Halogen bulbs keep burning out

[Vgkid]

The halogen outdoor light at my grandmothers house keeps dying. Generally they used to last about 6 months, but lately they last between 1-2. With the last one lasting about 2 weeks(hopefully it is just that one). It doesn't seem to matter which brand id installed. The proper steps are taken on installation(using a paper towel to install it). There is no water ingress into the light fixture, that I can find.
Thoughts...

[fourtytwo42]

Try a LED replacement bulb, I have heard they are very good.

[edpalmer42]

Check the line voltage.  A high voltage is an obvious problem but, oddly enough, a low voltage can also doom a halogen bulb to a short life.  Halogen bulbs run very hot to give a nice white light.  Normally, this would be a bad thing, but in a halogen bulb, the high heat and the halogen gas act to move tungsten atoms off of the inside of the bulb and back to the filament.  This keeps the bulb clear and the filament strong.  If the voltage is too low, this cycle fails and the bulb will darken and fail early.  The same thing will happen if you use a dimmer on the bulb.

Another thing that will kill a halogen bulb is fingerprints on the surface of the bulb itself.  This isn't a factor if the actual halogen bulb is inside an outer bulb, but if it's a bare halogen bulb, fingerprints can cause the glass to overheat and fail.

Ed

[Ian.M]

Apart from skin oils carbonising and increasing the IR absorbed, its also the salts in your sweat.  The sodium and potassium ions fuse with the high temperature fused quartz envelope, locally changing it to a glass with a lower melting point, forming a weak spot that blows out.   If you even *think* you've touched the bulb surface, wipe it thoroughly with a white paper towel or tissue wetted with IPA, Methyl Hydrate or Everclear.

Long halogen filaments are also extremely vibration sensitive when hot.  If the fixture mounting is loose and its shaking due to windy weather, expect much shorter bulb life.

Long tubular Halogen bulbs need to be installed fairly close to level so there isn't a temperature gradient across the length of their envelope, otherwise the halogen cycle can redeposit the tungsten unevenly towards one end reducing their lifespan.

[Specmaster]

You don't say how you're controlling the bulb, is it on a PIR at all? If so how often does this switch on/off, for instance is the PIR pointing towards say a road and may be detecting moving cars etc and so is switching frequently. Is it only switched on for a few seconds at a time? Halogen lights don't take too kindly to being frequently switched on and off quickly, much happier if they are allowed to come up to temperature and then remain there for a while before switching off again.

So if it's controlled by a PIR, check what is triggering it on and also check the time period before it switches off again, most PIR's have an adjustment so that you keep the light on a for a set period unless of course it gets reset again during the time out period, in which case it will revert to the maximum period that it was set for again and time out from there.

[G7PSK]

With a PIR lamp bad contacts in the relay can cause the lamp filament to blow as can poor condition lamp holder contacts, change the whole fitting for an LED one.

[Vgkid]

I always handle the bulb with a clean napkin.
The bulb is turned on by a regular switch, and the voltage between the bulb contacts with the switch in the off position is 44.4Vrms. Every time one of these bulbs fail, the inside of the glass gets silvered.  I see a crack in the glass for this bulb, looks pretty neat. Will post a pic.

[fourtytwo42]

I know this sounds completely mad but the way you describe that bulb its REALLY blown!
I know in the states you have both 110V and 220V circuits in your houses, well if this has been happening since the lamp was installed maybe its been wired across the 220V (L1/L2) by mistake (or it got that way recently after someone did some wiring changes) ?
Other possibility is the front glass is missing from the fitting and its getting hit by raindrops
Or or or you have an insect invasion in the fitting (Earwigs get everywhere!).

The 44Vrms meter reading is usually caused by parasitic pickup due to its high input impedance.

[SeanB]

Best is to replace the halogen fixture with a LED one, as sadly most of the lamps these days are made in China, where they have cut cost by making the filament thinner, thus shortening lamp life, and by using poorer quality and contaminated fill gas and poorer contact materials which also cause cracked seals, and use cheaper metal alloys in the whole construction, along with poorer work quality. I used to have halogen lamps last years ( Phillips, Osram, not GE as they went to junk a decade or more ago with the closing of the US assembly lines) but the recent ones are all poor quality, forcing me to get LED retrofit lamps in some cases, and in others just replacing the whole fixture.

Changing the fixture to a warm white one ( best match to original lamp, but might be hard to find) will both have longer life and lower power use, which will pay for the fitting in around 2 years if it is on dusk to dawn. When changing it put in a daylight switch as well, it makes life easier, and as most these days come with a short lead attached put in a junction box there next to the lamp to make the connections.

[Ampera]

I know this sounds completely mad but the way you describe that bulb its REALLY blown!
I know in the states you have both 110V and 220V circuits in your houses, well if this has been happening since the lamp was installed maybe its been wired across the 220V (L1/L2) by mistake (or it got that way recently after someone did some wiring changes) ?
Other possibility is the front glass is missing from the fitting and its getting hit by raindrops
Or or or you have an insect invasion in the fitting (Earwigs get everywhere!).

The 44Vrms meter reading is usually caused by parasitic pickup due to its high input impedance.

To my knowledge, we don't have 110v nor 220v circuits, we have 120v circuits, but petty insignificant differences aside, most 240v circuits are just two 120v circuits thrown together.

[Benta]

Every time one of these bulbs fail, the inside of the glass gets silvered.

This tells all.

Blackened glass: undervoltage.
Silvered glass: overvoltage.

Take it from there...

[Vgkid]

I have gotten them out being pure silver, some have a black mark where they burned out, and one was a combination of silver and black.
I need to clean out the gutters, so I will check the voltage.

[Kjelt]

HV halogen bulbs are lottery, the package of A brand manufacturers specify avg expected burning hours, you can buy 500 hrs , 1000 hrs even 2000 hrs.
But with direct HV you can have a significant drop in burning hours when switching on the cold lamp on peaks of the mains.
So I would suggest to put slowstart dimmer in front of the bulb and set it to 90-95% of the mains voltage.

For LV halogen I run my 12V bulbs with a slowstart electronic ballast ending at 11,6V DC and they are now working since I moved to my current home in 1999. They keep on going and going and going 

If you are going to switch to LED you can have the same issues but then the capacitor in the smps will be the weak link esp with noname lamps. But then we are talking about years 

[richard.cs]

Silvered bulbs can also be caused by something cooling the envelope (strong breeze, water ingress). I'd had that on a car where the fitting filled with water in the rain, the bulb got heavily silvered, then when checked later in the dry the cause wasn't obvious.