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Lots of light bulbs going out

Lots of light bulbs going out

Lots of light bulbs going out

(OP)
I seem to have an inordinate number of light bulbs going out at my house.  It seems like 5 or 6 have gone out in the last few weeks.  I've only been in the house for a few months, so I don't have any history.  The bulbs are all in recessed cans and are mostly 65W indoor flood bulbs.

Is this just a weird coincidence or do I have some strange power quality problem?

Any thoughts?

RE: Lots of light bulbs going out

1) The bulbs were all in the house and are old.

2) The recessed cans are the type that cannot have thermal insulation touching them, but they do.  This overheats the bulbs and shortens their life.  Eventually your house may burn down and you won't have to worry about the bulbs.

3. You have excessively high voltage, > 125-130 volts.

RE: Lots of light bulbs going out

(OP)
Thanks TheBlacksmith for your post.  1) The bulbs are probably old - no problem there.  2) I am fairly certain that there is no thermal insulation touching the cans.  3) I will check the voltage.  Let's assume that it is 125-130 volts.  What can i do about it?

RE: Lots of light bulbs going out

I had a similar problem with bulbs going out.

In the part of the Country where I live the utilities set the voltage at 125 VAC.

Most light bulbs I've seen in stores are rated at 120 VAC.

I went to an electrical supply store and ordered bulbs rated for 130 V, to "handle" our higher (125) voltage.

I have since noted the lightbulbs lasting much longer, since they are getting hammered by overvoltage.

Also, bulb manufactures have a rough-service bulbs with a 130V rated.

RE: Lots of light bulbs going out

When you check the voltage in your house...do it at different times throughout the day.  If you are getting over 120V during peak usage times (say 6am-8am or 6pm to 8pm)....you probably should buy bulbs rated at 130.  Note that the bulbs (assuming the same wattage) rated at 130 may not be as bright as a bulb rated at 120V.

RE: Lots of light bulbs going out

If you measure more than 126 V at light load times and over 120 V at peak usage times, call the utility.  They may change the taps on your transformer to lower the voltage.  If your voltage is less than 120 V at peak usage times, you might want to leave things as they are - your voltage may get too low if the utility changes the taps.  Low voltage may cause other, harder to solve, problems.

RE: Lots of light bulbs going out

Don't forget to check the lamp sockets for corrosion. I have seen lamps fail due to overheated bases, caused by corroded sockets.
The high voltage mentioned by others is by far the most common cause, however.
respectfully

RE: Lots of light bulbs going out

Light bulbs vary from brand to brand.  You may find the cheap ones from Wall Mart don't last whild the cheap ones from Home Depot do?  I did a semi formal research porject on  this once and found the GE ones from Hungry lasted better.
Is suspect by now somewhere on the web there is a site evaluating the different brands.
Replace as many as you can with compact floruscent bulbs, they are cheaper.

RE: Lots of light bulbs going out

Do realize that light bulbs are highly engineered to run X hours.  If they were all put in at the same time they will all burn out about the same time.

My lighting costs sky rocketed about the time I was stoopid enough to use compact fluorescent bulbs.  I have never had one last even a year!! So all their claims of "look how this overpriced bulb of ours will save you a fortune over it's 7 year life" are a load-oh-cr@p as far as I'm concerned.

A dimmer switch could possibly help a lot.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

Interesting about your compact fluorescents burning out so soon itsmoked.  Mine have been burning for years now.  However, at my folks place.... theirs rarely last a year.  Something to do with brand perhaps?

RE: Lots of light bulbs going out

Could be.. I have only tried about 3 brands.  Most I believe are designed rite-at-the-limit.  And a lot of them get so hot I wonder how they save much energy.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

BronYrAur;  Let me explain why the voltage is important to the bulb life.

The life of an incandescent bulb is a function of the voltage.

Life of bulb = (Design voltage/Actual voltage)12 X Life at design voltage

That  y12  means things change very fast !

Example: 120V bulb used at 125V
Life = (120/125)12 X 1200 hrs
      = 735 hrs

Raising the voltage 5 volts above design voltage cuts the bulb life in half!!

