Domestic Lightning Conductor

[jaiyenyen]

My friends home was recently hit by lightning. The house stands on it's own, surrounded by farmland, in a fairly high up location, hence the lightning strike. After the roof is repaired, I'd like to arrange for a lightning rod to be installed. This is a basic farm house, so I'm not too worried about surge protectors etc, just trying to prevent future damage to the roof.

Any ideas about specifications and rough ballpark prices would be welcomed.

[Crossy]

What is the house structure, wood, concrete? How about the roof?

 

We took a direct hit to our (concrete with a steel roof structure) home a few years back, blew off a couple of ridge tiles and very little else structural.

 

At the time I looked into adding rods and decided against it on a cost and aesthetic basis. The numbers being quoted by a local outfit were just crazy (like hundreds of k Baht), mainly I suspect as they hadn't done domestic before and were quoting commercial prices.

 

It should be noted that our roof structure is a VERY good ground, the steel is continuous right into the piles although the joints are just wire tied.

[jaiyenyen]

Thanks for your reply.

Sounds like a similar structure. Cement roofing sheets over a steel frame. The only damage was roofing sheets. This house has only been built a year and I suspect they are in for a few more hits over the years. I just want to try to prevent the continual replacement of roofing.

I'm not even sure where the best place is to buy the cable and rod. There's not much to a basic installation, so I cant imagine it would cost the earth.....Excuse the pun 555

[sometimewoodworker]

32 minutes ago, jaiyenyen said:

Thanks for your reply.

Sounds like a similar structure. Cement roofing sheets over a steel frame. The only damage was roofing sheets. This house has only been built a year and I suspect they are in for a few more hits over the years. I just want to try to prevent the continual replacement of roofing.

I'm not even sure where the best place is to buy the cable and rod. There's not much to a basic installation, so I cant imagine it would cost the earth.....Excuse the pun 555

The cable, but better flat copper bar, needs to be substantial to be effective. It is not at all inexpensive and is a magnet for thieves as they can easily see it and cut it.

 

you will probably find that metal sheets for the roof will do a far better job.

[farmerjo]

I think i paid about 4500 baht for 2 lightning rods,cable and 3 metre copper rods.

https://forum.thaivisa.com/topic/1036774-nothing-can-save-you-from-a-direct-hit/page/4/#comments 

[jaiyenyen]

Thanks for the link.

Did you buy your materials locally? or did you get them online.

[bankruatsteve]

A lightning rod can help catch a strike but no guarantee.  Odds are good that another direct strike would (also) hit the roof.

[farmerjo]

2 hours ago, jaiyenyen said:

Thanks for the link.

Did you buy your materials locally? or did you get them online.

I bought the gear at a local electrical business.

Global house etc have in stock as well.

[sometimewoodworker]

Just for interest, and my education, is there any research into the kind of buildings commonly found here which, with the rebar tied into the roof metal and metal roofs.

 

Is there any need for lightning protection?

 

I would think that that kind of construction would virtually eliminate any benefits of lightning rods as the whole roof becomes lightning protecting. Comments are welcome. 

[Crossy]

2 hours ago, sometimewoodworker said:

I would think that that kind of construction would virtually eliminate any benefits of lightning rods as the whole roof becomes lightning protecting. Comments are welcome. 

 

That would be my feeling too, our direct hit did a whole 1,500 baht of damage (including labour) to the roof although we did lose some electronics which was outside the Faraday cage formed by the roof and column re-bar.

 

I toyed with the idea of welding rods to our roof structure (copper/steel air-terminals are readily available in Global etc.) but Madam didn't like the look of them and worried that they would actually attract the lightning.

 

[bankruatsteve]

4 minutes ago, Crossy said:

Madam didn't like the look of them and worried that they would actually attract the lightning.

According to lightning gurus... nothing 'attracts' lightning.  They say that it is more likely to hit taller objects but time and again, it doesn't - hitting the ground next to a tall building for example.

https://stormhighway.com/small_metal_objects_attract_lightning_myth.php

[sometimewoodworker]

21 minutes ago, Crossy said:

That would be my feeling too, our direct hit did a whole 1,500 baht of damage (including labour) to the roof

I wonder if you didn't have tiles if, the strike would have happened and if it did if there would have been any damage. Though with the extremely high voltages involved it's difficult to know what will happen. Quite possibly the paint may be enough insulation to negotiate the benefits. 

 

Luckly the area we are in doesn't get a great many ground strikes, though enough that one person from a nearby village discovered that the best place to be in a thunderstorm is indoors, regrettably a fatal mistake.

 

[farmerjo]

33 minutes ago, sometimewoodworker said:

I wonder if you didn't have tiles if, the strike would have happened and if it did if there would have been any damage. Though with the extremely high voltages involved it's difficult to know what will happen. Quite possibly the paint may be enough insulation to negotiate the benefits. 

 

Luckly the area we are in doesn't get a great many ground strikes, though enough that one person from a nearby village discovered that the best place to be in a thunderstorm is indoors, regrettably a fatal mistake.

 

My research on the matter and belief is it cannot hurt.

If inside a building and it strikes the lightning rod,it goes directly to ground.(of 3 metres)

Without the rod it may pass through the roof,through you and then to ground which on thai homes is lucky to be 700mm deep.

I have seen a tower crane counter turn 6 times having a rod and highest point in workplace. 

 

[Crossy]

9 minutes ago, farmerjo said:

Without the rod it may pass through the roof,through you and then to ground which on thai homes is lucky to be 700mm deep.

 

Good point, we are on 16m driven piles (Bangkok clay).