"Andrew Gabriel" wrote in message
news:bpsu56$re6$1@new-
Yes - they short-circuit during spikes, absorbing some of the
energy (rest lost in cable impedance). They have a fixed amount
of energy they can absorb before they are destroyed, and each
spike absorbed (except very small ones) uses up some of the
device.

Big ones would be mounted in an armoured case

A large spike which would require more energy to be dissipated
than the device is capable of can result in it exploding, and
they can also fail to a permanent short circuit which might
have the same effect. They can be destroyed by the back-emf
from inductive loads too.


Thanks all for the advice. It's only £11 from Screwfix, but I'm wondering
if it's really worthwhile or not. Just about to get a new PC in a few
months so the more protection the better. Ideally I'd like to have a UPS to
condition the power and prevent loss from power cuts (battery life not
really important), but I can't find anything that falls into the small,
cheap and quiet category!! I'm used to dealing with 5U monsters in racks to
power my servers - noisey and very expensive!



a