Lightning Protection

[messy]

When conducting a fire risk assessment, it's obviously important to consider all possible causes of fire and introduce control measures where necessary. So  how do you quantify the risk of lightning strikes? - indeed, do you consider this risk as part of your usual FRA process?

I am aware that there is specialist software and companies who will provide an assessment service based on various factors including the geographic location of the risk area, but is the risk so slight, special measures aren't viable?

I am not talking about sites such as Buncefield or any special risk, I am thinking of your 'normal' risks such as warehouses, Offices , Shops, Schools etc.

I have rarely seen mention of this risk on any FRAs other than PAS 79 type templates, so what do you do??

[kurnal]

If a premises has a lightning conductor system I always ask for evidence that it is inspected and maintained.

If the premises do not have a conductor but  are in an elevated, exposed position or are higher than surrounding property I usually recommend that they seek specialist advice.

We cant predict where lightining will strike but we can predict the consequences - often multi seated fires throughout the building.

[Ken Taylor]

I was once told that a particular listed building didn't need lightning protection as it was 'within the cone of protection' of an adjacent church that had a lighning conductor. Not long after lightning struck the building via a metal window and knocked out the phone system. Needless to say they then went for an installation.

The FRAs that I've organised ask whether there is lightning protection and, if so, when it was last inspected. Hopefully this serves as a reminder to the assessor to consider that particular risk.

[jokar]

As an act of nature surely it is a consideration as an ignition source.  A  hotel in Hampshire burnt down 2 years ago after a lightning strike.

[AnthonyB]

Agree with all the others, presence & testing of lightning conductor is a standard in our FRAs. It's worth reading the actual certificate and ensuring that (a) it is passed as well as tested & (b) if not passed has the remedial repairs been completed as it's not uncommon to find a nice stack of year on year test certs, but that each one is a Fail!

Lightning strikes have caused fires in a few buildings we have encountered and it certainly isn't a one in a million occurance

[Redone]

Found a conductor cable terminating on route to the ground via a 3/8th Whitworth into the handrail on the top floor of an external escape, still waiting for the report on suitability.  Tallest building for about a mile.
Who wants the desk by the window in a storm...

Tricky topic, as buildings can be hit in the side not just the top, only a 'herring bone' type of grid will give protection.

[Peter Wilkinson]

As defined in BS6651, the probability of a structure of building being struck by lightning in any one year is a product of the lightning flash density and the effective collection area of the structure.  The suggested acceptable risk figure has been taken as 10-5 per year, i.e. 1 in 100 000 per year.

See the standard for details of the (quite simple) assessment procedure.  Then you will be able to determine whether lightning protection is required.