Standard Domestic Voltage?

[Spehro Pefhany]

It doesn't because its wrong. The official standard in the US *IS* 120V.

Is there a government agency that specifies and enforces the voltage
and frequency, and tolerances? Or is 120V just a defacto standard that
most utilities adhere to? And what about the allowable range?

For product design I use a lopsided tolerance- 120V +10/-20% minimum
for example, preferably +15%/-30% or more under most conditions,
especially for dips of < 1 second. I don't like marginal tolerance to
line voltage that results in dropping out or resetting when motors on
the same circuit start etc.


Best regards,
Spehro Pefhany

 

[Michael A. Terrell]

The problem with incandescent bulbs is that they are very inefficient (at
creating light) at lower voltages. They are, however, almost 100% efficient
at creating heat. So, incandescents are OK in the winter, as they are just
another heat source. The color of the light also changes with voltage, which
may or may not be desirable. Compact fluorescents are much more efficient,
and are now very low priced. They seem to last much longer, and are probably
more tolerant of higher voltages. Their drawbacks are mostly their harsher
bluish color, and they don't work as well in cold temperatures.

Paul

Which is why I use the 130 volt bulbs in places like the gatepost
lamps and other unheated areas. The rest are fluorescent.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Robert Baer]

This has become an issue of debate here in teh office so I thought I'd
ask the public. What is the standard voltage for domestic supply in
North America? I've heard anything from 110V to 125V, and I've measured
it at anywhere from 115 to 122 so what is the "official" standard?

Cheers,

Chris

AFAIK there is no "official" standard and apparently never was one,
per se.
40 or so years ago, "everyone" called it 110VAC and later called it
115VAC, and the common nomenclature is either 115VAC or 120VAC depending
who you alk to.
I clearly remember tube radios designed to run on 110VAC after 10
years(?) then having failures stemming from higher line voltage.
And now, i see that the line voltage is commonly 120VAC to 125VAC,
which clearly wastes energy and is un-necessary.
Remember, power increases as the square of the voltage.

 

[Jim Thompson]

AFAIK there is no "official" standard and apparently never was one,
per se.
40 or so years ago, "everyone" called it 110VAC and later called it
115VAC, and the common nomenclature is either 115VAC or 120VAC depending
who you alk to.
I clearly remember tube radios designed to run on 110VAC after 10
years(?) then having failures stemming from higher line voltage.
And now, i see that the line voltage is commonly 120VAC to 125VAC,
which clearly wastes energy and is un-necessary.
Remember, power increases as the square of the voltage.

And the power companies get to charge for it ;-)

...Jim Thompson

 

[Pooh Bear]

And now, i see that the line voltage is commonly 120VAC to 125VAC,
which clearly wastes energy and is un-necessary.

Since power transmission is more efficient at higher voltage would you care
to elaborate on that curious claim ?

Graham

 

[Joel Kolstad]

And now, i see that the line voltage is commonly 120VAC to 125VAC, which
clearly wastes energy and is un-necessary.

What makes you say that? In something with a switching power supply, there'll
be less current drawn and hence efficiency will actually improve a skosh
thereby saving energy.

As for it being unnecessary... well... compared to what? Much of the rest of
the world thinks that 220V-240V is the way to go... Japan thinks 100V is where
it's at (at least that's a nice round number!)... etc...

 

[Pooh Bear]

AFAIK there is no "official" standard and apparently never was one,
per se.

Let me guess......

" no goddamm Commie is going to force a standardised voltage on me ! ".

Graham

 

[Jim Thompson]

Since power transmission is more efficient at higher voltage would you care
to elaborate on that curious claim ?

Graham

All the motors and lamps designed for 115VAC ???

...Jim Thompson

 

[Pooh Bear]

All the motors and lamps designed for 115VAC ???

...Jim Thompson

The lamps won't last long enough to care about ( if incandescent ). Who in their
right mind would use incandescent much these days anyway ? You obviously do know
it's a trade off between efficiency and lifetime and are just being silly minded
over lamps.

As for motors. Who wound them for 115V in the first place ?

