220 V table saws and ground

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J. Clarke wrote:

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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 marginal.
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.
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J. Clarke wrote:

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 same benefit.
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"dpb" wrote:

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 system.
Longer life incandescent lamps are purely for convenience except traffic signal lamps where the cost of servicing a signal enters the ownership cost equation.
Lew
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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.
Martin
dpb wrote:

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wrote:


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.
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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: http://www.dealextreme.com/details.dx/sku.26514
seismo malm
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snipped-for-privacy@gmail.com wrote: ...

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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).
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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.
Mike M
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No fallacy at all. Need less light? Use a lower wattage, or fewer bulbs.

That's a big assumption. The fact is that we use light to see.
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snipped-for-privacy@gmail.com wrote: ...

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).
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Then why don't you use a 60W in stead of a 100W, for example?

You're simply fooling yourself.
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snipped-for-privacy@gmail.com wrote:

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.
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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.
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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 else.
--
Nonny

ELOQUIDIOT (n) A highly educated, sophisticated,
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On Fri, 11 Dec 2009 16:40:43 -0600, the infamous snipped-for-privacy@host122.r-bonomi.com (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.
--
Don't forget the 7 P's:
Proper Prior Planning Prevents Piss-Poor Performance
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On Sat, 12 Dec 2009 09:12:03 -0800, Larry Jaques

Speaking of ghastly, CFLs define the term. Yuck! Wouldn't own one.

Get real. The reason you have an $18 bill has nothing to do with CFLs. Hell, I'd put up with CFLs if they'd run my heat pump and water heater.
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"Larry Jaques" wrote:

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If the lamp is to be "On" for at least 10 minutes, CFL makes sense.
Less than 10 minutes it's a poor choice.
Lew
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On Sat, 12 Dec 2009 14:01:35 -0800, the infamous "Lew Hodgett"

Erm, how many lights to you flick on and off, Lew? Who are you signalling?
--
Don't forget the 7 P's:
Proper Prior Planning Prevents Piss-Poor Performance
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Larry Jaques wrote:

The Enterprise. ;-)
--
Morris Dovey
DeSoto Solar
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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 a joke!)
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. snipped-for-privacy@upwardaccess.com
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