# Porch Light Bulbs Failing



## Franko (Dec 12, 2016)

I have two motion sensor porch lights at my home. They've worked fine for 6-7 years. I use bug lights in them and they generally last about a year.

Recently, the lamp on my back door has started eating light bulbs. I replace the bulb and it burns out in a week or so.

I'm stumped. Why would a light fixture suddenly start burning out bulbs at such a fast pace?

It is on an original circuit that has always been on the house. For years, it worked fine, but has suddenly started eating light bulbs. The identical one on the front porch works fine.

Is it possible that a wire connection has become loose? I don't see any damage, or charring on lamp socket or connectors on the light bulbs. The lamp is probably working as when I go outside and it senses my movement, I can hear it click.


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## mzayd3 (Dec 12, 2016)

It probably has a bad connection in the fixture itself. Just replace it.


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## FOMOGO (Dec 12, 2016)

You might also want to check the breaker that it's associated with in the main panel. I had lights flashing in the house, and it turned out to be a bad breaker. First time I've run across that. you could see it arcing in the panel. Mike


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## RJSakowski (Dec 12, 2016)

A major cause of early failure of incandescent bulbs is frequent switching on and off.  The thermal expansion/contraction cycle causes mechanical stresses leading to ultimate failure.  It's possible that you've had a parade of critters activating the sensors.  

It also seems that light bulbs aren't as robust as they used to be.  I have had name brand bulbs fail on the first power up a number of times.  One way to get extra lumens/watt is to run the bulb at a higher temperature which unfortunately has the side effect of shortening the life span.

They are making led bug lights now which should give you extended service life.


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## mksj (Dec 12, 2016)

Many of the generic incandescent bulbs are rated at a lower voltage, often 110V. Feit bulbs are stocked by many big box hardware stores, and the bulbs tend to burn out very quickly, especially if your voltage grid runs a bit high, mine is 124VAC. As RJ mentioned, the motion sensor switching on/off exacerbates there failure.  I have had much better luck with brand name Philips and Sylvania bulbs, even though they are all made in China. Pretty much switched everything to LEDs at this point, although I still until purchase Philips and Sylvania brands, the failure rate of the Feit and generic LED bulbs has been high.


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## David S (Dec 12, 2016)

I know that you mentioned yellow.  There are lamps (bulbs) rated for "rough service", often used in trouble lamps etc.  They are rated at 130 vac and should last longer, but I think they are only white.

They are also better for garage door operators that subject the lamp to a jerk every time it operates.  The filament in these lamps has more structural supports as well.  Any chance the door closer is allowing the back door to slam?

David


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## brino (Dec 12, 2016)

What kind of bulbs? (incandescent, compact fluorescent, LED?)

I bought a pack of new LED bulbs that are supposed to last 22 years and save you hundreds of dollars over that life.
What BS! 

After the third one died within months, I opened one up and found a bad connection inside.
I presume the entire package of 5 bulbs are built the same.

-brino


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## CluelessNewB (Dec 12, 2016)

RJSakowski said:


> A major cause of early failure of incandescent bulbs is frequent switching on and off. The thermal expansion/contraction cycle causes mechanical stresses leading to ultimate failure.





Franko said:


> The lamp is probably working as when I go outside and it senses my movement, I can hear it click.



It's interesting that you hear a click.  All of the motion sensor lights that I have encountered have solid state relays with no audible click.  If yours has a mechanical relay rather than solid state and it is failing, it may be stuttering causing early bulb failure like RJS describes.


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## Franko (Dec 12, 2016)

Too many comments to quote everyone. Thanks for input.

These aren't cheap lamps. They are commercial quality porch lamps. I haven't changed the kinds of bulbs I've used in them.

RJ, I know that switching them on and off shortens the life, but I doubt that's what is happening here. If anything, what I've noticed is that the bulbs stay on longer than in the past. So, they aren't flickering — at least perceptually. At least on the last bulb I replaced, I didn't ever see it turn off. It seemed to just stay on at night, until it burned out in a few days.

Brino, I have used all three kinds of bulbs in the fixture. Incandescent seem to work best. CF are useless and one of the last bulbs it ate was a fairly expensive LED.

Rich, I hadn't thought of the motion sensor causing the problem. I assumed it was solid state but still utilized some kind of relay.

This seems to be a problem that is fairly common, but (not just here, but everywhere I've searched) I've yet to see any real explanation of how or why a loose connection or faulty relay would cause the bulbs to suddenly start to burn out prematurely.

So, here may be my real question. How does a bad connection cause a bulb to burn out? I can imagine how a surge would damage a bulb, but I don't see how weakened electron flow would.


