All landscape bulbs blown in one night?

[mark32]

Over the summer I installed 6 low voltage path lights along with the associated items. I received a call saying that none of the lights were working so I stopped by today to check it out. GFCI that trans is plugged into, good.
Timer that operates the GFCI, good.
Trans output, 12v's
One splice I made connecting two runs together, good.

I was stumped, I pulled one bulb, visually it looked good. Meter says I have 12v's at socket, huh? Switched meter to continuity and checked bulb, bulb no good, huh? I checked another and the same thing, so I replaced two bulbs because that's all I had. How is it that all the bulbs could blow in one night? I am guessing a power surge could have taken them out, is this a viable theory? There are a number of line voltage lights on the same circuit that feeds the transformer but those are all okay.

 

[readydave8]

also possible that they didn't all go out at the same time, although many times customer didn't notice until they were all out.

 

[MikeyinLA]

also possible that they didn't all go out at the same time, although many times customer didn't notice until they were all out.

True, I have seen this happen for years, many, many times.

 

[danickstr]

did anyone megger the LV wire in the middle of the night?

 

[satcom]

How long was the run? Is the transformer sized correct ? Is the wire run the correct size ? Often when the run is long and sized wrong the lamps will not last

 

[brantmacga]

also possible that they didn't all go out at the same time, although many times customer didn't notice until they were all out.

even so, to have every bulb in a 6/mo old installation fail is something to worry about.


could've been surge i suppose.

did you check the lamp voltage?

i have a contractor friend that installed new fixtures labeled as 12v, but had 6v lamps installed. they came like that from the factory; blew the fuse on the first night.

 

[kwired]

How long was the run? Is the transformer sized correct ? Is the wire run the correct size ? Often when the run is long and sized wrong the lamps will not last

If the run is long and undersized the lamps should last longer just not operate as bright.

I would guess that not all lamps burned out the same night or they are not the correct voltage lamps.

Another thing - if one lamp burns out or is removed from the circuit the voltage will rise because of less load on the source, but at the same time on long runs there will be less voltage at the last lamp than there is at the first - simple voltage drop issues at work here and at 12 volts it doesn't take much drop to make an impact on performance.

 

[charlietuna]

Too many lamps causes low voltage and lamp life was seriously reduced ..

 

[iwire]

How long was the run? Is the transformer sized correct ? Is the wire run the correct size ? Often when the run is long and sized wrong the lamps will not last

That does not make sense, reduced voltage will greatly extend the life of incandescent lamps.

 

[iwire]

Too many lamps causes low voltage and lamp life was seriously reduced ..

Low voltage extends lamp life.

 

[K8MHZ]

Chinese QC failure.

I'll bet all that happened was that he got a bunch of bad bulbs.

 

[satcom]

Chinese QC failure.

I'll bet all that happened was that he got a bunch of bad bulbs.

The bulbs are most likely ok, there may be to long a run, I ment to say bulbs will not light not last

 

[kwired]

The bulbs are most likely ok, there may be to long a run, I ment to say bulbs will not light not last

That would mean there is a severe drop in voltage he said he had 12 volts at the socket and no continuity through the lamp.

I have another suggestion - vibration, physical shock. was there windy conditions shaking the luminaires?

 

[K8MHZ]

The bulbs are most likely ok, there may be to long a run, I ment to say bulbs will not light not last

From the OP

Switched meter to continuity and checked bulb, bulb no good, huh? I checked another and the same thing,

All the bulbs in the string that seemed to burn out at the same time may have been from a batch of defective bulbs, most likely too short of a filament wire, improper or non-existent evacuation or bad base sealing.

 

[satcom]

Chinese QC failure.

I'll bet all that happened was that he got a bunch of bad bulbs.

That would mean there is a severe drop in voltage he said he had 12 volts at the socket and no continuity through the lamp.

I have another suggestion - vibration, physical shock. was there windy conditions shaking the luminaires?

There are so many things that could go wrong, just last week we had a call for landscape lights out, turned out the landscapers were digging in the yard to plant a shrub and cut the run

 

[al hildenbrand]

How is it that all the bulbs could blow in one night?

The only other thought that comes to mind is mechanical shock or vibration. A lit lamp is more susceptible to filament failure when the whole fixture is shaken or struck by, say a stick.

Does the client have kids?

 

[bolthead]

It is not unusual for all the lights in a run to go out at once. One of my clients is a "Big Box" home store and in two years I have caught maybe three to five calls and showed up to relamp the displays. The calls were all at different stores and the displays come from the vendor, so they were installed according to manufacturer suggestions. Relamp the lights and check back with the customer by phone every month or so. That way they will have to take note of one or two outages. Also the lamps are inexpensive, you could leave them a pack and show them how to change them.

 

[K8MHZ]

The only other thought that comes to mind is mechanical shock or vibration. A lit lamp is more susceptible to filament failure when the whole fixture is shaken or struck by, say a stick.

Does the client have kids?

Indeed, incandescants are very susceptible to vibration related failure. I know first hand as my Harley has the tail / stop light mounted to the swing arm. I get more miles to a tank of gas than a tail light bulb. (Re-mounting scheduled for winter).

But look at the application. These are path lights. What could possibly cause enough vibration to wipe out all the lights, which aren't physically connected to each other?

I have seen short life due to vibration caused by slamming doors which made the fixture shake, proximity to airports during jet stunt shows and vibration from heavy equipment traffic, so I know it's possible. It just doesn't seem likely in this particular case.

 

[wdemos]

Must have slept through an earth quake.

 

[al hildenbrand]

But look at the application. These are path lights. What could possibly cause enough vibration to wipe out all the lights, which aren't physically connected to each other?

Kids with sticks, etc.