Effect of Lightning Strikes on a Building

Tim · Jul 24, 2013

Good evening guys,

I have just had a call to go and have a look at a hotel tomorrow that was hit by lightning yesterday morning. All i know is that its a 2 story building and was hit and now has a hole in the roof and that there is no lightning protection system in place.

They are worried that the strike may have damaged the electrics in the building and therefore voided their insurance. I have no experiance with lighting protection systems or the effects of a lightning strike on a building, I'm hoping someone on here has some insight on the main things to check. I will be recommending that they have the site assessed for an LPS by a specialist contractor as this is not something I or anyone in the company i am working for is competent to do.

My plan is as follows:
Go to site, ask the manager that was on duty at the time what happened and if anything went down/caught fire/made funny noises etc.
Then check out a sample of RCBO's/RCD to ensure the electronics in them were not damaged by the EMP.
Check Bonding and Earthing conductors and clamps for signs of overheating.
Do the usual Ze and Pfc test to check the main earthing conductor has not been damaged.

Can anyone suggest anything else that would likely have been damaged by a strike? I am working on the assumption that the strike hit some metal work on the roof (AC unit??) that was connected to the MET and that was the route to earth for the strike.

Any advice would be appreciated as this is not one of the things you come up against on a daily basis. And of course i will post up pictures when i get to site.

Cheers,
Tim

GLENNSPARK · Jul 25, 2013

darkwood said:
The church i worked on had had its lightning line pinched by copper thieves but like any religion there building normally have a spire or symbol of some sorts but also due to the obvious attraction for lightning they are fully protected..

What makes me laugh is if they didn't use science/physics to protect their building they have a high chance of been struck .... now as its claimed as an act of god surely he wouldn't attack his own places of worship......food for thought

yep...and science and religion at loggerheads all the time as well.....
cobblers it is....

Engineer54 · Jul 25, 2013

GLENNSPARK said:
yep...and science and religion at loggerheads all the time as well.....
cobblers it is....

I don't know what happens in the UK these days as far as house insurance goes, but i know for a fact that both earth quake and lightning strike are both covered on my house insurance policy i have in Cyprus. Both could be considered as natrual acts or acts of god!! lol!! Even covers flooding, but not much chance of that, the house is located on a low rise hill.... lol!!

GLENNSPARK · Jul 25, 2013

Engineer54 said:
I don't know what happens in the UK these days as far as house insurance goes, but i know for a fact that both earth quake and lightning strike are both covered on my house insurance policy i have in Cyprus. Both could be considered as natrual acts or acts of god!! lol!! Even covers flooding, but not much chance of that, the house is located on a low rise hill.... lol!!

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

Darkwood · Jul 25, 2013

It relates to the strikes per mile sq in any area i believe if you are in a high risk area then you dont get cover unless you have lightning protection..... most of UK is low risk so not usually a clause but their are high risk zones where cover is denied if your don't protect you building.

GLENNSPARK · Jul 25, 2013

darkwood said:
It relates to the strikes per mile sq in any area i believe if you are in a high risk area then you dont get cover unless you have lightning protection..... most of UK is low risk so not usually a clause but their are high risk zones where cover is denied if your don't protect you building.

but they will slip all kinds of `get outs` and other little nastys in there if they can get away with it....

Engineer54 · Jul 25, 2013

GLENNSPARK said:
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 · Jul 25, 2013

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 · Jul 25, 2013

Were does religion and engineering come together?

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

Tim · Jul 25, 2013

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)

[ElectriciansForums.net] Effect of Lightning Strikes on a Building

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 · Jul 25, 2013

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 · Jul 25, 2013

darkwood said:
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 · Jul 25, 2013

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 · Jul 25, 2013

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 · Jul 25, 2013

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 · Jul 25, 2013

darkwood said:
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

Effect of Lightning Strikes on a Building

Tim

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GLENNSPARK

Engineer54

GLENNSPARK

Darkwood

GLENNSPARK

Engineer54

shagbite

Knobhead

Tim

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Darkwood

Tim

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Darkwood

Tim

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Darkwood

Tim

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