Interpower^® Manufacturing Cable & Power Cords in Lamoni—Made in the U.S.A.

The Interpower power cord and cable manufacturing facility on the outskirts of Lamoni, Iowa, rises east of the overpass above I-35 like a steel colossus in homage to manufacturing. Out of 99 counties in the state, Decatur County ranks 86 in population making it an unlikely candidate for a manufacturing renaissance anytime soon. Despite the county’s limited population and manufacturing resources, the Interpower facility turns 25 this year, a quarter century of producing world-class North American and international cable and country-specific power cords including an extensive hospital-grade line.

American Values and the Not-So-Silk Road

A trend in the 1990s was for U.S. and European countries to expand or relocate manufacturing facilities to China for cheaper labor and favorable building material costs—a trend that grew exponentially. However, the Americans and Europeans may have given up more in the bargain: a percentage of ownership of said facilities to the Chinese government.

Prior to 1993, Interpower (then the Panel Components Corporation) had only relocated in the state of California. In 1993 the company moved to a less restrictive manufacturing environment by moving its headquarters to Oskaloosa, Iowa, which included a manufacturing facility and new equipment to make North American cable and country-specific power cords. In 2000, Interpower began cord and cabling operations at its new Lamoni facility, which manufactures all the company’s North American and international cable as well as several power cord lines including hospital grade. Interpower also opened a distribution center in the UK, which does not manufacture products.

“In Iowa, we cross-train our manufacturing employees so that they can be proficient on various machines and processes in multiple departments. This lets us maintain our 1-week U.S. lead times,” said Mike Boyle, Interpower Vice-president of Manufacturing & Logistics at Interpower. “They embrace our mission which requires teamwork to provide customers with high-quality products and services. They’re trained to run a variety of machines and equipment that helps them advance their careers.”

Lamoni Cable-making

Interpower manufacturing is a world of conductor cabling, thermoplastic molding of country-specific cords and cord sets including hospital-grade cords and components. 

Individual conductor wire speeds down the line upwards of 1,000 feet per minute, its diameter continually measured by multiple readers using lasers integrated with computer hardware and software which measure to 1/10,000 of an inch. The readers are spaced along the line at optimal distances to deliver vital real-time measurements. The bare copper wire is cleaned along the line before being extruded in resin by extruders 1-3. Extruder 1 contains the natural, light-colored material while extruders 2 and 3 extrude separate colors such as blue and brown to coat the natural resin material—colors are alternated from extruder 2 to 3 by turning a switch on the crosshead of the extruder. The insulated wire is measured before and after extrusion while “hot” and measured after cooling (“cold”) once immersed in the water trough via a filtrated chiller.

Various colors designate ground, line, and neutral conductors according to North American, international, and Japanese agency standards. However, four- and five-conductors may be required if one or two additional lines are required. The insulated wire is spark-tested to ensure one hundred percent coverage over the copper. The extruded conductor wire is now ready to be placed on a reel for power cord processing at the cabler to make the three-conductor length of lay run.

Jacketing Conductors

The cabler simultaneously unspools the three separate reels of color-coded insulated wire and winds them into a braid of conductors: the same line, neutral, and ground wires. Three-wire conductors are a Class I configuration. Another common configuration is Class II, which consists of two lines with additional insulation but without a ground wire.

The length of lay: the length of one colored wire woven to make a complete revolution under another colored wire, which will make the bunched and soon-to-be jacketed wires more flexible. Before being jacketed, the bunched length-of-lay conductors are coated in talc (for easier wire-stripping) before being jacketed in natural resin and a single layer of colorant. Extruder 1 is the workhorse for jacketing since cable requires much more natural resin than the individual conductors to hold the three conductors in place while remaining flexible. Then a single layer of colorant is added onto the wall of the cable.

The jacket runs through a printer down the line to receive agency-approved markings (UL/CSA/VDE, etc.), file numbers, approval marks, voltage and flammability ratings, jacket material such as “SJT” and sizes in AWG and mm along with the manufacturer’s name (Interpower). The cable is now ready to be reeled onto a wooden spool where it is wrapped in plastic and properly labeled. The cable is now ready to be shipped.

The Immediate Future of Manufacturing

Despite Interpower’s manufacturing contribution, U.S. manufacturing lost ground 2021-2024. Toward the end of 2022, many companies spoke openly about reshoring at least part of their manufacturing back to the U.S. from—most notably—China. Manufacturing Today, among others, expect the manufacturing sector to rebound “heavier” than expected in 2025 while others, such as Deloitte, have taken a more neutral approach by positing factors ending in two or more outcomes by offering multiple scenarios. In spite of forecasting the unforecastable, one outcome remains unchanged. Made in America.

“Often customers ask, ‘Where are your cords made?’” said Raina Baker, Interpower Customer Service Supervisor. “When we tell them we make them right here in Iowa, they love that. They love U.S.A.-made cords and components because they know our cords will ship the same day if we have them in stock.” Not to mention the quality. Interpower tests their power cords after every stage of manufacturing to ensure all crimps are rock solid to ensure electrical continuity.