I have energy saving light bulbs which have started flash when they are turned off. Is this a problem?

Question

I have energy saving light bulbs which have started flash when they are turned off. Is this a problem?

Answer 1

Most Probably.  

The reason they flash occasionally when the switch is off is that a tiny amount of current is able to bypass the switch and slowly charge up the electronics.  Eventually there is enough energy to trigger a starting pulse, but because the switch is off, the light only flashes for an instant.

None of this arises with an ordinary filament lamp as current can pass merrily along the filament without any obvious effect unless it is sufficient to heat the filament to the point where it emitts light.

Potential downsides here include reduced lamp life (as each flash represents a starting attempt), slightly increased electric shock risk when replacing a lamp and nuisance flashes, especially if you are trying to sleep!

The big question is, why is current able to leak through the circuit?

The current is able to leak past the switch in situations where the wires (to and from the switch) run parallel and very close together.  This looks like a component known as a capacitor which allows alternating current (ac) to pass.  Normally this is not an issue, unless there is a problem with the circuit polarity or wiring insulation.

This situation can indicate that the live and neutral connections to your light fitting are reversed: live wire should go to the switch then from there to the light.  The neutral wire normally goes directly (unswitched) to the light. Where they are reversed, the light is effectively pressurised with electric charge continuously that is searching for a path to discharge.

This situation also gives rise to the increased shock risk when replacing a lamp, as there is live power present at the lamp holder even when the switch is off.

The leakage may alternatively indicate that the wiring insulation in your home is deteriorating (especially if it's more than 20 years old) and needs to be checked or that the switch is defective.

If you are confident with electricity, I suggest that you check the circuit polarity (live-neutral orientation) first; this can be done by removing the lamp and with the switch off, checking for power at the lampholder contacts with a phase tester (screwdriver with a light inside). If you get a power indication, then the polarity is probably reversed.

Fixing the situation or investigating the insulation is a task for a professional electrician.

Answer 2

Those CFL lights have a few problems not to mention containing mercury, causing problems to recycle.

Some say they also trigger epileptic attacks. Others have complained about severe headaches.  I don't know if your flashing problem is due to a dimmer switch or if the bulb is bad, but get used to using these light bulbs because in a few years they will be the only ones available legally.

I'm against the government banning products that don't pose any danger, so I was upset that they will be banning incandescent lights by 2012 in the US.  All because of false claims about global warming.  It's a shame we're losing so many freedoms so quickly.

Answer 3

Compaq flourescent bulbs don't work so good in lights with dimmer switches.  They tend to flicker  a little when they are on.  Is this what is happening to you?

It's only a problem if it bothers you.