Second LED bulb in each fixture burns out, what should I replace?

Question

We have a number of inexpensive light fixtures in our house, each of which takes two bulbs. Most, but not all of these, are on newer dimmer switches (two with sliders, one with remote). We're having a consistent problem where one (but only one) of the bulbs in each of at least 4 different fixtures fails every 1 to 4 months. The other bulb will continue working, at least for the 2 years since we installed them.

Since LED bulbs are supposed to last for 5-10 years, and are difficult to dispose of, this bulb burnout is kind of a problem. So we're looking for advice on what is most likely to be the problem, and what I need to fix/replace to stop burning out bulbs.

Here's what the bulbs & fixtures have in common:

• The fixtures are all inexpensive "home depot" models.
• Because of their shallow profile, the fixtures are effectively fully enclosed (do LED bulbs overheat?).
• All bulbs are supposed to be dimmable
• The LED bulbs are on the more inexpensive end, most having been purchased from CostCo.
• Bulbs are from 9.5W to 13W
• Dimming works fine, up until the bulbs fail
• The electrical wiring in the house is mostly from the late 1980's, but some of it may date back to the 50's.

Here's what they don't have in common:

• The two slider dimmers are older (made for incandescents), but the dimmer with the remote is new and supposedly LED-compatible
• The one in the dining room tends to flicker for a while before it dies, but in other fixtures the bulb just burns out.
• Burnout (again, one bulb only) has also happened in one fixture that does not have a dimmer.
• There are two different designs/models of fixture involved.
• The dead bulbs did not show any strong evidence of damage from arcing, as (presumably) they would if not making contact was an issue.

So, ideas/suggestions? What is the most likely cause of this one-of-two bulb burnout, and what's the first thing to try replacing?

Answer 1

Your comment about the fixture being fully enclosed is probably the key. Indeed, LED bulbs (actually, the driver electronics in the base) are heat sensitive and can die from overheating. Probably, once one dies, the heat level reduces enough that the other can survive.

If you look carefully at the packaging for the bulbs, you’ll probably find something like “not for enclosed fixtures”. You need to look for ones that don’t say that.

BTW, it’s my belief that the clear bulbs that look like old-fashion filament bulbs do not have significant drive electronics and do not have this issue. These are what I use in enclosed fixtures.

Answer 2

Older dimmer switches are not necessarily compatible with "dimmable" LED lamps. Replace the dimmers with those designed for LED's, or replace with a standard wall switch, and use remotely-controlled lamps.

BTW, there is no problem disposing of "dead" LED lamps -- most should comply with RoHS and contain little or no hazardous material. While the emitters may contain tiny amounts of arsenides, they're well sealed in plastic. Perhaps you're confusing LED's with fluorescent lamps, which have small amounts of metallic mercury.