Why whole house surge protectors are not enough

Anyone care to explain how a vaccum clear, or anythig inside a home, can cause a surge? Surges always come from outside the home.

@carlsbad2 Depends on how you classify them. Some statistics say 80% or more come from inside, especially whenever inductive loads (i.e. big motors) start or stop. Of course, this includes very small surges we might expect equipment to shrug off. They tend to be small, but may accumulate.

Anyone who has ever heard a thump through their stereo when a vacuum, ceiling fan, AC or hair dryer has turned on or off has literally heard a surge.

Awww, thanks @terry9 

@carlsbad2

Sorry I didn’t really answer your question. As I understand it, the most common cause of a surge inside the home is when a large inductive load (motor) is turned off. The magnetic field has inertia and until it collapses is present and the motor tries to feed that energy back into the system.

This is the best description I've found:

...However, because you have current flowing in an inductor at the time of turn off there will be a transient voltage produced. Much of this voltage will occur across the power switch contacts. There maybe some very short transient rise in voltage on the supply wiring. Could be several thousand volts next to the switch and diminish as you move further from vacuum connection point. ...

https://forums.mikeholt.com/threads/can-a-vacuum-cleaner-cause-a-surge.60537/

From an important textbook:

"... it is not possible to turn off the current (to an inductor) suddenly, because that would imply an infinite voltage across the inductor’s terminals. What happens is that the voltage rises abruptly and keeps rising until it forces current to flow. ... in a case like this ... (20 VDC supply) it may go to 1000 V before the switch contact "blows over". "

"Art of Electronics 3rd Edition", Horowitz and Hill, page 38.

Erik, thanks for this thread! This brand was recommended as the very best by an electrician recommended from a reputable audio dealer:

https://transientprotectiondesign.com/products/residential/breaker-panels/breaker-panel-surge-protection/

Any comments on this brand? They are pricey at $1400 but have lifetime warranty and made in US. They have a few pdfs showing complex protection for the home. By putting it in the panel and behind a pair of 30A breakers, I assume that the idea is that the MOVs will be just slightly removed from the signal path and so interfere with that wave less during normal operation and have less detriment to sound quality.

How are we to understand Maximum Limited Voltage in this context? I'm looking at model TK-TTLP-1S240-FL with MLV ratings as follows:

2kV,67A - 36V, 6kV; 3kA - 590V; and 20kV, 10kA - 970V. I think this means for an impulse of less than 2kV and 67A, the clamping voltage will be about 120+36=156V.

I agree that a panel installed protector does nothing for induced EMF from a nearby strike, but I had a strike 20 years ago that took out the speaker and amp channel that were closest to it but not the other channel. I assume that was due to induced EMF in the speaker wire or even voice coils. Point is, if lightning strikes really close, all kinds of problems may occur including on the ground leg.

Does anyone have an opinion on these? https://ep2000.com/products/home-protection-products/premium-surge-protection-filter/?v=e75edac1b83f