Likewise a 120V bulb used at 115V
Life = (120/115)12X 1200 hrs
      = 2,000 hrs  a big increase.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

I've had the same experience with compact fluorescent lamps.  Lower life than incandescent in a lot of cases.  Probably a quality control problem instead of a design problem.  Some of the lamps have lasted years.  So, they're guaranteed for 5 years or 7 years, or whatever.  Who keeps warranty information and receipts for light bulbs?  And a 15W compact fluorescent doesn't give nearly the lumen output of a 60W incandescent.  I don't care what they claim.

RE: Lots of light bulbs going out

Hmmm. This being a homeowner post not withstanding, I'll chime in before it gets RF'd.

Compact fluorescents have EVERYTHING to do with brand and cost. The very real benefits and rebates from utilities make for a choice market in which the purveyors of cheap junk can thrive. Unfortunately many of the big-box home improvement stores have buyers with absolutely no real-world experience, so they get sucked in just like everyone else. Notice too that I said cost not sell price, because unfortunately the worst offenders have also figured out that if they raise the price on their junk, it will be percieved as being better quality!

The answer is to read reviews of specific brands from people like Consumer Reports. They make very good assessments of quality and longevity. I bought several brands of cr@p as well, but after doing my own due dillegence I now have CFLs that have been installed for over 7 years.

Eng-Tips: Help for your job, not for your homework  Read FAQ731-376

RE: Lots of light bulbs going out

(OP)
Sorry for not being a renter (i.e. a "homeowner") but I thought my question had an engineering basis.  I wasn't asking how to wire a light!

RE: Lots of light bulbs going out

jghrist; Quality control problems are design problems in my book.infinity


jraef; What brand have you had the best luck with?

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

Someone needs to turn this over to the MythBusters.

RE: Lots of light bulbs going out

Hurray jraef!  I couldn't agree more about marketplace junk, particularly with big discounters.  Surprisingly, even water heaters are being "junked out" for low price sales, with max. lifetime of only 5-6 years, when they used to be no less than twenty.

I never buy anything w/o checking with Consumer Reports.

RE: Lots of light bulbs going out

Why would lightbulb life vary as V^12?

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

RE: Lots of light bulbs going out

BronYrAur,
It's not about renting or owning, it's about the rules of this forum (not mine). By "homeowner" I meant not related to a professional engineering issue, the charter of this forum. I didn't RF this thread, but I think the admins eventually might. That's all I was saying.

Back to you original issue, another approach is to find some little discs called "Bulb Savers" at the hardware store. Cooper Electric Bulb Saver link They are sold to save energy but they also make your bulbs last 100 times longer (no joke). They are a diode that goes into the lamp socket before screwing in the bulb. They make the bulb work on 1/2 wave AC, but other than a reduced lumen output you would never know. Human eyes can't pick up strobing higher than about 16Hz, so at 30Hz (effectively) you don't notice any flicker. The trick around the reduced lumen output is to increase the wattage of the lamp. That defeats the energy savings of course, but 100 times the lamp life is worth the effort, especially if the lamp is in a hard to reach area. These things have fallen out of favor since the advent of CFLs but I still see them around in places.

Kieth,
The funny thing is, I can't tell you! It's been so long now I'll have to go remove one and read the name off of it. I do know that "Lights of America" is some of the cheapest cr@p out there IMHO. Some of those didn't even last 3 months.

I have some here in my office from Techna Bright bought at Costco, but they are only about 2 years old so the jury is still out on them. I installed some other brand based on Consumer Report's recommendation on my front porch fixture when I moved here in Oct. 1997 and I know I bought them all at the same time. Some already died, but they were burning base up which isn't too good for CFLs because the electronic ballast heats up. The porch light is base down, 9 years and counting, with timer operation so it burns every day for 10 hours (roughly). The only drawback is the warm up time. I'll get the name and post it tomorrow.

Eng-Tips: Help for your job, not for your homework  Read FAQ731-376

RE: Lots of light bulbs going out

A small correction (not important to the main point).  I think the full-wave rectified current would contain components at 60, 120, 180 etc hz. Not 30hz.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

RE: Lots of light bulbs going out

A small correction (again!)... I meant half-wave

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

RE: Lots of light bulbs going out

Well, here's my pennies worth--I personally had a short bulb life issue years ago when I was living in Texas.  I started noticing about a month after a direct lightning strike to my house.  Decided to monitor before/after work.  Morning voltages were anywhere from 128-134, afternoon was still running 127-131.  Called utility company and told them what I had been monitoring.  They were there within the hour, and had the pad transformer changed out in two hours. Their assumption  was that "the lightning strike most likely caused the neutral connection to burn." [their quote, not mine]

RE: Lots of light bulbs going out

P = V2/R
Then the temperature is some power of a power.

