Light Bulbs Keep Burning Out - help!


Old 01-30-07, 03:56 PM
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Light Bulbs Keep Burning Out - help!

I am a renovator and have been installing recessed lighting consistently and without issue for years. I have one particular client home that has me boggled. Random lights keep burning out, it seems to be two at a time. At first I thought it was a bad batch of bulbs but even the odd replacement has burned out now.

Here's what we have:

2 x 15amp circuits, the first circuit with 15 lights, the second circuit with 12 lights. Both circuits contain 4" recessed lights with 50 watt par20 bulbs.

The problem is occuring on both circuits. What can be causing this? If it was a short, the breaker would trip. If it was too many, the breaker would trip. I'm only at 750 watts on a circcuit that handle almost double that.

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Old 01-30-07, 04:29 PM
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Is it just the newly installed lights or do exisiting lights burn out too? I'd check the voltage I'm betting your getting a little more than 120 , the poco can install a monitor if it is serious or you could just use 130 v bulbs ...
Old 01-30-07, 05:27 PM
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Yeah, 130V bulbs are the trick for small voltage spikes....with the frequency of bulbs blowing, it does seem a voltage spike to me.
Old 01-30-07, 05:31 PM
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You sure that they dont get to hot?? Insulation around the cans????
Old 01-30-07, 06:19 PM
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you are a renovator. does that mean that you are not a licenced electrician, but you are doing electrical work in other people's homes?????

this is a DIY forum. Getting paid to do electrical work is not DIY, it is contracting.

maybe you should hire a licenced electrican. He would be able to help you solve your problems.
Old 01-30-07, 06:32 PM
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50 watt par 20 sounds OK for a 4" can, but you should verify from the label on the can that it is listed for that bulb.

Consider the possibility of a bad neutral connection somewhere.
Old 01-30-07, 07:03 PM
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I can think of many possible explanations for people, like renoman, to come to this forum to ask questions - none of which require applying a narrow definition of "DIY", or a litmus test to determine if someone is being paid for a project. At the end of the day, does it really matter?

We are all enriched when people share knowledge. I know that I have learned a tremendous amount from participating in this forum, and I am grateful to both the amateurs and professionals who take their valuable time to share the benefits of their experience with others.

The operative concept here is "participate". This forum wouldn't exist if people didn't ask questions, anymore than it would without those who respond.

Please, let's not shoot the questioner. They are a valuable part of what makes this forum so successful.
Old 01-30-07, 07:26 PM
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A DIYer is coverd by his/her home owners insurance.

A contractor pays for insurance to cover his/her work.

An unlicenced person doing electrical work for profit, is a hazzard with no coverage.

That is the difference.
Old 01-30-07, 07:26 PM
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jwhite, I'm not sure what it matters to you or why, the fact remains I have a question that needs answered. I still did the electrical myself, so technically it's a DYI. And where I come from it is perfectly legal for a contractor to do electrical work on peoples homes, as long as it's inspected, it doesn't matter who does it.

I have literally installed hundreds and hundreds of these lights and never encountered a problem. I have inquired with "master" electricans who have shrugged their shoulders. That is why I am here today. Jwhite, you shrugged your shoulders like the rest of them, so here I am.

594tough, these lights are specifically meant for par20 bulbs, they have a directional gimbal trim that fits no other bulbs.

Ed, there's no insulation around them.

so far its not:

-too many lights
-insulation around the cans
-poor socket prong

So the questions remains, can faulty wiring cause this problem? If so, please explain.
Old 01-30-07, 07:40 PM
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poor quality voltages from the utilty can cause the problem.

measure the utility voltage. if needed put a recorder on the house for a day or two.
Old 01-30-07, 07:57 PM
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"Standard" bulbs have a rated life of about 750 hours at their rated voltage. A month has about 720 hours so a bulb lit constantly would last about a month. Running even slightly higher than rated voltage will drastically lessen the lifespan of a lamp bulb.

Shock (vibration) will also lessen a bulb's life. The inrush current when turning on a lamp lessens its life, even moreso when voltage is high.

In my house most of the incandescent are on dimmers and they "ramp up" to full brightness when I turn them on.
Old 01-30-07, 08:12 PM
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There's at least a dozen reasons why bulbs burn out prematurely. Most of these reasons have already been mentioned in this thread. However, so far we have no quantified information that would indicate that the bulb failure is premature. You have 27 lights. They will burn out. If the bulbs only last an hour, then I'd agree that it is premature. So how long do they last anyway?

Check out all the reasons that have been suggested so far. I count at least eight different suggestions in this thread.

No matter what the cause, putting the lights on a dimmer will make them last much, much longer. Be sure not to exceed the wattage capacity of the dimmer.
Old 01-31-07, 05:18 AM
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The odd bulb goes every few days. The rest of the house is fine and the rest of the circuits are fine except for these two. It's not voltage spikes or bad bulbs, it has to be wiring related. But if it is, then what am I to look for? Can a loose connection cause bulbs to burn?
Old 01-31-07, 06:48 AM
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I think you are dismissing some of the possibilities too lightly. And it seems that you haven't even considered some of the possibilities at all.

No, I don't believe a loose connection can cause this, unless the connection is so loose that it's arcing.

You said that "it has to be wiring related." I disagree. Quite a number of other real possibilites exist.
Old 01-31-07, 08:24 AM
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Is there any source of vibration in the walls or ceiling above or near the lights? Kids playing upstairs? Air handling equipment? Any of those can shorten bulb life.

Possibly a weak service neutral which intermittently causes high voltage on the light circuit. A data logging voltage meter could test that possibility.
Old 02-01-07, 08:54 AM
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Nope, no kids in this house..

I just took every one of them down, checked the connections and nothing. I'm lost.
Old 02-01-07, 07:18 PM
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I had a problem with porch lights and a post lamp a few years back.. turned out to be the neutral wire was a problem.. quite evident inside the panel, the wire had gotten hot, it was loose.. tightened it and never had another pre-mature lamp failure after that.. just 2cents, but worth looking at?..
Old 02-02-07, 06:48 AM
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Dumb question - are you sure the bulbs are failing? Is it possible that the thermal switches are opening due to overheating?
Old 02-02-07, 08:01 AM
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Following up on Wayne Mitchell's question.....I understand that par 20 is the bulb size, and as I mentioned, 50 watts is probably OK, but please confirm on the fixture that it is listed for 50 watts par 20. The fixture possibly has the thermal disconnect as W.M. mentioned.
Old 02-02-07, 04:36 PM
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:You're not using a common neutral for both circuits are you?

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