Positive and Negative pin of Halogen Bulb


Joined Jan 27, 2019
The filament looks blown to me.
Can you measure the resistance across the terminals?
IN the absence of an ohmmeter, you can try connecting power (polarity doesn't matter) and very gently tapping the lamp. Many times the break is very small and it will weld itself back together. I used a halogen desk lamp, which I dearly loved, for many, many years and I was able to extend the life of the lamps by as much as four times be carefully "restoring" the filament this way. Success, and the degree of it, depends on the nature of the fault, but it works to frequently that it became routine and replacing lamps was the exception.


Joined Sep 24, 2015
very gently tapping the lamp
Had a car headlamp that would go out. I'd roll down the window and rap on the fender and the light would come on. Did that for months before it wouldn't work anymore.

Yes, GENTLY tapping on the lamp MIGHT get it to light up. But if the filament is melted back significantly then no amount of rapping will work.

Like others have said, a halogen lamp is not polarity sensitive. You can wire it up either way. However, and this point has also been covered, you NEVER touch the glass bulb with bare hands. Cotton gloves or a tissue are needed. Why? Because oils from your hands or dirty rags WILL severely shorten the life of the lamp. The bulb runs extremely hot, and oils on the glass will prevent the bulb from dissipating that heat. The bulb will burn out much sooner. In some cases it'll burn out in a few hours - from what I've witnessed. I, too, learned the hard way not to touch the glass bulb with bare hands.


Joined Mar 13, 2020
learned the hard way not to touch the glass bulb with bare hands.
Me too.

Yes. No polarity. An incandescent light bulb is just a very large resistor. It can be hooked either way. An LED lamp IS polarity sensitive. So if you replace the halogen with an LED lamp then you have to pay attention to polarity.