Lightning protection using a mast. When do you use it instead of lightning rods on the roof? 1

[Dvhez]

I've been told that a single lightning protection (franklin type) mast covers around 250 meters (800 ft). The total area under study is between 200 and 300 m2. Under which standard are these masts covered?

Thanks!

 

[cuky2000]

A single lightning mast of 20m (~60 ft) in height above of the target could cover approximatelly 300 m[sup]2[/sup] (3,220 ft[sup]2[/sup]) .

ANSI/IEEE Market places:
SUBSTATION: IEEE 8O- IEEE Guide for Safety in AC Substation Grounding
BUILDING: NFPA 780: Standard for the Installation of Lightning Protection Systems.
[sub]NOTE: There are difference in the rolling sphere radius considered in both standards.[/sub]

IEC Market places:
GENERAL: IEC 62305 (4-part) Protection Against Lightning.

For additional information in this matter see the following Link

 

[Parchie]

Hahaha! No one can predict where a lightning bolt will strike! Been there! Can't even explain why a bus tube tap was hit when the Franlin rods are way,way higher on the structure!

 

[KillBill7]

You can use IEEE 998 (Guide for Direct Lightning stoke shielding of Substations) as well for substation applications. It does discuss different methods like the fixed angle, empirical method, and electrogeometric model (rolling sphere method).

 

[jghrist]

What are you protecting? Generally, it is less expensive to protect a building with air terminals (lightning rods) on the roof instead of masts around the building. Protecting an outdoor substation that way is difficult because there is no roof over the substation.

The area protected by a mast depends on the height of whatever it is that you are protecting.

 

[cuky2000]

Parchie: Although it is true that there is no method to fully predict a lightning strike, the standards offer a probabilistic method to access the risk of lightning strikes.
What alternative do you suggest to address the lightning strikes: Not protection, partial protection or best practice with available shielding protection methods.

 

[Dvhez]

We have containers with offices inside and the lightning protection mast is supported to a container with galvanized pieces. Also it has three steel wind wires attached to the top of these containers. All of this containers are grounded. Could it be a problem with this configuration?

Edit: It's important to clarify that this lightning protection mast is connected to a ground grid.