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LED shop lights getting hot: normal or electrical issue?

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Forum topic by AM420 posted 06-18-2017 09:57 PM 3069 views 0 times favorited 20 replies Add to Favorites Watch
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AM420

186 posts in 588 days


06-18-2017 09:57 PM

I just installed six 4’ LED shop lights in my garage. After they have been on for a while I noticed the metal housing was getting pretty hot. Not so hot that they burn my fingers but hot enough to make me worry. I assumed that since they’re LED they wouldn’t generate much or any heat at all.

A little info on the setup: I have two rows of lights from one light box. I spliced the wires from box to the first two lights on either side and then linked the rest together from the first fixture in each row. The fixtures have a ground, but the house wiring is old and doesn’t have a ground so I just cut it off on the future.

Thanks for any advice.


20 replies so far

View JBrow's profile

JBrow

1366 posts in 1124 days


#1 posted 06-18-2017 10:45 PM

AM420,

I have some LED lighting experience as a consumer. I must say that there is a good part and bad part to my experience. Over the last three years I replaced most of the frequently used lights in the house and installed recessed LED lights for the workshop.

The good part of my experience is that I like the quality of light produced. I also believe that I have seen about a 10% reduction in the electric bill.

The bad part I suspect goes to your question about heat. Since a LED lamp is an electronic device, it generates heat like most other electronic devices. After having 5 of 11 LED recessed shop lamps fail and one kitchen LED lamp fail (at $30 each), I dug into LED lighting a little. Apparently one reason for failure is excess heat; heat in excess of what the lamp’s heat sink can dissipate. In short, too much heat, LED failure.

If your shop lights are in an enclosed housing with a diffusing cover, I might be a good idea to run the lights without the diffusing cover. Doing so should allow some of the heat you are now experiencing dissipate and potentially prolong the life of the lamps. Here a vendor article concerning LED lamp failureā€¦

https://www.shineretrofits.com/knowledge-base/lighting-learning-center/why-do-led-s-fail.html

Since it is fairly easy, reinstalling the fixture housing equipment grounding wire and connecting it to the circuit would ensure an added margin of safety.

View SignWave's profile

SignWave

451 posts in 3239 days


#2 posted 06-18-2017 10:53 PM

LED lights don’t radiate heat the way that incandescent bulbs do, but the electronics do produce some heat. If they are not in enclosed fixtures, then the heat should dissipate without any problem. Many screw-in LED bulbs will indicate that they are not suitable for enclosed fixtures, for this reason.

Are your lights mounted in a way that air can circulate around them? If so, I would not expect them to get so hot that you’d have a problem. I have some that are surface mount (touching the drywall ceiling) and some that are hanging on a short chain, both of which seems to be sufficient. The base of the fixture is a bit warm, but not dramatically so.

I don’t know if this helps or not… :)

-- Barry, http://BarrysWorkshop.com/

View MrUnix's profile

MrUnix

7053 posts in 2403 days


#3 posted 06-18-2017 11:31 PM

LED’s get hot… real hot… particularly the newer high-output ones. If it were not for the heat sinks on the new-fangled bulbs, they would melt.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View AM420's profile

AM420

186 posts in 588 days


#4 posted 06-19-2017 12:48 AM



LED lights don t radiate heat the way that incandescent bulbs do, but the electronics do produce some heat. If they are not in enclosed fixtures, then the heat should dissipate without any problem. Many screw-in LED bulbs will indicate that they are not suitable for enclosed fixtures, for this reason.

Are your lights mounted in a way that air can circulate around them? If so, I would not expect them to get so hot that you d have a problem. I have some that are surface mount (touching the drywall ceiling) and some that are hanging on a short chain, both of which seems to be sufficient. The base of the fixture is a bit warm, but not dramatically so.

I don t know if this helps or not… :)

- SignWave

I assumed they would get warm, but not as hot as they are. They are flush-mounted to the ceiling, so that may be making it difficult to dissipate the heat. They’re made to be flush-mounted, but I may try to find a way to let them separate a little with longer screws an shims. I can’t take the cover off. They’re sealed.

Hopefully these things last a while…

View htl's profile

htl

4241 posts in 1363 days


#5 posted 06-19-2017 01:40 AM

Very interesting!!!

-- An Index Of My Model making Blogs http://lumberjocks.com/htl/blog/116729

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woodbutcherbynight

5720 posts in 2613 days


#6 posted 06-20-2017 02:18 AM

For giggles measure the temp with a infared thermometer. The lights themselves should not be getting hot but the electronics that make the magic work do get hot. Since them make them cheap this is the part of LED’s that most often fails. The bulbs should last a long time, this they brag about. The electronics, not so much.

