Lots of light bulbs going out 1

[BronYrAur]

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?

 

[TheBlacksmith]

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.

 

[BronYrAur]

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?

 

[SphincterBoy]

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.

 

[Senselessticker]

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.

 

[jghrist]

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.

 

[waross]

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

 

[BJC]

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.

 

[itsmoked]

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

 

[Senselessticker]

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?

 

[itsmoked]

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

 

[itsmoked]

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

 

[jghrist]

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.

 

[jraef]

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

 

[BronYrAur]

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!

 

[itsmoked]

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


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

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[SphincterBoy]

Someone needs to turn this over to the MythBusters.

 

[SphincterBoy]

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.

 

[electricpete]

Why would lightbulb life vary as V^12?

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

 

[jraef]

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