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Business Description
Maddox Industrial Transformer, founded in 2015 and headquartered in Greer, South Carolina, manufactures, distributes, and remanufactures padmount, substation, polemount, and dry-type transformers across the United States, with a dedicated product line serving bitcoin mining and data center operators.
Brothers Camden Spiller (CEO) and Mac Spiller (VP of Sales and Marketing) launched the company from a single remanufacturing shop in Simpsonville, South Carolina, drawing on a founding team with a combined 95-plus years of transformer industry experience. By 2018, Maddox had expanded to Battle Ground, Washington to serve West Coast customers, and subsequently added facilities in Idaho, Ohio, Texas, and Tennessee. The company employs more than 400 people across those locations.
The product catalog spans single- and three-phase padmount transformers, substation units, and dry-type transformers, sold as both new and remanufactured. Maddox carries thousands of units in stock at any given time (the company markets this as the largest ready-to-ship transformer inventory in the U.S.) and offers custom-build ordering for non-stock configurations. Beyond sales, Maddox operates transformer rental, repair, and rebuild services, and purchases surplus transformer inventory from third parties.
Within the bitcoin mining segment, Maddox maintains a dedicated project page and has published technical guidance on sizing and de-rating transformers for crypto mining loads: ASIC-heavy facilities generate triplen harmonics, requiring transformers to be sized to roughly 120% of expected load to avoid thermal de-rating. Named mining customers include SCATE Ventures, a renewable-energy operator running approximately 6,000 miners, for whom Maddox supplied transformers as part of that company's capacity buildout. Maddox's liquid-filled and dry-type units appear in Hashrate Index coverage listing the company among the top transformer suppliers for North American bitcoin mining and data center deployments.
Maddox has appeared on the Inc. 5000 list of fastest-growing U.S. private companies for seven consecutive years (2019, 2025). The company ranked No. 556 nationally in the 2024 cycle, reflecting 798% three-year revenue growth, and No. 979 in 2025, reflecting 436% three-year growth. The company has also been recognized by regional outlets including The Reflector of Battle Ground, Washington for its expansion and hiring activity in that market.
