Interpower Hospital-grade Cords & Components—When AC “Patient Power” Is Critical
For over a century, AC power has played a vital role in the welfare of patients and staff in hospitals and clinics worldwide. Today, hospital-grade electrical cords, such as those manufactured by Interpower, are designed to provide the correct amperages and voltages for a broad range of medical equipment—portable CT Scanners, X-ray machines, heart monitors, ECMO machines, and hospital-grade treadmills. Interpower North American (NEMA) 5-15, 5-20, 6-15, and 6-20 hospital-grade cords are tested beyond UL 817 and CSA C22.1 no. 21 agency standards. The hospital-grade certified “green dot” is found on both NEMA and the Japanese JIS 8303 plug, which meets JIS T 1021 hospital-grade standards.
Country- or continent-specific agencies such as UL, CSA, and VDE have created safety standards through testing methodologies that have transformed the typical household cord into cords and components which are robust and reliable cords for the medical community. Besides country-specific standards, many countries also recognize IEC standards. Countries that do not use any formal hospital-grade standards use their existing household cord standards for medical equipment and devices.
Australia
In Australia, hospital-grade cords must meet AS/NZS 3200 standards, and for plugs AS/NZS 3112. An Australian rewirable 3-pin plug must be clear or “see-through.” For molded plugs, clear or colored is optional. The preference for many Australian hospitals is orange cable terminated in a clear plug.
Denmark
Danish hospital-grade cords, plugs, and sockets in medical applications are under the SB 107-2-D1 requirements. The socket is designed to prevent non-hospital-grade plugs from connecting and disrupting the main circuit in medical settings. The preferred color for hospital-grade cord sets in Denmark is red.
Japan
In Japan, cord plugs and sockets must carry the PSE approval mark under DENAN, a Japan Ministry of Economy, Trade and Industry (METI) mandate. Noteworthy is that Japan has two frequencies. The Fuji River is used as a geographical reference point for the two frequencies: on the eastern side (Tokyo, Yokohama) 50 Hz is used; on the western side (Osaka, Kyoto, Hiroshima) 60 Hz is used. Europe mainly uses 50 Hz, and the U.S. uses 60 Hz. Typically, frequencies aren’t mentioned in the standards, whereas the emphasis is put on amperages and voltages.
Europe & the World
EN 60601 is the medical equipment standard for European countries. Non-European countries follow the IEC 60601-1 medical standard (except for China, Korea, and Japan). There are over 100 medical equipment standards in IEC 60601. The most general and inclusive is IEC 60601-1. Subsequently, IEC 60601-2 through IEC 60601-118, focus on individual medical equipment and apparatus.
Hospital-grade Rings: Securing Conductors for Reliability
The stainless steel rings Interpower uses to retain the conductors in molded hospital-grade cords, and in clamped strain reliefs in hand-wired hospital-grade cords, are more than stout enough to ensure electrical continuity—the bunched and crimped conductors remain solidly clamped for electrical continuity inside the jacket of hospital-grade cords.
The length of hospital-grade cords should also be taken into consideration: “If you’re using medical cords longer than 15 feet,” said Dan Ford, Interpower Technical Support Specialist, “it becomes more difficult to meet the equipment standard requirements for resistance and leakage current for the entire electrical system. You don’t want high levels of electromagnetic interference (EMI) in equipment attached to the patient, which may happen if you’re using longer hospital-grade cords.” There are numerous standards for hospital-grade cords requiring specifications and tolerances.
For more information on voltage drop, see our blog:
The UL 817 Abrupt Removal Test is one example of strenuous hospital-grade cord testing. A plug is plugged into a socket. The wire from the hospital-grade plug is attached to a 10-lb weight which is then dropped to abruptly disconnect the plug from the socket to see how far the blades have bent, and to see if the wires have lost electrical continuity.
The Abrupt Pull Test is a standard NEMA 3-conductor cord test, including hospital-grade cords. A 2 ½ pound weight is attached to the plug’s cord and dropped 25 times from the connected plug and socket. Before the initial drop, three lights on the test equipment glow red showing electrical continuity. However, during the test, if one of the three wires fail (line, neutral, and ground) and one or more lights go out, the test is considered a failure. If that occurs, the plug is examined to see why electrical continuity was broken.
“We test more than is required by the standards for our customers as well as our own benefit,” Interpower Product Development Manager Ron Barnett says. “We go beyond the standards because it lends better reliability to our design—products become more reliable in that regard.”
Hospital-grade Cords Made Safer? Cord Clips!
Despite the universe of resin compounds listed on UL’s website, sometimes finding the perfect resin with the right additives is challenging, especially when mixing resin compounds with nonresinous material. Interpower’s cord clip can be molded onto 3 x 16 and 3 x 18 AWG cords as well as the 3 x 18 VCTF Japanese cords, and is constructed of a glass-reinforced Polypropylene resin compound to ensure molding consistency and optimal retention.
Cord clips take up excess slack to prevent tripping (safety) or the abrupt removal of the plug. They also reduce injuries when used with hand tools such as sprayers, and prevent wear from the cord dragging along rough surfaces.
