Electrical Earthing System Design & Soil Resistivity Testing
By Ian
Lightning frequency increase…very few consider that they or their assets will be struck by lightning. People relegate the threat of lightning to chance and are confident it will not affect them. This is a mentality that may come back to haunt them if new scientific research is correct.
Lightning! Incredible to view, frustrating to be affected by and fatal in proximity. We take a look at the beauty, strength and danger of lightning.
[Read more…] about Fear of Lightning Frequency IncreaseContinuing the theme for lightning design. I was having a technical discussion with a delegate, during a seminar in Germany. The question popped up regarding Lightning design on an AD plant (AD = anaerobic digestion). This site, with long-buried cable-runs, between plant areas. The delegates question, “What about the buried cables?”
What do we do about Lightning protection for buried cables in Lightning design?”
The question was not aimed at surge protection, but at physical protection of the cables from a direct lightning strike. And, before you say what? Yes, buried cables are at risk from direct strike attachments.
[Read more…] about Lightning design for buried cables – really?A common question on Lightning Protection Design that crops up time and again, is – “What is the rolling sphere method of protection?”
If you’re looking for a convenient definition in BS EN 62305. I can save you the hassle because there isn’t one! The closest you will get to a conveniently packaged definition is in para E.5.2.2.2 ..
… the positioning of an air-termination system is adequate if no point of the volume to be protected is in contact with a sphere of radius, r, rolling on the ground, around and on top of the structure in all possible directions. Therefore, the sphere should touch only the ground and/or the air-termination system.
Hmmm, not exactly succinct or useful, right?
[Read more…] about Why Rolling Sphere Method is bestThere are some 15 to 20 known Floating Roof Tank (FRT) fires per year. Floating Roof Tanks are especially vulnerable to the direct and indirect effects of lightning. Direct, or a nearby lightning strike can cause electrical current to flow across the tank shell and roof. When these lightning currents arc across the roof/shell interface, they can ignite any flammable vapours present with devastating effect.
[Read more…] about Floating Roof Tank Earthing Strategies – Bypass conductors for lightningThe most exciting concept to come out of the Lightning Protection sector for centuries is the idea of ‘Lightning Strike Prevention’.
Now, preventing lightning itself is outside the scope of any working installation today. And maybe something for the scientific communities to think over. However, preventing an STRIKE-attachment to a structure IS something that is here and now! [Read more…] about Is prevention better than cure? | Lightning Strike Prevention