Oven Bulb keeps burning out.... Puzzled?!?

[edy]

Hi folks,

I am getting a bit frustrated with an oven bulb in a GE electric range. It is an appliance bulb 40W which turns on every time the oven door is opened. I can also turn it on/off using a switch on the top of the range. I expect several thousand hours of use but it will burn out after several days to several weeks even without having the oven actually used.

I've done some tests just turning on the lamp and leaving it on. Sometimes it lasts for months, sometimes for days only. I can't seem to pinpoint the cause. The contacts on the switches seem to be ok. I checked the area around the bulb, it doesn't appear to be overheating. Does anyone have any possible explanation? Should I be getting a different appliance bulb, something more heavy-duty, or rated at higher voltage?

Any help would be appreciated.... Unless this is just dumb luck with bulbs, I can't seem to explain the discrepancies. Or perhaps the way the bulb is finally oriented (since it is mounted sideways at the back of the oven) the filament is vertical or horizontal and heating up different amounts. I'm not sure what is going on.

I also assume I shouldn't think about using an LED bulb back there, as I don't know what kind of temperature that part of the oven experiences when it is on, I wouldn't want anything but a conventional metal/glass bulb.

Thanks for any ideas/suggestions on what to do or how to go ahead with testing this.

[Mr. Scram]

Forgive me for asking the obvious, but are you using actual oven bulbs? Do they get very greasy perhaps?

[coromonadalix]

check the socket if its damaged / deformed / greasy ...  bad contacts make current consumption higher

[edy]

Forgive me for asking the obvious, but are you using actual oven bulbs? Do they get very greasy perhaps?

Yes, I am buying the appliance 40 W clear bulbs meant for refrigerator/oven (at least when I went to buy them), there is a picture clearly on the package. No grease issues, the oven is very clean.... spotless. Sylvania brand, although there are Philips, GE, etc. Most are rated at least 1000-2000 hours. Unless we got some cheap-o bulbs from the dollar store (I believe my wife may have bought the last batch in a 4-pack) that could have been only good for "cold" applications (ceiling fan, refrigerator). She unpackaged them and put them in with our other bulbs so I didn't confirm whether they were made for refrigerator/oven? I will make sure she shows me the packaging first!  

One thing that I did notice occasionally, but have not yet experimentally tested, is that one of the 2 legs holding up that big long heating element on the bottom of the oven sometimes bends and the heating element is able to tilt a bit on one side and touch the bottom of the oven enclosure. I don't know if that has anything to do with it, I highly doubt that would make any difference to the heat distribution or affect the bulb which is far away at the top in the corner.

check the socket if its damaged / deformed / greasy ...  bad contacts make current consumption higher

Yes thank you, I will check the socket as well and see if there is anything wrong with it.

I have a feeling (and hope) that it is just a simple situation of my significant other getting those cheap dollar store bulbs that were probably for fan/fridge cold applications and not oven, which she mixed into my batch of refrigerator/oven bulbs, resulting in the life-span irregularity. Time to take control of the bulb stock and keep a close eye on things, and I'll get back to you with the results! 

[helius]

When you do get the proper bulbs that should last for years, you can experience the opposite problem of them getting welded into the socket and very hard to remove. A dab of dielectric grease on the base helps a lot with removal later.
On the ovens I've seen there is a glass dome over the bulb, which has a fiberglass spacer or mat behind it. If that mat is destroyed, hot gas can escape into the bulb area which is bad for the life of the bulb and also for the electrical wires behind there.

[amyk]

Check your mains voltage carefully, preferably with a logger. The lifetime of incandescent bulbs is inversely proportional to the sixteenth power of the voltage.

[jcw0752]

I don't think quality incandescents are being manufactured anymore. All the ones I have seen lately have unreasonably short lives.
John

[radar_macgyver]

Oven bulbs in north American appliances are run off one half of the split phase supply. Some older houses did not distinguish between neutral and ground (3-pin NEMA 6-50 connector instead of 4-pin NEMA 14-50), and if there's a wiring fault it could cause 240V to appear across the bulb (instead of the usual 120V). This would considerably shorten its life.

[Cyberdragon]

Oven bulbs in north American appliances are run off one half of the split phase supply. Some older houses did not distinguish between neutral and ground (3-pin NEMA 6-50 connector instead of 4-pin NEMA 14-50), and if there's a wiring fault it could cause 240V to appear across the bulb (instead of the usual 120V). This would considerably shorten its life.

That would make it considerably brighter and would be obvious. I would also think it would fry the control circuits if the oven was overvolted.

EDIT: Unless it has some universal switching supply that doesn't care (or runs on 240V anyway).

[Gregg]

Oven bulbs in north American appliances are run off one half of the split phase supply. Some older houses did not distinguish between neutral and ground (3-pin NEMA 6-50 connector instead of 4-pin NEMA 14-50), and if there's a wiring fault it could cause 240V to appear across the bulb (instead of the usual 120V). This would considerably shorten its life.

Radar_macgyver is right on track for the most probable causes other than crappy lamps.  240/120 volt power has a few nuances not commonly considered.  I don’t know why, other than saving a few dollars that it return on ground rather than running a real neutral is allowed with some appliances.  But in either case, a loose ground or neutral connection could be responsible.  It could be anywhere.  If something on the other 120 volt leg is drawing more power than the lamp and both share a bad return connection, the lamp voltage will go up as the other device voltage goes down. 
Another possibility is more than one ground to neutral bond; most likely in a sub panel but possibly in another appliance.

[PedroDaGr8]

Interestingly, I came across this with a range that was blowing bulbs left and right. With the appliance type sockets, it is VERY easy to tighten the bulb too much. Overtime, this results in the tab at the bottom of the socket getting pressed down and not making a good connection. I have seen a variety of explanations on how it can affect bulb life, but for all they claim it shortens bulb life. Figuring what the hell, let's try it and see. Sure enough, tab was pressed flat. Pulled it up with an insulated screwdriver and gently screwed the bulb in until it JUST turned on and then one more 1/4 turn. The current bulb hasn't burned out in the past 6 months (previously they were averaging 2-3 weeks). While this is ENTIRELY anecdotal, it worked in this case.

[NiHaoMike]

Find a cool place to install a series diode.

[cvanc]

The lifetime of incandescent bulbs is inversely proportional to the sixteenth power of the voltage.

Wow, really?  That's pretty mind-blowing... can you provide a citation for that?

[basinstreetdesign]

The lifetime of incandescent bulbs is inversely proportional to the sixteenth power of the voltage.

Wow, really?  That's pretty mind-blowing... can you provide a citation for that?

https://en.wikipedia.org/wiki/Incandescent_light_bulb#Light_output_and_lifetime
About 3/4 way down the page.

[Cubdriver]

It's already been mentioned, but I'll reiterate - double check the neutral and/or ground connection.  If it's not making good contact somewhere along the line back to the panel, you can get higher voltage across the lamp than it likes.

-Pat

[saabman]

The problem quiet self evident. It’s cooking the globes   

[amyk]

It's an incandescent bulb. It's supposed to get hot. You also missed the part where he says he didn't use the oven and it still burnt out.

[Psi]

just sounds like a dodgy/counterfeit batch of bulbs to me.
Try buying a different brand from a totally different source