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Old 07-12-2016, 11:28 AM
Horatio Hellpop Horatio Hellpop is offline
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Cheaper to leave the lights on?

The bane of the Straight Dope is those little factoids someone told us years ago that we never questioned, or even heard elsewhere one way or another, so let me get to the point.

A buddy of mine from decades ago once claimed that turning a light on and off during the course of uses more electricity/costs more money than just leaving the light on during waking hours. (Mind you, this was back in the 70s, before these freakishly long-lasting light bulbs he have now were invented.)

Is it even remotely possible that this is true? My dad was of the "Turn the lights off when you're not using them" stripe and that's always been my inclination.
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Old 07-12-2016, 11:35 AM
Me_Billy Me_Billy is offline
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Some industrial/commercial lights are like that to a limited extent. But for a home these days, shutting off lights when not in use will save the most electricity.

Replace all your bulbs with LED bulbs and you will save even more!

Last edited by Me_Billy; 07-12-2016 at 11:35 AM.
  #3  
Old 07-12-2016, 11:47 AM
running coach running coach is online now
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Mythbusters did that as a MiniMyth.

Summary
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The answer is…according to the MythBusters show: "Yes there is a spike when you flip the switch on but it is in no way significant enough to be considered money saving to leave your lights on for a few minutes while you leave the room. So it is best to turn off your lights even for a few minutes, than to leave them running fearing the spike in energy and a spike in your electricity bill. Also if you were to use energy saving bulbs in the bathroom and were constantly flicking them on and off you would have to replace them sooner and in the end you be paying more for the bulbs than your month's electric bill."
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Old 07-12-2016, 11:52 AM
bob++ bob++ is offline
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I remember reading that in Canada, where electricity was cheap (at the time) many office blocks left all their light on 24/7 because the fluorescent tubes lasted longer and replacing them was the more expensive option.

At home, I used to have two fluorescent tubes in the kitchen, and left them on all evening on the (probably mistaken) belief that it was somehow 'better'. I now have LED tubes which not only give out a huge amount more light for the money, but don't have that horrible flickering you get with fluorescents. Naturally, these are left off as much as possible. In fact, all the lights in our house, apart from the tube in the garage and the lamp in the loft (both not used much) are LEDs.

Last edited by bob++; 07-12-2016 at 11:55 AM.
  #5  
Old 07-12-2016, 12:00 PM
Thudlow Boink Thudlow Boink is online now
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Originally Posted by bob++ View Post
I remember reading that in Canada, where electricity was cheap (at the time) many office blocks left all their light on 24/7 because the fluorescent tubes lasted longer and replacing them was the more expensive option.
Cecil made this point back in 1980.
Quote:
Originally Posted by The Straight Dope
At one time, manufacturers strongly advised against switching fluorescent fixtures on and off frequently because you could reduce tube life as much as 20 percent. Downtown office buildings once left their lights on all night on the theory that it was cheaper to burn the extra juice than send a maintenance worker around every few months to change the tubes. However, the 70s saw the introduction of longer-lasting, rapid-start tubes that last for 20,000 hours, as opposed to 10-12,000 with the old ones. These you can flick on and off a little more casually, since you'll only be reducing tube life from 5 to 10 percent.
Of course, that column was written long before modern LED lights, or even today's fluorescents.
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Old 07-12-2016, 02:50 PM
dtilque dtilque is online now
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For fluorescents, you still don't want to turn the light off and on casually. It not only shortens the life of the tube but also the life of the ballast.* Even with today's fixtures. The break even point is somewhere around 20 to 30 minutes. If you're going to need the light before then, leave it on.

