Copper helps serve and protect Lightning Alley

September 26, 2011 |










Lightning Alley is not just a catchy name for a street or the local bowling lanes. It's the name dubbed to a notorious region in central Florida that is in the heart of the most lightning-prone area in the entire country. And that lightning strike may come at the most inopportune time.

Not only can this force of nature cause bodily injury and severe damage to property, it also has the power to disrupt or destroy a police department's 9-1-1 communications system, which is intended to assist residents during an emergency. That's exactly what happened in the middle of one Florida storm.

When a Walmart in the city of Bushnell was relocated, the facility was donated to the county for their use. The Sumter County Sheriff's Department decided to open its new offices in this building, including housing its emergency communications there.

One serious problem was that the electrical system was built for a 1970's vintage department store, not a critical communications and public safety facility. During one lightning storm in particular, the 9-1-1 system failed, leaving county residents without police, fire or ambulance response.

Inspection of the existing electrical system showed that it was badly flawed, mainly due to improper connectors and poor bonding and grounding. The communications tower, for example, had its own independent and inadequate grounding. The emergency generators and building structure were all independently grounded, each with its own ground rod, exposing its poor design. The main grounding electrode consisted of a single galvanized steel rod from the 1970s, with very high resistance to earth.

A new system was designed and installed for under $40,000, a minimal cost considering the value of the equipment protected, and improved public safety it brought to the residents of Sumter County.

"To be effective, the entire grounding system needs to be properly designed, using listed connectors and corrosion resistant materials," said Dave Brender, National Program Manager for the Copper Development Association, CDA.  "Lightning protection systems in particular must be well-grounded to work properly, and could make matters worse if they are not. Copper and its alloys are the most common materials in use for this application because they provide superior corrosion resistance and avoid oxidation problems at connections.

Copper is also easy to install and durable," Brender added.

Central Florida is not the only region in the U.S. affected by severe weather.  Similar 9-1-1 and broadcast facilities are employed in areas all over the country where communications is critical and the chances for lightning strikes are quite high. Having proper copper-based grounding and bonding should be a top priority where an entire system can get crippled by lightning.

In the case of the Sumter County Sheriff's Department, the upgrade included three new copper-clad electrodes at the base of each transmission tower leg with a bare copper ring ground exothermically welded to the electrodes, and the tower bonded to a new master ground bus. A copper bar was also installed on the tower above the point where coaxial cables make a 90 degree turn toward the building to ground the braid of the coaxial cables. Additionally, 100 feet of bare copper conductors were buried in a trench about 20 ft. behind the main building. This helps directs lightning energy away from the tower and building, and also helps reduce the grounding system.
For the emergency generators, copper conductors and proper connectors were installed to overlap the flimsy existing grounds. Since the 9-1-1 system upgrades, there have been no service disruptions, which is crucial for emergency communications.
In the end, the modest investment to upgrade the grounding system was just that - a modest investment. The 98,000 Sumter County residents can rest easy that a modern copper-based system is minimizing any chances of interference from the forces of Mother Nature in Lightning Alley. BD+C
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