How to Measure a Receptacle With a Voltmeter

Switch on the digital voltmeter. If you use a traditional analog meter, it will not require power, so there will not be an "On/Off" switch.

Set the voltmeter to measure alternating current. This is the type of electricity used in buildings and is identified on the meter by either the letters "AC" or one of two symbols; a short horizontal line above a wavy line or a wavy line on its own.

Set the meter to measure an appropriate voltage range. For safety reasons, always select a scale that allows for a larger than expected voltage. You can reduce the range once the actual voltage has been established. For example, if the receptacle voltage is unknown, assume that it is 240 volts and select the next highest range, often 750 volts. Auto ranging meters do not have a range selector; they calculate the best range automatically.

Check that the probes are connected to the correct sockets on the meter. The black probe connects to the black socket, often marked as "COM." The red probe goes to the "V" socket, or the "AC V" socket if one is present.

Insert the black probe into the smaller of the two vertical slots in the receptacle and the red probe into the larger one. Ignore the circular grounding pin.

Observe the voltmeter reading. A reading of zero volts may indicate that the probes are not touching the receptacle contacts. Move the probes around and try to obtain a reading. A persistent zero reading indicates that there is no power at the receptacle. Any other reading indicates the magnitude of the voltage present. For example, a reading of 117 indicates a voltage of 117 volts.