Graham

 

[Jim Thompson]

The lamps won't last long enough to care about ( if incandescent ). Who in their
right mind would use incandescent much these days anyway ?

Me ;-)

You obviously do know
it's a trade off between efficiency and lifetime and are just being silly minded
over lamps.

Fluorescents don't have the same light output when retro-fitted.

As for motors. Who wound them for 115V in the first place ?

Graham

The A/C manufacturer.

...Jim Thompson

 

[Don Klipstein]

The lamps won't last long enough to care about ( if incandescent ). Who
in their right mind would use incandescent much these days anyway ? You
obviously do know it's a trade off between efficiency and lifetime and
are just being silly minded over lamps.

As for motors. Who wound them for 115V in the first place ?

Graham

It has been generally considered that household AC line voltage is at
its specified voltage at the "service entrance" or at the breaker box.

Plenty of equipment was designed to work optimally or work
closest-to-specifications at at a slightly lower voltage that anticipates
voltage drop in wiring downstream of the breaker box.

Also, I have heard enough to build quite an impression that the
"USA-typical" household AC voltage (when delivered to appliances) has
increased slightly over the decades. As in 117 in the mid-late 1950's and
the 1960's, 115 in the earlier postwar times, 110 in the earlier years of
widespread home electrification, and 120V in the 1980's with shiploads of
anecdotes of more like 125V from the late 1980's to now.

Motors also have to work both in "normal conditions" and in times of
slightly reduced line voltage.

High current draw motors, such as air conditioner motors, have to be
optimized for typical voltage drop in a typical residential circuit.
Given high current draw of air conditioners designed to work on 120V AC
circuits, I consider it reasonable to optimize them for 115 VAC.

Keep in mind that I have heard enough of "good practice guidelines" (it
may be code) to design household wiring to have a voltage drop no more
than 5% "full current" (which is typically 20 amps for new work with 12
gauge wire, mainly around and after the 1070's, and 15 amps for 14 gauge
wire, which was mainly well before the 1970's - ROUGHLY!).

- Don Klipstein ([email protected])

 

[Michael A. Terrell]

All the motors and lamps designed for 115VAC ???

...Jim Thompson

Time to cut back on the wine so you can read the labels. Bulbs come
in 120 & 130 volt versions, and I haven't seen a new motor marked 115
volts in over a decade.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Paul E. Schoen]

AFAIK there is no "official" standard and apparently never was one,
per se.
40 or so years ago, "everyone" called it 110VAC and later called it
115VAC, and the common nomenclature is either 115VAC or 120VAC depending
who you alk to.
I clearly remember tube radios designed to run on 110VAC after 10
years(?) then having failures stemming from higher line voltage.
And now, i see that the line voltage is commonly 120VAC to 125VAC,
which clearly wastes energy and is un-necessary.
Remember, power increases as the square of the voltage.

This is true only for linear loads, such as heaters, and if they are on a
thermostat, they will just heat the room (or water) faster, and be off
longer. Incandescent lamps increase resistance as they run hotter and
produce more light, so you might get by with a 60W lamp instead of a 75W if
you use a higher voltage and just compare lumens. Fluorescent lamps are
limited in current by the ballast and their specific characteristics, and
modern energy saving systems compensate for line voltage. I believe the new
LED lamps are also current regulated.

Motors tend to draw the amount of power they need, so they will draw more
current at lower voltage to do the same work, and run less efficiently due
to line drop. You will probably burn out a motor faster on low line voltage
than high, within reason. Also, many motors are designed for 50/60 Hz, so
that provides about 15% higher allowable voltage at 60 Hz before you will
get overheating due to saturation at the voltage peaks.

New appliances are being designed that use 3 phase motors and inexpensive VF
converters, which rectify the line voltage and then synthesize the correct
voltage and frequency for most efficient operation at variable speeds.
Computers and other electronics gear use switching supplies which draw less
current at higher voltage, so there is less line drop and greater
efficiency. If it is a severe and persistent problem, a simple bucking
autotransformer can correct the voltage by subtracting 6, 8, 12, or 16
volts.

Paul E. Schoen
www.pstech-inc.com