Stinkin Christmas Lights

[larryllix]

I dont' think you understand. They were working, they weren't moved, they stopped working. Movement that happened 3 weeks earlier is not going to break a fillament today.

 

And again, all 50 bulbs burned out all at the same time. Movement that burns out 50 bulbs at precisely the same instant seems highly unlikely.

 

Only an electrical condition would have affected all 50 bulbs at precisely the same instant in time.

If these are the same as the old bypass mechanism used they have problems with increasing voltage every time another bulb bypass mechanism shorts out.

 

So each bulb starts out with say 120 volts divided across 30 bulbs giving each 4 volts.

 

Once say 5 bulbs become shorted out now the remaining 25 good bulbs each have almost 5 volts across them.

 

With aged filaments the increase in voltage burns out the rest exponentially until the last one needs to vapourise the shorting mechanism across the 120 volts alone.

 

 

 

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[apostolakisl]

If these are the same as the old bypass mechanism used they have problems with increasing voltage every time another bulb bypass mechanism shorts out.

 

So each bulb starts out with say 120 volts divided across 30 bulbs giving each 4 volts.

 

Once say 5 bulbs become shorted out now the remaining 25 good bulbs each have almost 5 volts across them.

 

With aged filaments the increase in voltage burns out the rest exponentially until the last one needs to vapourise the shorting mechanism across the 120 volts alone.

 

 

 

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Except as I mentioned, the shunts (on at least the vast majority) didn't trip.  I didn't test every one, but most of the shunts were still open circuits.  So, again, you would have to have nearly instnantaneously burning out bulbs.  As soon as a single bulb burns out and (for whatever reason) the shunt stays open, then the rest of the working bulbs will shut off, not burn out.  In addition, all 50 bulbs were lit the day before. . . .none burned out/shunted.

[DrLumen]

Incandescent bulb filaments get brittle as they get used due to being heated. Bulbs in lamps don't get moved much, those in ceiling fixtures even less so. Not so with bulbs that are decorative which get moved a lot. The more brittle the filament, the more likely it is to break, most especially when power is first applied. That's why a bulb is most likely to burn out when it's turned on.

 

Bulbs that have been packed, most especially if they were warm when packed, and unpacked a lot are especially likely to have a filament break, even if they've not seen a lot of use. If the bulb was clear, then you can actually see the break. If it's a string of lights in series, then a string of them will burn our concurrently. That's less likely if they are wired in parallel, but even those are subject to the brittleness problem. LED bulbs don't have that problem.

 

Very true. Not only do they become brittle but if they are still hot and moved or struck the filament can break as it is near a molten state.

 

As to problems after storage, it is possible that the vacuum was lost in the bulb during the ~year in storage and the filament could have corroded. Or, with air in the bulb, they simply burn out when turned on after taken out of storage.

[apostolakisl]

Very true. Not only do they become brittle but if they are still hot and moved or struck the filament can break as it is near a molten state.

 

As to problems after storage, it is possible that the vacuum was lost in the bulb during the ~year in storage and the filament could have corroded. Or, with air in the bulb, they simply burn out when turned on after taken out of storage.

Except as I mentioned, the shunts (on at least the vast majority) didn't trip.  I didn't test every one, but most of the shunts were still open circuits.  So, again, you would have to have nearly instnantaneously burning out bulbs.  As soon as a single bulb burns out and (for whatever reason) the shunt stays open, then the rest of the working bulbs will shut off, not burn out.  In addition, all 50 bulbs were lit the day before. . . .none burned out/shunted.

[larryllix]

 

Except as I mentioned, the shunts (on at least the vast majority) didn't trip.  I didn't test every one, but most of the shunts were still open circuits.  So, again, you would have to have nearly instnantaneously burning out bulbs.  As soon as a single bulb burns out and (for whatever reason) the shunt stays open, then the rest of the working bulbs will shut off, not burn out.  In addition, all 50 bulbs were lit the day before. . . .none burned out/shunted.

 

Can you actually see the shunts? The shunts are supposed to close if and when the filament breaks so that one or the other always maintains the circuit. With my scenario, post #51, the shunts would are be blown clear as the whole string blew and shorted out. The indicators for that would be every filament is open and many  shunts are blown clear.

[apostolakisl]

Can you actually see the shunts? The shunts are supposed to close if and when the filament breaks so that one or the other always maintains the circuit. With my scenario, post #51, the shunts would are be blown clear as the whole string blew and shorted out. The indicators for that would be every filament is open and many  shunts are blown clear.

You can see the shunts, yes, but I don't know that there is a difference in appearance between a tripped and non-tripped shunt.  The sure way is tp chceck with a multimeter for continuity.  A tripped shunt conducts, a non-tripped shunt does not.  The bulbs (at least every one I checked) is an open circuit . . .not tripped shunt, burned out filament.

