Volt Meter Uses

An analog volt meter.

Volt meters are devices used to measure voltage. Voltage is a measure of the electrical force that causes electricity to flow through a conductor. To provide a comparison, voltage is to wires what pressure is to water lines. Volt meters come in both digital and analog, so you can either see a number readout or look at a dial to determine the voltage you are monitoring.

2-Wire Voltage Measurement

Most electrical circuits that we use in our homes are two-wire circuits. A volt meter is used to measure the voltage across these two wires. Typically, 110 to 120 volts is the voltage that you should see when measuring most circuits in your home. For security systems or other low-voltage circuits, you'll see 24 volts. To measure the voltage of two-wire systems, you'll place one of the two leads from the volt meter on each side of a device. When measuring an outlet voltage, you'll insert a lead into each side, being careful not to touch the metal.

3-Wire Voltage Measurement

Three-wire electrical circuits are typically either 110 to 120 volts or 220 to 240 volts. For 110 to 120 volts, it is measured the same as the two-wire voltage measurement in an outlet, just ignore the bottom ground hole. For a three-wire outlet, such as on an oven, there are two diagonal holes at the top and one vertical one at the bottom. Sometimes the bottom hole is a different shape, but it is still typically connected to neutral. The two diagonal are connected to line power and the bottom one is the neutral. If you put your volt meter leads across the two line power connections, you should see a voltage reading of 220 to 240 volts. If you measure between line power and neutral by putting one lead in a diagonal hole and one in the bottom, you should see a voltage of 110 to 120 volts.

4-Wire Voltage Measurement

Four-wire circuits are typically 220 to 240 volts. These types of circuits are common with ovens and dryers. The holes are on the top and the bottom and on both sides. If you place the volt meter leads in each of the side holes, you should get a reading of 220 to 240 volts. Between any of the others, you should see a reading of 110 to 120 volts.

References

• Appliance Aid: Electrical Testing

Resources

• All About Circuits: Using a Volt Meter