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-   -   Halogen bulbs keep burning in the basement (http://www.diychatroom.com/f18/halogen-bulbs-keep-burning-basement-157677/)

ardendolas 09-23-2012 12:17 AM

Halogen bulbs keep burning in the basement
 
Hi all, y'all seem quite knowledgeable, so I hope someone has an inkling as to what might be going on. We bought our house about 3 years ago, with a finished basement.

In the basement, there were four light fixtures with three GU10 sockets each, with halogen bulbs. They are controlled by two dimmer switches, two fixtures to a dimmer. When we moved in, we kept the original fixtures in the basement, but we changed and installed new fixtures (again, GU10 sockets with halogens) in the rest of the house.

We noticed very early on that bulbs in the basement would go out a lot quicker than the advertised duration, and for the longest time, we blamed the cheap bulbs we were buying at Costco, but we also noticed that the bulbs in the rest of the house didn't go out nearly as quickly, if at all.

Eventually, we took a shot in the dark and decided to blame the light fixtures in the basement, so we went out to the store and bought four new fixtures. I installed these myself. I'm not much of an electrician, but I've done a few such operations in the house (fixtures, switches, outlets...)

Well, that didn't fix it. It's been only a few months, and out of the 12 bulbs, 7 are already burned, and we hardly even use the basement nowadays. The annoying thing is that nowhere else in the house does this happen.

Any thoughts or suggestions would be greatly appreciated :)

andrew79 09-23-2012 12:50 AM

Mr16 and gu10 bulbs are notorious for blowing fast partly due to the intense heat they generate. If you run them at 30 percent or so you may get the 20000 hours out of them but at full bright they'll blow like crazy. I suspect that the basement lights are less ventilated than the upstairs. If you use led replacements you will find they last longer but they don't dim nearly as well unless you get the right bulbs.

ardendolas 09-23-2012 02:29 AM

Thanks Andrew for the pretty quick response. I see what you mean, I don't think I'd considered the overheating aspect of it. The upstairs is a lot better ventilated yeah, and we have A/C upstairs as well.

Now, my wife has convinced herself that the wiring for the lighting in the basement is most likely at fault. Is there a chance that might be the case besides the heating issue?

Thanks!

ddawg16 09-23-2012 06:25 AM

Halogen? It's worth reading up on it.....

The issue with Halogen bulbs is that if you put them on dimmers....you defeat the purpose of the halogen gas.

As a tungston bulb burns, it spits off molecules of tungston......notice how a burned out bulb has a gray look on the glass? That is tungston.

A Halogen bulb is the same as a regualr incandescent bulb....except that it has halogen gas in it. The idea is that when the tungston filement gets up to a hot enough temp...and starts to spit off tungston molecules....the tungston gas re-deposits the tungston back onto the filement...

But, when you put the halogen bulb on a dimmer...it does not get as hot...hence, the filement wears out like any normal incandescent bulb.

I don't have this problem......I use CFL's.

k_buz 09-23-2012 08:06 AM

My first thought would be that the heat that these lamps produce, along with vibration of footsteps directly above them could explain why the basement ones burn out faster. If you have kids, I would suspect this is the case. The actual wiring shouldn't be an issue.

Oso954 09-23-2012 12:32 PM

Not sure where the idea that dimming a halogen defeats the purpose comes from. Dimming a halogen can make it last up to 20 times longer (dependent on how much/how often it is dimmed).

Vibration could be the issue.

Length of use may factor in. Depending how dark the basement is and how much you use the basement, you could be burning the bulbs 10 hours or more a day, versus 3 or 4 hours for the identical bulb in the upper part of the house. 50 watt gu10's are typically good for about 2000 hours (not dimmed).

12 bulbs at 50 watts each is 600 watts. I give some consideration to CFL's or LEDs to resolve the bulb problem and reduce energy use.

ddawg16 09-23-2012 12:54 PM

Quote:

In ordinary incandescent lamps, evaporated tungsten mostly deposits on the bulb. The halogen sets up a reversible chemical reaction cycle with the tungsten evaporated from the filament. The halogen cycle keeps the bulb clean and the light output remains almost constant throughout life. At moderate temperatures the halogen reacts with the evaporating tungsten, the halide formed being moved around in the inert gas filling. At some time it will reach higher temperature regions, where it dissociates, releasing tungsten and freeing the halogen to repeat the process. The overall bulb envelope temperature must be higher than in conventional incandescent lamps for the reaction to work.


Hence, if you dim them.....your not getting the halogen cycle because the bulb is not hot enough....

Oso954 09-23-2012 01:46 PM

"In ordinary incandescent lamps, evaporated tungsten mostly deposits on the bulb. The halogen sets up a reversible chemical reaction cycle with the tungsten evaporated from the filament. The halogen cycle keeps the bulb clean and the light output remains almost constant throughout life."

That the key statement about halogen bulbs. It's more about light clarity than filament life.

When you get to the part about redepositing the tungsten on the filament, it tends to deposit towards the cooler ends, more than it does towards the hot center. So even with redepositing that filament will tend to fail in the center.

If you run a filament cooler, there is less erosion of the filament. (that statement applies to both incandescent and halogen bulbs)
Slowing the erosion on the filament means it will generally last longer than a similar bulb run at full power.

ardendolas 09-23-2012 08:09 PM

Thanks everyone for the thoughts! I think might look into LED's then.


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