Wol

Last night with insomnia, we noticed that our patio lights were flashing dimly every 10 seconds or so.

They're fluorescent replacement globes, ES 18W and haven't been switched on for at least a week.

I put them on for a few minutes and, after switching them off, the flashing continued at the same rate but a little brighter (you wouldn't notice it even at dusk - it had to be fully dark.)

Anyone seen this before or got an explanation?

The only thing I can think of is that it was very very dry and very windy - perhaps there was static buildup which triggered the fluorescents?

Weird....

MartinLuther

I've noticed it in one of the lightsaving fluresent bulbs in the kitchen. If you take the bulb out of the socket it stops. Put it back in and it starts again.

Wendy

Are they on a dimmer switch?

ozoz

Its to do with the freqency (hz) of the power supply and the demand put up on the power station - it could be the power station shut down some capcitor banks for power factor correction due to excessive consumer demand, either that or your gas is runing short in the lamp

Wendy

Surely if that's what it is then all their lights would do it, wouldn't they?

Wendy

This may help Wol

http://www.hammerzone.com/archives/l...uor_ghosts.htm

LAM

No, it's either the flux capacitor or the dilithium crystal causing the fault.

lesleys

Can't resist a challenge................

http://www.repairfaq.org/sam/flamp.htm#fwo


To quote:


Newly Installed Fluorescent Lamp Flashes Every Few Seconds When Off
Compact Fluorescent Lamps (CFLs) and many other modern fluorescent lamps use an electronic ballast. (See the sections on ballasts.) In simple terms, this consists of a rectifier and filter capacitor following by a switching circuit. The switching circuit requires a certain minimum voltage to function and until it gets going, its input may appear as a high impedance, almost an open circuit. Any source of AC even a small amount of leakage through a defective switch, a switch with a neon lamp night light feature (lighted when off), an electronic timer, motion sensor controlled yard light, or a light dimmer that isn't fully off, may produce a small amount of current to the input of the fluorescent lamp. Depending on how severe the leakage is relative to the actual input impedance of the ballast's circuitry, this can cause the voltage to build up on the filter capacitor until the "startup circuit" kicks in producing a flash of light. The startup circuit usually has some sort of threshold device like a zener diode or diac that won't pass current until the voltage across it exceeds a spec'd value. When that happens, the lamp starts up and strikes but just for an instant since there isn't enough current available on the input to maintain it. Then the cycle repeats.

So, there is nothing wrong with the fluorescent lamp or fixture. But there may be a problem in what's feeding it.

Most fluorescent lamps and fixtures have warnings about avoiding their use on any type of circuit that doesn't involve a simple switch. Not only is it possible for this sort of problem to occur, but the electronic ballast may be destroyed.

If there are no lighted switches or high tech switched gizmos driving it, then there could be a potentially serious wiring problem. It has also been suggested that inductive or capacitive coupling between conductors in long runs of cable could produce enough leakage for this effect to occur, though I'm somewhat skeptical of this explanation except under unusual circumstances such as where the outlet or fixture is controlled from multiple locations and there a long "traveller" in the circuit. This would have 2 parallel wires in it, one of which is connected to the source, and the other is connected to the lamp

ozoz

It only shows it on the es lamps because es lamps will use a bimettalic coil strip to ignite the gas where as a fluro does not have a bimetalic strip different process therefore the induction process in the lamps is different and it becomes more prominent on the es lamp under heavy load situations put upon the power stations.If you put the lamp on during low peak period time say 3 in the morning my gues is the effect would not happen as much.Either that or the power station havent done ther calcs right and there a long way from unity in regards to frequency and power factor correctionn for the supply demand.

Wol

Some interesting replies here!

No, the lights are not on dimmers - just ornery light switches. Three are on one and two on another - both are dual-switched from different doors.

They are not the new "compact fluoros" that we have in the rest of the house - the GU10 replacement downlights - they are bog-standard ES "low energy" replacements you can buy anywhere. In this case I think it was Bunnings.

The most likely explanation is the one that the switches are in the neutral instead of the live wires: I will check it out.

steve`o

i`m going for the induced voltage route as they are wired on a two way circuit you have a live cable running parallel to the switch wire

is the cable twin and earth, twin with a separate earth, singles with an earth or no earth at all???

Wol

I haven't looked yet. The house is certainly wired up like a nuclear power station, cat 5 cable all over and outlets every few feet. Plenty of scope for induced voltages!

We *do* have all the power sockets with no on/off switches ("Como"): they have a litle red LED (I assume it's a LED) which is alight when something's plugged in. Nothing like that on the light switches though.

Wendy

This is Aus mate, probably all of the above

steve`o

i can relate to that we had a good mixture of each in this house
the shared earth is the one that worries me most

Wendy

Our wiring is really bad, our kitchen lights had the live and neutral wired in together. No earth, unless it works by magic here, cos that was wired in but not connected to anything, just stuffed in the ceiling.