On Sunday, October 18, 2015 at 9:07:06 PM UTC-4, Uncle Monster wrote:
Lightning strikes would often blow the hell out of the surge arrestors
but none of the very expensive equipment was ever damaged.

Obviously did not happen that way if one remembers how electricity works. If a current is incoming to an adjacent protector, then at the same time a current is outgoing into attached expensive equipment. Where is the protection?

A protector, blown to hell, has not provided protection. A surge is a current source. That means voltage increases as necessary to 'blow to hell' anything that tries to stop it. Voltage increased as necessary (causing catastrophic protector failure) so that current also flows into attached equipment. Both incoming and outgoing current paths must exist simultaneously. Where is the protection?

A surge current, too tiny to damage attached (more robust) equipment, also destroyed a grossly undersized protector. Where is protection?

Adjacent protectors are for tiny and completely different transients already made irrelevant by protection inside equipment. Adjacent protectors do not claim to protect from a typically destructive surge - that hunts for earth ground - that typically does damage.

Second, each layer of protection is not defined by a protector. Each protection layer is defined by what absorbs hundreds of thousands of joules - earth ground. As explained previously. Then protection inside equipment is not overwhelmed.

Facilities that had damage (even to protectors) start an analysis to discover a human created defect. Since energy must dissipate outside in earth - not inside. Unfortunately, many conclude only using observation. Not by first learning basic concepts. Protection is always about where hundreds of thousands of joules dissipate - harmlessly. A destroyed protector was grossly undersized - ineffective.

Intentionally undersizing a protector gets consumers (who only use observation) to recommended that ineffective protector and buy more. Undersizing increases profits.

Third, an IEEE brochure Figure 8 demonstrates same. A home had no properly earthed 'whole house' solution - no 'secondary' protection layer. So a plug-in protector earthed a surge current 8000 volts destructively via some nearby TV. It did what a protector does IF not properly earthed. To even make damage easier.

Fourth, if a protector was blown to hell, then it was a potential fire. Fire has always been a problem with undersized (plug-in) protectors - that are blown to hell. Protector part (MOV) manufacturers are blunt. That 'catastrophic' failure is unacceptable. APC recently announced some APC protectors are so dangerous as to be removed immediately.

A surge, too tiny to overwhelm protection inside equipment, destroyed a grossly undersized protector. Undersized protectors are a potential fire. An indicator light only reports one type of protector failure; that the protector failed due to undersizing. Fortunately it failed catastrophically without causing a fire.

Protection has always been about energy dissipating harmlessly outside; as Franklin demonstrated in 1752. Protectors that fail did not perform protection.

Informed consumers implement a 'secondary' protection layer. And inspect their 'primary' protection layer. A protector is only as effective as its earth ground. Protectors that are blown to hell were grossly undersized; did not do protection.