Lightning Rod Usage

If you were to do a Google search you may come upon several nice articles that go into great detail the history of Lighting Rods and such. Seems there was a lot of work being done in this area in the mid 18th century. Ben Franklin and several others worked on and placed pattens on devices in 1745 - 175?. Quite a story.

lighting rods requirment depend up on hight of building and type of eqipment used in building.

If your house very hight compaired to your surounding houses. it is must to provide LA's

They certainly will attract lightning that otherwise would not strike near the house. In doing so, they offer a measure of protection for everything below the tip in that, when lightning strikes, it will be preferentially attracted to the lightning rod rather than to any of the house or its wiring.

You will see lightning rod type protection systems on commercial buildings.

A good Answer.

But not always clouds (+) & Ground (-).

May be othewise at time.

In villages we had Hand-Pumps and we had a fun to touch the top end of extruding part and feel minor shock in cloudy days.

Depends on area.It is said that 2000 lightning happens in each second.Action of sharp point attracts lightning surges by basic physics.To the lightning rod 30degree vertically protection is covered.

You won't like the damage and effects if lightning strikes your house and it doesn't have a proper path to ground.......Fire, extensive damage, dead people etc.. are all possible.

What is the likelihodd, probably less than once in 1000 years if your house is lower than other houses and trees in the area, but if you (like me) are the second highest house in the village, then the odds are different.

We have been struck as far as I can tell (when I have been there!) about 4 times in 25 years, that is quite a way to get you standing bolt upright in bed as you get NO warning - flash and sound are 101% together......and boy is it LOUD!!!

We have never had ANY damage to house or property......not even to Sat aerials and receivers, though I really think that is still possible.....in that area we have just been lucky.....

I have had several ideas over the years on how to monitor strikes on the house, but have not had an idea that is safe up to now.....

My best idea (?) was to break the circuit about 3 or 4mm and place a thin piece of plastic in the gap, the theory being that the lightning will still jump the gap and leave a hole melted into the plastic......if anyone has a better I dea I would like to hear from them!!!

On one of the websites below, they note that:-

Approximately 6.5% of property/casualty claims are related to lightning strikes.

One link here had this posted from a lady without lightning rods, she was really luckiy not to have a bad fire:-

My home was struck by lightening last week. A large tree in
the yard (5 feet1 0 away was hit as well but luckily still standing)
All the electrical outlets were damaged and light bulbs blown out of their
sockets. Holes were torn in the eaves trough and a sensory light blown off
the wall of the house. As well, the heavy duty stove electriclal cord was
burnt through in two places even though the breacker had been turned off.

Its actually cheaper to have a properly installed lightning conductor system than to let this happen to your house.....

I found a few links that you may like to read related to the above comments:-

http://hffo.cuna.org/12433/article/628/html

http://www.newton.dep.anl.gov/askasci/wea00/wea00006.htm

Unfortunately if you have the three feet of wire and a strike is sustained, the structure will remain unprotected for the the duration of the strike as the fuse breaks the path. Each "strike" is made of many sequential strikes until discharge is complete. Your experiment would be cool in the back yard, but I wouldn't test it on a building you want to keep.

If the gap was small, the lightning would still rather jump the gap than enter bricks and mortar......

Its simply a factor of the resistance of each path.....

Normally the spark gap on a lightning arrestor is measured in mm or cm, not feet, that would depend on the overall design. The rod just provides a more appealing path. If it's not there, it hits the house instead. All of this is assuming the the house is in the original path to begin with.

I was thinking of about 5mm......I never thought of or mentioned feet!!

I may be confused, but I thought I originally replied to jimh77 who mentioned a 3 foot wire connected to a 5kV 100A fuse. Generally, these are on the order of 40cm or so. Also, I jumped the gun on the "wire". If he actually meant "wire rope" or cable, then that would suffice, but the 40cm gap created by the blown fuse would break the lightning path through the arresting gear.

Yes it would. I must have missed that post completely....

I was just thinking about a very small gap that even after the wire "fused", would still be the best path from ground to the sky.....(many believe its from the sky to the ground, but I do believe I am correct in saying that is either never like that or seldom...... as electrons flow from negative to positive. The earth is negative in relation to the clouds!)

Lightning rods have a sharp point at the top, which helps create a high electric field near it, so lightning will go for it first. One problem though! The build up of electric charge in the vicinity can create a plasma around the tip of the rod, which makes it look like a sphere. This sphere is not as attractive to lightning (no longer a sharp point). The lightning then looks for some other point (metal roof peak, wet cat tail etc) to hit.

Maybe it wasn't worth the money (Copper is worth around $5 kg scrap now, price of heavy copper strap new?).

Maybe the insurance companies would offer lightning insurance whether you had a rod or not. Insurance companies are the best to ask what are the probabilities of something happening. It's in their interest to research these matters.

Low probability of a lightning hit on a house in most areas? It usually hits the 11kV line near our place first.

I have had lightning damage from lightning hitting the power line into my house. From 1985 to 1990 I was hit 4 times. I installed a 30 ft tall wooden pole about 50 ft from the SW corner from my house and welded together 2 oilfield sucker rods (steel) and pushed this rod into the ground alongside the pole until only 1 ft stuck above the pole. The rod end was sharpened with a grinder. This "lightning Rod has been hit 8 times to my knowledge. The end of the pole looks like a cigar that had exploded!! However the house nor the power lines were struck. This only works with close lightning. I still suffered extensive damage from a power surge on the rural electric line last year when lightning hit.

Try my trick when I lived in the sticks, I had a bank of transorbe diodes connected line to earth. The ones I used didn't conduct until 600V.They were rated at 20KA each. I used 5 per phase!

Reason for 5, they're as cheap as chips!

It cost less than £50 to put the whole lot together

I even fitted the 150V version them to the phone line. Stopped the answer phone exploding!

basically, lightning rods are only one of the scheme of air termination of LPS (lightning protection system). lightning rods can be replace with a mushroom type, or a mesh network composing of bare copper conductor, or a loop conductor. or simply the G.I. roof itself. if the roof has a .5mm thick then lightning rods are not necessary, all you have to do is to connect the roof to the grounding system (if any) through down conductors. thats why some houses do not require any lightning rods. yes, it is beneficial. it would protect your life and your properties together with your neighbor and it purely depends on so called Zone of protection.

One major reason you don't see them nowadays as much as we used to is that lightning rods were seen as a kind of magic talisman back then. Stores would carry them, but would not guarantee them, so people wouldn't "waste" money on a non-guaranteed product. Hence, the door-to-door salesmen took up the yoke and sold them in great numbers and provided their personal guarantee that it would work fine, just fine friend! Lightning rod salesmen were near as abundant as Kirby salesmen years ago. All of this relates to the U.S., of course. I can't speak for other countries.