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-   -   Two questions about LED light bulbs... (http://www.diychatroom.com/f18/two-questions-about-led-light-bulbs-136133/)

bobsmithhome 03-06-2012 02:27 AM

Two questions about LED light bulbs...
 
My electric company will rebate 50% of the cost of LED bulbs, so I'm thinking that now may be the time to buy a few. However, at their current costs I want to know more about their life expectancy before buying. I can recall all the hype about the life expectancy of the CFLs when they first came out, but they didn't last nearly as long as claimed - not even in the ballpark - so I'm very skeptical about LEDs.

QUESTIONS:

1) It appears that LED life expectancy is affected by heat. The fixtures I'm interested in putting them in have bulbs that are pointing downward (over a kitchen island) with glass shades that are enclosed at the top. Will this significantly reduce their lifespan?

2) It is my understanding that the lifespan of incandescents is determined largely by how often they are turned on and off. I read about a bulb burning in a fire-station for 110 years (and still going), largely because it is left on 24/7. Will the lifespan of LEDs also be greatly diminished if they are turned on and off a lot, or does this not apply to LEDs?

frenchelectrican 03-06-2012 03:21 AM

Quote:

Originally Posted by bobsmithhome (Post 871693)
My electric company will rebate 50% of the cost of LED bulbs, so I'm thinking that now may be the time to buy a few. However, at their current costs I want to know more about their life expectancy before buying. I can recall all the hype about the life expectancy of the CFLs when they first came out, but they didn't last nearly as long as claimed - not even in the ballpark - so I'm very skeptical about LEDs.

QUESTIONS:

1) It appears that LED life expectancy is affected by heat. The fixtures I'm interested in putting them in have bulbs that are pointing downward (over a kitchen island) with glass shades that are enclosed at the top. Will this significantly reduce their lifespan?

2) It is my understanding that the lifespan of incandescents is determined largely by how often they are turned on and off. I read about a bulb burning in a fire-station for 110 years (and still going), largely because it is left on 24/7. Will the lifespan of LEDs also be greatly diminished if they are turned on and off a lot, or does this not apply to LEDs?

1A.) Most case yes it will affect by heat by LED driver ( ballast or controller ) but as long it is not complety enclosed it should not be a major issue but some of the cheap LED bulbs they simiply can not handle addtional heat load and they can burn out quick ( they seems little more picky than CFL are but not much difference at all ) but check the manufacter labeling about useing in enclosed or semi enclosed luminaries.

2A.) The lifespan of Incandsecents are determed by voltage they are rated and manufacter specs and with some cheap bulbs they can burn out pretty fast and like example use 130 volts bulb instead of 120 volts bulb they can last longer with slight dimmer than 120 volt verison and less senstive to viberations that is one of few items that can kill incandscents ( over voltage will kill them pretty fast as well )

For the LED rapid flashing it will not affect the LED bulbs itself but the driver it may affect depending on how it set up.

And the super cold weather it will not affect the LED as well.

With good qualinty LED bulb or luminaire they will generally go 35 000 to 50 000 hours easy but heard some can hit 100 K hours.

LED bulbs are dimmable ? most case oui they are as long they are rated for it.

LED do come in few differnt colour tempture like cool white or warm white or brilliant white ( sorta a bleuish hue ) or whatever other colours they can throw in the mix.

I am aware the cost of LED bulb/ luminaire are pretty expensive but as soon it get more common the price will go down somehow what but how much they will knock it down that I don't have magic globe to take a look at it.


I am sure other readers will throw more details in here.

Merci,
Marc

joed 03-06-2012 07:32 AM

A major concern with LED lighting is the colour. Many people do not like the colour of the light produced.

Signal Guy 03-06-2012 07:55 AM

Quote:

Originally Posted by joed
A major concern with LED lighting is the colour. Many people do not like the colour of the light produced.

But they are improving.

We have been using them for on-street lighting for a few years.

joed 03-06-2012 11:59 AM

On street lighting would be fine. It's when you try and read by them. They tend to be bluish. I know they are constantly updating and improving. It is just something you need to be aware when switching over to LED. CFLs had/have similar issues.

tadc 03-06-2012 12:08 PM

I used these guys to replace the 50w PAR20 Halogens in my kitchen can lights. I was doubtful about the color temperature and brightness but I have to say I'm quite satisfied with how they look. There's a tiny difference in color temp (3000k vs 2700k for the halogens) but quite acceptable to me and (more importantly) my wife! :) The are also rated slightly less bright and have a narrower beam width than the halogens, but not that I really notice.

A small trade-off for going from 300w to 48w! Of course it will be years before the raw dollars-and-cents savings pays for them, but theoretically they should last that long and I have the added benefit of not feeling like I need to compulsively turn off the kitchen lights all the time to save power. :)

Also my cans are open (no cover) so not really a comparison to your question. Since the LED itself is the size of your pinky nail and the most of the rest of the body is basically a heatsink, they should be pretty good at dissipating heat, but definitely check with the manufacturer.

For those concerned about the color of the light (technical term "color temperature") - they have done a great job of improving options in recent time and packages are usually labeled according to color temp. The higher number, the "bluer" ("cooler") the light. Also the bluer LEDs are a bit more efficient. If you want something close to incandescent in color, you want to pick something around 3000k or lower (incandescent is about 2700k, aka "warm").

