IEC 60601-1 Edition 3 is an international standard with general requirements for basic safety and essential performance for medical electrical equipment. This standard has its own medical terminology where insulation is called means of protection, basic insulation is called one means of protection and reinforced insulation refers to two means of protection. There is further division of who is receiving the protection from medical electrical equipment: operator or patient. Two Means of Patient Protection (2 MOPP) provides the highest level of protection that is equivalent to reinforced insulation for the patient.

The minimum DTI requirements in this standard are also somewhat similar to IEC 62368-1. Although Clause 8.8.2 requires 0.4 mm minimum DTI for supplementary or reinforced insulation for peak working voltage greater than 71 V, but it also provides an option to bypass this DTI requirement to components with solid insulation in clause 8.9.3 if they pass thermal cycling, humidity conditioning test, followed by high AC withstand voltage of clause 8.8.3 except that the test voltage is multiplied by 1.6.

Using the example of a semiconductor device described earlier, we first determine the maximum working voltage that’s possible with a minimum creepage and clearance distance of 8 mm. For this, we refer to Table 12 of IEC 60601-1. Table 5-2 is a partial representation of Table 12.

So, with a minimum creepage distance of 8 mm, this component will be limited to a maximum 354 V_DC or 250 V_RMS of working voltage to provide two means of patient protection. Next, we determine the dielectric strength of solid insulation that the component must pass after thermal cycling and humidity preconditioning treatment. Clause 8.8.3 refers to Table 6 of IEC60601 – 1 (partially represented by Table 5-3) to answer this question.

The component must pass a dielectric withstand voltage of 6400 V_RMS (= 1.6 x 4000 V_RMS) to claim 250 V_RMS or 354 V_PEAK working voltage with 2 MOPP from mains circuits.