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I recently moved into a new home, and I was replacing a light bulb when I found this after removing the glass cover. ceiling light fixture with insulation

Now, I don't know much about codes and regulations, and I'm new to working on my own home, but this screams "fire hazard" to me, so I want more input before I install a bulb and continue to use this. Is this okay to have insulation next to something that gets hot? Why is/isn't it?

Graham Harper
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    glass does not burn if you are worried about the fiberglass insulation – jsotola Aug 16 '20 at 01:40
  • that doesn't look stock. but the globes are less powerful than the max so it's probably not getting too hot for the expased wiring. – Jasen Aug 16 '20 at 01:44
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    @Jasen I've replaced old fixtures in my house that had _exactly_ that kind of insulation in them, and I've actually installed a couple of newer ones with _exactly_ that kind of insulation. I'm 99.99% confident it's stock. – FreeMan Aug 16 '20 at 12:26
  • My only concern would be that the stuff has been pulled out. You need to press it back into place somehow. – Hot Licks Aug 16 '20 at 17:17
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    FYI, with that sort of light you will need premium LED bulbs rated for enclosed fixtures, I have a similar (identical?) one in my apartment and overheated/killed several sets of CFLs before understanding what the problem is. Since then I've had a set of Cree bulbs in that look like new when I checked on them a few minutes ago. – Dan Is Fiddling By Firelight Aug 17 '20 at 01:56
  • @HotLicks you just push it back up and kinda stuff until it's more-or-less flat. It's probably best that the foil not touch the bulb for longevity, but I can neither confirm nor deny that touching is an issue. – FreeMan Aug 17 '20 at 14:49

2 Answers2

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This is a good question - seeing some insulation in your light fixture can be a bit of a shock.

Think about it, though. Those incandescent bulbs are inside a glass globe. One of the best features of an incandescent bulb is its ability to turn electricity into heat. What's that heat going to do when it's trapped inside the globe - it's going to melt the wiring or catch the ceiling on fire.

The silver reflective foil reflects heat and light away from the ceiling material and the insulation helps keep whatever heat doesn't get reflected from moving through and melting your wire's insulation which could result in a short and the whole house getting really hot and a visit from the fire department.

TL:DR; Yes, that insulation should be there - it's for your safety.

FreeMan
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    Never exceed the wattage indicated on the sockets. +1 – JACK Aug 16 '20 at 01:35
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    Is this a regional thing?  In the UK I can't recall ever seeing insulation (or reflective foil) inside a light fitting.  (Of course, incandescent bulbs are going the way of the dinosaur now, and LED bulbs in particular don't get anywhere near as hot.  But even back before CFLs…) – gidds Aug 16 '20 at 17:41
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    It's reasonably common in the US, @gidds. Note how small the base of light is - there's not a lot of space/material to dissipate heat, and the fact that this fixture is designed with a glass globe, it's just a little greenhouse with its own built-in heating source. This type of simple, little fixture usually has insulation in it. – FreeMan Aug 16 '20 at 22:08
  • @FreeMan I'm familiar with the type of fitting: in this very house I have three of them, with just enough room for two bulbs — but no insulation to be seen, just the glass bowl below, and the metal base of the fixture above.  Never heard of them being considered a fire hazard particularly. – gidds Aug 16 '20 at 22:53
  • Maybe it _is_ a regional thing then, @gidds, I dunno... – FreeMan Aug 16 '20 at 22:57
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    @gidds, I have seen (installed) ceiling fixtures where the fiberglass insulation is hidden. Take the glass cover off, and all you see is sheet metal, but there's a hidden space, filled with fiberglass, between the sheet metal and the ceiling. I'm actually a bit surprised to see the exposed fiberglass and the foil. Usually I only see that in fixtures that hold compact halogen bulbs. – Solomon Slow Aug 16 '20 at 23:05
  • @gidds I never encountered this either in Netherlands, Belgium, Germany and UK. And I have hung a lot of similar light-fixtures in all 4 countries over the years (I moved a lot myself and helped friends and family renovating.) – Tonny Aug 17 '20 at 14:44
  • @Tonny and others questioning this - if you click the image then click again, it'll zoom in and you can read "120v" on the light bulb. It's entirely possible that this is a US-only phenomenon. – FreeMan Aug 17 '20 at 14:47
  • The heat produced is proportional to the power (and bulb efficiency), isn't it?  So it wouldn't be affected by the difference in voltage (since the current would adjust to match)? – gidds Aug 17 '20 at 14:59
  • @freeman I'll write it down then under same heading as customary units and Fahrenheit :-) – Tonny Aug 17 '20 at 15:30
  • @FreeMan - I've been banging on about including location for a while now. Does anybody take notice? It's often pertinent to the question. – Tim Sep 16 '22 at 10:03
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Putting the insulation inside a light fixture is a very bad idea. This was probably invented by some US electricians/contractors/light fixture makers that had absolutely zero idea about heat transfer.

Think about this first. The US construction code requires the ceiling space around high-heat-generating fixtures to be cleared, i.e. no insulation on top of ceiling lights, unless the fixtures have a high heat-resistant rate. There is a reason for it. The temperature increases when the heat concentrates in a small space. Heat from light bulb needs to be dissipated into the air to prevent burning/melting. Then some people put insulation both on top and inside the fixtures, adjacent to bulbs. That becomes a perfect heat trap. I’ve seen melted bulb bases, burned wires, and melted fiberglass thanks to that.

There is sadly a lot of misuses of batt insulation by homeowners/contractors. In this case, it becomes an obstacle when repairing the fixtures or replacing the bulbs. In construction, adding obstacles means adding risks. Moreover, this is considered a mod. Adding mods to light fixtures means taking all responsibility for any potential damage.

Inhaling fiberglass is a common cause of lung problems in construction. And with this insulation stick around, you might need to wear face-mask and eye-protection for just replacing a bulb.

What to do instead: use low-heat bulbs, use correct-sized bulbs, keep the space on top of the fixtures cleared, choose a well-designed fixture.

esju
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    I have a suspicion the engineers at UL are better versed in heat transfer than you – whatsisname Jul 03 '22 at 17:49
  • @whatsisname Your suspicion is very irrelevant and doesn’t have any basis. That’s why it would forever be a suspicion. – esju Jul 03 '22 at 18:06
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    The insulation was put there by the manufacturer and was tested that way for UL rating. – DaveM Jul 03 '22 at 19:17
  • @DaveM That make them not mods but some bad designs: melted wires and bulb bases inside the globe; fiberglass and reflectors turn to fine dirt and cause an inhaling hazard when being handled. Fixtures made without those insulation are safe and don’t have the dirt trouble. – esju Jul 04 '22 at 11:00
  • I have purchased & installed several brand new, still in the sealed box, UL listed/certified, ceiling-mount light fixtures and every. single. one. has had insulation in the base, just like the one in the OP's picture. Well, OK, some were a neater installation than this, but they all had insulation & foil. – FreeMan Sep 16 '22 at 11:18