Ironic that Choreboy would mention Zerosurge. Zerosurge
demonstrates with pictures how ineffective plug-in protectors
can be:
http://www.zerosurge.com/HTML/movs.html

They even remove MOVs from a plug-in protector; remove the
protection components. Lights still say the protector is
working just fine. What kind of protection is that?
Ineffective - and a protector that also is not properly
earthed. Even lights that are suppose to report a good
plug-in protector are 'lying by telling half truths'.

In the meantime, Zerosurge forgets to mention that a
transient bypasses the series mode protector via safety ground
wire. Which is better - series mode protectors or plug-in
shunt mode protectors? At least the $100 Zerosurge product
does supplement an effectively earthed 'whole house' protector
(and provides other advantages). The traditional $15 or $50
power strip (or UPS) protector does nothing effective for one
simple and obvious reason - all but no earth ground. No earth
ground means plug-in protectors are ineffective as well as
overpriced and undersized. And then we have those lights.
Zerosurge pictures even demonstrate the problems.

Choreboy wrote:
w_tom wrote:
No wonder those plug-in manufacturers avoid all discussion
about earthing.

Zero Surge used to discuss it on their website.