Effect of Lightning Strikes on a Building

[Tim]

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

 

[Darkwood]

Due the the massive voltage and current along side the massive magnetic fields generated by a lightning strike the install will require a 100% EICR, the main strike comes with many spurring less intense fault paths that may run through circuits that seem to be away from the main damage and will only show up in ELI tests and Insulation Testing.

Ive seen lightning strike to a church blow out the full length ring main of buried pyro cleanly out off the wall leaving a nice chase and plaster on the floor...the pyro was undamaged but it blew out due to an induce EMF as the lightning went through the building not because it was part of the path it tried changing shape in a split second with the induce magnetic field and whip-lashed itself out of the wall.

 

[Tim]

Due the the massive voltage and current along side the massive magnetic fields generated by a lightning strike the install will require a 100% EICR, the main strike comes with many spurring less intense fault paths that may run through circuits that seem to be away from the main damage and will only show up in ELI tests and Insulation Testing.

I hadnt thought of that, i was imagining that all the damage would be around one area, the spurring strikes didn't even cross my mind.

I have been allotted 2 days to check out the building, this wont be enough time to do a 100% eicr, but my purpose on site is to let them know what should be done after seeing the extent of the damage, so a 100% eicr is defiantly on the cards as a recommendation.

Cheers, Tim

 

[SirKit Breaker]

Last lightning strike i looked at needed a full rewire, and the insurance paid for it. Failed IR tests, damaged CPC's and melted sleeving in CU. I think it was the lightning strike that pushed a poor installation over the edge though, not just damaged due to the lightning strike. i would look at the meter as well, it may need replacing with one that will withstand Cat 2 impulse voltage.

Cheers............Howard

 

[Darkwood]

As its and hotel you may be able to do a progressive test where you start on all circuit local to point of strike and work away from that point until your reading are all clear, a previous test report would be good to understand the condition and readings that had been tested in the past ....lightning is so random and varies so much one strike can show cosmetic damage to building only and the next can totally take out the electrical system.... it all down to where the leader stroke paths went ..whether multiple paths were realised and has induced current damaged any sensitive equipment or circuits... Check all rcd's fully function as a priority this may be the life saver as you build your report.

 

[Farmelectrics]

Ill bet there insurance is void anyway with out the lighting protection

 

[Darkwood]

I got told once insurance void due to act of god.... a while back... i legally challenged the to prove that god exists or oblige the claim.... they backed down and payed then reworded all of their insurance policies... they said it was a recognised term i just said im an athiest and so i don't recognise it and questioned their legal teams professional stance for using a religious clause as an exemption within a insurance policy..... no comment lol :wink5:

 

[Silly Sausage]

Hahaha...nice one!
No way Jesus came from your loins either.

 

[Darkwood]

Hahaha...nice one!
No way Jesus came from your loins either.

Very apt profile pic lol

 

[Tim]

As its and hotel you may be able to do a progressive test where you start on all circuit local to point of strike and work away from that point until your reading are all clear, a previous test report would be good to understand the condition and readings that had been tested in the past ....lightning is so random and varies so much one strike can show cosmetic damage to building only and the next can totally take out the electrical system.... it all down to where the leader stroke paths went ..whether multiple paths were realised and has induced current damaged any sensitive equipment or circuits... Check all rcd's fully function as a priority this may be the life saver as you build your report.

That sounds like a proper plan, ill start at the strike point and work out from there.

Cheers for the replys guys, ill be back tomorrow with pics

Tim

 

[GLENNSPARK]

Due the the massive voltage and current along side the massive magnetic fields generated by a lightning strike the install will require a 100% EICR, the main strike comes with many spurring less intense fault paths that may run through circuits that seem to be away from the main damage and will only show up in ELI tests and Insulation Testing.

Ive seen lightning strike to a church blow out the full length ring main of buried pyro cleanly out off the wall leaving a nice chase and plaster on the floor...the pyro was undamaged but it blew out due to an induce EMF as the lightning went through the building not because it was part of the path it tried changing shape in a split second with the induce magnetic field and whip-lashed itself out of the wall.

too bloody rite it will

 

[Engineer54]

Ill bet there insurance is void anyway with out the lighting protection

That would depend on whether or not the building came within the recommended criteria of needing/requiring a lightning protection system.

 

[GLENNSPARK]

I got told once insurance void due to act of god.... a while back... i legally challenged the to prove that god exists or oblige the claim.... they backed down and payed then reworded all of their insurance policies... they said it was a recognised term i just said im an athiest and so i don't recognise it and questioned their legal teams professional stance for using a religious clause as an exemption within a insurance policy..... no comment lol :wink5:

bloody farce innit....

 

[GLENNSPARK]

That would depend on whether or not the building came within the recommended criteria of needing/requiring a lightning protection system.

what?...if it were an act of god?...
what if it were a mosque?

 

[Darkwood]

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

 

[GLENNSPARK]

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]

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]

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]

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]

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]

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

 

[Darkwood]

The construct/building and earthrods all look recent ,10yrs old ...You should be able to get building plans and subsequent LP system info to boot.

 

[Engineer54]

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

It can and often does!! Lightning strikes always go for a weak point...




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

Yep, get the so-called specialists in, because bits of tape sticking up out of the roof apex does not make for a working LP system. Air conductor spikes are around 12'' long with a prominant point to them. That or the tape needs to be completley external and follow the line of Apex as well as the edges of the roof complete with cross connections. (A bit difficult to explain fully here)

Save to say, from what your telling us, it sounds like a bit of a pig's ear of an LP installation!! ...lol!! And has already proved to be ineffective!!