A failed $20 protector means it did no protection. An appliance protected itself while the protector disconnected as fast as possible from the surge. Left the surge connected to the appliance. If disconnecting too slow, then a grossly undersized protector may create a house fire. Have your attention?
Called a protector means it does something useful? Not without numbers. Defined repeatedly was what does protection:
" low impedance (ie 'less than 10 feet') to single point ground. "
Where does energy dissipate? Only the informed can answer that question.
Knowledge from the NEC only defines simple concepts for "human safety". Electrical concepts for "transistor safety" are different. NEC addresses concepts such as wire thickness and resistance. Surge protection involves wire length and impedance. A low resistance wire can also have excessive impedance.
Of course, that was posted previously and repeatedly.
Return to what everyone was taught in elementary school science. How a lightning rod works. Lightning (the typical surge) seeks earth ground. Finds a conductive and destructive path to earth via a church steeple. Yes, wood is electrically conductive. Now, numbers not taught then. Wood is not very conductive. So 20,000 amps creates a high voltage. From high school science: 20,000 amps times a high voltage is high energy. Church steeple destroyed.
Back to elementary school science: Franklin earthed lightning rods. Do lightning rods do protection? Of course not. A lightning rod is useless without its 'short as possible' connection to a best earth ground. To what harmlessly absorbs energy. Now 20,000 amps creates a near zero voltage. 20,000 amps times a near zero voltage is near zero energy. No church steeple damage.
A lightning rod works when a surge connects harmlessly to earth. A ''whole house' protector does same. DonL's protectors are like the wooden church steeple. A poor connection to earth (creates a high voltage). Informed homeowners install a 'whole house' protector with a conductive (ie 'less than 10 foot') connection to earth. Then have near zero voltage. No damage even to the protector (or to gas discharge tubes). A low impedance (conductive) connection to earth means even protectors do not fail.
Grossly undersized protectors fail on surges too tiny to overwhelm superior protection inside appliances. This gets the naïve to recommend them. Sometimes a protector does not disconnect fast enough. Then a house fire can result. Another problem when a surge is permitted inside the building.
Those, who learned science, were hired to undo a mess created by naive radio station personal. The naive foolishly thought grounds were causing problems. Probably due to NEC knowledge rather than how electricity works. A case study explains a solution by fixing the compromised earthing system. At no time did they waste money on protectors adjacent to electronics:
http://www.copper.org/applications/electrical/pq/casestudy/nebraska.html
Bottom line - a protector is a connection to earth or it is "useless". A point made constantly because so many will have difficulty unlearning myths and propaganda promoted by advertising and hearsay.
Step one: did the advertising provide any numbers? If not, it was probably a lie. Step two: did advertising discuss where energy dissipates? If not, again a sales myth. No low impedance connection to earth means no effective protection. A protector is only as effective as its earth ground.