Gotcha! Lightning StrikesBy David F. Carr | Posted 2004-01-27 Email Print
A high-end power-protection system cost only about $30,000, Suncoast's experience shows it is possible to protect against even the most severe surges.Even for organizations back in the U.S., the environment can be hazardous. In 2000, Suncoast Schools Federal Credit Union's data center took a direct hit from lightning. A bolt to a 480-volt utility cable leading into the building vaporized the Tampa facility's electric meter and left the service panel twisted and blackened. But the data center kept runningoff a generator. Millions of dollars worth of business could have been lost if the servers and data in that building had been fried, says facilities manager Eric Brendle. Given his investment in a high-end power-protection system cost only about $30,000, Suncoast's experience shows it is possible to protect against even the most severe surges.
Problem: Not all surge protectors are created equaland a single layer of protection may not be adequate.
Resolution:Deploy high-capacity surge suppressors. Suncoast Federal deployed serious surge suppressors and hired a specialist, Power & Systems Innovations (PSI) of Orlando, to install them. The highest-capacity units installed at the electric service entrance to Suncoast's data center could take a hit of 200 kiloampsthe highest recorded strength of a lightning bolt is about 250 kiloamps, according to PSI. Behind that first line of defense, PSI added up to six layers of suppressors to protect branch circuits and specific data-center equipment. That way, when a surge blew past the first line of defense, there were other suppressors to protect the equipment.
Problem: Surge protectors are only as good as the grounding system to which they're connected.
Resolution:Test your grounding system. PSI president John West, Sr., recommends that the electrical resistance between the grounding wires and the earth in which they are buried should be no greater than 5 ohms, a measure of resistance. If the resistance is too high and can't be lowered by moving the grounding rods, soil additives such as bentonite clay can boost conductivity, he says.
Problem: Surges may be diverted toward, rather than away from, your equipment if provided with more than one path to the grounding system. Resolution:
Resolution:Ensure your network and electrical systems are designed to provide a single path to the ground from any given point. Segments of your network and power systems that are connected to different grounds should be electrically isolated to minimize the potential for ground loops.
Problem: Surges come across external network cables and telephone wires, not just power lines.
Resolution:Wires strung between buildings can act like an antenna to attract lightning if not properly shielded. Make sure your surge-protection systems cover network and phone lines as well as power outlets. Between buildings, consider using fiber optic connections, which do not attract lightning because they conduct pulses of light rather than electric signals.