ERMCO

ERMCO, the Electric Research and Manufacturing Cooperative, was incorporated in 1964 by rural electric cooperatives and started transformer production in Dyersburg, Tennessee in January 1972 with 30 people. It’s now the country’s largest manufacturer of oil-filled distribution transformers, turning out single-phase and three-phase pad-mount and pole-mount units, plus transformer components through its ECI arm. Buyers are mostly electric utilities and cooperatives, with industrial and commercial work coming through acquired brands. The Dyersburg campus covers about 1.5 million square feet on 150 acres and built its 9 millionth transformer in 2025. ERMCO bought GridBridge in 2017 and Spire Power Solutions in 2022, added a 158,000-square-foot plant in Bristol, Wisconsin in 2025, and is opening a Maricopa County, Arizona plant in 2026. Employment tops 3,700.

The original build was modest by the standards of what stands there now: construction started in 1964 on a 32,000-square-foot, $350,000 single-phase facility – described by the company as the first plant in the country built solely by rural electrics to make single-phase padmount transformers. Production opened in January 1972 with thirty employees turning out about thirty units a week.

The growth curve is easy to read in the numbers ERMCO publishes. Dyersburg expanded to 145,000 square feet through the 1980s, with a 45,000-square-foot tank manufacturing building added in the 1989 expansion. The first three-phase transformer came off the line in 1999. Annual output went from 70,000 units in 1988 to roughly 650,000 in 2024, and headcount from thirty in 1972 to more than 3,700 in 2026. As of 2021 the company was the largest employer in Dyersburg with over 1,450 people.

The acquisitions have added capability rather than just volume. GridBridge, bought in 2017, operates as an Advanced Learning Center in Raleigh developing hardware, software and data-management tools for utility partners. Spire Power Solutions followed in 2022, bringing the Power Partners, Pioneer Transformers, Jefferson Electric and V&F Transformer brands into the group.

The 2026 Maricopa County, Arizona expansion is a first of its kind for the company – its first manufacturing site west of the Mississippi, adding three-phase production and around 500 jobs. It follows a 158,000-square-foot facility acquired at Bristol, Wisconsin in 2025.

Quality certification is held plant by plant: DQS, Inc. certifies ERMCO Dyersburg and the ECI facilities at Greeneville, Bristol and Reynosa to ISO 9001:2015. Tim Mills is CEO and President, and the business serves utility, renewable energy, public power, commercial and industrial customers.