Weird bulb failure

[Mark42]

Getting ready to head home from vacation I hook up the trailer and do a quick check of the trailer tail lights. First thing the passenger side light is out completely (1157 bulb) even with the parking lights on. So I clean the 4 prong connection and try again. Still nothing. So I remove the 1157 dual filament bulb and it looks OK to me without my glasses on. So I tap it with my finger to see if the filiments wiggle like when their broken, but I still can't tell, so I put it back in. Bingo! it lights up. I ask wife to put on brakes, and the drivers side it bright, but the passenger side is dim. She lets off the brakes, and the driver side is dim, and passenger side is bright. Remove bulb, check socket, and replace. Still working backwards. So we head off and pick up a bulb at the first hardware store we pass and the light works right after that.

When i got home I looked at the bad bulb with a magnifying glass, and the filaments had broken at the ends, then tapping them, they criss crossed and stuck on the opposite side electrode, effectively reversing the high and low filiments. How weird is that? What are the chances of that ever happening again?

Going to carry a spare set of bulbs from now on.

 

[Splat]

Re: Weird bulb failure

That is a bit wierd.


Although I have to admit. While reading your post I'm thinking to myself "it's a bad ground issue, this guy has been around here long enough to know that, what the hell is he thinking."

My bad, I bow to you sir, well played

Bill

 

[CheapboatKev]

Re: Weird bulb failure

That is about a one in a billion!
The tungsten filament re welded itself as soon as power went to it..
I am in the lighting biz and that is crazy!
I have to toss out there that LEDs would never have that problem, but ya know that...

 

[Mark42]

Re: Weird bulb failure

What was odd is how the filiments seem to have uncoiled. They were both much longer than they normally would have been. the cork screw filiments were able to catch the other electrode and hang on easy. Maybe it was a manufacturing defect, but it sure had me scratching my head for a while. And the bulb was not cloudy, its still nice and clear. I probably should have saved it.