-- Live to tell the stories, they sound better that way.

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MrUnix

7053 posts in 2403 days


#7 posted 06-20-2017 02:43 AM

The lights themselves should not be getting hot but the electronics that make the magic work do get hot.

The heat is generated at the diodes N-P junction and then dissipated through the substrate, which is then attached to a heat sink to dissipate it further. The ‘electronics’ is nothing more than a power supply that reduces the AC line current into a small DC voltage. Most LED manufacturers specify a junction temperature not to exceed 125-150C (< ~300F). Put a bunch of them together, like in the current bulbs, and that is a lot of heat :)

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View papadan's profile

papadan

3584 posts in 3573 days


#8 posted 06-20-2017 03:00 AM

I was in a Sams store today and looked at their 4’ LED shop lights. They have one on, in the display that has been on for almost 2 years non stop. The bulbs were cool and the top of the housing was just barely warm, no actual heat at all.

View woodbutcherbynight's profile

woodbutcherbynight

5720 posts in 2613 days


#9 posted 06-20-2017 03:34 AM

My shop lights are retrofitted T-10 fluorescent fixtures that have no ballast and two LED light tubes in place of the T-10 bulbs. Both have all the electronics inside the bulb and having been on all day read 88F, shop temp at ceiling height was 80F.

Don’t have any of the newer LED only lights to compare with which is why I asked about the actual temperature. I have a attic fan in my eve that comes on at 80F. This keeps the air in the shop moving from the open window through the shop and out the vent. Turn that off and the temp where the lights are goes up with no airflow. This also could be part of your issue with heat. I recently added a window fan which helped airflow as it pushes the air toward the vent.

-- Live to tell the stories, they sound better that way.

View melissag001's profile

melissag001

1 post in 33 days


#10 posted 11-14-2018 02:30 AM

I just installed this led light in my bedroom. it is the first light ive ever installed so i am a bit nervous as the lights become ridiculously hot, by hot i mean burning, i have actually burnt my finger on it. can this be normal? i’ve been avoiding turning on the light at all until i hear from an electrician. i am freaked out! any advice is much appreciated!

View Scap's profile

Scap

48 posts in 131 days


#11 posted 11-14-2018 02:40 AM



I just installed this led light in my bedroom. it is the first light ive ever installed so i am a bit nervous as the lights become ridiculously hot, by hot i mean burning, i have actually burnt my finger on it. can this be normal? i ve been avoiding turning on the light at all until i hear from an electrician. i am freaked out! any advice is much appreciated!

- melissag001

You’re sure that’s not a halogen fixture?

View robscastle's profile

robscastle

5497 posts in 2408 days


#12 posted 11-14-2018 09:49 AM

Any chance of sending wqwq on a one way space ship trip into outer space?

-- Regards Rob

View pottz's profile

pottz

3586 posts in 1188 days


#13 posted 11-14-2018 07:16 PM



Any chance of sending wqwq on a one way space ship trip into outer space?

- robscastle


who’s wqwq buddy? i might want to hitch a ride-lol.

-- sawdust the bigger the pile the bigger my smile-larry,so cal.

View splintergroup's profile

splintergroup

2436 posts in 1426 days


#14 posted 11-14-2018 10:21 PM

LED’s do generate heat! I used some LED arrays in an early chair side floor lamp project and they get very hot. Get your finger close to the bright part and you will get burned. LEDs do put out a bunch of infra-red and one of the challenges for manufactures is creating the phosphorus coating to not only make a pleasant light color but also not break down from the heat.

Basically the power in = the power out. More of that power is converted to photons (light) with LED’s, but the rest is turned into heat. Where an incandescent bulb has a large surface area, an LED is basically a point source so all the heat generated is concentrated. Your fixtures eventually absorb that heat and that is what you are feeling.

An interesting article

View lumbering_on's profile

lumbering_on

574 posts in 694 days


#15 posted 11-14-2018 11:01 PM

I was involved in spec’ing out an HVAC for one of our buildings, and it’s rather interesting to see how much heat LEDs can generate. A typical LED will generate 85% heat and only 15% light, or 85W per 100W is converted to heat. As 1W = 3.412142 BTU/hr, 85W ~290 BTU/hr.

This is a lot of heat to dissipate through a small LED housing. It’s actually enough to maintain a 2 ft3 box at 30F above the outside temp in winter.

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