In my bathroom I have six lights… all tied to the same on/off switch.
they are in 2 groups of 3, one group for each sink. In the 5 years I’ve lived here, the only two lights that have ever burned out are the bulbs closest to and furthest from the switch.
It’s probably a 3 to 1 ratio of the bulb closest to the switch burning out first. But today, I just lost the bulb furthest from the switch and it got me thinking that I’ve never replaced the 4 in between, and the bulb nearest the switch is the one that usually dies the quickest.
Any thoughts? I thought maybe the first bulb got the juice first in the series, so maybe it got more than it was ready for, but that really doesn’t make sense. Is it a wiring issue, just a fluke, or is there a real problem that needs to be addressed?
We have a similar issue with fairly recently installed lights in our bathrooms. We have two three-light fixtures with halogen bulbs. They’ve been in place about a year. On the fixture closest to the switch, I replaced all of the bulbs about six months ago (they all burned out within a week or so of each other). About a week ago, the first light (closest to the switch) on that same fixture burned out again. I have never replaced one of the bulbs in the other fixture.
Could be coincidence, I dunno. I initially chalked it up to the bulbs maybe being mishandled during installation, but I was very careful with the replacements and one of them has already burned out again (while the three original bulbs in the other fixture are going strong). The replacement bulbs I put in are slightly different from the originals (I couldn’t find an exact match), so it’s hard to make an exact comparison, but the new one in the problem fixture has burned out in very close to the same timespan as the first one.
The bulbs are wired in what is called a parallel circuit. If they were wired in series when any one bulb burned out current would cease in the circuit and no bulbs would light. (remember the old Christmas lights?) And as it’s an AC circuit all bulbs are receiving current simultaneously. My guess is that the 2 bulbs are blowing due to loose or dirty connections in the sockets. Look for any burnt or darkened spots on the threads of the bulbs. And before you screw in a new bulb wipe the threads with a little WD 40. It will displace any moisture that may be causing the problem.
If you’re handy you could check the wiring too but if you’re not familiar with electricity don’t attempt any repairs.
BTW - You might want to replace all the bulbs with compact flourescents. You know, saving money, being green and all that good stuff.
Could be heat. Are the end bulbs close to walls where the other ones aren’t? I had a bathroom fixture I mounted just a little to close to the ceiling and the bulbs didn’t last very long. I moved it down a inch or so, and now the bulbs hardly ever burn out.
Or perhaps some fluke of airflow leaves those two bulbs with a little less air movement, and so a little more heat.
In any case, it seems running even a little hotter can shorten the life of a bulb.
Don’t have an answer for you but I had a similar issue in my study. It has a ceiling fan with 3 lights. 2 of the bulbs would consistently burn out often only lasting a month. 4 years ago I replaced all the bulbs with CFL’s and they have been fine with no failures. It also dropped a 180W (3x60W) electricity consumption to 33W (3x11W).
Speaking as an hydraulics engineer, what you’ve obviously got is a standing wave in the wiring, with pressure peaks at positions one and six. Positions two and five should be pressure minimums; are those bulbs a bit dimmer than the others?
