Blowing light bulbs

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[Technically, it's not 2 phase. It's simply a center-tapped transformer winding.]

Yes.
If the neutral is not making a solid connection back to the center tap of the transformer, the apparent neutral-real ground voltage can be quite extreme, resulting in one leg of the feed being significantly lower than 120V and the other much higher. It simply becomes a voltage divider between whatever devices you have attached to the two legs.
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Chris Lewis, Una confibula non set est
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I would suspect, as others have mentioned, vibration beating up the filaments while they are hot. In bad cases foot traffic could do this. Also, do people slam doors nearby or dance on the floor above or do children dribble basketballs on the floor above? That can do this!
As for a possible solution: Get Philips SLS20 compact fluorescents with the R30 snap-on reflectors. Find an electrical/lighting supply shop that has these. Or find an online place that has these - I believe bulbs.com does. As far as I know, the reflectors can be removed and reattached to other SLS bulbs, so when they wear out you can get just replacement bulbs, which Home Depot has.
Philips SLS compact fluorescents are well suited for recessed ceiling fixtures for the 15 and 20 watt versions (not dimmable), and rated as acceptable for such use in the non-dimmable 23 watt version. Most other integral-ballast compact fluorescents, especially of similar and higher wattages, do not fare as well in recessed ceiling fixtures. You may want to try the 19 watt or whatever Feit Electric compact fluorescent floodlight bulb supposedly equal to 85 watt incandescent, (see if it will fit), available at Home Depot. 19-20 watt compact fluorescent with smaller reflector has performance compromised by compact reflector size, so expect equivalence to about 60 watts incandescent wide beam flood, and expect some dependence on using several of these so that their less-well-defined beams merge into each other.
- Don Klipstein ( snipped-for-privacy@misty.com)
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Random responses:
These are brand-new (less than a year old) ceiling pot fixtures. A "standard" HD brand of some sort. Cheapies, but reasonably well built. Rated at 100W I believe.
BR30s are medium size incandescent flood lights, 60W apiece - the fixtures are designed specifically for this size. The halogen equivalent is "PAR30" IIRC.
So heat is unlikely to be a problem. We haven't even installed the fixture bezels yet.
Vibration is certainly a possibility, but we're aware of it (I wrote the FAQ on that! ;-), and some of the lights that are dying aren't anywhere near floor space likely to have much vibration. CFs on the same area (in previous ceiling mounted J-boxes, same switches) also _seemed_ to have a relatively shortened lifespan.
There is no aluminum on (or upstream) of this circuit. The only aluminum is a subpanel feed to the garage.
No, we're not having dimming/brightening problems. Many other bulbs in the house have more than adequate lifetimes (ie: 10 year+ on some reasonably well used flood lights). So it's not an overall voltage problem.
As we've not had a lot of luck with CFs on this circuit already, I'm hesitant about going for them until I understand what's happening.
[Our kitchen ceiling lights also have similar problems, despite being on a dimmer.]
I should check the voltages on this circuit just in case. A pair of new switches is probably a good idea too.
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Chris Lewis, Una confibula non set est
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In case you want to spend a few bucks to prove or disprove the vibration theory, Home Depot carries an incandescent bulb by Philips, specifically labeled for use in ceiling fans. My fan was blowing bulbs almost weekly due to a nasty vibration transmitted through the ceiling from the monster of an exhaust fan in the bathroom 20 feet away. (I'll be dealing with that later this summer). I switched to the Philips bulbs - problem gone. They're 40 watt bulbs, shaped like normal lamp bulbs, but maybe 30-40% smaller in size. Might be worth a shot.
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Fixtures as described above are notoriously hard on compact fluorescents. (Less of a problem for most CFLs 13 watts or less, as well as Philips SLS excluding versions 25 watts or more or dimmable). So I suspect rough heat situation for early failure of compact fluorescents, and fair-good chance of a different reason for early failure of incandescents - most likely bad brand or bad lot of bulbs, after that significantly high line voltage or vibration.

If you are using the dimmer as a soft-starting means, please be aware that soft-starting usually increases incandescent lifetime only a little. Some incandescents even suffer vibration problems from the spiky current waveforms when dimmed by usual dimmers, to an extent such that dimming only slightly extends their lives. (Most incandescents have major life extension from dimming, although with energy efficiency decreasing badly enough for cost of achieving a given level of lighting to actually increase.) Most halogens have an aging mechanism slowed only a little by dimming and a few halogens have contaminants that dominate and wreak havoc when major dimming is done.

- Don Klipstein ( snipped-for-privacy@misty.com)
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Have you checked the voltage? You might have excessive voltage or a loose neutral.
Probably not, but if you haven't checked...
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Years ago I had a goose neck lamp over the work bench. Every time I turned on the grinder, the Phillips light bulb would blow. finally I tried a GE, which lasted a lot longer.
Try a different brand of bulb, they are not all created equal.
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Christopher A. Young
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snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

Hello, Considering the money youare spending in bulbs, it would seem to me that it would be a lot less expensive to just install a proper lighting system. It is all so easy now: they have things that you can pinch and squeeze onto a wire running along the beams. As far as running a wire, just do what it is that you are good at: use your imagination and just "N"-rig it . . .
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Standard recessed light fixtures and the bulbs that they're designed for installed as per instructions and electrical code aren't "proper"?

"Pinch and squeeze" 120V permanent fixture wiring?
Proper?
Good gracious me. Not.

I'm quite good at running wire, thank you.
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Chris Lewis, Una confibula non set est
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What are pot fixtures?
On Tue, 26 Jul 2005 20:47:49 -0000, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

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snipped-for-privacy@invalid.com wrote:

Your basic recessed light.
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Joseph Meehan

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