Then there is some tungsten in a vacuum evaporation curve that is probably a power owing to Area so you end up with a bunch of powers X powers of powers.  <just my guess>

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

e-pete,
What I meant was the bulb filament is only getting power to it 30 times per second instead of 60. With a sensitive enough light meter connected to a scope I have seen the flicker and it looks like 30Hz. My old analog light meter doesn't see it though, the movement is probably too slow to pick it up.

Eng-Tips: Help for your job, not for your homework  Read FAQ731-376

RE: Lots of light bulbs going out

Thanks for the info jraef.

I did try "Lights of America".  True garbage of the lowest quality.  None lasted more than two months.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

I guess I can see power^power.  But who'dve thunk V^12?

I wonder if it is the steady state condition or the inrush that limits life?

60hz sinusoidal current has 60 positive peaks and 60 negative peaks per second.  If you get rid of 60 negative peaks per second, you still have 60 positive peaks per second.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

RE: Lots of light bulbs going out

I'm getting really good bulb life on outdoor lights that are switched on dim at dusk by light sensors, and switched to bright by motion sensors.  Bulb life was disappointing regardless of brand in a succession of new fixtures in the same location, switched on manually at dusk and off at dawn.

Some premium bulbs had longer lifetimes, but not enough longer to justify the higher price.  Some premium bulbs are just high priced.

Mike Halloran
Pembroke Pines, FL, USA

RE: Lots of light bulbs going out

Let's see, radiated power is related to Ttungsten^4 - Tair^4.  Tungsten is about 2800K, so I can see filament temperature related to V^6.  Don't know how life relates to tempearture but it's probably exponential...

ko  (www.ecooling.biz)

RE: Lots of light bulbs going out

electricpete; It is purely the loss of tungsten through evaporation that kills the bulb.  As a metal evaporates it has to do with the temperatures of the surfaces "it sees".  This means the filament evaporates unevenly as some of the filament sees other filament some sees glass, etc.  Ultimately some point becomes thin enough that it presents extra resistance, and drops a little more voltage, over heats, and opens. Often at turn on.

By the way the longest burning light bulb in the world is just down the street <sorta> actually closer to jraef than me.  It has been burning for 105 years continuously.  In a Livermore firehouse.  It's so old it is a carbon filament bulb.  It's 4 watts.  And lights the fire truck bay. It was hand made and is likely built as a 150V bulb or something and it is making great use of the y12.

Math test anybody?
Following the equation above:
And using the assumptions;
1) Actual Voltage = 120V
2) Life at design voltage = 1200 hrs
3) Actual life 110 years

Life of bulb = (Design voltage/Actual voltage)12 X Life at design voltage

What was the design voltage?

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

Ttungsten^4 - Tair^4 represents REMOVAL of heat energy from the lightbulb.  That tends to LIMIT the operating temperature difference.

It brings to my mind an approximation.

Let's say resistance varies with temperautre
R = R0*(T/T0)^n where n>0

HeatIn=V^2 / [R0*(T/T0)^n]
HeatOut = T^4  (approximate that Tair is much smaller and that other energy loss mechanisms are insignificant compared to the radiation).

Equilibrium temperature occurs where HeatIn = HeatOut.
T4 = V^2 / [R0*(T/T0)^n]
  multiply each side by T^n
T^(4+n) = V^2 / [R0*(1/T0)^n]
  Raise each side to the power 1/(4+n)
T = V^2/(4+n)  * [R0*(1/T0)^n]^1/(4+n)
   Note the stuff on the right is all constant with respect to T and V.  Remove it and change = to ~

T ~ V^2/(4+n)
Since n>1, this is less than V^0.5, i.e. T varies as less than the square root of V.

jraef - did you see my comment above?




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Eng-tips forums: The best place on the web for engineering discussions.

