Electrical sockets deliver a standard voltage that varies depending on the country and usage. Electrical test meters used to measure voltage of common outlets in the United States will show 110 to 120 volts, although large appliances will use 220 volts. The voltage meter reading for outlets in just about every other nation will show between 220 and 240 volts. Personal computers are among the products made to get along with either voltage using a switch on the back to set the input for 115 or 230. A voltmeter will show the voltage for any outlets in question.
Set a voltage meter or any of the electrical testers that feature a voltmeter, such as a volt-ohm-meter, digital multimeter or analogue multimeter, to measure voltage. Set multimeters for AC, V, VAC or any of these shown with a curved line above. Set a VOM for volts.
Select the voltage to be measured by selecting an output that is higher than the expected reading. Set the meter to read 250 since the outlets tested may have voltage output as high as 240 volts.
Place one of the probes, or leads, from the meter into the slot on the upper left of the socket. Put the other probe into the slot on the upper right. Either lead can be used in either slot to measure voltage.
Wait two seconds for the voltage to register in the meter. Check the reading on the digital screen or needle graph. A reading between 220 and 240 shows the 230 voltage typical in most of the world. A reading far below 220 indicates the common U.S. voltage of 115.