What would cause a light bulb to glow despite it being off?

Okay I was going to sleep, and in my room there is an old neon light bulb that just keeps blinking when turned on, so I never use it. Last night, however, the strangest thing happened. Even though the switch was off, the bulb was lit. It was producing a very dim glow, and you could easily see the light. And not only that, but if I touched the light bulb, it would glow a little brighter around my finger( 7 cm wide halo ). I want to understand how and why this occurs.

Including sources is encouraged

7 Answers

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  • Anonymous
    3 years ago

    yo it has a short in it. Not safe. Not safe at all! Contact a licenced electrition immediatally sorry tried over and over to fix spelling on immedioutly but im vision impaired and my speech synthesizer wont pronoiunce it correct so I just gave up. I'm not a speller/writer just a sound engineer so I apolojise in advanced

  • 3 years ago

    THE TROUBLE WAS COME FROM WRONG WIRING ON THE SWITCH THAT WAS INSTALLED BY SOMEONE WHOM KNEW NOTHING ON ELECTRICITY. THE SWITCH NOW IS CUTTING OFF THE NEUTRAL LINE RATHER THAN CUTTING OFF THE HOT LINE. THE HIGH VOLTAGE HOT LINE POWER IS STILL EXISTED INSIDE THE TUBE CIRCUIT WHILE SWITCH WAS IN OFF POSITION. AS YOUR BODY WAS GROUND WHILE STANDING ON FLOOR, AND BECAUSE AC POWER NEUTRAL LINE IS TIGHTED WITH EARTH GROUND,AND YOUR HAND ACTS LIKE AN AC COUPLING CIRCUIT ( CAPACITANCE COUPLING ) TO THE TUBE, A SMALL ELECTRIC CURRENT PATH WAS FORMED TO LIGHT UP THE TUBE A BIT WHERE YOU TOUCHED. CORRECT THE SWITCH WIRING INTO HOT LINE CUT OFF CAN FIX THIS SIMPLE TROUBLE.

  • 3 years ago

    Because it's NOT off. You may have a faulty switch AND a faulty bulb, or it may just be the switch. And it isn't a neon bulb, these are specialist lamps used in displays/signs and need a high voltage supply. You probably have a fluorescent lamp where it is mercury vapour that glows. When a fluorescent tube dies it is common for it to glow an orange colour at the ends.

  • 3 years ago

    Actually, there are two possibilities for this to happen:

    1) there is a strong electric/electromagnetic field where the bulb is placed. This was used for example by people who had a garden plot underneath the Berlin radio tower to light up their sheds. No wires needed, just hold up the tube ;-). Although it is actually illegal.

    2) more likely, though (there aren't that many people living under a radio tower...), the power switch for that bulb is in the return path. Perfectly normal and legal, especially when using cross switches (i.e. you could switch the bulb from several switches). This means that the electrodes inside the bulb are actually "hot", and any stray current may light up the bulb (slightly). So your bulb acts similar to one of those plasma balls - when you touch it, you provide a ground path, a small current flows and lights up the bulb in the place where you touch it.

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  • You probably have one of those light switches that glow when turned off. Those switches glow by allowing a small current to pass through a bulb when the switch is off{open} . The resistance of those glow lights is HIGH compared with the low resistance of the incandescent bulbs that were traditionally used. However the new energy efficient CF and LED bulbs have higher resistance so the slight current passing through the glowing light goes to the bulb and that high resistance causes enough of a voltage drop across the bulb for it light dimly. I cannot tell why it might glow a bit brighter near where you touch it.

  • Anonymous
    3 years ago

    it's called phosphorescence the glowing of the material that gives the light when the lamp is switched on

  • Them
    Lv 7
    3 years ago

    You're leaking power through the switch - or back around in a "feedback loop". These are very odd and hard to track down.

    I've worked in houses where I had even the MAIN power switch turned off, and I was still getting shocked on the wires I was working on just a little. I think it read something like 14 volts on my meter.

    It's either magic......... or I could just never figure out the source. Everything worked OK even with that going on.

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