Blinking fluorescent light

[dlminehart]

I installed small fluorescent lights in two closets. The lights are compact fluorescents with an unusual plug-in base rather than the usual light bulb screw-in type, housed in a 4" circular dome. Available at HD for about $12. Both are wired to a junction box in the basement below, as is the furnace.

Both turn on and off fine. However, when off, one of them blinks on faintly and very briefly about once every second. It's been doing this for a couple months, and I'm at a loss as to the cause. Any ideas?

[LCHIEN]

two things come to mind:

one, the electronics is trying to light the bulb, ergo the switch/electronics is not really off. A little leakage current could be energizing the bulb just barely to the threshold of ionization - a bit of noise or surges on the line could be just passing the threshold and making it light briefly. What kind of switch, have you tried swapping bulb and see if it follows the bulb or the socket? is it a hard switch which usually won't leak any or a light-activated/motion-activated/dimmer/remote-activated using a solid state switch than can leak with a faulty switching component?

Two, fluorescent bulbs can be activated by strong electric fields - don't have to have direct electrical connection if the field is strong enough. You can fully light one by holding it next to a strong radio transmitted for example. Do you have anything with a modest electrical field nearby - high amperage feed line, radio transmitter etc that could just barely make it light?

[steve-norrell]

To second Loren's comments . . . .

When I was an active amateur radio operator the lights around the transmitter would glow slightly when ever I transmitted. The show got quite interesting when I was using Morse Code - - you could almost read my message by watching the lights.

The kids were still little then and I told them that the room was haunted -- it kept their inquisitive little minds safely out of the radio room, at least until they caught on.

The interesting thing about your lights is the once-per-second frequency. Wonder what that is?

Regards, Steve

[twistsol]

I've had the exact same problem with two types of switches. One was an electronic motion sensor switch. that I put in the garage to keep the family from leaving the lights on every time they left. Only the light closest light to the switch did this, the other four on the circuit didn't. The blinking on this switch was much more rapid than you describe

The other type was a three way switch that where the switch itself glowed when off. I measured the voltage on this one and it was constantly passing about 25v on the off traveler. This one was much closer to the once per second.

Check the socket for voltage with a multimeter with the switch off. I use one of those lightbulb to outlet adapters to make this easier.

Just a WAG on the once per second flash, I wonder if the starter in the CFL uses a capacitor and thinks the light is supposed to be on, builds up enough charge to start, but doesn't have the power to keep it running. No actual knowledge of how CFL's work went into this hypothesis.

[L. D. Jeffries]

Yeah, back when I was working an active radar landing system we used to put up fluorescent bulbs in the shape of a Christmas tree. Every time the radar sweep would pass the lamps they would light up. Kind a neat at the time.

[phi1l]

You can take a florescent bulb and use ti the check your microwave for leaks. just take the bulb & move it around the door when the microwave is running..


This almost sounds like socket might be wired with the ground & neutral wires switched..

[Mr__Bill]

Any switch that does something other than switch uses electricity. Most are set to not need a common and just trickle a bit of power through whatever is switched by the switch. This is very little and most often is not noticed unless you turn the switch off and stick your finger in the light socket... or have something attached that will respond to the trickle current.

This is not to say that the OP has a smart switch and that is the cause. Most likely it's a bad switch a wiring problem or there are Pookas in the house.

Bill

[dlminehart]

This switch is one with a built-in light. I'll bet that's the problem. I'll swap it out and see if that fixes it. Thanks for the suggestions!