Finding and Using Electrical Safety Testing Resources

James Richards

Useful electrical safety testing resources are plentiful and readily available--and just a click away.

Electrical safety testing must be performed on all electronic products before leaving the factory floor. Just what is this testing all about, how is it to be performed, and what equipment is required to do it? The answers to these questions are readily available to anyone with access to the Internet.

Many Web sites include tutorial information, technical articles, application notes, and equipment instruction manuals. Resources include equipment suppliers, organizations and associations, and publications.

A test engineer can be confronted with a variety of issues when faced with the task of establishing the safety testing process, namely:

• Understanding how electrical safety testing is performed.

• Knowing what standards to comply with.

• Finding the proper equipment.

• Learning more about a specific application.

Information Resources

Understanding Electrical Safety Tests. The first task is to develop an understanding of the techniques of electrical safety testing, i.e., understanding the functions of a hipot test, a ground continuity test, and a leakage test, and just how are they performed. See Table I for a partial list of sites that provide educational resources.

Product Standards. Manufacturers need to know and understand the safety standards that apply to their particular products. Significant changes are still taking place in safety standards development, with an emphasis on the worldwide harmonization of product standards and global specifications.

It is important to identify the applicable standards, and many Web sites provide standards such as UL 60950 (information technology products), UL 1026 (household cooking appliances), or UL 2601 and IEC 60601 (medical electronic products).
These standards specifically address electrical safety testing for compliance (the design phase of a product) as well as production testing. The standards themselves are rarely available free, but it is easy to order them from a variety of sources (see Table II.)

Test Equipment. Once a manufacturer has determined the applicable standards and the necessary tests for a particular product, it is then important to identify the appropriate test equipment. The tester must be capable of performing the tests required by the standard. Questions to be answered include:

• Is an ac or dc hipot test recommended?

• Is a ground bond test required?

• Does the product have multiple test points that may require scanning capability?

• Do the test results sometimes need to be logged and retained for future reference?

These are some of the important considerations when examining test equipment requirements. Manufacturers' Web sites generally include product descriptions, detailed specifications, and pricing. Finding manufacturers can be as simple as entering keywords (such as hipot or electrical safety test) in a search engine. Use these sites to gather information and evaluate products. Web sites enable engineers to review products, technical information, and product specifications.

Articles and Application Notes

It is important to identify and understand the applicable standards, and many product-safety-related Web sites provide articles, seminars, or analysis of specific standards. See Table III for a partial list of publications and other sources that can serve as educational tools.

Table III. Articles and application notes.

Medical Products

Electrical safety testing of medical products goes beyond the traditional testing of most other products. The requirements for electrical safety testing of medical electronic devices are much more stringent than those of other electronic devices. Many standards serve as the ruling authority in determining how medical products are to be built and tested.

The most widely accepted and implemented around the world is IEC 60601-1 (the International Electrotechnical Commission's electrical safety standard for medical electronic equipment). This standard has been used as a basis for many national standards.

National deviations to this standard are common; therefore, it is particularly important to be aware of related standards in order to design a product to meet the deviations that apply to the country where the product will be sold. Table IV provides a sampling of useful Web sites for manufacturers of medical electronics.

Table IV. References that address medical electrical safety.

Conclusion

Never before have informational resources been so readily available. The Internet has made such resources available literallyat our fingertips. There is no excuse for manufacturing and design engineers to lack electrical safety test information on product test requirements, techniques, and required test equipment. Many Web sites include tutorial information, technical articles, application notes, and equipment instruction manuals.

James Richards is marketing engineer for QuadTech Inc. (Maynard, MA). He can be reached at 800-253-1230 or via e-mail at jrichards@quadtech.com.