* The ballast thing is only applicable for non-compact light fixtures.
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Old 07-12-2016, 03:01 PM
Vicsage Vicsage is offline
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Hope you all bought your LEDs years ago, because I fear the newer ones won't last near as long. There's little money to be made in making a bulb last 20 years. And since the price on LEDs has dropped considerably over the last years, companies would go out of business once everyone switches over. When incandecent bulbs first came out, they lasted much longer. Companies reduces the thickness of the filament to shorten life and sell more.
  #8  
Old 07-12-2016, 03:19 PM
beowulff beowulff is online now
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Originally Posted by Vicsage View Post
Hope you all bought your LEDs years ago, because I fear the newer ones won't last near as long. There's little money to be made in making a bulb last 20 years. And since the price on LEDs has dropped considerably over the last years, companies would go out of business once everyone switches over. When incandecent bulbs first came out, they lasted much longer. Companies reduces the thickness of the filament to shorten life and sell more.
All the name-brand ones have the same warranty as they did three years ago.
For example, Cree has a 5-year 100% satisfaction guarantee.
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Old 07-12-2016, 03:37 PM
Machine Elf Machine Elf is offline
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Hope you all bought your LEDs years ago, because I fear the newer ones won't last near as long. There's little money to be made in making a bulb last 20 years.
This is conspiracy theory stuff. If mfrs aren't making long-lived bulbs, it's because no customer wants to pay what it costs to make them. If customers are willing to pay for long-lived bulbs, then somebody will make them, unless the entire industry is engaged in deliberate, illegal collusion; no single manufacturer will unilaterally decide not to make long-lived bulbs if that's what the market truly wants and is willing to pay for.
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Old 07-12-2016, 03:54 PM
Vicsage Vicsage is offline
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I hope you're right, but money talks and there's no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you've got them, make the switch to an inferior product. As to guarantees, I haven't read the small print, but I'd bet you'd need a proof of purchase of some kind and most people don't hold on to proof of purchases of low price items for any length of time.
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Old 07-12-2016, 03:59 PM
running coach running coach is online now
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Just because.
Livemore Lightbulb.
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the Centennial Bulb, the Longest burning Light Bulb in history. Now in its 114th year of illumination.
More exciting than the Pitch Drop!
  #12  
Old 07-12-2016, 04:07 PM
Vicsage Vicsage is offline
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If you doubt this has been done before, look up the Phoebus cartel.
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Old 07-12-2016, 04:28 PM
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Originally Posted by Vicsage View Post
I hope you're right, but money talks and there's no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you've got them, make the switch to an inferior product.
And then your company withers when a competitor arises and offers the long-lived product that your company refused to produce. Witness the demise of the Phoebus Cartel.

Hopefully some business/economics experts will chime in, but I assume that an arrangement like the Phoebus Cartel would be illegal under modern competition laws. Not to say it wouldn't happen, but participants in a covert scheme that stifles free-market competition would be risking jail time, as these guys found out.

LED lighting is an example of disruptive innovation. If there's not enough money to be made in selling long-lived light bulbs, then the answer is that some of the manufacturers will die, and the remaining few will gain market share; the trend will continue until the total sales for each of the remaining manufacturers is enough to sustain them.

Last edited by Machine Elf; 07-12-2016 at 04:28 PM.
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Old 07-12-2016, 06:32 PM
Hari Seldon Hari Seldon is offline
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Originally Posted by bob++ View Post
I remember reading that in Canada, where electricity was cheap (at the time) many office blocks left all their light on 24/7 because the fluorescent tubes lasted longer and replacing them was the more expensive option.

At home, I used to have two fluorescent tubes in the kitchen, and left them on all evening on the (probably mistaken) belief that it was somehow 'better'. I now have LED tubes which not only give out a huge amount more light for the money, but don't have that horrible flickering you get with fluorescents. Naturally, these are left off as much as possible. In fact, all the lights in our house, apart from the tube in the garage and the lamp in the loft (both not used much) are LEDs.
While there might be something to that, in my office building the explanation was very simple. There was a construction budget and it was very limited. So to save money, they skipped light switches in the offices and used a 350 volt supply that wired three fluorescents in series (each off had six fluorescents). They turned them off late in the evening and turned them all on in the morning. It wasn't to save operating cost; it was to save building cost. If I wanted to come late at night or on a weekend, I would have to go the circuit box and flick the switch that turned on my office and maybe a half dozen others. When I left I didn't flick them off because, who knows, someone else might have come in in the meantime and I would be plunging them into darkness.

Eventually, they added light switches. But what they had to was use the switch to turn a relay to turn on the lights in each office because it was against code to run 350 volts to a wall switch. Later on they replaced all the switches by new ones that included motion sensors that turned the lights off after 15 motionless minutes. I am capable of sitting just thinking for 15 minutes. But if my office goes dark all I have to do is wave my arm and the lights go back on.

