And one of those surges they protect from is the spikes caused by the power
grid response to strikes far from you cmputer. Turning off electronics is a
good idea, not because the little switch will protect from strike current,
as Larry points out, but because power instability from a strike across town
might overwhelm the surge protector of a dip as power is restored might let
the head of your hard disk briefly contact the platter surface (although
disk designs have greatly improved in this regard).

--
Roger Long