What LED failure rate is acceptable?

[Davisonp]

Hi,

What do people consider is an acceptable failure level for LED bulbs?

I have two examples, both from TLC "LEDLite" home brand lights.

1st, I fitted 6 of their 8W filament LED bulbs with 2 years guarantee in my parents house, and 3 have failed within the first year. (50% failure in half the guarantee period)

2nd I fitted 45 “LED Fire Rated Downlight” lamps (all in one fitting) with 5 year guarantee. Two years in and there are already 6 lamps that have failed, so that is over 10% failure in less than half the guarantee.

I would like to tell TLC that a 50% failure rate is unacceptable and get a full refund on all 6 lamps since they are not fit for purpose, but what about the 10% failure on the 45 lamps?

 

[DefyG]

Sorry for being silly, but wondering if anyone has come across any failures of GU10 fittings (the fitting itself, not the bulb)?

A few mechanical failures but not electrical, why do you ask?

 

[brianmoooore]

Had failures of the twist on GU10 connector and wires on occasions, but only with 50W incandescent halogen lamps, presumably due to heat. No fitting failures with GU10 replacement LED lamps.

 

[Alla Musica]

Had failures of the twist on GU10 connector and wires on occasions, but only with 50W incandescent halogen lamps, presumably due to heat. No fitting failures with GU10 replacement LED lamps.

That's interesting. For those halogen bulbs did they have aluminum or dichroic reflectors?

 

[brianmoooore]

That's interesting. For those halogen bulbs did they have aluminum or dichroic reflectors?

The lamps I kept on the shelf and used with fittings I installed were dichroic, but I never really took much notice when fault finding in customers' houses.

 

[Alla Musica]

A few mechanical failures but not electrical, why do you ask?

I had quite a few traumatic instances of damaging the plasterboard (or its finish) while replacing downlighters, which is part of the reason why I prefer front-load GU10 fittings which contain no electronics and technically should last almost forever (only the bulb would fail). Thus simply curious what might still happen to these fittings!

 

[brianmoooore]

Any GU10 can with a 50W lamp, that had been installed for a while would have seriously cooked the plasterboard around it, making it difficult to remove without ceiling damage. Best way was to pull one side of the fitting down a few mm, then flip the fixing spring off of one of its pegs, then pull down the other side and repeat. Risked never seeing the springs again, but that's preferable to a ragged hole.

 

[Alla Musica]

The lamps I kept on the shelf and used with fittings I installed were dichroic, but I never really took much notice when fault finding in customers' houses.

I see - dichroic lamps might indeed overheat anything located above, especially if enclosed by the fire can! Also eard from a few sparks complaining about their clients' ceiling voids (or something else) ruined by dichroic halogen reflectors. But we're in the era of LEDs now anyway...

 

[Alla Musica]

Any GU10 can with a 50W lamp, that had been installed for a while would have seriously cooked the plasterboard around it, making it difficult to remove without ceiling damage. Best way was to pull one side of the fitting down a few mm, then flip the fixing spring off of one of its pegs, then pull down the other side and repeat. Risked never seeing the springs again, but that's preferable to a ragged hole.

Thanks - this has been really useful

Not a fan of halogen lamps anymore - not to mention the power consumption or cooking up the plasterboard, mains halogen lamps could arc and explode badly in the wrong circumstances...

 

[Teddy Lop]

Thanks - this has been really useful

Not a fan of halogen lamps anymore - not to mention the power consumption or cooking up the plasterboard, mains halogen lamps could arc and explode badly in the wrong circumstances...

Any halogen lamp, and several other types, have the capacity to explode on element failure, which is why a GU10 lamps element is double sealed, and other forms such as linear floodlight bulbs must be behind safety glass (although open-rated hardened glass lamps were an option)

I've never come across a failed GU10 connector, MR16's became unreliable but then they had 20x the current @ 4 amps each to deal with in addition to 300 odd degree heat.

 

[Alla Musica]

Any halogen lamp, and several other types, have the capacity to explode on element failure, which is why a GU10 lamps element is double sealed, and other forms such as linear floodlight bulbs must be behind safety glass (although open-rated hardened glass lamps were an option)

I've never come across a failed GU10 connector, MR16's became unreliable but then they had 20x the current @ 4 amps each to deal with in addition to 300 odd degree heat.

Just curious, have you ever come across any LV halogen exploding? Since they work on a far lower voltage, would they be less likely to arc than mains halogen? I know the quartz capsule could explode if heated non-uniformly (especially if in contact with hand grease), but might arcing be another cause for explosion, I guess? (I might be wrong...)

And speaking of the difference in current, is it that LV halogen normally runs hotter than mains halogen of the same wattage?

 

[Teddy Lop]

Just curious, have you ever come across any LV halogen exploding? Since they work on a far lower voltage, would they be less likely to arc than mains halogen? I know the quartz capsule could explode if heated non-uniformly (especially if in contact with hand grease), but might arcing be another cause for explosion, I guess? (I might be wrong...)

And speaking of the difference in current, is it that LV halogen normally runs hotter than mains halogen of the same wattage?

Bulb elements can collapse and short circuit (back when stuff was made properly filament bulbs incorporated fuses so they didn't knock out the lighting circuit) but in halogens shattering it's more the hot ruptured element hits the glass and the thermal shock is too much, easier to see on this linear, the two blobs are fragments of element melted its way through the glass which has re-set instead of shattering

As for current, remember P=IV, so drop the voltage by x20 and for a given power the current has to increase. I=P/V, 50/12, 4.16 amps.

I dont know if LV officially runs hotter - they do seem a little hotter and are measurably brighter than GU10's for a given wattage though

 

[Alla Musica]

Bulb elements can collapse and short circuit (back when stuff was made properly filament bulbs incorporated fuses so they didn't knock out the lighting circuit) but in halogens shattering it's more the hot ruptured element hits the glass and the thermal shock is too much, easier to see on this linear, the two blobs are fragments of element melted its way through the glass which has re-set instead of shattering
View attachment 119176

As for current, remember P=IV, so drop the voltage by x20 and for a given power the current has to increase. I=P/V, 50/12, 4.16 amps.

I dont know if LV officially runs hotter - they do seem a little hotter and are measurably brighter than GU10's for a given wattage though

That's really interesting and informative

Back when I was little (in China, late 1990s), mains halogen reflector bulbs (GU5.3 MR16 / GU4 MR11) were popular when it came to spotlights, which then were superseded by 12V ones from 2000s onwards before being eventuality substituted by LEDs.

Wonder if mains or LV halogen came earlier in the UK (should you ever know a bit of history)?