It's been a week since a light bulb in the bathroom died. I'm wondering if the bulb is dead, does it still consume electricity if the switch is in ON?
The light is completely dead, no light whatsoever.
Electrical – If a light bulb is dead, does it still consume electricity if the switch is in ON
bulbelectricallightswitch
Related Solutions
This is a non-contact voltage tester. It's not telling you there there is current passing through the wires, just that AC voltage exists. Since you switch the hot connection within a light switch, there will always be voltage present around a switch (unless you have tripped the breaker). It's the wiring after the switch where you shouldn't see voltage with a non-contact tester. If you do, then someone may have miswired the switch and switched the neutrals.
Look closely at that light switch. See the two switch blocks (one blank) and the almost-square translucent fringe around both of them? That lights up. That is a backlight designed to help you find it in the dark. You may have known this and forgot to mention it, or maybe it doesn't work for a particular reason. Here is how those switches are wired internally.
As you can see, power flows through this circuit at all times. If it's not going through the switch, it's going through the backlight. Incandescent bulbs are quite low resistance when they are not burning (their resistance increases greatly as they heat up). These backlights exploit that by leaking a tiny amount of current through the incandescent bulb, too little to make it glow, but enough to light the backlight.
Well, LED bulbs monkeywrench this arrangement. They aren't low resistance when off. If current will go through the LED bulb with the backlight impeding flow, it may make the LED bulb function. It might even make the LED bulb work, and the backlight not. And that kind of thing is what you're running into.
Solution:
- Go back to incandescent bulbs. If it's a multi-bulb lamp, only one needs to be incandescent.
- Go to a plain switch with no backlight.
- Get a more modern switch that works the new way (not depending on leakage current, but requiring a neutral to the switch).
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Best Answer
It depends on the type of bulb.
Regular incandescents won't consume any electricity if the bulb is dead, since there's no continuous path for the current to take. It's just like an open switch.
With CFLs and LEDs, it depends on why the bulb burned out, but in general they will consume some amount of electricity even when burned out. Some CFLs may even consume up to 50% as much as a good bulb (older link, but a lot of burned out bulbs may be old). Newer bulbs may have circuits which eliminate most electricity usage on dead bulbs, as this answer from the electronics stack shows.
Smart bulbs have additional electronics, and so would consume even more electricity than an equivalent non-smart bulb, assuming of course that it's not the smart electronics that died.
The only way to be sure is to measure the usage, with a device like a Kill-a-Watt meter. You would need to install the bulb in a lamp or other fixture with a plug.