ECN Forum Forums General Topics of the Trade General Discussion Area light bulbs

I seen basements that had that problem. It turned out that it was more of a structial issue. Without going into detail but you could see the joists shake when someone was walking above.

Also how long are the bulbs on every day? Are they in common areas? 1,000 or 2,000 hour bulbs may not last long enough if they are on all the time.

The 130volt bulbs make a serious difference here over the 120 volt ones (by about 50%).. My incoming voltage is only 122/123V phase/ground.

Not just panel connections or main connections being loose could cause issues. Loose or arcing connections anywhere in the circuit path could do the same. Even, and especially the ones right at the bulb.... An A-19 for instance with a med. base not firmly screwed in will arc at the hot connection inside, and blow pretty quick. I see this problem often in worn, or 'inexpensive' lighting fixtures all the time. People screwing in the fragile bulb in hand are fearfull of giving it a good twist. Or most often are afraid to do so due to the cheap or old fixture falling apart in thier hands.

Really appriciate the input....gonna start by seeing what voltage shes using......because you know my feelings are hurt when shes looking for an answer:}

I would really like to hear a reason why

"Loose or arcing connections anywhere in the circuit path could do the same. Even, and especially the ones right at the bulb.... An A-19 for instance with a med. base not firmly screwed in will arc at the hot connection inside, and blow pretty quick."


would have any effect on lamp life.

I have heard it said by quite a few people but I have always doubted the facts of this.

Bob, I always heard the rational as being the glue around the base of the bulb melts due to the heat, thus letting the gas out of the bulb, which makes the filament blow pretty much instantley
-Will

iwire:

Theory of Why Lightbulbs In Arcing Circuits Blow Faster

- Fact: A lightbulb has a metal filament inside (let's only talk about those at the moment).
- Fact: This filament has a very low resistance when cold (dark). Take your multimeter and measure the resistance...! When it's hot, the resistance is much higher.
- Switching on thus causes a very large current to flow thru the filament in the moment of power on.
- This high current vaporizes a minuscule amount of the filament at each power up due to the very rapid heating. The filament is literally getting thinner - of course, not over the entire length, but at the potential defect spot(s).
- As soon as enough of the filament is vaporized, the filament breaks; usually in my experience at power up. This process is accelerated by vibration, the filament usually consists of tungsten and osmium, this alloy is very brittle and will crack with vibration.

Arcing is just fast and random switching off and on of the power, causing many power cycles. Even if they're not full on/offs, they do put a significant stress on the filament.

Supporting evidence:
- Lightbulbs in well-constructed blinking lights usually have a "keep-alive" resistor which prevents the filament from going cold between the "on" cycles.
[Sideline to ElectriKid Ian A.: This (the keep-alive resistor) is the way to use normal bulbs in blinking applications such as traffic signals at home and still get a decent lifespan out of them.]


Plausible?


Elviscat:
The glue is just to hold the metal socket cap to the glass. The glass itself is hermetically sealed (the glass in its molten state is pressed around the wires going into the bulb), no gas gets in or out.


Dilydalyer:
Get heavy-duty lamps if you can or maybe some of those energy-saving lamps. They last MUCH longer than anything that glows! [Of course, your "better half" will maybe have to approve of the new lightning ]

Nice theory, er...except that a bulb is switching off and on 60 times a second anyway, in harmony with any arc.
Most likely reason is crap chinese bulbs from Walmart at 15c each.

Alan

Exactly what I had in my mind.

Also how does a modern dimmer 'dim' a standard incandescent lamp?

It chops the heck out of the sine wave.

These dimmers prolong the life of the lamp.

I really do not think you will be shortening the life of a typical incandescent lamp unless you switch it off long enough for it to substantially cool down. I would think of and on periods of a couple of seconds would shorten the life.