Lightning Protection

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mutual transfer of knowledge is itself a gift to all of us.

Transfer some to this forum, then, and maybe worthwhile responses will be forthcoming.

The demise of Barad-Dur.

https://en.wikipedia.org/wiki/Barad-d%C3%BBr

https://cr4.globalspec.com/search/cr4search?query=Lightning&newSearch=new

A lightning strike, unguided by a grounding scheme, takes an unpredictable path...this can lead to many different scenarios from no damage at all to the entire house burning down, to individual electrical circuits and appliances being damaged...

Most homes are covered under their home owners insurance for lightning damage, but the best defense is a good offence....so some effort toward proper grounding should be according to building codes...and battery backup with surge protection for sensitive electronics is recommended if you are in a lightning prone area...

..."Lightning kills an average of 49 people each year in the United States and hundreds more are injured. Some survivors suffer lifelong neurological damage."..

https://www.weather.gov/safety/lightning-victims

https://lightning.org/lightning-protection-overview/

This helpful guide will help explain things and offer solutions.

Dehn Lightning Protection Guide

a lot depends on the earthing of, or in the building because of the lightning voltage and current. Back in the 1970s I was involved in a test and instrument section where lightning arresters were tested both for AC withstand and impulse passing.

A lot of research had been done and papers were available on testing of tower structures one of which was very interesting and I remember it well. During a storm the tower mounted on insulators bypassed by shunt resistors measured a direct strike of 1MV the current measured in each leg was around 100KA per leg and another approached 2MV with 200KA per leg.

If that were to flow through a building without lightning rods above it and being firmly grounded through heavy enough conductors then the voltage will find its own way through whatever metal is in the building burning whatever it touches.

During a recent storm a 30m high hoop pine was struck about 100m from the farmhouse which resulted in enough voltage being impressed across the wiring to cause a power point in a shed to explode and throw pieces 10m away in the building.

With lightning arresters on transformers you will notice that the arresters are close coupled to the input bushing and that is done for from experiments it has been found that the rise in potential from the arrester to the bushing is in the order of 210KV/m.

A 3m high room can have, theoretically at least, 600KV between the ceiling and floor. Given the unpredictability of lightning anything can happen from burning to melting of holes in metal.

As an aside my step brother was struck by lightning while playing golf, well actually holding an umbrella for the player. The umbrella vanished as did his hat and his shirt. The golf shoes he was wearing were driven into the ground around 100mm and the spikes top complete with the nail holes were burnt into his feet and the surface blood vessels on his back appeared so that his back looked like a road map and his ear drums were ruptured. The feet and back marks remained visible up to his second death for he died on the golf course but one of his companions was a doctor and revived him until he could be taken to hospital. Just goes to show Mechanical Engineers should not let electricity play with them.

Aside from the damages mentioned here,there is an effect that is seldom mentioned:

The EMP effects that do not need a conductor to travel.

A high voltage can be induced by the high magnetic flux generated by the strike.

I saw a house that had wall paper with a metallic foil pattern running through it.

All of the metal foil was melted,and the fabric was charred.

Fortunately,the vinyl wallpaper was on a gypsum drywall and no fire occurred.The strike was to a tree over 100 yards way from the building.

The metal foil on the insulation under the vinyl siding of modern houses may make the internal contents safer, and may dissipate the EMP due to the larger surface area.But it may actually make them more prone to a strike.

I do not recall a code requiring these to be grounded or bonded;probably because the insurance companies have not incurred many losses from this issue.

Here is a link to help you design a lightning protection system.

https://www.electrical-knowhow.com/2014/05/Protection-Angle-and-Mesh-Lightning-Design-Methods.html

great link thank you

In simple words ,If a lightning strikes a building, the building will get damaged. The extent of damage depends on whether any protection has been provided or not. Lightning strikes cannot be avoided, so proper lightning protection is required to be provided for all non-metallic structures ( high rise or isolated structures )

Once lightning strikes a building, energy frequently passes through a home's wiring or plumbing system to look for the quickest way into the world. Make sure you can either unplug or remove all electronics.