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## Ulma Doctor (Dec 12, 2016)

Franko said:


> So, here may be my real question. How does a bad connection cause a bulb to burn out? I can imagine how a surge would damage a bulb, but I don't see how weakened electron flow would.


in a word, RESISTANCE!
if the resistance rises, either amperage and /or voltage must increase to do the same work

i'd check the Neutral to the light .
you could have a faulty SSR or receptor

there is di-electric grease that you can put on a bulb tip to reduce resistance and prevent oxidation of the contact surfaces


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## jim18655 (Dec 12, 2016)

Is the light next to a door? Maybe the door is slamming closed harder and jarring the bulbs. Some of those motion sensor lights are soft start. Maybe it's coming on full bright to start now.


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## tq60 (Dec 12, 2016)

Makes no sense but try this.

Take bulb from other light and try it.

If it lasts then bad batches of bulbs.

WAIT...Check voltages it both fixtures and maybe a few outlets.

We had squirrels eat the neutral on the pole and all 240 vac things were fine but everything else was wonky and flipping on a light made everything different.

If you have a poor neutral L1 could be spiking while L2 dipping. 

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## Franko (Dec 12, 2016)

Ulma Doctor said:


> in a word, RESISTANCE!
> if the resistance rises, either amperage and /or voltage must increase to do the same work
> 
> i'd check the Neutral to the light .
> ...



Thanks, Mike. That is one of the answers I've seen on a couple of my searches, but not explained as well. I've seen several mentions of the problem being at the neutral.
I have used WD-40 on my light bulb connections for years, and it seems to help. If nothing else, the bulb screws in and out easier, as they tend to dry out after extended use and get stuck. I've seen WD-40 pull off what seemed to be electrical miracles many times.

I had surgery a couple weeks ago and haven't been very mobile. I think I'm up to pulling the fixture off and checking the connections tomorrow.


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## RJSakowski (Dec 12, 2016)

Since you've had failures with three different technologies, I would think that would rule out the bulbs.  
I think TQ is on to something.  A bad neutral connection somewhere in the circuit would shift the balance depending on the relative load on each half of the circuit.  

I had a problem like that years ago.  Whoever had done the wiring from the meter at the barn to the house didn't bother to run a neutral wire.  They depended on the connection to a water pipe from the barn to the house.  At some point before I moved in, the original steel pipe was replaced with polyethylene which in effect broke the electrical connection.  Current through the neutral was maintained by conductivity of the water and the ground.  Depending upon what the loads were on either leg, I had seen voltage swings as much as 40 volts.  I ran new service wiring and it ended the problem.


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## Franko (Dec 13, 2016)

Well, I opened it up this afternoon and think I found the problem. Both the common and hot wire were stranded and connected to solid copper with old ceramic connectors. I re-stripped the insulation for fresh stranded and cleaned the solid, applied a little WD-40 and reattached them with newer connectors that use the little wire spiral to screw on. Those connectors should dig in to make contact with both the stranded and solid wires.

I put a new bulb in it and I guess I'll have to wait to see what happens. It won't come on until dark, anyway. If that doesn't work, the next place to look is at the connections at the wall switch.


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## David S (Dec 13, 2016)

Franko, I guess the question that I didn't ask is..." when the lamp burned out, did you take it to another socket to verify that it was indeed open.  If you did then I am still not sure why a bad connection would cause the lamp to fail open.  However if you didn't then an intermittent joint surely could have been the issue.

David


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## Franko (Dec 13, 2016)

Yes, I checked the bulbs in a different fixture. They were dead.


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## KMoffett (Dec 17, 2016)

Ulma Doctor said:


> in a word, RESISTANCE!
> if the resistance rises, either amperage and /or voltage must increase to do the same work...


WRONG!
In a totally series resistive circuit (wire and light bulbs) and a constant power source(120VAC), as the resistance goes up the current goes down. A bad contact (R2) will only add the resistance of the lamp(R1) and reduce the current.  Do the math: I=E/R
Normal connection: I(current)= E(120V)/R1(lamp)
Bad connection= I (current)= E(120V)/R1 (lamp)+R2(contact)

I would look at neutral connections in the box or at the pole. Had this happen at my parents farm house. Lamps in some rooms lasted forever and in others, blew at short random times. Loose neutral at the pole.

Ken


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## Ulma Doctor (Dec 17, 2016)

KMoffett said:


> WRONG!
> In a totally series resistive circuit (wire and light bulbs) and a constant power source(120VAC), as the resistance goes up the current goes down. A bad contact (R2) will only add the resistance of the lamp(R1) and reduce the current.  Do the math: I=E/R
> Normal connection: I(current)= E(120V)/R1(lamp)
> Bad connection= I (current)= E(120V)/R1 (lamp)+R2(contact)
> ...




