The Problem
Lightning ground currents, also known as Lightning Ground Potential Rise (LGPR), occur when lightning strikes the ground in rural areas, near electronic sites that serve the telecommunications, pipeline distribution, railroad, and other industries. Even though these sites employ the best surge protection and grounding systems, lightning ground currents cause frequent, costly damage and outages.

When lightning strikes the ground, its energy is not immediately dissipated in the strike area. High-voltage gradients and the resulting fault currents propagate through the earth's surface, and a remote site's grounding system is momentarily elevated by thousands of volts. This energy can saturate the site's grounding system, while conventional surge protection will let this elevated voltage seek an alternative path to ground. A "back door" fault path through the site's incoming power circuit is created, resulting in a damaging voltage gradient across the electronic modules and components.

Rural sites experience LGPR damage because there is little nearby infrastructure to mitigate the ground current. Settled areas have more underground plumbing and wiring to dissipate the energy. So the current radiates further in rural areas, particularly in regions with low soil conductivity. Well-grounded sites in rural areas may actually be attractors of ground currents, since lightning energy will seek the easiest path to the lowest resistance ground.

The Cost
LGPR damage takes a toll on a company in the form of costly electronic equipment that must be replaced. There are other costs as well.

• For telecommunications companies, it means the loss of voice services, or the loss of broadband Internet or video services.
• For utility companies, it interferes with the efficient management of pumping stations and monitoring equipment.
• For railroads and other companies that rely on remote sites for communications, it leaves them in the dark about the status of their assets.
• In many cases, the losses of revenues and production far outweigh the costs to repair damaged equipment.

The Solution
LGPR damages can be avoided if rural electronics sites have the ability to perceive impending lightning threats. When a threat is detected, the AC power circuit can be opened in order to eliminate the fault path through the electronics.

This approach is like unplugging your home electronics when a storm approaches. If fault current can't flow across the open circuit, the lightning energy is forced to dissipate in the site's grounding system. During this period of "protected isolation," the site's electronics continue to operate, powered by the battery plant or standby generator.

When the threat has passed, AC power is automatically restored to the site.

About the Author
Gary Fox is co-founder and president of ALSET Corp, an engineering company focused on the development of intelligent technology to combat lightning ground potential rise. Prior to founding ALSET, Gary was president/CEO of ADIC, a public company that developed robotic technologies for data management systems. Previously, he and ALSET's co-founder and CTO, John Wruble, managed RACON, a developer of wireless technology for high-security installations.

About the Company
ALSET Corp.'s Lightning Shield is a cost-effective solution that works as described above, ensuring uninterrupted service for vital electronic equipment in rural and remote areas. For more information, visit www.alsetcorp.com.

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