Fun with electricity

[FireTiger]

No these are burned- all of them- the insides of the bulbs is cooked and the filaments are all blown open. This were nice three strand lights where as long as the bulb exist in the circuit they work. (I have six on of 50)

[bben46]

(Long boring technical explanation of why an LED is not like the incandescent lamp in your refrigerator removed as it is not relevant to this discussion :P )

 

The bulbs in question seem to be incandescent and not LED.

 

A high voltage surge may cause what is described. - the incoming line voltage increased from it's nominal 120VAC to - say 150VAC due to some temporary (seconds not hours) condition affecting the line. This does not usually affect most appliances as they are name plated at 120VAC, and are really designed to be able to handle quite a bit more for short periods of time. 130VAC for a short time is not that uncommon (you may notice your overhead lights brighten for a few seconds then drop back down)

 

On an inexpensive Christmas tree string of lights, the tolerance may not be as good and the sudden surge caused a failure. OR, the maker may have used a lamp that was not quite up to what was needed such as a lamp designed for a 100 lamp string used on a 50 lamp string to get a higher brightness. Due to the series circuit, as individual lamps fail, the voltage on the other lamps will increase proportionately. ( that voltage has to go somewhere) the other lamps will be slightly brighter also - causing the life of the other lamps to be shortened. As each lamp fails, the voltage on the rest goes up again. Some lamps will have a higher tolerance than others and last longer. In this case, the lights would ripple as they failed one after another with the remaining lamps getting brighter before failing.

 

Something like this would not get UL approval in the US (CE in Canada) or most other countries standards rating organization either. But there have been reports of bogus UL tags on cheap strings of lights from a certain country.

 

But. whatever the cause, I cannot see the magnets as having any effect.