How to Use a Digital Clamp Multimeter

The digital clamp multimeter or clamp-on ammeter is a complete electrical testing tool. The clamp portion of the multimeter is used for reading amperage that is flowing through an insulated conductor or wire. Typically, most digital clamp meters may not have the capability for reading ohms or resistance. They do, for the most part, have the ability to read amperage through the clamp-on device and voltage with the manufacturer-provided leads or probes. The main usage for a digital clamp multimeter is to read the flowing amperage through the wire, and then the voltage of the circuit. By multiplying these two electrical characteristics, you can also find the true power consumption in the circuit called "watts."

Things You'll Need

• Digital clamp multimeter

Instructions

1. Find the voltage of the electrical circuit. Turn the meter's selector switch to the "Volts AC" position. The meter should read "0.0 VAC." Insert the two probes into the meter. The red probe will go into the "Volts" connector or the red connector. The black probe will be inserted into the "Common" or black connector.

2. Touch the black probe to the metal frame of the circuit box. This is the ground of the electrical system. Contact the red probe to the electrical circuit you want to measure. As an example, it could be the screw terminal of a circuit breaker that is "On," and the device it is attached to is under operation. Read the multimeter, it should read "120 VAC."

3. Remove the probes from the testing area and pull them from the meter. Move the selector switch to the "Amperage" position. The meter should read "0.0 AC."

4. Open the clamp on the meter and place the wire that is being fed from the circuit breaker inside the clamp space. The meter should read any form of amperage if the breaker is on and the device is running. In this case, the meter may read "12.0 AC." This indicates that 12.0 amperes is flowing to the device.

5. Find the power consumption of the electrical circuit. Watts is equal to volts times amperes (w= v * a). The total power consumed is then 120 VAC times 12.0 amperes which is equal to 1,440 watts.

Tips & Warnings

• Double pole circuits, 220VAC, are read in the same way. Test each circuit breaker terminal for voltage to ground and then between each other. Test each wire for its own amperage flow.

References

• Clamp Meters
• Basic Electronics; Bernard Grob; McGraw Hill Publishers; 1977

Resources

• Fluke Meters