LED bulb glows after I turn it off

I have a faucet that does the same thing.

The other day I bought some LED light bulbs to replace the incandescents in a light fixture. The light was on most of the day and evening until I went to bed. When I got up this morning, the bulbs were glowing faintly – one brighter than the other four. I removed one of the bulbs and it and the others continued to glow. It doesn’t look like phosphorescence; they seem to be on, but at low power.

It’s not a problem in this particular application, but it would be in others. When I turn a light off, it should go dark. If they can’t make that happen, the manufacturer should market it as a feature – “New, Afterglow® technology!” – and charge a dollar more.

UPDATE: Less than three months later, 2 of the 6 that I bought have stopped working. Whether because they’re junk or because my old house’s wiring is bad I don’t know. But it’s something I’ll have to take into account. They also had a depressing blue tinge, and were far dimmer than the package claimed – almost unusable. I’ve put the rest in some little-used fixtures. I’m going back to incandescents for now.

UPDATE 2: This short post on LED lighting may be of interest.

UPDATE 3, 12 October 2010: Dave Farquhar “got an LED bulb, and it is fabulous”. I’ll have to give them another try.

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6 thoughts on “LED bulb glows after I turn it off

  1. I’ll bet it’s a sign that your house is wired wrong, that you have the hot lead going directly to the light instead of to the switch, so there is a small amount of electric current even when the switch is off.

    Of course I’m not an electrician, so I don’t actually know what I’m talking about.

  2. That’s possible, but something else is going on too. The bulbs stay lit after I remove them from the lamp. I could carry one around like a flashlight for at least an hour. There must be capacitors or some other energy storage mechanism.

  3. Maybe they’re chargeable. You could dock them overnight in the chandelier and then use them to read by in the evenings.

  4. 0.o

    That is very odd– all the LEDs that I worked with in electronic equipment when I was in were very good about turning on and solidly off.

    It’s got to be an artifact of the “bulb” housing– plain LEDs are, well, really simple…..
    http://electronics.howstuffworks.com/led1.htm

    ….K, I really need to go brush up on my electronics again, reading this stuff has my brain half-remembering stuff I haven’t touched since C-School…..

  5. It doesn’t have anything to do with your house wiring. The device uses a capacitor for current limiting through the LEDs. (Yes, I said capacitor, NOT resistor). That’s the least expensive circuit to operate LEDs from AC line voltage, and is how they’re wired in LED traffic lights, so it’s no surprise that they’re doing the same in “light bulbs” now. The capacitor retains some charge after the power is removed.

    I had something similar happen with an LED “bulb” last month. This one did not glow when removed from the socket, but when I touched both contacts with my hand, it glowed fairly brightly then faded over about half a second. My hand completed the circuit to allow the capacitor to discharge through the LEDs. The circuit topology must have been slightly different than that of the bulbs you describe.

  6. I have the same problem: an LED bulb that glows after being switched off. At first, I thought it had to be a capacitor, but the glow did not go away after as many as 8 hours. Also, it did not seem to glow when used in a different fixture, which would point to something other than the bulb itself as the culprit. I use the bulb in 50+ year old 3-way circuit. I have five 3-way circuits in the house and this is about the only one that’s wired to work correctly (both switches can independently control the light). I inspected the 2 switches and replaced the “light duty” one with a new “heavy duty” switch, hoping for a “soft open” in the switch, to no avail. I traced the circuit as best as I could, and it looks like the bulb is wired to the white wire (neutral) from the source, but for all I know, this wire could be the hot wire, given the attention to quality given to the other 3-way circuits.
    If anyone has any other thoughts or suggestions please let me know. The last time I contacted an electrician for a seemingly minor problem, he wanted $1600 to re-wire the circuit. (It turned out to be a loose wire at a fixture that had been recently replaced.)
    Thanks.

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