Spooky Fluorescent Lights
My home is 8 years old. I live in Michigan. I
have a good deal of home improvement experience but limited in many
My question: I have an electrical circuit in my basement that I installed
for lighting. Of the eight, 4 foot shop lights on the circuit, two of them
flicker faintly when the switch is off. Each of the lights are associated
with an electrical outlet. These two lights are clearly getting some
residual electricity when the circuit should be dead. What is the problem?
If you have the time to consider my question, I would be grateful for a
is something strange going on in your wiring. Does your house show any
other signs of being haunted?
Just kidding. But to have fluorescent lights flicker when the power is
OFF is quite weird. I have never heard of this problem, but there must
be a logical explanation.
I would start by getting a good electrical tester. I recommend two
actually. First, a "non-contact" electrical tester is handy
because you never have to touch any bare wires. It looks like a fat pen
with no ink tip. You press the "clip" to activate it, and it
beeps repeatedly when placed close to a hot wire.
I also recommend a decent-quality digital multi-meter. I have seen these
as low as $30. Necessary features are AC volts, DC volts (for cars,
cordless tools, and such) and Ohms (resistance) function.
My approach would be to get inside the light fixture. You might want to
turn off the breaker while doing this.
Remove the plastic cover, if any, remove the bulbs, remove the metal
cover that protects the wiring. Then replace the bulbs, you can't test
much without the bulbs present.
With the supply wires exposed, restore the power. With the switch off,
check for power at/near the hot (black) wires that supply the ballast.
The ballast is a black box-shaped device with wires running to it. Some
fixtures have separate transformers and capacitors (starters).
My suspicion is that someone wired the switch so the NEUTRAL wire is
being switched. (This would be a code violation) If there was voltage
present on the black wires, even when the switch was off, then there
might be enough of an electric field to partially energize the
In fact... just turning off the breaker to the light fixtures may give
you some clues. If the problem goes away with the circuit dead, then my
#1 suspicion still stands. Otherwise, consider these other
- Faulty switch may not be fully opening.
- Is a dimmer switch used? There are special dimmers for fluorescent
lights. I have seen regular dimmers leak a small amount of power.
- Is there a GFI receptacle upstream in the line? I have seen GFI's act
weird, like trip when I touched the ground wire.
- Is there a large wire near the affected lights? Current in wires
generates magnetic fields, which may be picked up by the transformer
that is built into the ballast.
- Is there a high powered radio transmitter nearby? It's a dumb question
but I gotta ask....
Strong electric fields can supposedly make fluorescent bulbs light up...
with no wires at all! Supposedly you can take a fluorescent bulb and
hold it vertically while standing under those very-high-multi-KiloVolt
power lines... and the bulb will glow! Supposedly. But I've never done
Please reply when you find out something... I'm dying to know what is
Bruce W. Maki, Editor.
( Terry later replied that the
switch was indeed on the neutral line instead of the hot line.)