Cloud to ground strikes are the most dangerous form of lightning for property and more importantly human life. Lightning Protection Systems increase the safety of properties, structures and surrounding areas by offering the energy from a lightning strike an easy path to ground, where it is safely dispersed.
Each year in the USA lightning is recorded as the cause of injury or death for hundreds of people. While over 10% are killed by lightning, 70% are seriously injured. Those that survive are often left with lifelong severe medical problems. Lightning strikes from thunderstorms on average cause more deaths in the USA than hurricanes and tornadoes combined.
It is estimated that every year, lightning is responsible for millions of pounds (sterling) of damage in the UK alone and nearly ½ billion dollars (US) worth of damage worldwide. This figure is believed to be growing as IT systems and communication networks become more important to business and their usage expands.
The immense current caused by a lightning strike generates a large amount of heat, less heat is generated when this current travels along a conductive material with low electrical resistance. Air is not a good conductor compared to other materials like copper so as the massive lightning currents travel through it, it becomes super heated to temperatures 3.5 times hotter than the surface of the sun. This burst of enormous heat produces an intense flash of light and causes a shock wave of thundering sound.
If lightning does this to air, imagine what it can do to the unprotected structure of your property. The electrical charge in lightning is always seeking the path of least resistance to ground. If lightning strikes a property the intense charge will search for the easiest route to ground no matter what it is; metal plumbing, pipes, radiators and taps, the wiring of a communications network and telephone system, metal railings on a stair well or the wiring carrying the mains electric that is not designed to carry such enormous loads. Anything touching or connecting to these objects is also highly likely to be injured or damaged. If the material carrying the current has too high an internal resistance the huge passing current, even though brief, will generate large amounts of heat causing primary damage by melting, igniting the conducting material or violently exploding it by rapidly expanding any air or moisture contained within. Secondary damage may also be caused by any resulting fire within the property, devastating contents within the building directly or from smoke damage.
With a lightning protection system properly installed the potentially dangerous current from a lightning strike is offered an easy and safe route to ground.
Workplaces in the Britain have a duty to ensure the health, safety and welfare of their staff under the Health and Safety at Work Act 1974 Section 2(1). Events must be thoroughly risk assessed, and if there is a risk of being struck by lightning this must be investigated and control measures like a lightning safety plan put in place. This may include the installation of building or regional lightning protection systems to create lightning protected areas.
The UK requires structural lightning protection to comply with BS6651:1999. This standard focuses on the protection of the building structure only from lightning strikes – something which is also required by most insurance companies.
Is Lightning Protection Still As Important Today As It Used To Be?
It is even more important today than it used to be. Today’s competitive businesses are demanding more sophisticated electrical systems and communication infrastructures. A lightning strike to an unprotected building today can cause greater destruction even if it is not visually apparent like structural damage or fire. Even an indirect lightning strike on a building or nearby utility can cause thousands of pounds of damage as its currents radiate out from the strike zone.
With the global climate also changing, it is predicted that Britain will experience more thunderstorms and lightning strikes in the future.