According to IEC 60601, what is the maximum allowable leakage current for a patient-connected medical device?

IEC 60601 is a series of technical standards for the safety and essential performance of medical electrical equipment. It specifies maximum allowable leakage current limits for patient-connected medical devices to protect patients from electrical shock hazards. Leakage current refers to the unintended flow of electrical current from the device to the patient or other grounded surfaces. The specific allowable limit depends on the type of connection and the device's intended use. For a patient applied part (Type CF), which has the most stringent requirements due to direct cardiac connection, the maximum allowable earth leakage current in normal condition is 10 microamperes (µA). Earth leakage current is the current that flows from the device's enclosure to ground. For the same Type CF applied part, the maximum allowable patient leakage current in normal condition is also 10 µA. Patient leakage current is the current that flows from the applied part through the patient to ground or other parts of the device. Under single fault conditions, such as a failure in the device's insulation, the allowable leakage current limits increase. For Type CF applied parts under single fault conditions, the maximum allowable earth leakage current is 500 µA, and the maximum allowable patient leakage current is 50 µA. For other types of patient applied parts (Type BF and Type B), which do not have direct cardiac connections, the allowable leakage current limits are higher, but still within safe ranges defined by the standard. These limits are essential for ensuring patient safety by minimizing the risk of electrical shock during medical procedures and monitoring.