Any protector that fails on the first transient was
defective when installed. Grossly undersized protector is
ineffective and overpriced. Any MOV that fails during a
transient did not provide necessary protection. Just another
fact that plug-in protector manufacturers hope you never learn
since such unacceptable failures actually promotes their
product among those who don't know what a protector should do.

Effective protectors perform their job so that you never
knew a transient even existed.

Stubby wrote:
And they usually employ MOV devices -- Metal-Oxide Varactors. They
work fine, but only once when the oxide gets punched. But there's no
way to tell if they have been damaged!