While any prudent business suscepti­ble to lightning strikes should protect it­self, FedEx Express’s stakes at its Memphis superhub were extraordinary. With more than a billion square feet of connected buildings and ramps, the superhub was a critical linkage point in the company’s expedited delivery service.

“One lightning strike, if severe enough, could conceivably shut us down at the time or caused us to miss our two-hour delivery window, if it had dis­rupted our power supply, sorting machinery, or other essentials,” said Marsh. “That’s not the case today, since we now have backup generators and multiple hubs. But we constantly want to minimize any disruptions, lightning-related or not, to meet delivery commitments.”

“Lightning strikes can be devastating in a range of different ways, but our pri­orities were clear,” said Marsh. “First, protect our personnel, especially those out in the open, since it was hard to clear the ramps and runways before storms arrived. Next, protect our planes, buildings, equipment, and assets.”

Lightning would sometimes strike buildings that were protected with tra­ditional lightning rods, a technology lit­tle changed since the days of Benjamin Franklin. Since the rods generated more strikes than no system at all, they demonstrated drawbacks as well. Many rods were grounded to buildings’ struc­tural steel, which allowed electrical surges to enter the buildings during lightning strikes. This tended to disrupt sensitive electronic equipment con­tained within those buildings.

“Damage to anything had down-the-line effects, like a row of dominoes,” says Marsh. “Everything from unloading and sorting onward had to work on-time, every time for us to meet our de­livery commitments. The ever-expanding number of aircraft also required us to put in above-ground fuel tanks. We wanted to protect those from lightning strikes as well.”

Because Franklin rod technology hadn’t performed to FedEx Express’s high standards, the company took the initia­tive in seeking out a better alternative. The company investigated a lightning prevention system that NASA had de­veloped to protect gantries and launch platforms for the Apollo and Mercury moon missions. FedEx contacted Lightning Eliminators & Consultants (LEC) to discuss Dissipation Array Systems (DAS), which prevent lightning strikes rather than merely directing them.

The Dissipation Array System is based on a natural phenomenon known to scientists for centuries, the “point discharge” principle. According to this principle, in a strong electrostatic field, a sharp point leaks off electrons by ion­izing adjacent air molecules, when the point’s potential is raised 10,000 volts above that of its surroundings.

DAS creates thousands of simultaneous ion-producing “points” over a large area, which prevents streamer formation, the precursor to lightning strikes. Since the ionization process creates cur-rent flow from the point(s) to the surrounding air, DAS removes the storm-induced charge on the protected site, transferring it to air molecules, which leave the site. DAS prevents strikes by continually lowering the volt-age difference between the ground and charged cloud to well below lightning potential, even in worst-case storms.

Because DAS prevents rather than redirects lightning, it’s possibly the best long-term solution to lightning strikes. Intrigued by LEC technology, FedEx Express sent representatives to visit sites where DAS was installed, including radio and refinery towers and even Disney world, which had blended DAS into a roof structure without affecting the aesthetics of the building.

LEC custom-engineered DAS for the Memphis hub, working closely with Marsh and his team, who oversaw in­stallation at the site. For example, some of the aircraft needing protection were close to active airport runways, which had structural height restrictions. LEC worked with them to stay within the re­strictions, meet FAA runway profiles, and still protect aircraft and ground equipment from the effects of lightning.

“At first we had our doubts about DAS, but the system works,” says Marsh. “We thought if we could elimi­nate half the strikes, it’d be useful. Eighteen years later, to my knowledge, there hasn’t been one strike. The only exception to this was when we took a DAS system off a building to reroof. That’s when lightning struck, but it did-n’t penetrate any of the protected areas.”

DAS also suits FedEx Express’s People-Service-Profit philosophy. “If DAS has spared even one employee from be­ing struck by lightning, then it’s been well worth the cost,” says Marsh. “And if the system has saved even one plane from severe damage by lightning strike, not to mention possible delivery slow­downs, then it has justified its cost at the Memphis facility.”

Today, additional LEC equipment is in­stalled each time the Memphis Superhub expands. LEC is listed as a source of lightning protection, and the only source of lightning elimination in a book of company standards given to new engineers, says Marsh, who has since moved on to projects at other locations.

About 15 years ago, at a FedEx com­munications center in Colorado Springs, Marsh faced another lightning-related problem. “A satellite dish was continu­ally hit by lightning, which was playing havoc with our electronics,” says Marsh. “Lightning would strike, or we’d get a huge static build up on the dish and its structure, which would disrupt our call center. We talked about erecting a degaussing shield, a protective metal skin, around the whole building, but we didn’t have to. LEC deployed DAS at the site, and along with current protec­tion on some of our underground cables, and our lightning problems stopped.”

Marsh is currently overseeing the construction of an office building hous­ing sensitive electronic equipment. For this, FedEx Express is installing LEC Spline Ball Ionizers (SBIs), hybrid de­vices that prevent lightning strikes with point discharge ionization. They also collect and redirect any lightning strikes that may get through.

“As far as I’m concerned, LEC tech­nology is standard equipment when we put in a new facility where there’s a high incidence of lightning strikes,” says Marsh.

“We’re protecting the life and safety of our personnel, we’re protecting our assets, and we’re preventing service dis­ruption for our customers. We’ve had very good results with DAS and related technology, which have been well worth the money.” FSM  Del Williams is a technical writer from Torrance, CA. For more informa­tion on Lightning Eliminators & Con­sultants, call 303-447-2828, or visit www.lightningeliminators.com.

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