The changes from the 2nd to 3rd edition as they apply to power supplies were more a matter of definition than actual performance. For example, 2nd edition Type BF applications need to meet the 3rd edition’s “two MOOP” and “one MOPP” requirements, and 2nd edition Type CF not only requires an IEC 60601-1 qualified supply, but must ensure an additional isolation barrier between the supply and the part that touches the patient. This is typically achieved with an isolation transformer or DC-DC converter with 8 mm creepage and double insulation as outlined in the “two MOPP” classification shown above. Regardless of edition or classification, medical devices may not exceed 500 µA leakage current and must have dual fused input protection.