Figure 87-5 The response to electric current flowing through an arm that accidentally touches a voltage terminal depends on the amplitude and the frequency of the current. Sensation of a 60-cycle current occurs at approximately 300 µA, and pain occurs at approximately 1 mA. If the current exceeds a certain value, called the let-go current, the person is unable to release objects. The value of the let-go current varies with frequency and among individuals. RMS, root-mean-square average.