Shows the value of short term thinking. But the building committee had just one budget and operating (or retrofitting) costs just weren't in their remit.
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Old 07-12-2016, 06:53 PM
beowulff beowulff is online now
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Originally Posted by Vicsage View Post
I hope you're right, but money talks and there's no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you've got them, make the switch to an inferior product. As to guarantees, I haven't read the small print, but I'd bet you'd need a proof of purchase of some kind and most people don't hold on to proof of purchases of low price items for any length of time.
That's their problem, not mine.
I save all my LED proof-of purchases, stapled to the receipt, and then write the date the lamp was installed on the base with a Sharpie.
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Old 07-13-2016, 11:05 AM
Orwell Orwell is offline
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That's their problem, not mine.
I save all my LED proof-of purchases, stapled to the receipt, and then write the date the lamp was installed on the base with a Sharpie.
And what happens when the store no longer replaces the bulb, or even carries the same model? If you read the warranties, most require you to ship the bulb back to the manufacturer for replacement. Are you really going to do that for a bulb that quits working a year or two or three from now?

I've had many CREE LED bulbs go bad, and Home Depot has been great about replacing them with no fuss, no muss. But as time goes on, I am sort of waiting for the response "we don't replace those any more; you have to send in the old bulb to CREE". At that point, I'll be upset, but I doubt I'll box up a bulb and pay postage to send it back.

Last edited by Orwell; 07-13-2016 at 11:06 AM.
  #17  
Old 07-13-2016, 11:15 AM
beowulff beowulff is online now
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Originally Posted by Orwell View Post
And what happens when the store no longer replaces the bulb, or even carries the same model? If you read the warranties, most require you to ship the bulb back to the manufacturer for replacement. Are you really going to do that for a bulb that quits working a year or two or three from now?

I've had many CREE LED bulbs go bad, and Home Depot has been great about replacing them with no fuss, no muss. But as time goes on, I am sort of waiting for the response "we don't replace those any more; you have to send in the old bulb to CREE". At that point, I'll be upset, but I doubt I'll box up a bulb and pay postage to send it back.
It all depends on the replacement cost.
  #18  
Old 07-13-2016, 12:37 PM
Bear_Nenno Bear_Nenno is online now
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I hope you're right, but money talks and there's no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you've got them, make the switch to an inferior product. As to guarantees, I haven't read the small print, but I'd bet you'd need a proof of purchase of some kind and most people don't hold on to proof of purchases of low price items for any length of time.
You act as if all the light bulb receptacles that will exist throughout the next 20 years are already out in the market with a bulb in it. This just isn't the case. There are new homes and offices being built every single day. All of these new buildings are going to need new light bulbs. To say that a company that sells long lasting light bulbs will go out of business once everyone buys their bulbs is ridiculous. The demand for new bulbs is not just related to the failure rate of old bulbs, it is also dependent on the production of new fixtures and buildings.

That's as insane as people who make similar claims with automobiles. CT nutters claims that if a company makes a car that lasts a long time, they will be out of business once everyone buys their cars, since the cars will never break. That completely ignores the fact that hundreds of thousands of people are getting their licenses every year or otherwise needing a car they didn't need before. The demand grows as the population and market grows.

Why do you think companies are still able to sell chairs? I mean, according to your theory, nobody should be buying new wooden chairs since they easily last for 50 years. Right? Or lamps, for that matter. When does a lamp ever break? It's usually the bulb that goes out. Lamps last forever. So there's no way any lamp company could possibly stay in business, right?
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Old 07-14-2016, 10:15 AM
MacLir MacLir is offline
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Let me throw another twist into this.

The building I work in has fluorescent lights in most of the enclosed offices, but mainly incandescent lamps for general illumination in the open areas (cube farms). Turning them off manually is discouraged (especially in cold weather) because the heat generated is calculated into the climate control. (Some are on circuits that turn off in the wee hours and back on for work hours.)
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Old 07-14-2016, 10:30 AM
Orwell Orwell is offline
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Originally Posted by MacLir View Post
Let me throw another twist into this.

