I hadn't looked up specific numbers; I only used the fact that the power
actually used is what controls the operating cost and that bulbs are
rated for their power consumption at the stated voltage. Hence, the
variability between an ideal 120V and our typical higher voltage that is
still rarely as high as 130V will cause the power consumption to be less
than it would otherwise be albeit w/ a loss of lumens altho I really
don't think it's terribly noticeable unless the lighting already was
Anyway, assuming the 1.6 exponent, the reduction factor would be 0.88
instead of 0.85 according to my trusty HP-97. In reality, altho I've
never monitored it for a period of time (altho come to think I do have
sufficient test gear I could; just never thought of doing so as doesn't
really make any difference as it is what it is and will continue to be
so) I'd guess our average would be around 124/125 based on the numbers I
generally have noted when did measure. So, would be less than that in
practice but it _won't_ be >1.0.
I use the same rating bulbs, yes. It is "nominal" 120V of course, but
generally we will be closer to 125-127V than 120V and on rural lines w/
long distances fluctuations and interruptions are more frequent than
most are used to; just goes w/ the territory of having only
1-and-a-fraction loads/mile on distribution lines as opposed to
residential distribution grids. Hence, the lifetime is greatly extended.
Interesting that Lew would point this out in a followup post that a
higher-cost bulb pays for itself even at lower power cost but can't help
but try to make a putdown to the logic of using a 130V to obtain the
At a typical 18-20 lumens/watt and 1,000 hour life, incandescent lamps
are never even a consideration for a low cost of ownership lighting
Longer life incandescent lamps are purely for convenience except
traffic signal lamps where the cost of servicing a signal enters the
ownership cost equation.
We bought a new house once and the contractor put in 130v bulbs.
Not he 115v ones we buy in the store - and run them on 120 or 125v.
Anyway - when we sold the house 11 years later we still had some of
the original bulbs.
Consider : P=E*I If E drops - the power drops. The bulb runs cooler.
P=E^2/R or R = E^2/P 130*130/100 = 13*13 = 269 ohms hot.
(rule of thumb 1/10 of hot = cold resistance or 27 ohms for surges).
I=P/E = 100/130 = .76 amps
Now - using the 130 bulb with 269 ohm filament and we run it at 120 :
P (used) = 120*120/269 or 14400/269 = 53.53 watts.
P=E*I so I=P/E I = 53/120 = .44 amps
lower used wattage, longer life due to the derrating.
You assume that the temparature, thus the resistance, of the filament
is the same at 130V as it is at 120V. This is certainly *not* true.
At 120V, the lower filament temperature not only will the bulb use
less power (though less than expected using your calculations) will
make the bulb less efficient (lumens per watt), costing you money too.
Much longer, yes. Bulb life is a function of something like the 16th
power of service voltage. It's still not saving money, unless there
is a cost associated with replacement in addition to the bulb cost.
And the cost of replacement must be huge. 1000 hours of use of 100 W bulb is
going to use 100 kwh, I pay something like 11 eurocents per kwh so energy is
going to cost me something like 11 euros. Higher voltage filament bulbs
would easily cost several times more for same light output. I am moving to
led lights myself (not for energy efficiency, fluorecents are about same but
for longer life). Now testing this:
There's the same fallacy assumption that Lew made as well -- _ONLY_ if
one is requiring the same or more lumens will there be a higher energy
cost to obtain them--as told Lew, for household lighting, a 100W bulb is
a 100W bulb and one gets the light one gets (at least that's what I do).
It's good enough and bulbs last.
Sure it's not much for an ordinary 100W bulb so the convenience of not
having to replace them is a factor but there's no economic penalty
associated w/ gaining that (again, assuming one doesn't go from 75W _to_
100W per bulb).
From GE 2006 large lamp catalog
100 A 130V 100 watts 750Hrs 1680 lumens
100A 130V@120V 89 watts 1950Hrs 1275 lumens GE shows rated watts as
89 at 120V.