 

Keep in mind, if even 1 bulb burns out and the shunt fails to trip, the strand shuts off.  All the other bulbs would just turn off, at which point burning out is no longer possible.  So how did all 50 filaments get burned out/broken?  If you whacked it you could physically break the filament.  But 1) the bulbs weren't whacked (not even touched) and 2) it would take a hell of a whack to break every single filament . . .every single one.

[oberkc]

My theory is that, as individual bulbs burn out, the voltage to the remaining bulbs increases. When hat voltage continues to increase, it reaches the point where it fries those remaining.

My theory is that, as individual bulbs burn out, the voltage to the remaining bulbs increases. When hat voltage continues to increase, it reaches the point where it fries those remaining.

[apostolakisl]

My theory is that, as individual bulbs burn out, the voltage to the remaining bulbs increases. When hat voltage continues to increase, it reaches the point where it fries those remaining.

My theory is that, as individual bulbs burn out, the voltage to the remaining bulbs increases. When hat voltage continues to increase, it reaches the point where it fries those remaining.

I can only assume something like that.  But still it is hard for me to understand how you get so many bulbs burn out simultaneous.

 

I could see a cascade maybe, where 1 bulb burns out, shunts, a second bulb immediately burns out, shunts, maybe 3 or 4 do this, and then the next shunt opening hits a voltage threshold on the remaining bulbs that they all burn out immediately upon that shunt opening.

 

I do not let bulbs burn out on my strands and stay burned out.  So for example, the most recent strand had all 50 bulbs lit the day before.  And they were not all bulbs from the same manufacturer since I had replaced maybe 25% of them over time as they had burned out.  Which make me question the sudden simultaneous burning out theory.  It would be easier to buy if all the bulbs were the same age, hours of use, and manufacturer.  You might expect in that case that there might be a voltage level that would cross a threshold at which they would all burn out simultaneously.

[DrLumen]

 

Except as I mentioned, the shunts (on at least the vast majority) didn't trip.  I didn't test every one, but most of the shunts were still open circuits.  So, again, you would have to have nearly instnantaneously burning out bulbs.  As soon as a single bulb burns out and (for whatever reason) the shunt stays open, then the rest of the working bulbs will shut off, not burn out.  In addition, all 50 bulbs were lit the day before. . . .none burned out/shunted.

 

 

I don't know why or was theorizing why your's went out. It was more for the OP's post about lights going out after being stored.

 

Are you sure yours burnt out? Perhaps there is a broken connection somewhere? Did you check the fuse in the plug?

 

While it is possible there was some type of domino effect like oberkc posted, I personally have never seen it happen. When 1 lamp blows it usually cuts power to the rest of the string - depending on how it is wired. With 50 or 100 or ... lights in the string, the voltage increase from 1 lamp going out or shunting would be minuscule across the rest of the string. Possible but not probable.

 

While not the voltage or power levels that stu described for street lights, some stage light effects use high wattage lamps in series. The strings I used were 4 lamps with a total of 1000 watts for the string. When 1 of those blew the hole string went out but only 1 lamp was bad. The really bad part was they were not cheap and the rated life was only 25 hours. So, when 1 went the others were usually not far behind.

[apostolakisl]

I don't know why or was theorizing why your's went out. It was more for the OP's post about lights going out after being stored.

 

Are you sure yours burnt out? Perhaps there is a broken connection somewhere? Did you check the fuse in the plug?

 

While it is possible there was some type of domino effect like oberkc posted, I personally have never seen it happen. When 1 lamp blows it usually cuts power to the rest of the string - depending on how it is wired. With 50 or 100 or ... lights in the string, the voltage increase from 1 lamp going out or shunting would be minuscule across the rest of the string. Possible but not probable.

 

While not the voltage or power levels that stu described for street lights, some stage light effects use high wattage lamps in series. The strings I used were 4 lamps with a total of 1000 watts for the string. When 1 of those blew the hole string went out but only 1 lamp was bad. The really bad part was they were not cheap and the rated life was only 25 hours. So, when 1 went the others were usually not far behind.

I am the OP.

 

Xmas lights as far as I have ever seen come in 35 and 50 bulb variety.  100 bulb or 70 bulb are just two sets of 35 or 50 in parrallel.  That is why someitmes you will get a half strand go out.

 

So you lose one bulb, voltage goes up by 1/50 or 1/35.  Taking 50 bulbs, each bulb is supposed to get 2.4 volts. If 10 bulbs shunt, you go up to 3v per bulb or 25% more than design.  Doesn't seem that crazy to me, and I have never had anything close to 10 bulbs shunting.  

 

Even if the filaments are brittle, I can't fathom how 50 working filaments would all break by putting them into storage and removing them.  I treat them quite gently.  Yes, I dont' doubt that maybe a few could break that were super brittle, but if they were all so brittle, I don't see how they could survive being taken down.  And like I said, I keep them lit as I put them away, so I know they are fine through the packing stage.  Plus, I have multiple strands of lights that are all the same, and maybe 1 out of 4 do this.  If the one strand was so brittle, then how do the other strands survive with zero failures having lived their entire life but a few feet away from each other.

