Compact Fluro Lamp Flashing When Switched Off

You did not give your location, but looking at your User-name, plus the voltage/frequency given, it appears you live on the "West Island" of New Zealand (= the Land of Oz).

So, any induced voltages would be either from leakage at the switchboard, induction from parallel cable runs, or leakage through the off/on switch.

The off/on switch can be checked easily by removing it from the circuit, switching the switch to "open = off" position,and using a 500VDC Megger, measure across the open circuited terminals. Often a high humidity, dust or other contaminants can give a low resistance across an "open" switch, thus enough leakage when switched "off" to give your symptoms.

Leakages at the switchboard, likewise induction from parallel runs of cabling is harder to track down. What I have done in the past, is to use an oscilloscope to locate the actual leakage voltage, then put a resistor across the oscilloscope terminals, with a sensitive current meter in series with that resistor. From this, the actual power leakage may be calculated.

Of course, it is possible you have old leaky cables, or new faulty cable in the installation, or some enterprising builder has spiked a cable with a nail.

Faulty new cables are more common than you think, and in over 45 years in the "trade" have discovered over 20 installations,in which the new cables were insulated with plastic compounds which were somewhat conductive, due to faulty batching at the various cable factories.

Some good answers already posted by others, other possibilities are a powerful Radio or Radar transmitter within a few miles of your position.

That's what I was thinking. The florescent light in the hangers clear across the flight line used to flash with each up/down of the 'Height finder' radar when it pointed that way.

But I'd think that would be isolated bulbs and less visible in the wiring.

It could be the radio signals as I noticed that my old car radio was picking up a humming noise every time the heathrow radar dish thing on top of the tower was facing me. THE RADIO WAS OFF!!!!!

The other thing that makes lamps go berserk is microwave energy. If you have a leaking microwave device you might have a problem altough you might have noticed in other ways such as exploding finger tips

If you do have a induction problem in the wires you could easily check by unscrewing the lamp from the socket but keeping it in the same position. If the blinking stops it must come from the wiring somewhere.

It does not have to be at such high frequencies, any radio transmitter will do this at almost any frequency, it is just a question of power and the correct distance....even a long wave station will do it I am lead to believe, though i have no personal experience here to call on.....

Hi, ausiandy!

Sometimes there is a measurable residual voltage across the neutral lines in a household.

Mark

Australia has a MEN = Multiple Earthed Neutral Mains Power system.

Everywhere the Neutral wire arrives at a main switchboard, it is permanently connected to an earthed spike, pipe,or buried earth electrode.

That means the Neutral line can never rise above a few Volts with respect to "ground", even under major fault conditions.

It makes for a safer installation, requiring only single pole switches and circuit breakers.

Hi, Sparkstation!

Same here in Canada. And yet I have measured as much as 30+ volts across a properly grounded neutral line coming off that "switchboard", which in this case is usually a point at which all the neutral lines are sent to ground on the house panel.

I have never given any thought to why this is so. But it would appear on the surface of things that the resistance to ground is not completely at zero, and with energy flow through lines that are not in the open position, there might be some back flow being available, when grounded (again!) through those that are open, measureable on the meter placed back to ground.

Whether that is enough to flash a grounded light or not I can't say.

Mark

Thanks for your comments,

In the site where i have come across this occurring there are also other compact fluros which do not flash which i guess rules out radio frequency causing the lamp to flash.

Having replaced the switch and performing IR testing from the switch board on the installation with a reading on >1M ohm. i believe that the most likely cause is a leaky switch wire as mentioned by Sparkstation.

The voltage was only read on a high impedance meter with no reading while using test lamps. Told the client to install a incandescent lamp problem fixed LOL.

Sparkstation you are correct I am writing from the land of oz, Did my trade in NZ but the mining money over here was to much of a temptation and it is too bloody cold in NZ