The building I work in has fluorescent lights in most of the enclosed offices, but mainly incandescent lamps for general illumination in the open areas (cube farms). Turning them off manually is discouraged (especially in cold weather) because the heat generated is calculated into the climate control. (Some are on circuits that turn off in the wee hours and back on for work hours.)
The "wasted" energy in any type of lighting is thrown off as heat. And, certainly, leaving lights on in the winter adds heat to the building, which can be viewed as a benefit. While some of the heat radiates downward to the occupied space, some of it goes up above the drywall or suspended ceiling and does not benefit occupants. But, certainly, leaving lights on during the heating season is better than leaving them on during the cooling season, where the wasted heat has to be removed by air conditioning.

If your building is actually dependent on byproduct heat from lighting, it sounds like the heating system is undersized. I can't imagine it makes sense to keep incandescent lights for the byproduct heat, since HVAC systems are more efficient at heating space than lights, but it is certainly a short-term strategy. If you are using incandescent lights, you are likely either wasting light or wasting heat, depending on the weather and time-of-day occupancy.
  #21  
Old 07-14-2016, 01:57 PM
carnivorousplant carnivorousplant is offline
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Originally Posted by Horatio Hellpop View Post
A buddy of mine from decades ago once claimed that turning a light on and off during the course of uses more electricity/costs more money than just leaving the light on during waking hours.
Perhaps he was thinking of fluorescent lights, which use a lot more current to start than to run. They use about twenty minutes cost of electricity to start.
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Old 07-14-2016, 02:09 PM
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Perhaps he was thinking of fluorescent lights, which use a lot more current to start than to run. They use about twenty minutes cost of electricity to start.
Do you have any evidence for that?

Quote:
~ the spike of current draw normally lasts no longer than 1/10th of a second, and draws the equivalent of about 5 seconds of normal operation. So, if you turn your fluorescent lamp off and on more frequently than every 5 seconds, you will use more power than normal. So, normal switching of fluorescent lamps has very, very, very little effect on a power bill.

http://forums.moneysavingexpert.com/...ead.php?t=6667
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Old 07-14-2016, 02:13 PM
iljitsch iljitsch is offline
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Originally Posted by carnivorousplant View Post
Perhaps he was thinking of fluorescent lights, which use a lot more current to start than to run. They use about twenty minutes cost of electricity to start.
Untrue.

http://energy.gov/energysaver/when-turn-your-lights
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Old 07-14-2016, 02:29 PM
carnivorousplant carnivorousplant is offline
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Would you believe seven minutes?
  #25  
Old 07-14-2016, 02:32 PM
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Originally Posted by carnivorousplant View Post
Perhaps he was thinking of fluorescent lights, which use a lot more current to start than to run. They use about twenty minutes cost of electricity to start.
A common claim, and I'm calling bullshit on it. If you can point to a cite, I'll have trouble trusting that source in the future.

Consider:
twenty minutes is 1200 seconds. A slow-starting fluorescent lamp might take 3 seconds to start up. An 80-watt fluorescent lamp troffer draws about 0.66 amps during normal operation. Your claim means that during that three-second startup, an 80-watt fluorescent lamp troffer draws .66*1200/3 = 264 amps. I'm pretty sure that would blow a typical 15-amp breaker. Heck, you could replace the 15-amp breaker with a block of solid copper, and then you would blow the main breaker on a typical house (usually rated for about 150 amps). If it didn't, it's unclear whether the 14-gauge wire feeding the lamp would survive three seconds of delivering 264 amps. According to the rated resistance of 14-gauge wire, you'd be dissipating 176 watts of heat into each foot of the line feeding the troffer (and another 176 watts per foot into the neutral). Things would get pretty hot.

