I have a client that has light bulbs exploding inside her fixtures. Have not been to to her house yet but she said she had 3 bulbs explode in one night and even a LED bulb has exploded. Just asking for opinions or personal experience with this kind of situation. Never heard of this before. Thanks in advance.
Light bulbs exploding
- Thread starter Jason H
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Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
Loose neutral or open neutral causing up to 240 volts on the light bulbs
Dsg319
Senior Member
- Location
- West Virginia
- Occupation
- Wv Master “lectrician”
mopowr steve
Senior Member
- Location
- NW Ohio
- Occupation
- Electrical contractor
If it’s a standard incandescent bulb there’s a possibility that the cement that holds the shell to the glass let go and introduced air into the bulb or vacuum seal tube cracked. Incidentally that usually creates a fast burn (or flash) of the filament and a pop sound can be heard. As for as an LED I don’t have an answer other than possibly a capacitor grenading.
This can be caused by cold air passing by a bulb. It’s been noted that bulbs near A/C vents tend to blow more often due to temperature shock.
One time I had a 200 watt bulb at a exhibit hall that the cement let loose or glass cracked at the base, the filament flashed and the glass crashed on the floor. A lady near it about had a cow thinking I did something to cause it as she thought it was like a bomb. Only thing I can think of why she freaked out so bad was that it occurred almost a year after 9/11 and she was probably still freaked out about it.
This can be caused by cold air passing by a bulb. It’s been noted that bulbs near A/C vents tend to blow more often due to temperature shock.
One time I had a 200 watt bulb at a exhibit hall that the cement let loose or glass cracked at the base, the filament flashed and the glass crashed on the floor. A lady near it about had a cow thinking I did something to cause it as she thought it was like a bomb. Only thing I can think of why she freaked out so bad was that it occurred almost a year after 9/11 and she was probably still freaked out about it.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
I swapped out a panel in a 1920s-30s home that had knob & tube wiring, and the lights in the entry and stairwell exploded when the lights were turned OFF.
Reason was California 3-ways, wired with H+N on what we call "traveler" screws - then a single conductor from each "common" screw to the light.
As it turned out, the switches on the main floor (entry door & stairs) were fed from a basement circuit, while the switches at the top of the stairs were fed from the attic on a different circuit.
In 2 of the up/down combination of switch flipping, the lights came on. In 1 up/down combination the lights were off. In the 4th up/down combination there was 240 volts at the lights, with exploding bulbs.
Found the two circuits in the panel and made sure they were on the same leg.
Reason was California 3-ways, wired with H+N on what we call "traveler" screws - then a single conductor from each "common" screw to the light.
As it turned out, the switches on the main floor (entry door & stairs) were fed from a basement circuit, while the switches at the top of the stairs were fed from the attic on a different circuit.
In 2 of the up/down combination of switch flipping, the lights came on. In 1 up/down combination the lights were off. In the 4th up/down combination there was 240 volts at the lights, with exploding bulbs.
Found the two circuits in the panel and made sure they were on the same leg.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Guys, applying 240V to a 120 V light bulb will not cause it to explode.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
ptonsparky
Tom
- Occupation
- EC - retired
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I don't see how. The only way I could see it happening is if the bulb stayed on long enough without burning out to get super hot where it caused enough stresses in the components to shatter.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Okay I just tried it. Six bulbs just blew right away, non catastrophically. One, actually did not burn out. I had it on for about 30 seconds. It was bright!
ptonsparky
Tom
- Occupation
- EC - retired
Aren’t you about 400’ from your xfmr?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
1900' from the service point, but 200' from my step down transformer. I do have 2400v available for testing...shall I try that?
ptonsparky
Tom
- Occupation
- EC - retired
Yes! Video!1900' from the service point, but 200' from my step down transformer. I do have 2400v available for testing...shall I try that?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Ok perhaps that would be fun. I should get some extra MV bayonet fuses first as I don't have any spares...not sure I can get those local.
different Fixtures or same fixture?
loose connection on the same fixture causes the bulbs to get too hot and explode.
Led caps can let all the current through when they go bad because of electrical stress from voltage fluctuations, caused by loose neutral.
Loose N would be my first look.
loose connection on the same fixture causes the bulbs to get too hot and explode.
Led caps can let all the current through when they go bad because of electrical stress from voltage fluctuations, caused by loose neutral.
Loose N would be my first look.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
What type of bulbs?
The ones I had were candelabra incandescent.
I had candelabra l.e.d. in the other fixture and they burned out but no explosion
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Just regular A base incandescent, 60+75 watt.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
Not sure if that would make a difference
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I think the rate of voltage increase might affect these reactions, and bad neutrals usually produce over-voltages that are still well below the full line-to-line voltage, allowing greater overheating time.
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