Have you ever come home to find your digital clocks flashing "12:00"? It's caused by a power blink - a brief interruption that's designed to prevent a longer power outage.

Blinks occur when an obstruction, like a tree limb, comes into contact with a power line or transformer. To minimize the possibility of damage to the utility system or your home, a circuit breaker interrupts the flow of electricity for a fraction of a second.

If the limb remains on the line, the breaker opens and tries to reclose again. If the obstruction is still on the line after the third try, the breaker opens and does not reclose automatically.

At this point, a utility worker must be dispatched to remove the obstruction and manually reset the breaker.

Power blinks rarely cause damage to equipment. Older digital clocks and other devices are the most vulnerable to blinks; newer models are designed to ride out these small voltage fluctuations.

If you're experiencing frequent power blinks, call your electric company.