Rapid-start fluorescent systems have an even shorter startup period, implying higher currents. Cut the start period down to 1 second, and this implies 3X the current, and 9X the ohmic heating in the house wiring. Is it getting warm in here? Do you smell smoke?
  #26  
Old 07-14-2016, 02:35 PM
beowulff beowulff is online now
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Originally Posted by carnivorousplant View Post
Perhaps he was thinking of fluorescent lights, which use a lot more current to start than to run. They use about twenty minutes cost of electricity to start.
I'm pretty sure this is confabulation.
I would suspect that the original assertion was probably 20 minutes of lamp life.
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Old 07-14-2016, 02:36 PM
carnivorousplant carnivorousplant is offline
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Originally Posted by beowulff View Post
I'm pretty sure this is confabulation.
I would suspect that the original assertion was probably 20 minutes of lamp life.
Perhaps so.
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Old 07-14-2016, 03:01 PM
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Would you believe seven minutes?
Your cite actually says seven minutes of power in the first five minutes - which implies about two minutes (120 seconds) of power in the first few seconds. We're still blowing breakers with this claim.
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Old 07-14-2016, 03:18 PM
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I would suspect that the original assertion was probably 20 minutes of lamp life.
This.
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Old 07-14-2016, 05:49 PM
Me_Billy Me_Billy is offline
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And what about high pressure sodium / HID / parking lot lights?
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Old 07-15-2016, 06:23 AM
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And what about high pressure sodium / HID / parking lot lights?
It's darker if you turn them off. And you have to wait before you turn them back on again. And then they have to warm up before they start lighting up. But they don't use much more power when turned off and on again -- they just give less light.
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Old 07-15-2016, 02:13 PM
beowulff beowulff is online now
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I design lighting control systems, primarily for parks and recreation. Most of the lights we control are HID. We have a feature built into our software that allows "stagger-on" starting, because some parks are billed based on maximum hourly demand, so they want to keep the instantaneous current low. The thinking is that there is a HUGE surge when HID fixtures start, so we offset the time when each pole starts to minimize this. I was always skeptical of this, so I measured a typical fixture, and found that there is an extremely short current spike when power is first applied, but within a few milliseconds the power falls to the lowest level, and then slowly climbs as the lamp warms up.
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Old 07-17-2016, 04:06 PM
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Originally Posted by carnivorousplant View Post
Would you believe seven minutes?
Not exactly what it says. It says it uses 7 minutes of power in the first 5 minutes. However, lamp life is shortened by 20 minutes every power on, so that is the reason for the 20 minute recommendation.

I am unable to find anything else to support the claim about 7 mins power in 5 mins.

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Originally Posted by Machine Elf View Post
Your cite actually says seven minutes of power in the first five minutes - which implies about two minutes (120 seconds) of power in the first few seconds. We're still blowing breakers with this claim.
That's only if the warm up cycle of a fluorescent bulb is efficient. The claim could be spreading that energy over the whole 5 minutes.
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Old 07-17-2016, 08:17 PM
carnivorousplant carnivorousplant is offline
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I plugged a fluorescent reading lamp into a kill-a-watt. It pulled 4 Amperes when it came on, but quickly went to 2.9A. That is an insignificant amount of time, but I can see why the urban legend began.

Last edited by carnivorousplant; 07-17-2016 at 08:18 PM.
  #35  
Old 07-17-2016, 08:53 PM
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sort of a topic derailment but ive heard the same thing about pcs where its safer for and cheaper is that load of bunk also?
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Old 07-17-2016, 10:07 PM
jjakucyk jjakucyk is offline
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The Mythbusters test found the tube fluorescent used about 23 seconds of its baseline running power to start, and that was the longest of all. The rest (incandescent, halogen, compact fluorescent, metal halide, and LED) all used less than two seconds worth of power to start. The tube fluorescent fixture looked like an older style T-12 with a magnetic ballast, so I'd bet more modern T-8 or T-5 fixtures with electronic ballasts are much more efficient at starting like the CFL.

Their analysis of effects on longevity was totally useless though, cycling all the lights on and off every two minutes for a month. All this revealed was that the LED was the only one still functioning, but there was no data presented on when all the others failed, and thus how it would compare to leaving them on. Re-lamping is certainly a factor in commercial or industrial cost calculations, especially in harder to reach areas, but I don't see it ever being worth leaving lights on all night when nobody's around at the very least.

