[Familyofmonkeys]

Whilst sat in the middle of a rather large thunderstorm today I wondered if there was any more risk of steel roof being struck by lightening, compared to tile roof? Are metal roofs earthed or am I just going barmy wondering about all of this?

[DMcG]

Unless you're the only high object in a large area, you're fine.
Lightning is far more likely to hit a nearby tree since it tends to strike high points. If your house was on top of a hill and the highest thing around - I'd consider getting a lightning conductor and strapping it to a mast.

Dougie

[james the mechanic]

Hi Familyofmonkeys,
I doubt that a steel roof it that dangerous to its occupants in the event that it is struck by lightning. The roof may actually act like a Faraday Cage, allowing the lightning to travel around its surface and go to earth by the path of least resistance,(possibly the spouting/gutters or nearby tree). This is the reason why you're safe in a car during a thunder storm, because the lightning will travel around the surface of the vehicle and then go to ground. The metal, being a good conductor, directs the current around it and discharges it safely to the ground. Country to popular belief, the tyres are actually more conductive than they are insulating.
The tallest object in a storm doesn’t always get struck by lightning. Its true taller objects have a higher possibility of a strike; however lightning can strike the ground at a close distance to a tall object. A lightning rod/conductor is not to ‘attract’ lightning as many people seem to assume it is merely to provide a low resistance path to ground.
In summary I think you are pretty safe in you steel roof house, but it may be worth noting that during a storm, you should stay away from plumbing pipes if you truly believe a strike is possible in the nearby vicinity.
James

[stu70]

Hi Familyofmonkeys,
I doubt that a steel roof it that dangerous to its occupants in the event that it is struck by lightning. The roof may actually act like a Faraday Cage, allowing the lightning to travel around its surface and go to earth by the path of least resistance,(possibly the spouting/gutters or nearby tree). This is the reason why you're safe in a car during a thunder storm, because the lightning will travel around the surface of the vehicle and then go to ground. The metal, being a good conductor, directs the current around it and discharges it safely to the ground. Country to popular belief, the tyres are actually more conductive than they are insulating.
The tallest object in a storm doesn’t always get struck by lightning. Its true taller objects have a higher possibility of a strike; however lightning can strike the ground at a close distance to a tall object. A lightning rod/conductor is not to ‘attract’ lightning as many people seem to assume it is merely to provide a low resistance path to ground.
In summary I think you are pretty safe in you steel roof house, but it may be worth noting that during a storm, you should stay away from plumbing pipes if you truly believe a strike is possible in the nearby vicinity.
James
Thanks for a very informative note. I learnt a lot today and hope others do too. Cheers

[jackie m]

:clap Well done James thankyou for your info I will be a lot more settled now when we have a storm. Hopefully not too many of then though lol.
Jackie

[Familyofmonkeys]

Thanks for info...will stop wondering about it now....as soon as you mentioned faraday cage, it all made sense to me. Been a bit paranoid for years about lightening. when I was a student my tutor got struck by lightening, when his pick axe started humming. Apparently you are supposed to drop your pack and run if that happens, but he didn't and ended up with burn marks all over his feet from the metal studs in the soles of his walking boots.

[Lupin]

Enjoyed that, cheers :)

[kzn2nz]

I live in a brick under corrugated iron house, and we have some seriously wild thunderstorms. The only incidence of damage due to a direct strike that I have heard of was exactly as other James said -water in the copper pipes boiled and the pipes literally exploded, sending plaster flying.

This was a freak incident and the only one I know of in over 15 years. I do not think that the roof was earthed, as many here are. There is genrally a 5mm thick aluminium strap connected to the roof sheets and this is lead directly to ground. Whether it s actually effective is debateable.

[bob_the_engineer]

That’s really funny, it never crossed my mind, thunder and a tin roof! I guess when you think of it eeeekkk

If you want to increase the electric field (which clearly you don’t in this case) then you need a sharp point. The increase in field strength of a metal point is dramatic, thousands of times higher. I don’t really remember the ins an outs, just vague memories from Uni!

Its all relative too, the conductivity of a material, particularly a relatively flat material, when faced with the energy in a lightening is sort of negligible.

Sure the paths a little easier if the conductivity is good, but field amplification is much more important. That I guess is why the height of a tree plays a big factor.

And off the top of my head you may be better off under a metal roof.

Any willing experimenters out there, get a long wooden pole, put a pin in one end (pointy tip facing up) stick it in the ground (a good distance from the house, and on a nice flat area) and see what happens.

Any children reading this, don’t even think about it, if the lightening doesn’t get you your mum will.

Bob (who takes no responsibility for anyone daft enough to try this out)

PS I guess a sharp pick in a thunderstorm is about as good an idea as those umbrellas with a point on top :exit

[StevieD]

Irresponsible Bob :laugh

Have lost a friend through lightning strike..... one of those things, but don't worry in a house - unless you on the telephone or touching piping etc.

One thing that is often overlooked it to unplug electrical equipment, from aerials as well as wall sockets, Can cause major damage if overlooked.

Only last year, sitting in M-I-L's house in Liverpool when the street lit up and there was a huge bang. Went outside to see what the hell happened. There was a strange smell and that sort of metallic look to the sky that you get in storms. Next minute, neighbour comes out of house all stunned looking, turns out she had just picked up the phone to make a call, lightning struck the telegraph pole and she was propelled across the room into the wall!!!! Burn marks on her wrist and arm where the charge exited. She was lucky I suppose, but don't put too much emphasis on the fact that it is a steel roof.

Steve