NFPA 780 Lightning Protection Calculator

[bbaumer]

Anyone who uses this in flash density zone 3 or higher ever had the calculation come back as "optional" and not "required"?

I live in Zone 4. Playing with the calculator and inputing "funny" numbers with the lowest co-efficients you can use it still spits out "required".

You have to use Zone 2 or lower and short buildings with no valuable content to get "optional".

I would think with Florida and the Gulf Coast being pretty much between Zones 10 and 14 that anything under Zone 5 would be medium to light risk and systems optional most of the time and systems would be optional as the rule, not the exception.

 

[Ben Franklin]

Almost anything to do with lightning protection is optional.

An owner / designer of a structure usually knows right off the bat whether an LPS will be installed or not regardless of the risk analysis or any other calculation one may perform.

I personally would be less worried about the flash density analysis and more concerned with what protections the structure type and contents necessitate.

Its a matrix of decision making. A low risk structure in a high risk zone may not need protection, whereas a high risk structure in a low risk zone would.

Its more common sensical than analytical.