Depends whether your more concerned about light level or life of the
lamp. Since there are so many better options these days it seems
pointles to even use them.
Well, I can assert that in my case (the only one that actually matters
to me :) ) it's not an assumption at all. I see fine using the same
wattage-rated bulb in 130V version as the 120V and as long as that is so
it's a win if they last longer...
If you or another finds that isn't the case, you'll/they'll have to
handle it however you/they choose but that wouldn't negate my usage
patterns nor increase my cost (which was the erroneous claim being made).
Because the difference in a 60W @120V wouldn't be enough for a location
that has a 100W in it, either. The substitution is as earlier
stated--simply 130V of whatever I'd use 120V in that location and I'm
good to go.
No, you're simply trying to make an argument that doesn't hold by making
a false requirement that isn't pertinent. IOW, the strawman argument;
if you change the groundrules to suit your purposes you can "win" but it
doesn't negate the conclusions of the original premise at all.
A 100 W 130V bulb operated at 120V has just about the same output as a 75W 120V
bulb. It's a wash on electricity cost, balanced against the cost difference
for the 130V bulbs, vs 120V ones. Plus the "convenience factor" of less
frequent bulb replacement. Drawback: the 130V bulbs give off a "yellower"
light than the 120V ones -- one may, or may not, notice it.
A 60W 120V bulb has somewhat more output than a 75W 130V bulb at 120V.
The 120v bulb is the _clear_ winner in this case. bulb is less expensive,
gives off more light, and uses less electricity. The -only- advantage to
the 130V bulb is less-frequent replacement.
At lower wattages (60W@130/40W@120 and 40W@130/25W@120), the cost advantage
also goes to the rated 120V bulb. Again, the -only- advantage to the 130V
bulb is less-frequent replacement.
What has gone unsaid is that a yellowish bulb gives the subliminal
impression of warmth. By dropping the voltage across the lamp
filament, you can fool the building occupants into turning down
the thermostat in the winter. This saves on heating oil, gas,
coal or electricity. Thus, it's obvious: a diode or series
wiring saves energy during cold weather. During the summer, just
boost the voltage up a tad and they'll be turning off the A/C and
putting on sweaters.
<grin> Please send all flames and men in white coats to someone
On Fri, 11 Dec 2009 16:40:43 -0600, the infamous
firstname.lastname@example.org (Robert Bonomi) scrawled the following:
Why don't ALL OF YOU stop wasting electricity and get rid of the
ghastly yellow lighting at the same time? CFLs are the way to go.
http://fwd4.me/83K ULA lights have worked well for me so far, and I
bought a dozen. They're a nice cool white. Whatever you do, don't buy
Lights of America brand which Homey's Despot used to sell. I had
HORRIBLE experiences with their cheap crap.
My electric bill last month was $18 and change. The only incans I have
in the house are in the fridge, stove (no replacements available for
the two previous lamps), laundry room (130v Rough Service which was
here when I moved in and refuses to die), and a pair of Reveal bulbs
in the security light outside.
I have yet to see a cfl lamp outlive an ordinary rapid start T8 or T12 tube. It
doesn't seem to make a
difference if it is a Phillips (one would think is toward the top of the line)
or a Fein (econo-cfl purchase
price), or anything in between brand-wise. In my frustration I decided to
analyze some of my failed units to
discover that NONE failed due to the tube itself. The cfl driver electronics
were the cause in each and every
one I looked at. cfls also bring the irritants common to all fluorescents as
well, like taking forever to
develop full brightness and flickering when it is cold. (Yes, I did try the cfls
rated for "outdoor" use, what
Meanwhile the chinese have continued to improve their LED technology and are
beginning to produce light bulb
E27 socket replacements that work well. I am replacing two motion activated
floods (75w) with two LED floods
with 82 multichip white LEDs each. 25$ for the pair on ebay gauranteed for two
years not to fail, no
flickering no slow to reach full intensity, 1/4 or less power required. I am
done with cfls, IMHO they have
never lived up to the hype since the beginning. regards Joe.
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