 

To my thinking, there has got to be some event that causes a sudden voltage spike across all the bulbs to get them to all fry at once, but not high enough to trip the shunts.  The shunts need maybe 100 volts to shunt, but the bulbs would probably die in a nanosecond if you even put 25 volts on any one bulb.

[stusviews]

 And like I said, I keep them lit as I put them away,

 

The single most damaging activity that can happen to decorative bulbs.

[DrLumen]

 Oh well, I think we have explored all possibilities and yet they are still out. I guess all I have left to say is sorry for your loss. Frost Bank has some good home improvement loans to cover the replacement costs.

[larryllix]

I can only assume something like that.  But still it is hard for me to understand how you get so many bulbs burn out simultaneous.

 

I could see a cascade maybe, where 1 bulb burns out, shunts, a second bulb immediately burns out, shunts, maybe 3 or 4 do this, and then the next shunt opening hits a voltage threshold on the remaining bulbs that they all burn out immediately upon that shunt opening.

 

I do not let bulbs burn out on my strands and stay burned out.  So for example, the most recent strand had all 50 bulbs lit the day before.  And they were not all bulbs from the same manufacturer since I had replaced maybe 25% of them over time as they had burned out.  Which make me question the sudden simultaneous burning out theory.  It would be easier to buy if all the bulbs were the same age, hours of use, and manufacturer.  You might expect in that case that there might be a voltage level that would cross a threshold at which they would all burn out simultaneously.

Same thing I was describing in two previous posts.

 

Shunts are not designed to open up. They are shunts. When the filament breaks the shunt metal strips fall together. When too many shunts across the broken filaments short out inside the string then whole string burns out as the filament vapourise and then the shunts follow. These little metal strips can't stand up to a 15A circuit breaker.

 

It was a cure idea but a potentially dangerous idea.

[DrLumen]

lol. OT but I like your location larryllix. It reminded of a comedy bit that used the University of Southern North Dakota  at Hoople as the location.

 

Back to your regularly scheduled programming.

[stusviews]

He's actually toward the east side of Northern SouthWestern Ontario

[larryllix]

He's actually toward the east side of Northern SouthWestern Ontario

Southern tip of Georgian Bay at the east side of northern Southwestern Ontario, close to upstate New York. My next door neighbour, with the same name, lives across the street.  (all true)

[apostolakisl]

Same thing I was describing in two previous posts.

 

Shunts are not designed to open up. They are shunts. When the filament breaks the shunt metal strips fall together. When too many shunts across the broken filaments short out inside the string then whole string burns out as the filament vapourise and then the shunts follow. These little metal strips can't stand up to a 15A circuit breaker.

 

It was a cure idea but a potentially dangerous idea.

My understanding of the shunts is that it is a wire covered in insulation wrapped around the two legs that feed the fillament.  The insulation however is designed to break down at 120v.  So, if the fillament burns out, then electron flow stops and all 120v are presented to the shunt.  The insulation then fails and conduction resumes.  With flow resumed, the curreent across that shunt is the same as through the bulbs.  So if the entire strand is 20 watts with all the bulbs working, then it would be 20=120*I or .16 amps.  Now if multiple shunts are blown, the current will go up if the shunts have ~0 ohms of resistance.  I have read that some bulb manufacturers however use a resistor on the shunt that mimics a bulb.

 

The problem with theorizing that the shunts themselves fry is that again, it would require all of them frying at the same time.  As soon as one fries, then there is no potential across any of the others.

 

I already threw away the bulbs or I would look closer at the shunts to see if they are physically intact.

[larryllix]

My understanding of the shunts is that it is a wire covered in insulation wrapped around the two legs that feed the fillament.  The insulation however is designed to break down at 120v.  So, if the fillament burns out, then electron flow stops and all 120v are presented to the shunt.  The insulation then fails and conduction resumes.  With flow resumed, the curreent across that shunt is the same as through the bulbs.  So if the entire strand is 20 watts with all the bulbs working, then it would be 20=120*I or .16 amps.  Now if multiple shunts are blown, the current will go up if the shunts have ~0 ohms of resistance.  I have read that some bulb manufacturers however use a resistor on the shunt that mimics a bulb.

 

The problem with theorizing that the shunts themselves fry is that again, it would require all of them frying at the same time.  As soon as one fries, then there is no potential across any of the others.

 

I already threw away the bulbs or I would look closer at the shunts to see if they are physically intact.

OK. It seems the style / tecnique may have changed. The old ones I had used the shunt metal strips to hold the filament. When the filament broke the shunt metal strips would collapse together under some spring tension. The bulbs I had were clear and mde viewing easy.

 

Resistor substitution would make the whole technique safer for sure. I remember that string with many bulbs shorted out and the rest absorbing the increase in voltage across the remianing bulbs wondering when the whole thing would explode.