Petroleum industry history for example provide ample evidence of the destructive nature of lightning activity. Millions of dollars of petrochemical products and facilities are destroyed each year by lightning related phenomena in many parts of the world, and lives are lost when these facilities are ignited or explode.
Mechanics of the strike:
Thunderheads are electrically charged bodies suspended in an atmosphere that may be considered at best a poor conductor. During a storm, charge separation builds up within the cloud. The potential at the base of the cloud is generally assumed to be about 10 KV per meter of elevation above earth. The charging action (or charge separation) within the storm cell usually leaves the base of the cloud with a negative charge, but in rare cases the opposite seems true.
This resulting charge induces a similar charge of opposite polarity on the earth, concentrated at its surface just under the cloud and of about the same size and shape as the cloud. As a storm builds in intensity, charge separation continues within the cloud until the air between the cloud and earth can no longer act as an insulator. The specific breakdown point varies with atmospheric condition.
Grounding System
The ionizer assembly alone is not sufficient. The system must be grounded. The Ground Current Collector (GCC) provide the source of charge to keep the ion current flowing through the array and discharge the site. Since the induced charged created by the storm is at the earth's surface, the portion of the earth's surface containing the facilities to be protected is usually surrounded with the GCC. The GCC is normally composed of the Ground Current Collector wire or copper tubing buried to a depth of about 25 centimeters and short ground rods along the GCC at intervals of about ten meters.
LEC's Chem Rod Grounding Electrode is an ultra efficient low surge impedence grounding system. It provide the perfect low resistance interface with true earth by continuously conditioning the surrounding soil, using specially formulated mineral salts evenly distributed along the entire length of the electrode.
The significance of the electrically isolated island ionic current flow can be summarized as below:
- The current flow from the ionizer through the air space above it reduces the potential of the protected site and facility with respect to its surroundings by draining the charge from the protected area and transferring it to the air molecules.
- The presence of free ions or space charge between the protected facility and the cloud structure forms a type of Faraday shield between them, thus providing isolation for the facility from the storm cloud's static field.
