Frequently Asked Questions about lightning protection:

What is lightning and a lightning strike ?

Lightning is a sudden electrostatic discharge during an electrical storm between electrically charged regions of a cloud (called intracloud lightning or as IC), between that cloud and another cloud (CC lightning), or between a cloud and the ground (CG lightning).The charged regions in the atmosphere temporarily equalize themselves through this discharge referred to as a strike if it hits an object on the ground

Where does the roll of thunder come from ?

The noise we all associate with a thunderstorm is caused by a rise in the electrodynamic pressure estimated at 2 or 3 atmospheres. The excess pressure drops when the flash is over, producing an acoustic shock wave. The duration and the acoustic intensity of the roll will depend on the form, length, intensity and brevity of the lightning strike.

How many times is the Earth struck by lightning within a year ?

On average, there are several hundred flashes every second.

What does"keraunic level" mean ?

The number of days per year when thunder was heard – not to be confused with "lightning density" which equals the number of strikes / year / km2.

How do we calculate how far away a storm is ?

Divide the time in seconds between the flash and the roll of thunder by three: this gives the distance in kilometers.

Is there just one lightning flash ?

Invisible to the human eye, a lightning flash is made up of up to ten successive arcs (return strokes).

What is a fulgurite ?

Also known as "lightning stones", fulgurites are solid lumps of matter formed by the vitrification of siliceous earth, especially sandy ground, under the intense heat produced by the lightning currents in the immediate vicinity of the point of impact.

What does "buzzing bee sound" mean ?

More scientifically referred to as the corona effect, this is a phenomenon witnessed just prior to a thunderstorm, whereby the tips of any prominent or metallic objects can give off a characteristic buzzing sound due to the rise in the surrounding electric fields causing small electrical discharges or sparks.

How were storms defined/explained before Franklin’s discoveries ?

In the 17th century, for example, it was thought that the phenomenon was caused when heavier clouds descended on the lighter clouds lying beneath them, compressing the air between the two cloud layers and producing a sudden release of heat, resulting in the flash and the roll of thunder.

Is there such a thing as a "ball lightning" ?

Yes, the phenomenon of ball lightning is well known and has been witnessed on many occasions. Scientists are very interested in this ‘globular lightning’, but no totally convincing theory or model has ever been put forward (particularly regarding its duration of several seconds).

Do people still use lightning rods? 

Yes. In fact, more lightning protection systems are installed now than ever before. Today’s lightning protection systems are inconspicuous. Since buildings today are equipped with many sensitive electronic systems, planners tend to include lightning protection systems not only to protect the structure but also to help protect the electronic systems and to keep the buildings up and running.

Don’t lightning rods attract lightning? 

No. This common misconception dates back to Ben Franklin’s day. Lightning rods simply intercept a lightning strike and provide adequate pathways to safely conduct the lightning to the ground. If lightning is zeroed in on a particular location, it will strike that location, whether there is lightning protection in place or not. It is helpful to remember that lightning travels several miles to reach the earth. Tiny objects on the ground have no influence on controlling the path lightning takes through the air. 

If there is a steel frame in a building is it already safe ? 

The structural steel of a building does conduct lightning, but you need a lightning protection system to provide the necessary interconnections to make sure that the lightning is able to pass harmlessly through the building.Without the lightning protection system, when a building is struck the lightning attempts to find a path to ground. If there are not enough interconnections providing a continuous path for the lightning to follow, there will be arcing or sideflashing. The lightning will also travel on other mechanical systems in a building such as the electrical or HVAC systems. The lightning current jumping from object to object within a building is dangerous and has been known to cause fires, explosions, etc.

How much does lightning protection cost? 

Cost varies greatly depending on the location of the structure, its size, its construction, the complexity of the roof-line and the ground conditions. Costs are lower when the system is designed and installed during construction. 
Retrofitting a system, is very common, but tends to be slightly more expensive. In comparison with other building 
systems, such as security or plumbing, the lightning protection is usually less costly.

Isn’t the purpose of lightning protection to prevent lightning from striking? 

Nothing can prevent lightning from striking. If lightning is zeroed in on a particular object it will strike that object regardless of anything that is on the ground. The purpose of lightning protection is to intercept the lightning strike and carry it to ground. This is accomplished by placing the rods at regular intervals on all of the highest and most exposed parts of a structure. These rods become the most likely point for the lightning streamer to attach, since they represent the shortest path to ground. The rods are connected by a network of highly conductive cables that provide a low-resistance path to ground.

Do I have to have all those cables running all over the roof? 

Some cables are inevitable, but if the system is installed during construction much of the system can be run under the roof, leaving just the air terminals exposed. The structural steel of a building can often be used in lieu of conductors. This also limits the number of roof conductors that you will see.


What's Early Streamer Emission Lightning Conductor ?

Early Streamer Emission Lightning Conductor also called as Early Streamer Emission Air Terminal is one kind of air terminal generating a streamer earlier than a simple rod air terminal when compared in the sameconditions.

NOTE – An early streamer emission air terminal is made up of a striking point, an emission device, a fixing element and aconnection to the down conductors.


Early Streamer Emission Lightning Protection System (ESE System)

Complete system based on one or more ESE Air Terminal and all elements to safely conduct lightning to earth inorder to protect a structure, facility or open area against direct lightning impact.

NOTE – It comprises both internal and external lightning protection system.


Earth Termination System

Part of an external Early Streamer Emission System which is intended to conduct and disperse lightning current into the earth.