News Roundup
Underground Distribution Studied
Homeowners may love the promise of an unobstructed view free of poles and power lines, but the potential of increased system reliability has more co-ops considering underground distribution to their consumer-members.
“Underground distribution is expanding among co-ops, particularly in fast-growing suburban areas,” said Marty Gordon, a Cooperative Research Network senior program manager.
CRN has developed a new edition of its underground distribution manual.
It is a comprehensive design guide for co-ops considering expanding their systems to include underground components or replacing existing overhead conductor with underground distribution lines.
The material addresses the entire range of issues that must be addressed, including system layout, cable specification and thermal loading, as well as the decisions co-op engineers must make before buried conductor can safely be energized.
“We’ve developed a step-by-step, methodical approach to each phase of an underground installation project,” said Gordon.
The 462-page CRN Underground Distribution Design Guide examines direct buried cable and cable-in-conduit systems as well as insulation, shielding and connectors.
It also features examples of experiences encountered by many distribution co-ops adding underground components to their systems. Those include cable runs, moisture control and component testing.
“As consumer-members ask co-ops to consider replacing lines and poles damaged in weather-related outages with underground systems, they will need to make sure the new equipment is reliable,” said Brian Sloboda, a CRN program adviser.
As of 2007, 16 percent of all co-op owned conductor is located underground—up from just 5 percent in 1980.
More than 79 percent of the nation’s distribution co-ops have at least 50 miles of underground distribution lines.
“Products and materials have evolved and best practices for design have also evolved,” Sloboda said, adding that it will also help engineers provide essential information to co-op management on component costs, future maintenance and other factors.
“This will help a co-op design and build more robust underground systems economically and in less time,” said Sloboda. “That will save consumer-members money.”