How to Measure an AC Signal in RMS
- 1). Connect the leads of the multimeter into their appropriate sockets; often, they will be color-coded. Red is the positive, or voltage lead, and black is the negative or neutral/ground lead, often marked "COM."
- 2). Set the dial to measure the highest level of AC voltage. The symbol for AC voltage resembles a wave. If you have a digital multimeter, it will calculate the range automatically.
- 3). Insert the leads into each outlet terminal. You should get an RMS reading of approximately 120 volts when reading a standard U.S. household outlet. Abroad, you will get higher readings due to different electrical code standards.
