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Failed Compact Fluorescent Bulb

An overhead light in the Basement Laboratory went dark:

Failed CFL bulb

Failed CFL bulb

One end of the twisty tube got really really hot as it failed!

The Lab didn’t smell of electrical death, so the bulb must have failed while I was elsewhere. Metal enclosures with actual UL ratings suddenly seem like a Good Idea …

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  1. #1 by MishaBurnett on 2017-11-04 - 09:15

    My experience at the university where I work is that spiral style compact fluorescent bulbs do very poorly in applications where the bulb’s heat is concentrated, like can lights or fixtures with metal shades. They usually fail either where the bulb meets the base (as in your picture) or with the glass breaking at the point of the screw. I have seen a few that have shattered, leaving just the base with a pair of pointed glass shards sticking out of it. The fluorescents with a bulb shape don’t seem to be as vulnerable to heat.

    • #2 by Ed on 2017-11-04 - 13:29

      I’m using them in exactly the wrong way: base up in a ceiling can, minus a ceiling around the can.

      Although LED bulbs seem to have the similar restrictions, a recently acquired box of lightly used CFL bulbs should suffice for the foreseeable future.

      • #3 by RCPete on 2017-11-04 - 15:29

        similar restrictions

        Seems to depend on the bulb. I’m seeing some with a disclaimer (do not use in enclosed fixture), while others seem to be OK. The disclaimer seems to be in fine print (Flyspeck 3, usually). We’re using two 7.5 W LED bulbs in a closed fixture made for two 60 W incandescents. Light use in the bedrooms, moderate in the utility/laundry room.

  2. #4 by RCPete on 2017-11-04 - 11:09

    I’ve evicted all CFLs from the house; the ones in the shop are either in glass-globe fixtures or bare bulbs hanging from the roof trusses. Haven’t found affordable 1600 lumen LED bulbs, so I’m considering putting some LED shop lights up there (14′ above the floor) to supplement. I’ve noticed that the bases on the 23W CFLs run too hot to the touch.

    In other fun with failing electronics, the timer/controller in our Sharp microwave oven has gone nuts. It’ll start itself at unpredictable times, sometimes for a couple of seconds, sometimes for longer. The ‘stop’ button is disabled for this behavior, too, but the door interlock turns it off. So far. A new (LG) microwave is on order; our kitchen uses a countertop oven in a cubby, and countertop units aren’t very popular any more. An over-the-range unit is a non-starter, and converting the cubby to handle a built-in gives Murphy a head start, so we wait. At least the oven circuit is a one-outlet per breaker one, so we can have it truly off when not needed. I think it’s 8 years old. [sigh]

    • #5 by Ed on 2017-11-04 - 13:31

      You’d hope the door interlock involves a hard power disconnect, but ya never know. Your next microwave will surely depend on semiconductor junctions.

      • #6 by RCPete on 2017-11-04 - 15:38

        I’m guessing it’s a bad cap or IC in the control processor circuit. We’ve had really good luck with LG; so-so with Sharp. The ones that Depot has in stock seem, er, inappropriate for us.

      • #7 by Vedran on 2017-11-05 - 01:31

        All the cheap ones I took apart had three beefy microswitches – guess they could be called mini switches :)
        I never stopped to check the schematic, but going by the wiring it seems they do route mains through at least one or two of them. So cheaper is better in this case? :)

        • #8 by Ed on 2017-11-05 - 05:52

          As far as I can tell, air works better than silicon when you want a dead circuit instead of a dead human …

          • #9 by Vedran on 2017-11-05 - 09:31

            Don’t have to tell me – I like to throw the switch off AND unplug the thing before working on it :)

            • #10 by Ed on 2017-11-05 - 11:16

              Having been trained by Mad Phil, I also put the AC line plug in my pocket!

            • #11 by tantris on 2017-11-05 - 20:20

              But I’d short the plug with a screwdriver first…

  3. #12 by tantris on 2017-11-05 - 20:10

    Back in the olden days before cheap LEDs (3 years ago?) I used a CFL upside down in a desk lamp and it failed the exact same way. The fix for the next one:
    1. Air vents in the base (once you opened one, you know where not to dremel).
    2. A fancy aluminum heat shield between magic tube of light and base.
    (empty your beer, cut circle out of can, punch two holes left and right of center to match tube diameter and distance, cut slit from one side, push over tubes)

  1. Another Failed CFL Bulb | The Smell of Molten Projects in the Morning

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