Effect of Lightning Strikes on a Building

[Engineer54]

well....as long as the footings are sound.....
and i`v heard a lot about that seismic brick they use out there n all....

The house is of a concrete frame with block/brick infill construction, sat on a 1m deep concrete raft foundation. Designed and overseen by a Consultant Structural Engineer. In fact most houses over there are concrete frame construction...

 

[shagbite]

religions: they're all bloody puddled.

i vaguely remember a world cup match a few years ago. i think it was saudi arabia vs iran. anyway, they were drawing with about 2 minutes to go when one of the sides went and scored. every player rushed to the side of the pitch, got down on their knees and started praying - thanking god for being on their side.

the game re-started (in injury time) and the opposing team managed to get an equaliser straight away - then THEY all rushed to the side of the pitch for a mass prayer, so they could thank god for being on THEIR side.

weirdos.

 

[Knobhead]

Were does religion and engineering come together?

My usual reaction to something going belly up is “Oh Hell, they’ll blame me!”

 

[Tim]

Quick update,

Ive been on site for an hour or so and so far nothing shows any signs of damage what so ever, apart from a missing tile on the roof.
I have the previous test results and so far everything tallys up perfectly.
The install here is very good, all neat and well labeled (a pic below of one of the db's)


All rcbos ive checked so far trip correctly. And no signs of overheating anywhere.

They have had major problems with the fire alarm system, lifts, mag locks, tills and AC, so pretty much anything with a circuit board.

The building will probably fall into the 'should have an lps' catorgry as its the tallest building for about half a mile, but i dont know the full criteria so may be wrong. The fact it was hit suggests it should probably have one.

Pic of strike damage, not very exciting.


If i find anything interesting ill post it up.

Tim

 

[Darkwood]

Its possible the circuit boards are damaged indirectly with EMP which may have induced damaging voltages to the electronics hence you have these issues ....as the F/A system is crucial for the hotel to remain open i would suggest they get a large team in to test repair or replace the system where necessary .... they may need to find out where they stand as a business without a functional fire alarm if this be the case..... if your a sole trader this probably an area to leave to a larger team as time is key factor here.

 

[Tim]

Its possible the circuit boards are damaged indirectly with EMP which may have induced damaging voltages to the electronics hence you have these issues ....as the F/A system is crucial for the hotel to remain open i would suggest they get a large team in to test repair or replace the system where necessary .... they may need to find out where they stand as a business without a functional fire alarm if this be the case..... if your a sole trader this probably an area to leave to a larger team as time is key factor here.

Emp was my guess for the damaged electronics, i still cant understand how nothing is damaged, ive found 1 screw with some burn marks, but that could well be a lazy maintanence guy who shorted out a cable.

The fire alarm system is being sorted by other contractors, they have 24hour watch on untill its fixed.

Cheers,
Tim

 

[Darkwood]

Don't forget the building is an extension of the ground it will all have built up a high charge as a whole building and the strike doesn't always effect electrical systems ....if the hotel has steel skeleton RSJ's etc they can easily shunt the damage away from the wiring systems .... its just pot luck at the end of the day, consider themselves lucky they weren't hit by the less common Positive strike as these are many magnitude larger and almost certainly would have seen major damage if the hotel didn't burn down.

 

[Tim]

Right, ive found something interesting.



As previously stated i know very little about lightning protection systems.

The pic is of what i think (and judging by the company name i am right) is a pit to send the lightning strike to the ground directly and not through the building.

My question is where is the conductor (i believe they are lead usually) that goes around the building to capture the strike? Could it be buried with the rod? There is no evidence one is fitted and i have accounted for all the cables from the met so if there is an lps its not bonded.

If i am right in thinking the rod pits have been installed but not connected, why would this be?

Cheers,
Tim

 

[Darkwood]

Looks like your building has a TNCS (PME) this is one of the multiple earth access points ...nothing to do with the lightning.

Although i question myself now looking at the name it maybe a rod for lightning?

 

[Tim]

Looks like your building has a TNCS (PME) this is one of the multiple earth access points ...nothing to do with the lightning.

Well that shoots my theory down. That didnt even cross my mind, i saw the company name and instantly thought it must be to do with an lps.

Cheers,
Tim

 

[Tim]

Ive just seen your edit, any speculation as to why the rods are installed but no conductors to the roof?

 

[Engineer54]

Right, ive found something interesting.

