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Incandescent Bulb Lifetime

One of the four 40 W bulbs in the classic 1955 fixture over the front bathroom mirror burned out, leading to this discovery:

40 W bulb - lifetime

40 W bulb – lifetime

Yup, I installed that bulb in late September 1998, when we repainted that bathroom (for the first time since the original owners painted it in 1955). Getting a decade and a half from an incandescent bulb in regular use ain’t all that bad, sez I. Two other bulbs appeared in mid 2014, replacing bulbs with barely 6 years of service. Inexplicably, the third bulb has no date; I must be slipping.

Having burned through the 40 W bulb stash, I put two 60 W incandescents in the center sockets, leaving me with four new-old-stock bulbs on the shelf. Might be a lifetime supply for this house…

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  1. #1 by William on 2015-02-12 - 12:54

    Wow, nice. I’m lucky to get 6 months out of a lot of these new “green” bulbs.

    • #2 by Ed on 2015-02-12 - 13:12

      Indeed, the shorter lifetime definitely offsets the higher cost! [scowl]

    • #3 by Red County Pete on 2015-02-12 - 16:30

      We put CFLs in the house in 2003. Started putting date codes on in ’11, but my SWAG is they’ll last 5 years [with a very low Q] in “normal” usage.(The shoplight on the mill-drill lasted 2 minutes with a CFL.) We put LED bulbs in fixtures where it was hard to swap, or where the CFL characteristics made them a pain. No failures in a couple of years, so far.

      We save our incandescent bulbs as light-emitting heaters for the pumphouse. 120 to 180 watts will keep things comfortable and non-frozen. We lost out on 100W bulbs, but got several years worth of 60 and 75W bulbs. FWIW, in the SF bay area, there’s a firehouse with 1900-ish vintage Edison bulb that ran constantly. It was still working when we left in ’03.

  2. #4 by Mike on 2015-02-14 - 12:55

    Bit of history here…
    Back in the mid 1960s my folks bought a house in southern Cal with a backyard in-ground pool. There was a light fixture embedded in the concrete in the side of the pool about 3 feed down at the point where the pool was about 5 1/2 feet deep. It used a single 400w bulb that seemed to be available only at the pool supply store. They’d last about 8 months to a year. My dad got fed up with the replacement frequency (the labor to swap the bulbs was a pain) and looked at life-extending techniques. He ended up taking a burned-out ceramic heater cone (the nichrome wire had fatigued-broken close to one end) and stripped it down to just enough nichrome to drop 20v when placed in series with the lamp (i.e. it was running on 100vAC). The next bulb lasted over 40 years and was still in place when the house was demolished in 2007.

    Another bit of history…
    You used to be able to buy “bulb savers” at the hardware store – a little button shaped device that would drop into into the socket and then screw the lamp on top of it. It was nothing more than a 1N4003, 5 or 7 diode, so the bulb would run on half-wave power. My mom had me put one in the ceiling of the landing on the stairs as changing that lamp required borrowing a long extension ladder from a neighbor. Adding that changed a ever-year replacement to over 15 years.

    The place where we live now has an outdoor light shining on the swimming pool deck. The light is on a SCR-based switch that turns it on at dusk and off at dawn. It’s in series with the “contacts” of a solid state time clock, and the combination results in the lamp switching on at dusk and off at midnight. When the bulb burned out the manager tried a CFL, then a LED based light and no combination worked correctly except incandescent. I suggested using a relay – I envisioned a KRP series mounted inside the breaker box – but they are sticking with incandescent… The maintenance guy has a “cousin” in Mexico and when they come up to SoCal for Christmas he brings incandescent bulbs… Must be the new smuggling…

    • #5 by Ed on 2015-02-14 - 14:24

      buy “bulb savers” at the hardware store

      I remember those! Back in the day, I never knew how they worked. Now, I know why drawing a DC load from the AC supply is a Bad Thing.

      The diodes were (allegedly) randomly oriented, but a branch circuit could put a nasty DC load on the pole pig out by the road. Didn’t used to matter nearly as much, though.

  3. #6 by Mike on 2015-02-18 - 08:46

    Random, yes, in two ways – the assembly person didn’t care as they assembled them, and the person installing it didn’t care.

    • #7 by Ed on 2015-02-18 - 10:11

      Guaranteeing that, somewhere, somewhen, one lonely pole pig faced an entire neighborhood with every diode oriented the same way…