The flicker is a voltage variation that is an indication that somewhere (not too far away) a powerline has been struck, causing a transient on the grid. The grid system is normally configured that the loss of one circuit does not result in an outage for large parts, the load being transferred to other feeds. Of course the loss of single radial feeds will result in an outage of all consumers on that feed. Many times it is very very short duration due to the auto-reclose facility on many feeders. Steve ,Fujeirah Emirate, U.A.E + 50 (in France) ...........................................................................