Also as far as using lights for supplementary heat, I honestly can't come up with a situation where that's ever the most economical solution unless your only other heat source is electric radiant, which is basically the same thing. Any other heat source is going to be more efficient and less expensive, and then there's summer air conditioning. In many commercial buildings they're already what's called internally dominated, in that the people, equipment, and lighting is the primary load on the HVAC system, not the exterior envelope of walls, windows, and roof. Thus many of these buildings are air conditioning all winter, so adding more heat isn't what you want. On the other hand, if the building is so poorly insulated that you do need the extra heat in winter, then you're also stressing the air conditioning all summer unless you're in a very cold climate, at which point what are you doing heating with electricity anyway?
  #37  
Old 07-17-2016, 11:47 PM
dtilque dtilque is online now
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Also as far as using lights for supplementary heat, I honestly can't come up with a situation where that's ever the most economical solution unless your only other heat source is electric radiant, which is basically the same thing.
During extreme cold spells, it can be best to leave the lights on for extra heat. The regular heating system is inadequate but the events are so rare that it's not economical to put in a heating system to handle them.
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Old 07-17-2016, 11:48 PM
Vicsage Vicsage is offline
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Don't know if its true, but I heard a few years ago that they switched traffic lights to LED's and away from incandescent. And cities up north during the winter had to keep send trucks out to scrape the snow and ice away. Incandescent lights had been hot enough to keep the cold out.
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Old 07-18-2016, 08:22 AM
jjakucyk jjakucyk is offline
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Blown snow on traffic signals is an occasional problem, that's because while LEDs do produce heat, that heat isn't in the beam of light itself, but dissipated via heat sink off of the electronics. I would think there's some way to let that heat get around to the front to help melt any snow, but I guess it's not a big enough factor to really matter. The point though is that sending out a few guys in trucks with air hoses to blow out the signals is still a lot cheaper than the cost of running older style incandescent fixtures 24/7/365. A 12" LED signal head uses only 10 watts compared to a 120 watt incandescent. Since they last so much longer not as many crews are needed for re-lamping, which is another cost saving. They're also quite a bit brighter (notably the reds, allowing red arrows to meet minimum lumen requirements that weren't achievable before in many places, for instance) and they don't burn up the plastic lenses that some jurisdictions used, especially problematic at actuated intersections where signals wouldn't change often.
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Old 07-18-2016, 10:09 AM
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Originally Posted by Orwell View Post
The "wasted" energy in any type of lighting is thrown off as heat. And, certainly, leaving lights on in the winter adds heat to the building, which can be viewed as a benefit. While some of the heat radiates downward to the occupied space, some of it goes up above the drywall or suspended ceiling and does not benefit occupants. But, certainly, leaving lights on during the heating season is better than leaving them on during the cooling season, where the wasted heat has to be removed by air conditioning.

