i.imgur.com/7tkZ2mm.jpg


230V is a different animal - that's a 3 phase voltage in the
US.

Not necessarily, my Unisaw is 3hp single phase, 60HZ, 230V as are
these and countless others:

SawStop
https://s3.amazonaws.com/vs-lumberjocks.com/lymffnt.jpg

Jet
https://s3.amazonaws.com/vs-lumberjocks.com/nl7owop.jpg