View attachment 19945

As previously stated i know very little about lightning protection systems.

The pic is of what i think (and judging by the company name i am right) is a pit to send the lightning strike to the ground directly and not through the building.

My question is where is the conductor (i believe they are lead usually) that goes around the building to capture the strike? Could it be buried with the rod? There is no evidence one is fitted and i have accounted for all the cables from the met so if there is an lps its not bonded.

If i am right in thinking the rod pits have been installed but not connected, why would this be?

Cheers,
Tim

Going by what i can see, the rod in this earth pit is connected by what looks to be a copper tape. And ''NO'', ...LP systems do not use lead conductors they will all be of high conductivity copper, usually hard drawn copper too, for strength/longevity etc, being exposed to the elements.


Hard to tell what this earth pit is being connected too, the earthing system could be a TT system or maybe was a TT system now converted to a PME system (as darkwood suggests)!! Hopefully they left the TT earth in place at the MET if it is a converted system...

 

[Darkwood]

You have a phone number on the lid .....can't do any harm to ring it and query what its purpose serves explaning what site you are on???? Let us know....

 

[Engineer54]

Ive just seen your edit, any speculation as to why the rods are installed but no conductors to the roof?

From what little i can see of the roof, there seems to be no indication of any LP system in place. Maybe it was originally planned to provide LP to this hotel but got dropped later, (are there several of these earth rod pits around the building?) after the ground works had already been completed. Which could mean an easy LP retro-fit if they so choose to fit!! lol!!

 

[Tim]

From what little i can see of the roof, there seems to be no indication of any LP system in place. Maybe it was originally planned to provide LP to this hotel but got dropped later, (are there several of these earth rod pits around the building?) after the ground works had already been completed. Which could mean an easy LP retro-fit if they so choose to fit!! lol!!

There are 7 of the pits around, i think as you said, the pits were there for the lps but it was never installed for some reason.

Ive tried to trace the copper tape with no luck. There is no structure on the roof that resembles an lps system.

Darkwood, i have tried phoning the number but it forwards to a mobile voicemail. Ill try again later.

Cheers guys

 

[Engineer54]

There are 7 of the pits around, i think as you said, the pits were there for the lps but it was never installed for some reason.

Ive tried to trace the copper tape with no luck. There is no structure on the roof that resembles an lps system.

Darkwood, i have tried phoning the number but it forwards to a mobile voicemail. Ill try again later.

Cheers guys

Sounds to me as though a provision has been made for an LP system for this hotel. The Tapes will/maybe be rolled up at the seven locations at the base of the building walls adjacent to the earth pit locations....

 

[Tim]

Well it looks like my information was wrong, the manager has just got in an confimed that there was an lps but doesnt know wether it 'works' or not.

I am poking around the hard to access parts of the loft now and look what ive found

 

[Darkwood]

Forecast is isolated thunderstorms all day...... Do you really want to be up there lol!......as you say it sticks out like a sore thumb ..... if your hair tingles get worried!!!! :sick:

 

[Engineer54]

Well it won't be doing any good below the roof tiles!! lol!! Unless you can see air conductors on the roof, be they spikes or external flat tape runs, then this building does not have an LP system... Should also be able to see down conductor test points about 1.3m from FGL on each down conductor.

Also, if that copper tape is for LP purposes, the fixing installation does not comply in any way shape or form to LP installation regulations.... The plot thickens!! lol!!

 

[Tim]

Forecast is isolated thunderstorms all day...... Do you really want to be up there lol!......as you say it sticks out like a sore thumb ..... if your hair tingles get worried!!!! :sick:

The sky is a bit dark round here, i think ill take shelter in the van, i know they say it never strikes the same place twice but i dont want to be the exception that proves the rule lol

Well it won't be doing any good below the roof tiles!! lol!! Unless you can see air conductors on the roof, be they spikes or external flat tape runs, then this building does not have an LP system... Should also be able to see down conductor test points about 1.3m from FGL on each down conductor.

Also, if that copper tape is for LP purposes, the fixing installation does not comply in any way shape or form to LP installation regulations.... The plot thickens!! lol!!

Looks like they need a proper inspection of the lp system then. I can see what looks like copper tape poking up from the apex of the roof about 8", is this a version of an air conductor?
Its too far for me to see in detail, but it looks like there are 8or so of these 8" strips.

Cheers,
Tim