| LED bulbs v incandescent I'm not a huge fan of the LED bulbs but there seems to be more of a variety on the shelves now. One that that has always stumped me however, is whether you can use a lower wattage LED in a regular incandescent bulb fixture. By that, I mean, for a fixture that says the maximum light bulb wattage is 100 watts, if I were to buy the brightest LED bulb that only uses 15 watts but gives off lumens of 150 watts, can I use it in my light fixture or is not safe? Or is it because my fixtures are old and therefore made before LEDs came out? |
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 shdesignsPowered By Infinite Improbabilty DrivePremium
join:2000-12-01
Stone Mountain, GA | The wattage rating maximum is for dissipated heat and/or current. If you use a 15 watt LED in a fixture rated for 100 watts, then it will get 1/6th as hot as an incandescent. |
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 cdruGo ColtsPremium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7 | Or to answer the original question directly, yes you can use a higher equivalent wattage rated bulb that exceeds the rating of the socket or appliance.
If you are looking more light, don't look specifically at wattage, look at the number of lumens the bulb produces. Almost all light bulbs should have that rating on the label similar to a nutrition label on food. |
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 tschmidtPremium,MVM
join:2000-11-12
Milford, NH
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| reply to obeythelaw
The fixture wattage rating is determined by the amount of heat generated by an incandescent bulb, CFL and LED bubs are much more efficient so they generate much less heat.
However, both CFL and LED bulbs use active electronics making bulb position important so waste heat can be dissipated. This makes inverted position fixtures a potential problem if they trap heat. CFL and LEDs are more efficient but still dump energy as waste heat that needs to be dissipated.
/tom |
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 dib22
join:2002-01-27
Kansas City, MO
kudos:2 | reply to obeythelaw
Watts ratings are the same so yes you can use a lower watt bulb in a higher rated socket.
The thing with LEDs to watch out for is dimmable.... if the circuit has a dimmer on it make sure you use a dimmable led bulb... otherwise you will fry the LED bulb and that $25 20 year bulb will be dead in minutes  |
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 rfharThe World Sport, Played In Every CountryPremium
join:2001-03-26
Buicktown,Mi | reply to obeythelaw
I just bought two new fixtures and they told me "Do not exceed a 100 watt incandescent light bulb, or a 26watt SBCFL" |
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| reply to obeythelaw
That's good to know. It appears that the 20 plus watt LED bulbs give off the most light when measured in Lumens. That is really what I am concerned about is lighting up rooms in lamps or ceiling fixtures. Unfortunately, my house is about 40 years old and there are no high hat lights and have to rely on lamps or single ceiling light fixture. The LED bulbs that give off the max light usually are relatively low in wattage. Usually, at most, 26 watts. |
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 pikePremium,MVM
join:2001-02-01
Washington, DC
kudos:3
1 edit | reply to shdesigns
said by shdesigns:If you use a 15 watt LED in a fixture rated for 100 watts, then it will get 1/6th as hot as an incandescent.
It's not quite that cut and dry. The waste heat output of a LED screw in replacement light bulb most certainly is not directly equivalent to that of a standard incandescent. You can't simply go by the wattage because "some" of that power is being turned in to light and "some" will be dissipated as heat. Without knowing these variables you can't make an assessment. The semiconductors and transformers in LED bulbs generate substantial waste heat and the exact amount varies accross manufacturing techniques and technologies.
That being said, given the typical 5% efficiency of an incandescent bulb, it's probably safe. |
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 AVDRespice, Adspice, ProspicePremium
join:2003-02-06
Onion, NJ | reply to tschmidt
said by tschmidt:The fixture wattage rating is determined by the amount of heat generated by an incandescent bulb,
how much electricity is used.
the equivalent rating is based on how bright the LED or CFL is compared to the wattage an Incandecent bulb sith equavalent wattage..
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AVDRespice, Adspice, ProspicePremium
join:2003-02-06
Onion, NJ | reply to pike
said by pike:said by shdesigns:If you use a 15 watt LED in a fixture rated for 100 watts, then it will get 1/6th as hot as an incandescent.
It's not quite that cut and dry. The waste heat output of a LED screw in replacement light bulb most certainly is not directly equivalent to that of a standard incandescent. You can't simply go by the wattage because "some" of that power is being turned in to light and "some" will be dissipated as heat. Without knowing these variables you can't make an assessment. The semiconductors and transformers in LED bulbs generate substantial waste heat and the exact amount varies accross manufacturing techniques and technologies. That being said, given the typical 5% efficiency of an incandescent bulb, it's probably safe. its not just the fixture, but also the wiring.
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 bobrkYou kids get offa my lawnPremium
join:2000-02-02
San Jose, CA | reply to obeythelaw
Yeah, we have to get away from looking at wattage and figuring out what the equivalent lumens are. |
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 DKSDamn Kidney StonesPremium,ExMod 2002
join:2001-03-22
Owen Sound, ON
kudos:2
·Bell Sympatico
| said by bobrk:Yeah, we have to get away from looking at wattage and figuring out what the equivalent lumens are.
