[bwall]

I've added some Halo mini cans to my basement that I'm finishing/finished. I have one mini can that keeps burning out double life bulbs in an area that is finished. The bulbs are sylvania 50W R20's. After they burnout they turn white instead of being clear like they look when bought new. This is a non-ic can without insulation around it, on a dimmer switch with two other lights of same setup on same switch. Lights are not on that much and seems to burn out a bulb sooner than it should. The other two mini cans do not have the problem. I heard putting them on a dimmer will burn out lights quicker. Still seems like it is hardly on before it goes.
I have four mini insulated cans on a regular switch in another room that I'm working on. Two of them have burnt out a bulb after a few hours of running. The burnt out bulbs in these look like a burnt out bulb (blackish/clear). There is insulation around these cans. These are Halo H99ICT's.
What is causing these bulb burnouts?
Thanks
Bob

 

[bwall]

lights are not pigtailed at the fixtures. They are chained with the last light being the end of the chain. Black to Black, White to White, and the grounds to grounds from fixture to wire, hence no pigtails. The first light (closest to switch) is then run straight to switch with black linked to top terminal. The power source comes out of a junction box from a home run to panel. The power source black is tied to bottom terminal on switch. The two whites are then wired nutted together in switch box.

The switch 15A 120
The breaker 15A 120
Wire 12-3
4 mini cans

Same setup as this diagram except the wire is 12-3 and no pigtails and on extra light.

I borrowed this diagram from a Mike Finley post.

 

[PipeGuy]

What is causing these bulb burnouts?

oxidation of the filament :cheesygri

if i remember my high school electronics correctly (there's a good chance i don't, it was first period) then current (amps) increases in relation to an increase in impedance (resistance). if that's the case a poor connection at the fixture, a faulty lamp socket, etc. might cause the current through the bulb to be higher then it's otherwise supposed to be and that might be causing the premature failures. just a guess.

 

[jbfan]

My first thought would be a loose connection inside the j box. Did you use the push locks or cut them out and wirenut the wires? Another thought would be a loose neutral between the last good fixture and the one that blows bulbs. A loose netural could raise the voltage that your fixure is seeing, thus the lamp goes pop inside. Is the fixtures that are blowing the lamps at the end of the run? You can acess the jbox without removing the fixture, but it is a pain! Let me know if this helps.
Keith

 

[bwall]

Keith
The light in the finished part are all ideal push locks. My friend wired those up so I'll have to talk to him about that one.

The part that I'm working on now have push locks in the j box and wire nuts in the fixtures. I can access the j box, and also have the ability to still take drywall off of ceiling and recheck connections at fixtures. I was working around that walls in that area just in case. I'll check the wires tomarrow or monday.

I spoke with halo today and they said it could be because I didn't have trims up in the lights yet and they were getting to hot. So, I put the trims in the lights in area working in and they ran all day today with no burnouts.

Thanks for the info. Any other ideas are welcomed.
Bob