[westom]

Originally Posted by joelg236

I'm wondering about lightning strikes, as to why people (At least some people who I know) are so concerned about surges and power outages damaging electrical components. Specifically (And I think this is due to the misconceptions that a lot of people have about computers - imagine 'ohhh, shiny'), people seem to think that computers can be seriously damaged by lightning strikes.

Due to advertising, most failures get blamed on a surge. All appliances contain protection superior to what might be attached to its power cord. A destructive surge, large enough to overwhelm that protection, occurs maybe once every seven years. So any failure gets hyped as if surge damage.

Most failures are manufacturing defects. One example were electrolytic capacitors made with counterfeit electrolyete. Most other failures are speculted into "it must be a surge".

Your telco's CO, radio stations, munitions dumps, etc all suffer direct lightning strikes without damage. The solution has been well understood for over 100 years. But is not promoted by advertising, retail salesmen, and hearsay. So most have never heard of the well proven solution. Most have only heard of another completely different device, also called a surge protector, that does not claim to protect from typically destructive surges. Some numbers follow.

A destructive surges is a microsecond event. A connection from the cloud to distant earthborned charges. First that current exists at the exact same time everywhere in that path. Then much later, something in that path fails. To be damaged, an appliance must have one incoming surge wire. And other completely different outgoing wire. That is electricity. It does not enter an appliance, do damage and just stop as so many are told to believe.

Fuses, circuit breakers, a UPS, or anything else that might stop a surge take milliseconds to respond. Surges are done in microseconds. Nothing stops a surge. As in nothing. Nothing inside the house absorbs a surge. Surges are hundreds of thousands of joules. View numbers on the most popular protectors or UPS. They only claim to absorb hundreds of joules. A surge easily blows through such devices. Protection is always about where energy is absorbed. Destructively inside a building. Or harmlessly outside.

Electronics atop the Empire State Building may suffer 23 direct strikes annually without damage. The number was 40 for the WTC. Routine is to suffer a direct strike without damage. But that means relearning a concept originally taught in elementary school science. Franklin's lightning rod.

Lightning seeks earth ground. A best electrical connection was via wooden church steeples. Yes, wood is an electrical conductor. But not a very good conductor. So lightning, maybe 20,000 amps, will create a high voltage in that wood. From high school physics. 20,000 amps times a high voltage is high energy. High energy dissipates in wood resulting in steeple damage.

Franklin simply put a lightning rod on that steeple. Does the rod do protection? Of course not. The rod is only a connecting device to earth. 20,000 amps will create a near zero voltage due to a connection (a wire) to earth ground. 20,000 amps times a near zero voltage is near zero energy. Near zero energy dissipates on that connection. Hundreds of thosuands of joules dissipate harmlessly in earth. Most important is the earth ground and its connection - not the rod.

A lighting strike to AC wires far down the street is a direct strike to all household appliances. The incoming path IF that surge is permitted to go hunting for earth inside the building. Nothing will stop that destructive hunt if a surge is inside. As in nothing.

Informed consumers and all faciliitles that cannot have damage, instead, earth a 'whole house' protector. With a connection that is low impedance (ie 'less than 10 feet') to earth. Wall receptacle safety ground obviously is not an earth ground (excessive impedance, much more than 10 feet, etc). A surge connected to earth via a wire (cable TV, satellite dish) or connected via a 'whole house' protector (AC electric, telephone) need not enter a building. A surge connected to earth before entering does not hunt for earth destructively via household appliances.

Protection was always about energy not even inside. But advertising says a 2 centimeter part inside a magic box will stop or absorb that energy.

Nothing inside will stop, block, or absorb a destructive surge. Once inside, that surge will find earth destructively via appliances. A minimal 'whole house' protector is rated to connect 50,000 amps harmlessly to earth. Then no surge is inside. Even that protector remains functional after a direct lightning strike - as numbers confirm. Protection has been performed that way in every facility that cannot have damage - even 100 years ago.

Protecting the building is about earthing lightning rods. Protecting appliances is about earth incoming utility wires; either with a hardwire or with one 'whole house' protector.

Earthing (not a protector) is the most important component of any protection system. A lightning rod is only as good as its earth ground. A protector is only as effective as its earth ground. Most educated by advertising do not even understand why the art of protection and most all attention should be refocused on earthing. Do not even know the best protector costs about $1 per protected appliance.