Halogen bulbs keep popping.

[Dust]

I have a set of under-counter halogen puck lamps for a cabinet at work. They are 120v plug ins, 25 watt bulbs. On the back of the pucks I glued a neodymium magnet so that I can reposition them on the metal cabinet.

They keep blowing bulbs. They'll last for up to a month, and then pop. I can also see the light shimmer, and the filament vibrates. I have tested the power with my volt meter and am getting a steady 119-120v at 59-60hz. The only time it drops is when the air compressor kicks on and draws power from every circuit in the shop.

Could the strong magnets be affecting the filament, causing it to vibrate with heat? Or am I just getting crappy bulbs? I buy Feit Electric brand bulbs from Home Depot, since it's just around the corner from my work.

 

[Torque1st]

The magnetic field will cause any alternating current carrying wire or a filament to vibrate if it is free to move. That is why a motor works.

 

[ArthurPE]

The magnetic field will cause any alternating current carrying wire or a filament to vibrate if it is free to move. That is why a motor works.

what he said...

 

[fourfeathers]

Are you keeping the bulbs clean? Oil from fingers causes hot spots.

 

[nadogail]

Are you keeping the bulbs clean? Oil from fingers causes hot spots.

Do not touch the bulbs with your fingers when changing them, use the sleeve from the carton.

 

[Tscott]

I agree with the above about the magnet. Try removing one of the magnets and see if it solves the problem. Magnetic fields and electricity are kissing cousins and can effect each other in odd ways.

Tom

 

[Dust]

I use clean and dry latex gloves when changing them, or a handy paper towel. These bulbs don't have paper sleeves for packaging. The bulbs don't actually pop either, the filaments break.

I was thinking the magnets. They're pretty strong rare earth magnets, so I'd imagine their affect on bulbs powered by A/C might be weird.

 

[rocketman]

Lose the rare earth magnets.

VELCRO TAPE

 

[rinny_tin_tin]

I have a set of under-counter halogen puck lamps for a cabinet at work. They are 120v plug ins, 25 watt bulbs. On the back of the pucks I glued a neodymium magnet so that I can reposition them on the metal cabinet.

They keep blowing bulbs. They'll last for up to a month, and then pop. I can also see the light shimmer, and the filament vibrates. I have tested the power with my volt meter and am getting a steady 119-120v at 59-60hz. The only time it drops is when the air compressor kicks on and draws power from every circuit in the shop.

Could the strong magnets be affecting the filament, causing it to vibrate with heat? Or am I just getting crappy bulbs? I buy Feit Electric brand bulbs from Home Depot, since it's just around the corner from my work.

Halogen bulbs run hot and they blow quick anyway. I'd be surprised if the magnets do anything to shorten their lives, and the field from a magnet is fixed - that is not alternating like a motor. So - there should be no movement owed to the magnet. Also, inasmuch as neodymium magnets are "strong" when compared to other magnets, the field drops quickly. Vibration and shock will impact filament lamps. Is the counter subject to vibration/shock?

 

[mrb]

try some 130v lamps. or put it on a dimmer and dim it to 85-90%

 

[Dust]

Is the counter subject to vibration/shock?

A little more so than a often-used kitchen cabinet, but nothing that would be considered abusive or anything.

 

[Torque1st]

the field from a magnet is fixed - that is not alternating like a motor. So - there should be no movement owed to the magnet.

The alternating current is in the filament and interacts with the fixed magnetic field. The magnet field strength is strong locally.

http://en.wikipedia.org/wiki/Magnetic_field#Force_on_current-carrying_wire

 

[rinny_tin_tin]

A little more so than a often-used kitchen cabinet, but nothing that would be considered abusive or anything.

At the high temperatures Halogens operate at, it won't take much vibration to interrupt the iodine depositing process and cause "necking" of the filament (a hot spot that serves as a weak link). Halogens are more sensitive to vibration than other filament systems. Using a dimmer or soft start means is effective in increasing halogen life - and is the means used commercially.

Another item that may possibly contribute is heat buildup if the generated heat cannot convect up and away. If it is shock/vibration, a damped mounting arrangement such as a floating - say a board with the lights mounted but connected to the countertop via suspended cables...like how the DJs used to isolate turntables in the old days.

However, I can guarantee that your problem has nothing to do with the magnets.

 

[Stuey]

How about a test? Remove the magnet from one of the pucks and see if the bulb outlasts the others.