Copper cabling helps multiply power capacity at WTC.

Since the World Trade Center (WTC) opened its doors in New York City 22 years ago, growing clusters of electronic devices have begun to burden the center's electrical system, which contains some 3,000 miles of electrical conductors and about 100,000 lighting fixtures.

To address the

The WTC's electrical system was originally designed to provide tenants with four watts of power per square foot, but today's computers, facsimile machines, and advanced telephone systems require more power. "We're finding that tenants are now requiring a doubling of capacity to operate some of their highly sophisticated electronic equipment," says Robert DiChiara, WTC assistant director. Capacity will be increased to between eight and 10 watts per square foot.

The WTC's six buildings are powered by the New York City utility Consolidated Edison Co. Presently, Con Ed provides eight feeders running to 23 substations throughout the center. Boosting wattage to the complex will involve increasing the number of feeders to 10. The change will also increase reliability.

The first step in the upgrade program will be to replace aluminum cables with copper cables from the complex's power distribution center to the 41st floor. Four transformers will also be replaced with copper wound transformers.

Some 13,760 feet of copper cable will be installed in horizontal runs from the primary distribution center to the buildings, while 8,800 feet of high-voltage feeder cable will be installed in vertical risers. Copper was selected for the mammoth project because it can handle the higher capacity required, and can be installed easily into existing conduits.

Still, the project will not be a cakewalk, says Charles Semah, staff services engineer at the WTC. "But the extra effort to use heavier cables is outweighed by their ability to deliver much more power reliably."

WTC officials are also concerned about saving energy. "We've been in the energy-saving mode since 1973 and have taken advantage of every opportunity concerning base building systems. That's one of the reasons for selecting copper for this upgrade," says DiChiara. Information about copper building materials from the Copper Development Association, Inc. Circle 303 on the Reader Service Card, page 143.