Costco LED shop lights?

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BigDumbDinosaur
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Re: Costco LED shop lights?

Postby BigDumbDinosaur » Mon Mar 20, 2017 1:15 am

epanzella wrote:I'm just guessing here, but I believe LEDs use only half the wave form of 60cycle AC so would that tend to have a strobe effect on rotating machinery?

Not exactly.

Household LED lamps use an internal switch-mode power supply to generate low voltage direct current to power the LED cluster. Hence the current flow through the cluster is continuous, not cyclic. Also, light conditioning phosphors are used to give LED illumination a particular color temperature and to diffuse the light output to mimic what a frosted incandescent lamp emits. As phosphors have persistence, any residual flickering is suppressed.

By the way, you should take the life expectancy claims of the LED lamp manufacturers with a grain of salt. The LED cluster is probably good for 50,000 to 75,000 hours total lifetime (no one is certain right now, as the technology hasn't been used en masse for residential lighting for a statistically significant period of time). However, most failures are likely to occur in the power supply, not the LED cluster. This is a failure mode similar to that seen with compact fluorescent lamps (CFL).

Typically, a CFL's fluorescent lamp has a nominal 10,000 to 12,000 hour lifetime, assuming no more than one start cycle in 24 hours. In practice, few CFLs make it past 5,000 hours due to failure of the electronic ballast. The first generation of CFLs that were released in the 1990s used magnetic ballasts, and generally achieved the 10,000 hour lifespan. The desire to make them cheaper led to the use of the electronic ballast.

Another potential problem with LED illumination is heat-induced failure due to use of LED lamps in improperly ventilated fixtures. LEDs of the types used in residential lighting operate at relatively high (by LED standards) power levels and do emit heat. The power supply is not 100 percent efficient and also emits heat. Lacking adequate ventilation, the LED lamp will overheat and fail in short order. In some cases, the power supply may catastrophically fail and stink up the room, trip a circuit breaker, or both. Take a careful look at any fixtures into which you plan to install LED lamps. If they don't have openings at the top to allow heat to escape do not install the LED lamp.
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SteveM
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Re: Costco LED shop lights?

Postby SteveM » Mon Mar 20, 2017 8:45 am

earlgo wrote:WHY would anyone not just replace the fixture complete with bulbs for slightly more than half the cost?


I think the target markets for those are:
1: Homeowners that just barely know how to change a light bulb, much less a fixture
2: Commercial applications where the cost to change the fixture includes the cost of an electrician (probably extra for having them work after hours). This could run into serious money if you were replacing, say, all the bulbs in a grocery store.

Steve

earlgo
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Re: Costco LED shop lights?

Postby earlgo » Mon Mar 20, 2017 9:19 am

SteveM: Points well made.
BDD: Once again I envy all you electron watchers. I am a total EIE.

--earlgo
(electrical incompetent extraordinaire)

tornitore45
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Re: Costco LED shop lights?

Postby tornitore45 » Mon Mar 20, 2017 1:13 pm

I am just guessing here, but I believe LEDs use only half the wave form of 60cycle AC


Doubt that very much.
1) There are regulations about minimum Power Factor, in other words the current waveform has to meet some requirements that would disqualify a 1/2 wave rectifier.
2) The difference between 1 diode and one bridge for full rectification is only penny's and well worth the LED performance increase.

Not to say that some single LED used as a tell tale lamp on a minor appliance can't be run off a diode and a resistor for ballast. But then again, the designer of such a gizmo should be shot.
Mauro Gaetano
in Austin TX

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BigDumbDinosaur
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Re: Costco LED shop lights?

Postby BigDumbDinosaur » Mon Mar 20, 2017 3:43 pm

tornitore45 wrote:
I am just guessing here, but I believe LEDs use only half the wave form of 60cycle AC

Doubt that very much.
1) There are regulations about minimum Power Factor, in other words the current waveform has to meet some requirements that would disqualify a 1/2 wave rectifier.
2) The difference between 1 diode and one bridge for full rectification is only penny's and well worth the LED performance increase.

Not to say that some single LED used as a tell tale lamp on a minor appliance can't be run off a diode and a resistor for ballast. But then again, the designer of such a gizmo should be shot.

I'm guessing you don't read other replies to posts, such as the one to which you replied. :D
Science makes it known. Engineering makes it work.

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BigDumbDinosaur
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Re: Costco LED shop lights?

Postby BigDumbDinosaur » Mon Mar 20, 2017 3:45 pm

earlgo wrote:SteveM: Points well made.
BDD: Once again I envy all you electron watchers. I am a total EIE.

--earlgo
(electrical incompetent extraordinaire)

Me watch electrons? They whiz by too fast for me. That's why I like playing with static electricity. :shock:
Science makes it known. Engineering makes it work.

tornitore45
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Re: Costco LED shop lights?

Postby tornitore45 » Mon Mar 20, 2017 7:27 pm

BigDumbDinosaur Thanks for pointing out a post that without your watchful eye I would have missed.

Your guess is wrong. I generally read all post on a thread, but sometime the computer scroll is hard to manage after a page change I may be under the impression to be at the top but actually am in the middle of the screen.
I pledge to be more careful and read the thread with the same diligence as it was a McMaster catalog.
Mauro Gaetano

in Austin TX

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Rich_Carlstedt
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Re: Costco LED shop lights?

Postby Rich_Carlstedt » Mon Mar 20, 2017 8:10 pm

After my above March Post of last year, I decided to try one of those Costco LED fixture's and installed one over my lathe
The brightness compared to the twin tube fluorescent which it replaced was readily apparent.
The light on the lathe with the tubes about 4 feet above was almost frightening. It really is nice.
I have not had any long working periods on that lathe , so do not know if it is tiring or not.
I would estimate it is 50 % brighter. As I mentioned in my earlier posts, I thought the light was directional, and it is.
The bench area under the lathe is darker and more difficult to sort raw material stored there...but it may be possible that my eyes are accustomed to bright light..

Rich

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BigDumbDinosaur
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Re: Costco LED shop lights?

Postby BigDumbDinosaur » Mon Mar 20, 2017 11:40 pm

Rich_Carlstedt wrote:As I mentioned in my earlier posts, I thought the light was directional, and it is.

Directional light output is an innate characteristic of LEDs and was one of many technical issues that had to be resolved to make them practical for general lighting. The use of phosphors inside the glass bulb produces a more diffused light (though not as diffused as a frosted incandescent or a fluorescent lamp), as well as the particular color temperature you see.

The bench area under the lathe is darker and more difficult to sort raw material stored there...but it may be possible that my eyes are accustomed to bright light.

Most of those LED shop lights produce a dazzling white output that almost exactly balances the three primary colors. A side-effect of this is the light doesn't diffuse as much as it would at a lower color temperature. Hence light doesn't scatter as it does with an incandescent lamp or a SPEC30 fluorescent lamp, producing the dark areas you are seeing.
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