ECN Forum Forums General Topics of the Trade General Discussion Area lamp failure

I keep getting this question from customers:

My light bulbs keep burning out. What's wrong? Is there something wrong with my electricity?

I have heard it's cheap bulbs....old fixtures.....too much heat.....arcing at the edison base.....power spikes or surge.....vibration from motors or HVAC units.
Does anyone know what the main cause of premature bulb failure is?

I have noticed if you use the bulbs that are rated for 130 volts they last longer. Exessive vibrations will also shorten the life of incandescent bulbs.

Don (resqcapt) taught me this one:

The sockets may be causing excessive heat at the base of the bulb due to poor connection due to arcing (carbon build-up), corrosion, or fatigue. This in turn can get hot enough at the contact point to actually melt the solder on the bulb, releasing the inert gas (or "vacuum", as it was) and causing the bulb to expire prematurely.

Neat, huhn?!



It is also my experience that 130V bulbs can cure the blowout problem in new fixtures that aren't suspect to the above description.

We find over here,that fitting a surge-diverter unit,
in the main switchboard, usually cures the
problem, as lamps burning out regularly can be caused by a messy power supply.
Not sure wether, you guys have a similar device over there,but it fits between the main incoming phase(s) and earth(GND), with as shorter leads as possible.

Here in New York City we get no-name "heavy duty" 130-volt lightbulbs at the dollar stores.

I always buy these....I've had some last for over a year!! And under daily use!!!

Amazingly, the filaments on these cheap-o bulbs are supported at five points, whereas the more expensive "name brand" bulbs like Sylvania and General Electric have the filament draped over two supports (the current carrying ones).

Maybe if you're lucky you get some that have one support wire in the middle. So of course, because of heat-cycling, the filament eventually sags and breaks off the contacts.

Rowd,

What I commonly find is that the occupant has been putting 75 to 100 w bulbs in a 60 w fixture, this causes excessive heat damaging the wiring in the base and any soldering at the connections. Replacing the fixture and doing a show and tell usually solves the problem.
The other problem are those $4 porch lights that are mounted right next to a door, slam the door and guess what, no light.
Bob

The dual bulb fixture that is in the cieling over the kitchen "eats" bulbs. When they die, they die with a Kabang! enough to give you a heart attack at 4:30 in the morning. Tried almost everything, the bulbs aren't too big, the bases are in good shape, why only that fixture? the last thing that I know to try is the little buttons that fit on the base of the bulb.
Is it possible that the switch itself might be at fault? if the switch arcs when it makes, would that send some high current, and voltage spikes to the bulb?

beats me

Trainwire

[This message has been edited by Trainwire (edited 10-14-2002).]

Bobp has a good point. I've seen many places where an oversized lamp is used in a fixture (sometimes as bad as a 200w. lamp in a socket/fixture rated at only 75 watts...the lamp is so big, they can't put the diffuser on, and if they did, it would immediately melt ). In some locations at our community theater here, I've resorted to using traffic light bulbs, since it seems that everything else available is of such poor quality. The traffic light bulbs come in really strange wattages (67 and 116 watts, I think) and cost somewhat more, but the life expectancy is vastly higher. I keep one burning backstage 24 hours a day near the MDP and main disco, and it usually lasts about 2-3 years. In other parts of the building (lobby, rest rooms, dressing rooms, etc.), I'm constantly changing lamps even though I'm careful about oversizing and screwing lamps in too loose or too tight.

I think it's just the poor quality of the beasts...

Trainwire: Never have tried the "little buttons"...what are you referring to?

Mike (mamils)

[This message has been edited by mamills (edited 10-14-2002).]

He's referring to these little buttons you stick on the bottom of the bulb's screw base.

It's essentially a diode that "chops" the AC current into half-wave DC and reduces the voltage across the bulb's filament. The bulb will be dimmer, but is supposed to last longer...

Sven: Do you know how much dimmer the lamp will be? Also, do these guys come in different sizes (for various wattages of lamps)?

Thanks for the info.

Mike (mamills)