Question of the Month with Comment
MedSun: Newsletter #7, September 2006

Questions:
What are the requirements for two-wire AC-powered medical equipment in the United States?
Please list regulatory references. Does the two-wire power cord need to be polarized?

Comment:
From FDA: These questions were forwarded to the Office of Science and Engineering Laboratories of the Center for Devices and Radiological Health. The answers are summarized here.

What are the requirements for two-wire AC-powered medical equipment in the United States? The FDA does not have a mandatory standard (requirement) for two-wire AC-powered medical equipment. It does, however, expect manufacturers to meet a recognized standard, such as IEC 60601-1 or the equivalent. A manufacturer may also provide test results to demonstrate that its equipment is electrically safe.

Does the two-wire power cord need to be polarized?
In some cases, yes, and in other cases, no. Polarization is necessary: 1) when one or more components in the device must be connected to the ungrounded conductor in a two-prong system; and 2) when reverse insertion of the pins of the two-prong plug could create a hazard— for example, making a light socket “hot” even when the light switch is off.

Polarization is not necessary: 1) when there is no need for circuit components to be connected to either the ungrounded or grounded conductor in a two-prong system; and 2) when the devices are double-insulated consumer types of components, such as power tools and portable electronics.


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