I have a light fixture over the landing of a staircase. It’s controlled by a couple of 3 way switches, one at the top and one at the bottom.
Last night, my wife noticed that the switches were no longer turning the light completely on or off, but instead the light was in a constant twilight mode, and the switch did not affect this. I checked this morning and at least one time the switch made it flicker a bit, and if you turned it on and off a bunch of times it sometimes went entirely off, but for the most part it’s just in this partially on mode.
The bulb is an LED.
What’s up with this? I assume it’s a problem with the switch(es) and not the fixture.
(And I certainly hope so. This fixture is about as inaccessible as you can get, being about 13’ off the ground and over the point where the landing meets the top stair of the lower steps. I installed a hanging light so as to be able to access the bulb when necessary, but did that work while standing at the top of a stepladder which was mounted on some planks which ran between the fourth step of the upper stairs and a couple of cinder blocks which were standing upright on some kitchen chairs I had placed on the landing. Don’t want to do that again. :))
It actually sounds like a grounding problem, which can cause feedback on the neutral conductor, but without looking at things, that’s just a guess. You probably need an electrician.
Assuming your guess is correct, is that an issue with the fixture connection or the switch(es)? In general, can you be a bit more specific as to what it is that you’re speculating? Thanks.
I’m having a similar problem with a 2 bulb fixture where I recently changed a dead bulb for an LED. It is not a no-name bulb though. The switch for the circuit cuts the common line from what I can tell which is not standard practice. The switch is quite old and may be original to 1960. So perhaps different practices back then.
When I turn off the switch, one side has 37 VAC to ground and the other remains 0 VAC and I get a dim glow from the LED bulb. When the switch is on, both sides are 0 VAC. So I suspect a bulb issue to go along with bad wiring.
Generally, it’s an issue of unbalanced load at the main panel and an inadequate house ground. It’s fairly unlikely that this is the problem, as you would likely be seeing “ghost” lighting in other fixtures and other problems. Someone mentioned crappy Chinese bulbs, which I was unaware of, so that may be a simpler explanation. When troubleshooting, it’s always best to try the simplest solution first, so I’d get the bulb replaced with a more reliable one like Cree, and see if the problem persists.
I think if it was the cheap bulb problem, then it would have to be neutral being switched and also some sort of break in the switched line since it can’t be turned fully on or off.
I would also be turning off the circuit breaker and getting it checked out in case there is some dangerous arcing going on anywhere.
Yeah, a switched neutral could cause similar problems to an unbalanced load, I’m thinking. It’s also very dangerous and against code unless you live in Europe.
Great and cheap! When I taught Construction Electrician “A” school in the Navy, we did a troubleshooting phase where the instructor would create faults in a wired cubicle that the student had wired up. A fault that I always included was to screw a burned out bulb into a fixture. I don’t ever remember any student first trying to replace the bulb as a likely fault. I doubt that any of them ever forgot the lesson.
So I replaced the bulb a couple of days ago, and all was well. Today, I got a short in that circuit. The circuit breaker tripped and won’t stay off unless both three way switches which control that fixture are in the OFF position. This is so even when there’s no bulb in the fixture.
I don’t know for sure if it’s related, but it’s the same fixture and a few days apart, which is suggestive.
Is there a way to know for sure whether it’s one (or both?) of the switches or the fixture without taking things apart? Replacing the switches would be pretty straightforward, but the fixture is extremely inaccessible, as above. But I’m wondering if perhaps the fact that there’s an issue even with no bulb, or the fact that turning either switch ON causes the issue, could be instructive before even taking things apart.
I doubt you’ve got any significant resistive leaks through the switches. You’ve probably got a small current leak enabled by capacitance through the wiring. There’s not much you can do about that, although one fettle would be to add a resistive shunt across the bulb, at the expense of adding a little heat and reducing the overall efficiency of the bulb.
Another odd leakage mode with LED or CFL lights is to have the things slowly strobing when the switch is off. This again is generally due to capacitive leaks, where a small amount of leakage current builds up a DC voltage on the capacitor on the output side of the bulb’s rectifier. When the voltage gets sufficiently large the bulb turns on, discharging the capacitor and turning the bulb off again. Rinse and repeat.
If I read this right, you’re saying that if you try to turn the light on, the breaker trips? If so, that’s not a problem with a switch, but a problem with the wiring.
An LED bulb can glow dimly if there’s a voltage applied only to one side. I think this is because the light has a little capacitance, so it takes a charge which discharges slowly (and is constantly replenished) as the LED emits light. One way this can happen is if the fixture is wired backwards, so the threaded part is the hot side. I suspect that your first problem was a high-resistance short that energized the threaded side of the fixture. This could have caused it to glow dimly both when the light was supposed to be turned off (because of what I just described) and when it was supposed to be turned on (by lowering the voltage across the bulb).
If my thinking is correct, you somehow disrupted this short when you replaced the bulb. Then, a few days later, it reappeared as a low-resistance short on the hot side, so that when you energize the fixture it trips the breaker.
To diagnose this problem, it would help you to have a non-contact voltage tester, AKA a “chirper.” This will tell you whether a conductor is energized without having to take things apart, and without needing a ground to test against.
I suspect there’s something wrong in the wiring of the light fixture. If you’re competent with electricity, you might want to fix it yourself. If not, you should call an electrician. This sounds like a dangerous problem.
Oh, and you might want to tape the light switches into an “off” position until the problem is fixed.
The most recent few posts are going over my head, unfortunately. I’ve replaced a lot of light fixtures, switches, outlets, etc. over the years, but that just means I know how to follow printed instructions and connect black to black and white to white etc. Anything past that is beyond me.
My understanding - which could of course be wrong - is that a short simply means that there’s a wire connection being made at some point where there is not supposed to be a connection (via incorrect wiring, worn insulation, or the like). So the “short circuit” means simply that the circuit is not as “long” as it should be, since the loop is being made at an earlier point in the setup. For whatever reason, this overloads the system, and therefore trips the breaker.
The problem is that there are wires everywhere in the system. The switches are connected to wires, the fixture is connected to wires at another point, and the fixture itself has wires in it. So saying it’s the wires doesn’t really tell me anything, because all shorts are about the wires, but the question is which wires or at which point in the wires it is. ISTM that there are 3 possibilities, 1) the wire connection between a switch and house wiring, 2) the wire connection between the house wiring and the fixture, and 3) some internal wiring in the fixture itself.
As previous, the only possible clues I can think of are that 1) the short occurs if either three way switch is flipped to ON, and 2) this happens regardless of whether there’s a bulb installed. Though these may not be instructive at all - as above, I am ignorant about such matters.
