Light Fixture Problem

[Jerry Simon]

I replaced the two pendant lights above my kitchen island.  One of the fixtures kept burning-out bulbs after about a week.  Happened four times in a row, so obviously something amiss (but again, the bulbs lasted about a week each, using fixtures a few times a day).   Thought maybe a bad bunch of bulbs.  Happened with new bulbs.  All the while, the adjacent new fixture was fine & dandy.

Okay, loose neutral.  Nope.  Tightened up everything at both fixtures.  Same result; new bulbs last about a week.   

Okay, bad fixture.  Nope.  Returned and exchanged, and no good; burned out the bulb in about a week.

Okay, voltage amiss.  Nope; 123 volts, just like its new neighboring fixture.

Could voltage somehow fluctuate at just the one fixture?

Any help would be appreciated. 

(And, no, this isn't the caulk issue I asked about earlier; aside from a burnt-plastic odor every time I use that fixture, it worked great.  Kidding. . .)

[Jim Katen]

Try swapping the two fixtures, just to see what happens. 

[Marc]

Incandescents?

Are both fixtures on the same switch, same circuit?

Is the cooking range on the island?

[Jerry Simon]

1 hour ago, Jim Katen said:

Try swapping the two fixtures, just to see what happens. 

Will do.

[Jerry Simon]

18 minutes ago, Marc said:

Incandescents?

Are both fixtures on the same switch, same circuit?

Is the cooking range on the island?

Yes.

Yes.

No.

[Chad Fabry]

Is one fixture directly below the elephant pen?

Is the fixture that burns the bulbs first or second in the circuit?

 

 

[Jerry Simon]

2 minutes ago, Chad Fabry said:

Is one fixture directly below the elephant pen?

Is the fixture that burns the bulbs first or second in the circuit?

 

 

No.

Yes, it's first or second.  When I switch them, as James suggested, I'll see which is first and which is second.  What's your thought here?

[Marc]

4 minutes ago, Jerry Simon said:

No.

Yes, it's first or second.  When I switch them, as James suggested, I'll see which is first and which is second.  What's your thought here?

Corrosion in the socket maybe.  Corrosion generates heat, shortens the life of an incandescent bulb.  Remove both bulbs and examine both sockets.

[Chad Fabry]

6 minutes ago, Jerry Simon said:

No.

Yes, it's first or second.  When I switch them, as James suggested, I'll see which is first and which is second.  What's your thought here?

If the fixture with a long-lasting bulb is first, it may have a compromised neutral connection and the filament in the second fixture is carrying that current back. 

[Marc]

8 minutes ago, Chad Fabry said:

If the fixture with a long-lasting bulb is first, it may have a compromised neutral connection and the filament in the second fixture is carrying that current back. 

That describes a series connection where one lower resistance path provides a neutral to a second higher resistance path if one of the neutral connections were lost in certain locations.  It's the path with the higher resistance that gets the most voltage.  If Jerry's two bulbs had the same wattage, they'd each get half the available voltage.  They'd each glow dimly.

[Jerry Simon]

38 minutes ago, Chad Fabry said:

If the fixture with a long-lasting bulb is first, it may have a compromised neutral connection and the filament in the second fixture is carrying that current back. 

The  long-lasting bulb is first in the circuit.   *Evil* fixture is second in the circuit.  I just switched fixtures.

If bulb in (now-switched) second fixture in the circuit burns out again, I'll pull new wire from the first fixture to the second fixture (unless someone's got a better idea).

41 minutes ago, Marc said:

Corrosion in the socket maybe.  Corrosion generates heat, shortens the life of an incandescent bulb.  Remove both bulbs and examine both sockets.

Fixtures are brand new.  *Bad* fixture is twice brand-new.

Edited November 14, 2017 by Jerry Simon

[inspector57]

What else is on the circuit? I would be looking for changes in voltage or spikes with other loads were switched on/off. You can get some funky stuff (technical term) going when back stab or otherwise bad connections are involved.

[Jerry Simon]

Here we are, ten days later after switching the two fixtures as James suggested.

Same fixture, now on the left side instead of the right, just burned out a bulb.  (Again, I already replaced this almost brand new fixture with an even newer one, suspecting it was the fixture itself.)   This is odd.

[Marc]

Get some LED lamps.

 

[Jim Katen]

10 hours ago, Jerry Simon said:

Here we are, ten days later after switching the two fixtures as James suggested.

Same fixture, now on the left side instead of the right, just burned out a bulb.  (Again, I already replaced this almost brand new fixture with an even newer one, suspecting it was the fixture itself.)   This is odd.

So, you've narrowed the problem down to the fixture itself. I suspect a flaw, probably a loose connection, that affects a large percentage of the fixtures. You just happened to get two bad ones in a row. Does it use typical screw-base lamps? If so, the little tab at the bottom might not have enough spring to make good contact with the bottom of the lamp. Try using a chopstick or bamboo skewer to bend it up a bit. 

[John Kogel]

I can see a faulty connection, weak contact in the socket, but to actually burn out the bulb suggests a surge, over-current. Also suggests you are buying crappy bulbs, always from the same bad batch.

There may be an intermittent wiring fault, but that wouldn't usually burn out the bulb. Nope, i don't have a clue.

[Nolan Kienitz]

Well, maybe it is time for this tried and true lighting fixture ... 

[Jim Katen]

4 hours ago, John Kogel said:

 

There may be an intermittent wiring fault, but that wouldn't usually burn out the bulb. Nope, i don't have a clue.

1

I've got an ancient little desk lamp that I use daily. There's some kind of wiring flaw in it because if the metal cowl (shade, whatever . . .) is turned just the right way, the bulbs tend to cycle back & forth between bright and slightly less bright. If I let them go on like that, the bulb burns out really quickly. If I tweak the position of the shade then the cycling stops and the bulbs last for months. I'm sure that the shade is pulling on a wire somehow and causing a connection to loosen a bit. 

[John Kogel]

What happened to bulbs that last for years?

Anyway, I Googled it and at least one opinion is that loose connections can cause minature surges which are bad for the filaments. Sounds like cheap bulbs to me.

[Marc]

4 hours ago, John Kogel said:

What happened to bulbs that last for years?

Anyway, I Googled it and at least one opinion is that loose connections can cause minature surges which are bad for the filaments. Sounds like cheap bulbs to me.

Rough service bulbs?  Yeah, Jerry could try that out.

[Jerry Simon]

17 hours ago, John Kogel said:

Sounds like cheap bulbs to me.

Could be.  I'm gonna switch the one original bulb that's lasted several months to the suspect fixture.  This bulb is from the same batch as the ones that burned-out, but it's lasted quite a while. 

I'll also tweak the contact at the bottom of the socket per Mr. Katen's suggestion.  Perhaps these actions will enlighten matters.