I may not have a clue, but my guess would be that the problem is mechanical. I would suggest swapping one of the sockets with a standard replacement from a hardware store.. There are several possible issues, the most likely of which is that the socket is expanding / contracting in such a way that it is applying torque to the glue holding the bulb in the base.... I have seen intermittent lamps resulting from cheaply made sockets where there was an unused switch leaf. I guess it was easier to disable the switch leaf than to manufacture without it....Every time the socket warmed up, the leaf bent because there was no knob to hold it in place... My guess is that if the sockets were all installed at the same time, they are the same make. probably same production lot. Probably made in some totally unknown factory in a remote location. The rest of the lot are probably scattered throughout the known world... Just some thoughts, probably erroneous, but maybe worth a try. Best of luck, Martin At 03:30 PM 7/16/01 -0400, you wrote: >Thanks for the suggestions. Here are some facts: > >* The bulbs are incandescent, not halogens. >* The fixture is hanging from the ceiling, 3 bulbs, each with a metal >reflector above it - looks like plenty of ventilation to me. >* Each socket is rated for 100w. >* All three bulbs that separated were 60w. >* We have used 60w and 100w bulbs - failure rate is about the same. >* The mysterious off again / on again bulb is 100w. >* Thermal shutoff cannot explain mysterious bulb because it will not light >even when fixture has not been used for hours and I measured the voltage in >its socket while it was not working. > >--BobG > >-----Original Message----- >From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On >Behalf Of Marc Reinig >Sent: Monday, July 16, 2001 1:14 PM >To: PICLIST@MITVMA.MIT.EDU >Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected > >Sounds like you have recessed cans and Halogen spot or floods. First check >with the manufacturer to verify that the bulbs you are using can be used in >that fixture. If the glass is separating from the metal fixture, it sounds >like the bulb is not appropriate for the socket in some way. Most of the >recessed cans have a thermal shutoff. It sounds like yours is tripping. >This is a good sign that there is something wrong with your bulb/can >combination. If you are using the large bulbs, then it might be possible >that you are either using too high a wattage, a halogen bulb where you >shouldn't, or a bulb that is physically too large to allow the correct >amount of air circulation to keep the lamp cool. > >Marc Reinig >System Solutions > > >-----Original Message----- >From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On >Behalf Of Robert E. Griffith >Sent: Monday, July 16, 2001 9:15 AM >To: PICLIST@MITVMA.MIT.EDU >Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected > >I have been having a problem with the light fixture in my kitchen going >through bulbs fast (bulbs lasting about a month). This fixture uses the more >expensive, large diameter bulbs. When the last one went out, I did not >replace it right away. Several days later, it came back to life! > >Since then, it has gone out several times (for 2-7 days) but has, so far, >always come back to life. > >I have measured the voltage in the socket during one of the bulb's dead >periods and verified that there is power in the socket (117v). > >I imagine that somewhere in the bulb is an intermittent short. The room is >air conditioned so temp does not vary that much (except when the bulb is >on:) > >Another strange thing: Three times now, when other bulbs have gone out in >this fixture, the glass bulb separates from the metal socket while the light >is on and drops to the table below! > >So I guess my question is "Should I be concerned that this fixture is >haunted?". Should I call Bill? (Maurry - not Gates) > >--BobG > >-----Original Message----- >From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On >Behalf Of Jinx >Sent: Saturday, July 14, 2001 9:54 PM >To: PICLIST@MITVMA.MIT.EDU >Subject: Re: [EE]: Bulb Life > > > Ha ha! They don't want to educate you, they want > > to keep you as stupid as possible and buying as many > > bulbs as possible. Evil empires are like that! ;o) > > -Roman > >Appropriate then that this is posted under an [EE] Evil Empires >tag. What truth is there really to planned obsolescence ? Any >proven examples ? Light bulbs and tyres spring to mind as >products widely believed to be "improvable" > >btw, as I travel around I pop into the odd electrical wholesaler >and always leave a copy of my bulb life web page and some >comments from the list (anonymous of course) about extending >filament bulb life. Had a few "ooohs" from counter staff as they >realised the implications > >-- >http://www.piclist.com hint: To leave the PICList >mailto:piclist-unsubscribe-request@mitvma.mit.edu > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads