Money has little relationship to either 'quality' or
'effectiveness' of
a surge protector. A $5 surge protector of same joules rating
as a $50 protector will have same life expectancy - its
quality. Joules -
not dollars - is the significant number that determines life
expectancy.
But even a million joule surge protector is still not
effective if not connected short to central earth ground.
Joules determines life expectancy. Earth ground determines a
surge protector's 'effectiveness'.
An adjacent protector can contribute to damage of a powered
off computer. This has been demonstrated by identifying surge
path, replacing damaged IC, and learning how surge entered and
left the building. Only analysis at IC level can identify how
surges damage electronics. Two powered off computers were
incoming to a surge via adjacent, power strip surge
protectors, and damaged due to no 'whole house' protector
connected less than 10 feet to earth ground. Plug-in
protector only contributed to surge damage because) a less
than 10 foot earth ground connection was missing and 2)
computer was too close.
Computers already have effective internal protection - that
assumes a destructive surge will be earthed before entering a
building. That internal protection is so strong that some
grossly undersized protectors are damage by surges too small
to damage adjacent computer. Computer and surge protector are
connected in parallel - see same surge equally. Makes no
difference whether computer plugs into surge protector or into
outlet shared by surge protectors. Both see surge equally.
But a grossly undersized protector is damaged by a surge too
small to overwhelm internal computer protection. The naive
simply assume, "the surge protector sacrificed itself to
protect the computer". Bull. They make conclusions without
first learning facts such as what a surge protector does and
surge protector quality - defined by joules; not money.
'Whole house' protectors have that less than 10 foot
connection to earth and are properly sized - more joules. But
moreso - they cost 10 or 50 times less per protected
appliance. Look at those costs. 10 or 50 times less per
appliance for protection that is also sufficiently sized
(joules) and is effective (connected less than 10 feet to
earth ground).