On Monday, October 19, 2015 at 2:02:33 PM UTC-4, wrote:
You are not totally correct. When a "protector" conducts to ground
without failing, it is doing it's job 100%. If the surge is too big
for the protector, it starts dissipating the durge to ground,
lessening the amount of surge getting past it, and when it "blows"
...
When a surge protector on the fused side of the panel conducts it
SHOULD pop the breaker as well - and if the surge is strong enough to
destroy the wholehouse surge protector

Problem is your term 'ground'. Which ground? Chassis ground? Analog ground? Floating ground? Receptacle ground? Ground bus in a breaker box? Digital ground? Some are even electrically interconnected and are still electrically different. A critically important expression cannot be ignored: low impedance (ie less than 10 feet). That term explains why interior protectors cannot do and to not claim to protect from the destructive type of surge.

No breaker or fuse pops to stop a surge. The number of reasons why are too many for this discussion. Some that you must know before every recommending protection: 1) a surge is done in microseconds. Fuses and breakers take milliseconds, seconds, or minutes to open. How many consecutive surges would pass through a fuse or breaker before it trips? 300? 10,000?

2) All fuses and circuit breakers have a voltage number. For example, many line fuses are 250 volts. That means the fuse continues conducting current if voltage exceeds 250 volts. A surge current increases voltage as necessary to blow through anything that might stop it (as explained earlier). That means a fuse blows and the surge would continue conducting through that fuse.

Claiming that a fuse or circuit breaker can avert a surge is a classic soundbyte myth. Posted in but a few sentences and without numbers. Reality takes paragraphs. And always includes numbers. Just another reason why those urban myths are quickly identified. Problem is a majority believe those myths; do not learn from the fewer who actually do this stuff.

So how does a surge protector fail? More facts that can only be explained in many paragraphs. A microsecond surge does damage. The actual damage takes milliseconds to occur - long after the surge is done. And then something even more powerful that a surge occurs - called a follow through current.. The now damage protector (that has no visual indication) is then further destroyed by a follow-through current - sometimes causing a fire.

BTW, you ignored the paragraph about fire. Fire is another problem when a protector is so grossly undersized as to fail during any one surge. Why ignore fires created by undersized protectors? That is not a rhetorical question. It is often ignored by many who have no idea what a protector really does and why it must never fail catastrophically.

Protectors that fail do not protect electronics. Also create other serious problems. So many reasons why that facilities (that cannot have damage), instead, spend tens or 100 times less money on a completely different and well proven solution - called 'whole house'. Because protection does not exist during if a protector failed during that surge.

You assumed those near zero and many times more expensive protectors somehow connect to earth ground. Explained before you even posted: low impedance (ie less than 10 feet, no sharp wire bends, etc). Protectors adjacent to appliances do not have an earth ground. Plug-in protectors can only block what three miles of sky cannot. Or its hundreds of joules must magically absorb a destructive surge (ie hundreds of thousands of joules). A post that defines reality and protection (exposes urban myths) say so with numbers. Because the author has done this stuff - direct strikes without even protector failure.

BTW, if a 'whole house' protector fails on any surge, then it was grossly undersized. Numbers posted even for that. A direct lightning strike is typically 20,000 amps. So a minimal 'whole house' protector is 50,000 amps. Because effective protectors must never fail catastrophically during any surge. If a 50,000 amp 'whole house' protector fails, then it is replaced by a 100,000 amp protector. Nothing new here. This stuff has been well understood long before PCs even existed (ie more than 100 years ago).

What is essential to even protect HVAC? A 'whole house' solution with an often upgraded single point earth ground. And a low impedance (ie less than 10 foot) connection to the only ground that does protection.