Question for Electricians

[Walter Rego]

I have one of those 37 watt CFL bulbs in a bathroom combo light/exhaust fan fixture. Recently I noticed it flashes just for a fraction of a second like it's trying to start, and this is happening when the wall switch is off. It's not a bright flash like the full wattage but enough to see in a darkened room and if you blink you will miss it.
Is this anything I should be concerned with ? Should I replace the wall switch ? How the heck could the bulb be getting power with the switch off ?
Thanks

 

[Straightshooter2]

Out of curiosity does this happen all the time or just at certain times? Is there any source nearby that radiates any type of RF energy?

CW

 

[shouldazagged]

Poltergeist?

 

[rimfired]

Pull the covers on all switches and outlets on the same circuit.
I've seen the old very small metal outlet boxes have the larger switch/outlets installed with the unused screws not tightened. Close enough for a mild "potential arc" to occur.

Turn breaker off, tighten screws, or perhaps align the switch tightly in the box.

Loose connection screw will display same.

Wrap connections with e-tape just to be safe.

 

[Lee in Quartzsite]

CFL bulbs are a Chinese conspiracy to do us all in and it's promoted by our Congress. They are all pre-programmed to explode at exactly the same moment sometime in the near future, covering everyone and everything in mercury. Yours probably has a defective timing mechanism.

Important information about energy saver light bulbs - YouTube

 

[foxeye]

I hate those CF pig tailed bulbs with a passion. For what they cost its unreal. Tell me the manufacturers and politicians and so called greenies do not sleep in the same bed.

 

[Berserker]

Loose screws are always something to check. But it flashes, without even throwing the switch? I think you need to break this down more.

A switch sparking, when thrown, is possible. They are cheap, replacing wouldn't hurt.

 

[Walter Rego]

I'll check the switch and installation to make sure it is not arcing. Maybe replace the switch as they are inexpensive. It doesn't flash as bright as it would if you quickly flicked the switch on and off. I only notice it if I walk into the darkened bathroom. At first I thought it was my imagination, but after looking up at the light fixture and watching it for a short while I can definitely see it happening. Odd...

 

[1morethan8]

You maybe picking up a slight voltage by having cable running next to each other.
If the CFL has a dimmer switch it could also be getting a slight charge from the switch.
I don't think it's much to worry about, I would be concerned by having a CFL in an enclosed fixture, not a good idea.
It doesn't take but a small voltage leak to excite a CFL...
let me guess... it's made in China?

 

[setxn]

I did a search on this because I had never heard of this happening. There were 980,000 results on Bing with almost that many different answers. It seems that any voltage present will recharge the capacitor in the ballast and it will discharge with a quick flash. Reasons varied from current feedback on the neutral leg, switch not on the hot leg , trickled voltage through a lighted switch or problems with a 3-way switch. Good luck and please post a solution.

 

[rwsmith]

This isn't exactly what this thread is about....

But it's got me started. I voluntarily use CFLs in any light fixture where it is practical. I haven't gotten a year out of any I have bought (major brands, Sylvania etc.) They sometimes don't work out of the box. The one that is in my closet right now gives off "half-light' except on rare occasions when it just decides to give full light. Cold affects them. I could go on but just put me down for thinking that CFSs are a great idea that hasn't worked out for me one bit. They are expensive and don't work. That is a great combination.

 

[Brian41]

I'd check first and see if the switch is wired to the neutral leg instead of the hot. If so the bulb is getting power and the slightest ground will cause the light to flash. That's where I'd start first as I've found similar mistakes in old houses I've owned and someone wired the wall switches wrong.

 

[Etemmu]

Have installed thousands of lights in my career and I have seen what you are describing many times- especially since electronic ballasts have taken over. Without being able to inspect your wiring, I could at least suggest that what you are seeing is normal. Good idea to verify that the switch and the fixture are properly wired and grounded back to the panel/earth. If all checks out and the "phenomenon" persists, I don't think you have anything to worry about. The bulb can get power from the electronic circuit within the ballast after the wall switch is off. If you want to eliminate the switch as the problem, remove it from the circuit and just touch the wires together manually-this poses a shock hazard to you regardless of how careful you are...so be careful. Or... You can do this without having to handle any hot wires by using wire nuts(in place of the switch) and the circuit breaker(have someone shut the circuit off while you stand there watching the light).