What is the lowest acceptable overvoltage category rating for a voltage tester that will be used to test electronic equipment and circuitry?

The lowest acceptable overvoltage category rating for a voltage tester used to test electronic equipment and circuitry is typically CAT II. This category is suitable for measuring voltages in appliances and devices that are connected directly to the mains supply, ensuring the tester can handle transient overvoltages associated with such environments safely. For more sensitive electronic circuits, a CAT III or CAT IV rating may be preferred for added safety and reliability.