Preserving a Power Legacy

At the Belfast Switchyard near Columbia, Tennessee, a nearly century‑old bushing continues operating inside a 161‑kilovolt breaker.

Manufactured in the 1920s, this fishbowl‑style bushing comes from an era of American engineering defined by open‑air designs, oil‑filled insulation and porcelain housings built to last. And while these components are increasingly rare, TVA’s Power Service Shops have the know-how to keep them reliable, safe and resilient.

“We’ve been refurbishing bushings as far back as I know,” Chad Quinn, electrician foreman at TVA Power Service Shops, said. “The knowledge has been passed down from each person, and I’m blessed to work on these old bushings with my team and our engineers.”

At the Power Service shops, from left, electrician Ethan Mahers, electrician foreman Chad Quinn and electricians Darren Elliott and Remington Medley work to refurbish a 1920s-era General Electric bushing.

Transmission Treasure

Out of the nearly 700 craftspeople and support professionals at the Power Service Shops, only a handful specialize in transformer bushings – the components that safely conduct high-voltage electricity into and out of transformers.

Today, fewer than 20 bushings from the 1920s remain in service across TVA’s seven‑state region. Their longevity makes them treasured pieces of TVA’s transmission infrastructure.

“They’re really good bushings, especially once you refurbish and get them back to their original state,” Quinn said. “It’s like older cars. They’ll keep on running.”

Made by General Electric, the fishbowl bushings are recognizable by their glass‑domed tops. Unlike modern sealed units, fishbowl bushings are “free‑breathing” units that allow internal insulating oil to expand and contract with temperature changes. While this contributes to long-term durability, the design also allows moisture to accumulate over time, making periodic refurbishment essential.

Replacing a bushing of this age is rarely an option, Tim Montgomery, construction manager at TVA Transformer Services, said. Most manufacturers no longer support these components, and modern alternatives often come with long lead times. Even when replacements exist, the cost of purchasing, shipping and installing a new unit is significantly higher than refurbishment.

“The question of why refurbish instead of using new technology depends on the type of bushing,” Montgomery said. “Most of the time, there are no new bushings available and the lead time to get one can be up to 156 weeks.”

The fishbowl bushings are recognizable by their glass-domed tops.

'Keep Them Running'

Earlier this year, the bushing at Belfast developed a faulty seal. Only a few facilities worldwide possess the specialized skillset required to refurbish units like this – and the Power Service Shops is among them.

TVA ran electrical tests that measured the bushing’s overall integrity and the condition of its internal insulation. They compared those readings to past test results to check for any defects, contaminants, unwanted moisture or deteriorating insulation. Those results showed the bushing was still electrically sound, making it a strong candidate for refurbishment.

"Our team worked diligently to test the bushing," Jay Rosson, transformers engineer at TVA Power Service Shops, said. "When we compared those results to past findings, we knew that refurbishing the bushing made sense. They’re strong, functional and help us save money."

Once testing confirmed the bushing needed service, the Belfast Transmission team moved quickly and removed the unit from the breaker. The Power Service Shops crew transported the bushings to the PSS Bushing Shop to drain and test the aging oil and clean every component. The parts then spent 72 hours in a temperature‑controlled oven to remove deep‑seated moisture.

After cooling, the team reassembled the bushing with new gaskets, pulled a vacuum to remove trapped air and refilled it with fresh, degassed mineral oil. Final electrical tests verified the unit met TVA standards before it was repainted and prepared for shipment back to Belfast.

From removal to reinstallation, the process took about a week – a turnaround time that makes a major difference for system reliability.

“It’s huge,” Quinn said. “You’re talking about three or four months of not being able to support a 161‑kilovolt line if you’re waiting on a new bushing. Instead, we can have that breaker back online in six to 10 days.”

Refurbishment offers multiple benefits: restoring components to near‑original condition, reducing downtime, lowering costs and extending the lifespan of proven infrastructure.

The Belfast project highlights the broader value of the Power Service Shops, where the team also fabricates custom components, restores transformers and breakers, supports field crews and ensures TVA has the in‑house expertise to respond quickly to unexpected equipment issues.

It’s a capability few utilities possess.

For TVA, this means faster recovery times, greater flexibility and a stronger, more resilient power system. As TVA’s Power Service Shops continues caring for these legacy components, the ingenuity of American engineering will keep supporting the region’s modern grid for years to come.

“If a plant needs help, we can be there in a couple of days," Quinn said. "We know these components inside and out and we can keep them running. That’s the difference."