Exactly. And different bulbs are better in one situation than another. However, after changing all my lights to LED's, I cut my hydro bill by 30% month over month.
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| reply to obeythelaw
What's safe and what is not is rather tricky when you use a bulb other than incandescent.
Incandescent bulbs are very simple, very tolerant of heat, inherently self regulating (if the filament gets hotter its resistance increases which leads to decreased current and less heat generation) and if they do fail, they normally fail as an open circuit that stops working altogether.
LED/CFL bulbs on the other hand contains electronics that are heat sensitive, certain components may be probe to thermal runaway, and failure modes can include nasty ones like catching fire. 
Because of these, fixtures cannot be well insulated -- they need to be able to take away enough heat so that the temperature of the LED/CFL bulbs cannot go too high.
Because CFL/LED lights generate much less heat, bulbs that output the same amount of light as incandescent are *usually* safe in the same fixtures. If in doubt, look for fixtures that contain ratings for CFL bulbs, or employ a bit of common sense.
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 SparkChaserPremium
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Downingtown, PA
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| reply to bobrk
said by bobrk:Yeah, we have to get away from looking at wattage and figuring out what the equivalent lumens are.
The word is efficacy and demonstrated here in a graph. This happens to be for down lights but it gives you the idea. lm/W
»cool.conservation-us.org/byorg/u···leds.pdf
tschmidt  and aurgathor explained why there is a heat problem.
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tschmidtPremium,MVM
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| said by SparkChaser:The word is efficacy and demonstrated here in a graph. This happens to be for down lights but it gives you the idea. lm/W
Interesting chart, I had assumed LED would fare much better in downright compared to CFL since they are so directional, but there seems to be a lot of overlap.
/tom |
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 MsradellP.E.Premium
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Louisville, KY
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| reply to bobrk
said by bobrk:Yeah, we have to get away from looking at wattage and figuring out what the equivalent lumens are.
That's part of the problem these days. Everyone is so used to buying lightbulbs by wattage they really don't know how many lumens they need. One needs to happen is that a requirement that output lumens needs to be displayed prominently on the packaging of each new bulb (color temperature would also be handy). People and could refer to a chart showing that their old conventional bulbs produced and determine what replacement to use. Even now, some manufacturers claim that they are a replacement for a 40 W bulb and that output ranges from 350 lm of to almost 500 lm! There certainly needs to be some type of standard. |
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| My brother had one 15 Amp circuit in his 80 year old house with 9 electrical outlets and 5 built in overhead lights, plus one track light. I urged him to put in LED bulbs and throw out his wife's electric hair dryer so the circuit couldn't be overloaded.
But that situation aside, it seems to me that LED bulbs are ridiculously expensive. For situations where you care about the quality of the light, this new generation of halogen incandescent bulbs seems more intelligent than LEDs. If you are replacing a traditional 100 Watt bulb, these new halogens use about 72 Watts and are roughly twice the price.
They don't have the extreme energy savings of the 26 Watt CFL (but also none of the issues(long startup time, lousy color), and while on paper a $30 LED bulb may save you money over the next decade, that is just to long of a payback time for me. The new halogen bulbs were designed to just barely meet the energy objectives of the new laws. |
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I recently picked up a couple of these and I've been very pleased with them:
»www.homedepot.com/p/t/203991774?···WidgetID |
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Outland
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1 edit | My local Lowes has a $10 850 lumen dimmable LED bulb using a standard socket, the bulbs use 13.5 watts per the box. These aren't the most energy efficient LED bulbs, but are inexpensive and seem to have a greater area of coverage than many other LED bulbs. These are more similar to traditional incandescent in that they seem to be less directional when lighting an area.
In our renovation, we installed 6" ceiling cans, and are using dimmable recessed LED bulbs with integrated trim kits. The same kit costs $25 at Home Depot, and $30 at Lowes. These are 13 watt 825 lumen.
In part of the addition, we needed low profile ceiling cans (due to 2 x 6 construction in the 40 year old part of the house, as opposed to 2 x 8 construction in the newer part). Home Depot was least expensive with $30 LED bulbs with integrated trim at 800 lumen's.
Outside, I picked up Par 38 floodlight bulbs for $25 each that are 22 watts and rated at 1025 lumen's. The floodlights are likely the least efficient LED in my home, but are instant on, and still use a lot less energy than incandescent. They run mostly at half power (being dimmable, the floodlights are set to half intensity unless motion is detected for 4 hours after sunset or after activation after sunset).
In some applications, CFL may be more energy efficient, though as an incandescent replacement, my preference is for LED. The high cost per LED bulb is partially offset by the estimated lifetime.
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