EMC Laboratory 
4000 Enterprise Dr. 
Missouri University of Science
and Technology
Rolla, MO 65401
emclab@mst.edu

EMC Regulations

Commercial Products Marketed in the USA

The FCC Rules and Regulations, Title 47, Part 15, Subpart B regulates "unintentional radio-frequency devices". Products regulated include any unintentional radiator (device or system) that generates and uses timing pulses at a rate in excess of 9000 pulses (cycles) per second and uses digital techniques. This includes almost every product that employs a microprocessor including workstations, personal computers, point-of-sale terminals, printers, modems, and many electronic games. It is illegal to sell or advertise for sale any products regulated under Part 15, Subpart B until their radiated and conducted emissions have been measured and found to be in compliance.

Most products regulated by Part 15, Subpart B fall into one of two categories. Class A devices are those that are marketed for use in a commercial, industrial or business environment. Class B devices are those that are marketed for use in the home. Class B limits are more stringent than Class A limits and the Class B certification process is administratively more rigorous than the Class A verification process. The radiated and conducted EMI test procedures are defined in the ANSI Standard C63.4. FCC Rules and Regulations, Part 15, only regulates radio frequency emissions. Currently there are no FCC regulations pertaining to product immunity to electromagnetic fields.


Military Products Marketed in the USA

EMC requirements for products that are marketed for use by the US military are contained in a document titled MIL-STD-461. This standard can be applied to a wide range of systems including everything from power tools to workstations. Unlike the FCC Regulations, MIL-STD-461 includes limits for radiated and conducted immunity as well as radiated and conducted emissions. Different sections of MIL-STD-461 describe independent tests.

You can obtain MIL-STD-461E here. M461E.pdf (970 kB)

This and other U.S. Military Standards can be obtained from the US The Department of Defense Single Stock Point for Military Specifications, Standards and Related Publications.

 


Commercial Products Marketed Outside the United States

EMC requirements vary from country to country, however most countries have requirements on radiated emissions similar to the FCC requirements. Countries in the European Economic Community (EEC) and many other countries have adopted a radiated emissions standards based on a document called CISPR 22. CISPR is a committee of the International Electrotechnical Commission (IEC), which promulgates standards in order to facilitate trade between countries. The CISPR 22 standard categorizes products as Class A or Class B and specifies a test procedure and emission limits that resemble (but are not exactly the same as) the Part 15, Subpart B requirements. Notable differences between the FCC and CISPR requirements are the lower frequency limit for conducted emissions tests and the radiated emission test distances. Also, CISPR 22 specifies both quasi-peak and average limits for conducted emissions test. FCC limits are all specified as quasi-peak levels.

Many countries have adopted EMC requirements based on IEC standards. The IEC has published a guide titled, IEC-EMC.pdf, which provides a good overview of EMC standardization efforts.


Want to find a particular EMC standard?

Try this web page, NSSN, A National Resource for Global Standards.

 Other Standards Sites: