Exploding light bulbs

[kweiss]

Had a recent warranty inspection client call today to seek my advice on a problem they had forgotten to mention at the inspection.

Today they had a kitchen can light flood bulb "explode" while in use. She explained that this had happened once before in a different fixture in the Den in the next room.

I told her that I cannot say that I have heard of this problem before. I explained how can ceiling fixtures typically work with a heat sensor in the circuit. She said they have had fixtures in the home go out briefly, presumably from the heat sensor. These fixtures are located in the first floor ceiling so should not have insulation around them.

I told her that I would tend to suspect a bulb problem, but could not be sure and that I recommend she contact the builder and have them send an electrician to check the fixtures/circuits. This is a better builder in the area and I expect they will send someone out without hesitation.

The bulbs were:
The light bulb that exploded today was...
Philips
Indoor BR40 flood
630 lumens
65 watts
2000 hrs.

* had JUST replaced this bulb today...maybe 40-50 minutes before it exploded.

Same kind as previous exploded bulb but from a different box.

Anyone have any further ideas? Panel was checked under light load with infrared and nothing unusual was observed. Not worried from any liability standpoint, just would like to help my client find more information to help solve the mystery.

[mnahrgang]

When you say "explode" do you mean, broken glass flying all over the place?
Or do you mean the filament pops loudly, and the bulb quits working?

I've had the latter happen on numerous occasions, and is just the bulb failing. My only experience with the former involved very high heat bulbs that failed because they were touched my a person with their bare hands. The oil from their skin, caused that portion of the glass to overheat and fail. (Projection bulb at a movie theater.)

[kweiss]

"Explode" as in glass falling all over the place hot element/filament singing the floor.

[mnahrgang]

Originally Posted by kweiss

"Explode" as in glass falling all over the place hot element/filament singing the floor.

I don't know then... My guess would be faulty bulbs. Hopefully one of the sparkies here will have some light to shed for us (no pun intended).

Unfortunately Paul A is under a sabbatical right now, so we can't benefit from his knowledge.

[Mike Whitt]

Two much voltage will cause a bulb to explode.

Why is Paul under what ever that thing is you mentioned and just what is that thing you mentioned?

Has this web site gone completlly to hadies?

[kweiss]

That's what I said as well. Never heard of that particular problem and defective bulbs make the most sense to me. But I am not a licensed sparky.

[mnahrgang]

Originally Posted by Mike Whitt

Two much voltage will cause a bulb to explode.

Why is Paul under what ever that thing is you mentioned and just what is that thing you mentioned?

Has this web site gone completlly to hadies?

Mike, just sent you a PM.

[mnahrgang]

Originally Posted by Mike Whitt

Two much voltage will cause a bulb to explode.

...

Mike,
I'm sure this is a remedial electrical question, but I'll ask it anyway... What would cause "too much voltage" to be present in a light fixture? How does that occur?

[Mike Whitt]

Originally Posted by mnahrgang

Mike,
I'm sure this is a remedial electrical question, but I'll ask it anyway... What would cause "too much voltage" to be present in a light fixture? How does that occur?

A very good question.

Not to long ago I got a call from a home owner that had exploding bulb in the pantry. The bulb would only blow when both lights were on at the same time.

After a few minutes of checking I found that the kitchen lights and the pantry were on separate circuits with the two circuits tied together in the pantry light fixture.

When the kitchen light was on and the switch was turn on for the pantry one or both bulbs would blow without tripping the breakers in the panel.

Separated the circuits and the problem was solved.

When both lights were turned on at the same time the lights was at 240 volts. Unless the switch was made for the pantry each circuit was at 120 volts.

[Speedy Petey]

In all my years and literally thousands of lamps (light bulbs), I have never experienced this, not even at home.

[Marc D. Shunk]

There are several scenarios under which higher than normal voltage can be present at an incandescent lamp (loose neutral on a multiwire branch circuit chief among them). This will pop the filament and the lamp will extinguish. The bulb envelope does not explode. It simply doesn't happen like that, and I feel pretty good about saying that 99% of the tales you hear of exploding incandescent lamps are fables.

[brian winkle]

I have had this happen twice. A couple years ago I noticed the 4 lamp halogen fixture in the bathroom getting really bright one morning. I switched it off, then back on at which time one of the 50 watt bulbs exploded, also shattering the glass shield that many halogen fixtures use over the lamp. I removed the fixture from the wall, finding the neutral wire from the fixture so loose it fell out of the wirenut when I pulled the fixture down. This is all I could find wrong. The voltage to the fixture was fine when I checked it. I re installed the fixture and it has been fine ever since.

The second time was about a month ago. We came home one evening and turned on the kitchen pendants and the laundry room light. I noticed the laundry room light looked brighter than normal, but I wasn't too concerned. I went into my office. I heard my wife remark that the kitchen lights sure were bright, just as she went out side to smoke a cigarette. I heard a pop and glass breaking at that instant. In the kitchen I found one of the 60 watt incandescents from one of the pendants in pieces on the floor.

This time I checked voltages at the sub panel and at the main service, both were even at around 121. I called the POCO next day, they came and pulled the meter and checked voltages and connections. It all checked out ok, regardless the line man tightened the lugs a bit anyway.

I also called my neighbor who is on the same txformer to ask him if anything unusual had happened at his house that night around 8:00. He said why yes, he was changing some receptacles about that time (non electrician) and he accidentally created a dead short, tripping a breaker.

To this day I am not sure what happened, or if my neighbor's accident could have caused a temporary rise in voltage, which makes no sense to me. I had pretty much figured that the loose neutral was the cause of the first incident, but the second is still a mystery to me. Common sense points to a bad neutral connection somewhere, but I can't find it. There are no multiwire circuits involved with these two branch circuits, in fact the only multiwire circuit in the house is the main service.

Meanwhile, I have installed a whole house surge suppressor. If it happens again I'm not sure where to go next.

I did shake the OH drop around quite a bit while the lineman was checking voltages to simulate wind, but there was no variance.

[scorcoran]

Ok don't laugh at this but I do find it interesting that the bulb was just changed. Could oils from ones hands getting on the bulb cause a problem? I've often seen the warnings on halogen bulbs to avoid touching the surface. Anyway just a thought. I guess it would be pretty easy to determine if 240 volts are present.

[kweiss]

Thanks for the thoughts.

Based on the circumstances described to me, I don't think it would be a voltage problem. These are rooms that the family regularly uses and has for the past year. These lights were on when I was there. So an intermittant voltage problem seems unlikely to me.

To me it comes back to a bulb flaw. I don't think I have seen the warning not to touch the glass on the typical indoor floor bulb, though I have on different specialty bulbs.

Will post back if/when I get some followup.

[Ms Sparky]

I would suspect a manufacturing flaw in the bulb(s) first. I've had a whole case of bulbs with the same manufacturing flaw. QA/QC must have missed it.

If it's a new home, all those cans were probably relamped from the same case of bulbs.

Voltage increases high enough to blow a bulb would surely effect electronics in equipment such as a microwave. I would think it wouldn't be isolated to just that fixture. It would effect everything on that circuit.

If anything, I would think it would be a high resistance/low voltage situation. That would generate heat. That would accentuate any manufacturing defects in a bulb.

I've run across some weird wiring jobs over the years. With this being a new home and a reputable builder...you would think that wouldn't be the case.

I would try a new make and model of bulb. If it does it again. Call an electrician ASAP.

In thirty years, I don't think I've actually seen a light bulb explode....but I have not seen and done it all by far.