A multimeter is an invaluable tool that allows you to measure voltage easily and accurately. In this guide, we'll explore how to check power supply voltage using a multimeter, taking you through the basic concepts, the procedure, safety precautions, and troubleshooting common issues. Component selection. Alternating Current (AC) voltage is the electrical potential that powers residential and commercial buildings, characterized by a current that periodically reverses direction. Frequency: The rate at which the current alternates, typically expressed in Hertz. Whether troubleshooting a circuit, ensuring power supply consistency for preventive maintenance, or verifying safety standards, an accurate voltage reading is essential.