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Maintain the safe zone around pad‑mounted transformers By Derrill Holly

Jordan Overbee was driving to work when he saw them. The elementary students were ­waiting for the school bus, but they were sitting on a big green metal box. Inside was vital electrical equipment, distributing electricity to several homes on the street. 

“It was a bad place for a school bus stop,” Overbee recalled. “There were five kids gathered there to wait for a bus, ­sitting, talking and ­playing for a few minutes because it was between driveways.”

As manager of ­operations for Wake Electric Membership Corp., Overbee knows a lot about pad-mounted ­transformers. They make up about half of the trans­formers used across the North Carolina-based co-op’s system. 

“Transformers change ­voltage from higher levels to voltages people use in their homes.” said Overbee. “Each of our transformers can be vital to ­providing electricity to several homes.”

After seeing the kids waiting at that same transformer ­several days in a row, Overbee pulled over and talked to some parents. He explained that high voltage electricity flowed through the transformer inside the casing and encouraged them to move a safer distance away. “The parents hadn’t thought much about it, so once I explained the risks, they were happy to move to another driveway,” Overbee said. 

While overhead power lines are mounted on utility poles and ­substations are protected by security fences, pad-mounted transformers, switch boxes and pedestals are at ground level. “We have about 5,400 pad mounted transformers on our ­system,” said Van Crawford, vice president of ­operations at Peace River Electric Cooperative, headquartered in Florida. “Of that number, 4,800 of them are located in the western ­district of our service territory.”

In many newer residential ­areas, overhead lines are no longer an option. Burying power lines also reduces potential system ­damage from high winds and storms. While consumers seldom see technicians working on the transformers unless there are power outages, they are ­regularly inspected by co-op crews. 

“We can see fault indicators from the road,” said Crawford, adding that one of the biggest ­concerns is safe access when repairs or ­adjustments must be made. “That’s why it’s important that landscaping and other ­barriers be kept clear of co-op equipment.”

Co-op technicians need at least 10-feet clearance at the opening side of a pad-mounted transformer. Approximately four feet of open space is preferable at the rear and sides of the metal housing. 

That distance allows for tool use, including hot sticks—­typically eight feet in length, used to work with energized equipment. It also ensures that the tech­nicians ­working on a transformer have space to maneuver should they have to back away if problems occur. 

Pad-mounted transformers are connected to ­primary high voltage lines, and secondary lines can extend in ­several directions to distribute power to homes and ­businesses. That’s why it’s important to check with Clay Electric Co-operative before planting shrubs or trees, ­setting fence posts, installing ­sprinkler systems and ­digging where it might damage underground lines. 

“Clay Electric Co-operative recommends that you ­contact the Illinois One Call, JULIE at 811 for a site assessment and marking before proceeding with projects that might disrupt utility service,” said Luke Johnson, operations ­manager at Clay Electric. While pad-mounted transformers in ­developed, suburban or urban areas are ­regularly inspected for damage from vehicles, many ­utilities use marking sticks or pennants to alert ­tractor, snow plow or heavy equipment operators of their locations. 

Clay Electric also ­encourages public works and transportation departments to keep equipment, supplies and road debris at least 15 feet away from pad-mounted transformers. Derrill Holly writes on cooperative issues for the National Rural Electric Cooperative Association, the Arlington, Va.-based service arm of the nation’s 900-plus consumer-owned, not-for-profit electric cooperatives.