I'm not wrong, you missed my point

TO DO THE SAME WORK the amps and/or voltage must increase if the resistance raises

resistance adds heat to a circuit, the heat increases the resistance further. if there is no spare voltage, the amps must raise to do the same work


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## jim18655 (Dec 17, 2016)

A light bulb can't do the same work, unless you can find a way to suck the light out of it, so it will only get dimmer.  Imagine two bulbs in series  - they just dim due to the voltage drop because of the resistance. Think old school rheostat dimmer. A motor driving a machine, however, would over heat due to the load placed on the motor to try to do the same amount of work.
I could see a poor connection causing a flicker in the lamp which would increase the thermal shock to  the lamp.
If this is a multi-wire branch circuit then the current could increase through the lamp because of the two sides of the circuit trying to balance out without a neutral to carry the unbalanced load to the panel.


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## tq60 (Dec 17, 2016)

The claim is part accurate but not good for light bulb as it is a non loaded resistive device.

A motor will try to do a certian amount of work and as the voltage lowers it will draw more amps but if the lowering voltage is due to a poor connection then the amps may be limited but this causes yet lower voltage and if the current flow is such that the motor still operates it can get damaged.

DC plants on battery do same where as battery voltage drops the regulated equipment draw more amps due to lower voltage to produce same work...power is same but inputs vary...volts lower and amps higher but watts constant.

The op likely has a bad neutral and there are cases where some electrical folks have used creative wiring where they use 2 hots at 240 and single neutral to save a wire as it meets load and code but a poor connection to the neutral in that circuit can make that circuit go wonky and let the rest be fine.

Suggest checking voltage at the fixture and if not wanting to open it up get a 2 bulb adaptor or screw in adaptor to cord which would allow measurement and testing.

After unloaded voltage measured next install large watt bulb of if cord adaptor used plug in hair dryer and measure voltage under load.

If it drops much then you may have a bad neutral which requires some trouble shooting with a voltmeter checking both hot and neutral voltage to other outlets and fixtures and the extension cord makes this easier.

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## markba633csi (Dec 17, 2016)

Call an electrician! Just kidding
MS


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## Franko (Dec 17, 2016)

Redoing the connection from the solid house wires to the stranded fixture wires seems to have fixed the problem.


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## JPMacG (Dec 19, 2016)

Vibration causes incandescent bulbs to fail.  Has anything changed at the location that would cause the bulb to be exposed to more vibration?   A few years ago we replaced our heat pump and a  pedestal light in our family room started burning out bulbs.   It was located over the main HVAC trunk.  Vibration from the new system was causing the bulbs to fail.


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## KBeitz (May 12, 2018)

Vibration check X 2.....


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## tcarrington (May 12, 2018)

Glad you found a fix. Our house was located close to the neighborhood transformer which has a loose tap. I am told that cause the voltage to drop and peak rapidly. Whatever, we ate bulbs until that transformer was replaced or re-tapped. Richardson would have old transformers as does Plano - it is also likely your house has some of the Federal breakers that are notoriously bad.


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## Franko (May 17, 2018)

Nope, no Federal breakers in my house.
It's been a year or so and I've had no more problems with the porch light. The bad connection seems to have been the culprit.


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## cg285 (May 17, 2018)

2  houses, both identical expensive american made lamps. same problem. at present 2 on gate, one on driveway. chinese incandescent lamps last from one day to about a month - no matter the brand.  same with identical lamps on prior house. there are no electrical problems. and led bulbs are not compatible with the photocell in these fixtures

on shop 2 american made outside industrial fixtures. led bulbs. one has been running  almost 2 years, the other just blew (little over 2 years)

when i get time i am switching out the photocells and putting in leds in the other lamps


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## wyodano (Jun 7, 2018)

could be the lamp socket is loose allowing the bulb to shake and jar in the wind or when the door is closed hard.


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## Blackjackjacques (Jun 20, 2018)

Could be the triac in the motion sensor device used to switch on and off the power to the light is problematic.  Triacs conduct in all four quadrants, but if there is defect such that one or more of the quadrant "switches" is not working, then you could be work hardening the filament - resulting in premature failure.   The triacs in these devices are the business end and what typically fails first.  Generally, triacs fail to short, and a total failure usually results in the load being on all the time.   If you are handy, pull the triac and test, or just simply replace the triac.  In my devices, I simply toss and replace the whole motion sensor device but retain the bulb fixture.  On another note, someone mentioned suffering premature failures with LED devices.   This most often occurs where the LED is fed from a dimmable control intended for an incandescent (triac) rather than something else like a PWM type of control.


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