Grampa Bud 03-06-2012 01:39 PM

I have changed out ALL my outdoor soffit and front door wall sconce incandescent bulbs with LEDs and all the lighting in our greatroom, master bedroom, hallway, and bathroom with LEDs. I have to change out the can light bulbs in the kitchen, the chandelier in the dining room, and the ceiling light in the back bedroom, but I have accrued a bit of knowledge on the matter.
1. Incandescent bulbs generally emit white light in the 2600 - 3200 Kelvin range.
2. Halogen bulbs emit white light in the 4000 - 5000 Kelvin range.
3. LEDs, because of their solid state nature and the metal used for the light emission emit white light over a range of 2600 - 8000 Kelvin with 2600 - 3200 to match incandescent, 3200- 4500 for bright white, 4500 - 5500 to match daylight white, and 5500 -8000 for commercial white with anything over 6000 leaning towards blue.
4. LEDs draw so little power that ordinary household bulbs with and without heatsink bases will not get hotter than skin temperature or about 90-100 deg F. However if you enclose most of the LED bulbs in a globe or behind a glass bezel of some kind with limited air flow their life expectency will definitely be shortened. After all they were designed to work in an open air socket in the first place. Check with whomever you get your bulbs from if they are "Inside Only", "Indoor-Outdoor", or OK for outdoor and damp conditions. Indoor bulbs will work outdoors for a few months, but will start quiting one lamp at a time usually because of small bugs getting into the lamp base breather holes at night and with small amounts of humidity they will be electrocuted as they short out the LED driver built into the lamp base.
5. Whereever you get your LEDs try not to get ones that operate on a fixed value of say 120 vac. The North American power grid has power spikes all over it and LEDs are extremely sensitive to any fluctuation in voltage. A lot of the LED manufacturers have or are switching to a 'worldwide voltage' of 85 to 265 vac. This means the electronics in the bulb base is perfectly happy with the entire range and won't pop with a 10% change in voltage like the 120 vac models do.
6. Life expectancy of all bulbs is based on a 24/365 burning schedule. You can burn any bulb out sooner with repetitive on/off cycling; however if you normally have a light or group of lights on for a set time like lights in the bathroom, or kitchen, or dining room, or timed lights outdoors as long as it is over about an hour in length every day LEDs will definitely far outlast all other comers.
7. LEDs still have two major drawbacks that need to be corrected. They are very pricey and they are still struggling to match lumens from incandescent to LED. The CFLs are less pricey and out match incandescent bulbs in lumen count.

ddawg16 03-06-2012 01:51 PM

Guys.....lighting is sort of a hobby for me.....and the above information from tadc is correct.

The only thing I can add.....if you want the dimming feature, make sure the bulb supports it. On the cheaper ones, the regulator is a cheap design and does not reduce the voltage to the LED as the AC voltage is reduced.

bobsmithhome 03-06-2012 03:43 PM

Thanks for the replies. I learned a great deal that I had not seen in the articles I read online. This forum is great.

There were a couple of references to cheap designs and the drawbacks associated with those. How do I know if a bulb has a cheap design? Should I be shooting for the pricier bulbs, or are premium prices sometimes charged for cheap designs? A specific brand or brands? Is there specific wording I should be looking for on the packages that will let me know the design is top notch?

Yoyizit 03-06-2012 04:31 PM

Quote:

Originally Posted by joed (Post 871754)
A major concern with LED lighting is the colour. Many people do not like the colour of the light produced.

http://www.google.com/imgres?q=LED+i...1t:429,r:5,s:0

Half of the watts/$ were between 0.17 and 0.70 with mean value = 0.41 w/$.

tadc 03-06-2012 04:47 PM

Quote:

Originally Posted by Yoyizit (Post 872134)
http://www.google.com/imgres?q=LED+i...1t:429,r:5,s:0

Half of the watts/$ were between $0.17 and $0.70 with mean value = $0.41.

Is that the right link? It doesn't seem relevant to your comment.

Yoyizit 03-06-2012 05:00 PM

Quote:

Originally Posted by tadc (Post 872148)
Is that the right link? It doesn't seem relevant to your comment.

The LED spectrum compared to other spectrums shows why LED light appears unpleasant to people.
The other was about how much these LEDs typically cost, about $2.40 per watt but it varies widely.
LEDs have a luminous efficacy of about 100 lumens/watt and they seem to pay for this by having unpleasant lights. Sodium vapor lights are even worse.

ddawg16 03-06-2012 05:17 PM

If you want some really detailed information on LED lights....there is a web site...candlepower.com that is dedicated to just lighting....ALL kinds of lights.....there is one section just for fixed lighting as well as LED's....go browsing through there...It will answer more of your questions...there are also some threads on specific brands (not done by manuf).

There is one section dedicated to just flashlights....if you think stamp collectors are anal....you should see some of those flashlight collectors.....geezzzzzz

bob22 03-06-2012 06:50 PM

ddawg: I don't think candlepower.com is the right link is it?

ddawg16 03-06-2012 09:18 PM

Quote:

Originally Posted by bob22 (Post 872252)
ddawg: I don't think candlepower.com is the right link is it?

Sorry bout dat....

Here is the correct link

http://www.candlepowerforums.com/vb/forum.php

But don't blame me for spending too much time there....


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