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Light bulbs blowing

Discussion in 'Electrical Engineering' started by Simon Lee, Dec 22, 2005.

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  1. Simon Lee

    Simon Lee Guest

    I have a Light fitment in my kitchen that takes 4 40 watt R50 Small Screw
    Cap spotlight bulbs.
    The problem is that I very rarely am able to have 4 bulbs all lit at once as
    almost every week, a bulb or two will stop working.
    Then, just a moment ago I walked into my kitchen and when I turned the light
    on, a bang occured, a flash of white light across the kitchen and all the
    other lights went out.
    Once I reset the trip switch, I switched the lights back on again and found
    another two blown, one of which was only replaced a few days ago.
    I haven't a clue about electricals and wouldn't even attempt to mess with it
    myself but can anybody tell me what the problem could be.
    One last note, this only happens in my kitchen. I don't have this problem
    with any other lights or light fitments.

    Thanks For any Help.

    Simon
     
  2. SQLit

    SQLit Guest


    Additional thought,

    Have you checked all of the connection in/to and through the fixture?
     
  3. Simon Lee

    Simon Lee Guest

    No I haven't although I will do so when I have chance along with all the
    other suggestions kindly made by Palindr?me.

    Thanks for the help. When I check them I will report back.
     
  4. daestrom

    daestrom Guest

    One other thought. Lamp life is severely shortened if running overvoltage.
    If you feel comfortable doing it, check the voltage at the lamp socket and
    compare to the bulb rating. Even a modest overvoltage just 6% can cut bulb
    life in half.

    daestrom
     
  5. John Savage

    John Savage Guest

    Welcome to the mystery of short-lived light bulbs! In my apartment stairwell
    there are 5 light fittings, and bulbs in the top one never last very long.
    As the circuits are in parallel, there is no obvious reason why one circuit
    should be harder on the globe than any other. I swapped to CF globes, and
    still globes in that socket have shorter lives, about 75% shorter. (My
    'solution' has been to not replace the globe in that socket, enough light
    relects up the stairwell that we don't need a globe on every floor anyway.)

    My Mum has two 4-globe light fittings. Like yours, a globe goes u/s every
    couple of weeks. The electrician told her that he used to have a similar
    fitting with multiple 40 watt globes, and was always replacing a blown
    globe, and he said the only solution was to replace it with a fitting that
    uses a single higher power globe. My conclusion is that the low wattage
    incandescent globes are simply not electrically robust for regular, long
    term use. (I can't comment on the halogen spot light bulbs.)
     
  6. daestrom

    daestrom Guest

    There are two things that shorten the life of incandescent bulbs. Chances
    are very good it is either high voltage, or vibration.

    Even a modest overvoltage can cut bulb life in half or worse. Easy to
    check/detect if you have a decent meter (and decent meters don't cost that
    much anymore). Harder to fix though.

    Vibration is sometimes harder to detect. Some places you can find a 'rough
    service' bulb that has extra supports for the filaments that will last
    longer in such cases. The extra supports built into the bulb help keep the
    filament from resonating and causing failure.

    daestrom
     
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