I have a front porch light fixture hanging from the porch roof. The light bulb inside is upside down. The top of the bulb points towards the ground.
I was told that upside-down light bulbs tend to wear out faster. Is this true?
Someone else said that this outside fixture may not be wired properly and that causes the light bulbs to expired after a few weeks of nighttime use. Could this be true?
I was thinking of trying a CFL (compact florecent lamp) bulb instead. Supposed to last much much much longer and saves on energy costs. Can these bulbs be placed upside down?
I suspect the problem isn’t the upside down bulb but that the fixture has no way to circulate air past the bulb which overheats. Enclosures that hang down from their connection to the building should have and open bottom and vents at the top and almost none of them do.
No, they don’t burn out any faster, BUT the heat will be concentrated on the base, which can cause the bulb and base to separate more frequently than bulbs mounted the other way. Don’t screw the bulb in more than finger tight, and you shouldn’t have any issues.
No. The bulb doesn’t care which wire is the hot and which is the neutral; reversing them will not affect the operation of the light. Although, if it IS miswired there is a greater risk of electric shock. There’s no harm in having a qualified electrician inspect it if there’s doubt as to its safety.
By all means. My entire house is lit with CFLs. You can get the light equivalent of a 60 watt bulb, but only draw 13 watts. Plus they last much longer than incandescents, and they run cooler.
I’d guess that the porch light gets turned off/on much more than other lights in your house, this is hard on the filament. Temp. extremes might also contribute. Replace it w/ a “Rough Service” bulb, or one of those new compact flourescents.
Most stage lighting bulbs are specifically designed for the bulbs to be mounted upside-down (metal base up), and will burn out much faster if they aren’t kept this way.
The purpose is that heat rises, and the metal base of the bulb transfers the heat into the metal housing of the light fixture, thus keeping the bulb cooler. If it’s run with the glass part of the bulb up, the heat concentrates in the glass, and can only radiate out into the air, and so it overheats and burns out faster.
The same thing is true for standard light bulbs, just not as critical because they are much lower wattage than stage lights. Regular light bulbs would run cooler if the were held with the metal base on top. Provided that the fixture is designed to provide adequate ventilation that way. That’s a big if – most common fixtures are designed to mount a specific way, and the ventilation won’t work right if they are mounted differently.
That’s why light bulbs in basement ceiling often burn out quickly. Unless the fixture has enough venting, heat buildup becomes a deciding factor in bulb life.
Nitpick; heat itself doesn’t rise - hot air rises.
I don’t doubt the rest of what you say, but another explanation of how to treat theatrical lighting was offered to me - by my theatre studies teacher way back in secondary school - he said that having used a lamp in one orientation, it shouldn’t be inverted and used in another orientation, because of stresses that develop in the filament the first time it is used. I’m not offering this as a refutation of your statement; it may be that he was just wrong, or it may be that both explanations are true.