RE: Lots of light bulbs going out

I did electricpete, I see your point (all 60 of them I suppose tongue) and I should have known better considering I work with variable time base zero cross SCR controllers. D'oh!

The wave shape on luminosity from the scope threw me off course though because it looked like 30Hz. Can't think of why in light of your clarification, maybe measurement error or response delay in the filament. I was letting my observation cloud my reasoning. Dangerous thought process.

Eng-Tips: Help for your job, not for your homework  Read FAQ731-376

RE: Lots of light bulbs going out

Thanks for catching my mistake, electricpete.  

ko  (www.ecooling.biz)

RE: Lots of light bulbs going out

Now that we've re-invented the wheel, has anyone checked this guy's system for a bad neutral?

Get a voltmeter and check your voltage leg to ground. Turn on a heavy 120 volt load (like a microwave oven)on the other leg and see if your voltage goes up. If it does, go check your neutral connections.

RE: Lots of light bulbs going out

CFL's - I put 8 GE's in my garage a few years ago and I'm happy with them so far. They're the ones with 3 U loops coming out of the base, not the typical spiral. I think they are 18W - in any case they are very bright and completely silent in operation.

I was half expecting to have 8 extra CFL's to find a home for but they actually exceeded my expectations. At the time, they were selling for $12/4 with a $5 mail in rebate.

RE: Lots of light bulbs going out

Many years ago an eye doctor I was seeing informed me about a problem caused by mercury vapor lights: subliminal flicker, which is hard on the eyes.

Regular filament bulbs do not exhibit this problem.

I also use the compact flourescent bulbs in my house, but for my reading lights, I use the filament bulbs (130 V).

I've noticed that when the compact flourescent bulbs run continuously, they burn out quickly.  If you want 'em to last long, you have to make certain they do not operate 24/7.

RE: Lots of light bulbs going out

(OP)
I'm glad this thread has interested so many of you.  Thank you all for your ideas.  I measured my voltaghe all weekend and found it to be an average of 125V, although it was not very hot here (Chicago).  Should I wait and measure the voltage during a peak condition, or should I call the utility now.  Had another bulb go out too.

  

RE: Lots of light bulbs going out

LionelHutz; Interesting.. But names.. need names of quality bulb maker. (not shape)infinity

SphincterBoy; I'm with you on that! I read at least an hour a night (SciFi) and dimmable tungsten is the only way to go for the color and the lack of flicker.

BronYrAur; We're getting a lot of mileage out of your question!!lol    I think I would call them and complain that all your bulbs keep burning out quickly due to your voltage.   See what happens and what they say.  Can't hurt and could help!

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

'smoked,

In Europe the best CFL's I've found for longevity are made by Philips. I've used them in the exterior lighting at home with better life than I got from GE and some of the anonymous types out there. I'm not sure how much of the improvement is related to our climate - England is pretty damp, so perhaps the Philips design is better suited to it. I'm also suspicious of low amplitude vibration of the luminaire caused by wind. I'm certain this contributes to the premature demise of the tungsten filament lamps, but I wonder if some CFL cathodes are also susceptible to this failure mode.

Aside: I keep receipts for the mains voltage halogen lamps bceause they're expensive, and if they don't make it past 6 months I take 'em back. I've never been refused a refund!

----------------------------------
  I don't suffer from insanity. I enjoy it...

RE: Lots of light bulbs going out

Keith,
The one in my porch light fixture that has been operating for 7 years or so is a Phillips EL/O 18, 18W Outdoor rated. it's only rated officially for 10,000hrs, but I must have more than that by now.

RE: Lots of light bulbs going out

Scotty, jraef;  Thanks a lot.  I appreciate your efforts. I will get a few Philips and try them in my kids rooms. Perhaps the exterior ones are better built to boot,(no venting).

Scotty; I set up an entire system for returns.. keeping the blister packs, labeling, the bulbs, and the receipts, to return the failures.  That got labor intensive.

Let the testing begin!

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Lots of light bulbs going out

Keith - since you missed it the first time GE would be the manufacturer. Once again - GE :)

RE: Lots of light bulbs going out

LionelHutz; Thanks for persisting. I guess I was doing that 'moron' thang when I read your post.
I will pick up some GEs too (imagination at work).  I like the quiet!

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

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