The AAMI standard test load for electrical risk current measurements

The AAMI standard test load prescribed in AAMI's American National Standard, Safe Current Limits for Electromedical Apparatus, addresses the need to accurately measure electrical risk currents associated with the use of electromedical patient care equipment. Its purpose is to simulate a good electrical contact to the body and to roughly approximate the body's physiological response to electrical current flow as a function of frequency. Although the AAMI test load meets these needs well for most measurement situations, it may overstate the risk current arising from low-impedance sources when higher frequencies (greater than 1 kHz) are present. This problem of source impedance emphasizes the need for standards to express requirements in terms of performance rather than to require that specific test methods be used. Specific test methods may be appropriate if they adequately cover the requirements of the measurement or if any limitations they have are clearly understood by everyone. The present AAMI test load can remain an effective measurement tool, provided users understand its limitations.