If your building is actually dependent on byproduct heat from lighting, it sounds like the heating system is undersized. I can't imagine it makes sense to keep incandescent lights for the byproduct heat, since HVAC systems are more efficient at heating space than lights, but it is certainly a short-term strategy. If you are using incandescent lights, you are likely either wasting light or wasting heat, depending on the weather and time-of-day occupancy.
Notwithstanding all this, which I was aware of, I think the theory is that the lights will be turned on anyway during occupancy, and the waste heat needs to be factored in (and they do get hot - they are mostly HID or something like). Since it's factored into the heat balance for day, it follows to use the heat at night (seasonal? I don't know) rather than increase the size of the building heaters for peak load. Again, I don't know why it was done that way, but it is what it is, and an engineer who was supposed to know what he or she was doing designed it that way.
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Old 07-18-2016, 10:22 AM
jjakucyk jjakucyk is offline
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That could be a first-cost saving measure, similar to not installing switches. Bigger HVAC equipment is more expensive, but is downsizing the heating equipment worth the cost of upsizing the air conditioning equipment? Using the lights as supplementary heat seems to be a pre-energy-crisis strategy of the 1960s and early 1970s, because it does increase operating costs even if it may save on initial equipment installation. Of course the trap is that if you're going to switch to high-efficiency lighting, it means the HVAC system needs to be re-engineered as well. There's not enough heat in the winter, and now the a/c is oversized so unless it has modulating capability it will not be able to dehumidify sufficiently.
  #42  
Old 07-18-2016, 10:35 AM
carnivorousplant carnivorousplant is offline
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Quote:
Originally Posted by jjakucyk View Post
Bigger HVAC equipment is more expensive, but is downsizing the heating equipment worth the cost of upsizing the air conditioning equipment? Using the lights as supplementary heat seems to be a pre-energy-crisis strategy of the 1960s and early 1970s, because it does increase operating costs even if it may save on initial equipment installation. Of course the trap is that if you're going to switch to high-efficiency lighting, it means the HVAC system needs to be re-engineered as well. There's not enough heat in the winter, and now the a/c is oversized so unless it has modulating capability it will not be able to dehumidify sufficiently.
I thought the same heating and cooling loads were used to size the heating and the cooling.
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Old 07-18-2016, 10:47 AM
Machine Elf Machine Elf is offline
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Quote:
Originally Posted by carnivorousplant View Post
I plugged a fluorescent reading lamp into a kill-a-watt. It pulled 4 Amperes when it came on, but quickly went to 2.9A. That is an insignificant amount of time, but I can see why the urban legend began.
2.9A? At 120V? You have a 350-watt fluorescent reading lamp? Does it come bundled with a welding mask?
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Old 07-18-2016, 11:01 AM
jjakucyk jjakucyk is offline
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I thought the same heating and cooling loads were used to size the heating and the cooling.
Oh no, it's rare that they're ever the same. You need to go pretty far south before they even start to come close to converging. Think about it like this, even in the hottest desert (at least in the US) the biggest spread between inside and outside temperature is no more than 40-45 degrees. In most of the country though it's pretty rare for temperatures to get above 100, and that's only a 25 degree differential if you're cooling to 75 degrees. If you're heating to 70 degrees, a 25 degree differential is only 45, and even south Florida has hit freezing a few times.

So unless you're in one of those "internally dominated" commercial buildings that have a lot of volume compared to their surface area, the heating load will almost always be higher than cooling, in many cases 2x-3x as much. However, that doesn't mean heating equipment is necessarily more expensive to purchase or operate, but it's hard to separate them out from one another.
  #45  
Old 07-18-2016, 01:22 PM
carnivorousplant carnivorousplant is offline
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2.9A? At 120V? You have a 350-watt fluorescent reading lamp? Does it come bundled with a welding mask?
I probably was looking at milli-Amperes, not Amps. Thanks.

Last edited by carnivorousplant; 07-18-2016 at 01:23 PM.
  #46  
Old 07-18-2016, 06:06 PM
oara oara is offline
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This is conspiracy theory stuff.
It surprises me when people say "conspiracy theory" as if conspiracies don't happen, as if invoking the phrase makes the opponent wrong.
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Old 07-18-2016, 06:17 PM
jjakucyk jjakucyk is offline
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It's certainly not unheard of. Apparently Singer (sewing machines) had a policy for a while of destroying any old machines they could get their hands on, because they lasted so long. https://youtu.be/g_qLCdrbU78?t=23m23s
  #48  
Old 07-18-2016, 10:50 PM
Machine Elf Machine Elf is offline
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It surprises me when people say "conspiracy theory" as if conspiracies don't happen, as if invoking the phrase makes the opponent wrong.
"Conspiracy theory" as a casual descriptor identifies a category of organizations for which evidence is nonexistent, or which require such massive, unfailing secrecy or cooperation as to be extremely unlikely.

In the case of anti-competitive business conspiracies, there are two factors that make them extremely unlikely, or short-lived:

-if an anti-competitive conspiracy is legal, it is unstable. All it takes is one maverick upstart to disregard the conspiracy and set a price (or sell a product) that undercuts them all. The Phoebus cartel lasted only nine years before a competitor did exactly that. And these days, there are even more billionaire venture capitalists who would be happy to fund a startup that undercuts the entire extant long-life light bulb market.

-if an anti-competitive conspiracy is illegal, all it takes is one single person who fears the law and decides to spill the beans. This was the undoing of the Indiana concrete price-fixing conspiracy I linked to upthread.

Bottom line is that if someone posits an anti-competitive business conspiracy, they may be right - but they won't be right for long.
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