What is a Clamp Meter : Construction & Its Working

A clamp meter is one kind of test equipment and it is also known as Tong Tester. This equipment is very simple to use and operate. The main function of this device is to measure a live conductor in the circuit without damage or power loss. By using this equipment, one can measure the high-value current without turning off the circuit while testing. The main drawback of this meter is, the long tester accuracy is significantly low. This article discusses an overview of what is a clamp meter, construction, and its working.

What is Clamp Meter?

Definition: A device that is used to measure current in an efficient, convenient, and safe manner without using test leads is known as clamp meter. We know that the magnetic field can occur when the current flows throughout a conductor. So by using this device, the magnetic field can be detected to provide the reading of the corresponding current. These devices do not disrupt the flow of current so that the technicians can measure quickly and very safely. The clamp meter diagram is shown below.

Clamp Meter Device
Clamp Meter Device

These meters have become very popular instruments because of the following reasons.


These meters allow the technicians to avoid the traditional technique for cutting into the wire as well as placing the test leads of this meter into the circuit to take the measurement of current in-line. The transformer clamps of this meter do not require contacting a conductor throughout a measurement.


Throughout a measurement, it is not compulsory to deactivate the current-carrying circuit.


The specifications of the clamp meter mainly vary based on the manufacturing company. For instance, the meter which is designed by FLUKE mainly includes the following.

  • The range of AC current is 40.00 A or 400.0 A
  • The range of DC current is 40.00 A or 400.0 A
  • The range of AC voltage is 600.0 V
  • The range of DC voltage is 600.0 V
  • The range of resistance is 400.0 Ω or 4000 Ω or 40.00 kΩ
  • The continuity is ≤ 30 Ω
  • The capacitance range from 0 – 100.0 μF or 100μF – 1000 μF
  • The frequency ranges from 5.0 Hz – 500.0 Hz
  • The AC response is True-RMS
  • Backlight and Data hold
  • Contact temperature ranges from -10.0°C -400.0°C
  • They offer less range of current like 0 A – 100 A.
  • This range may vary based on the model of the meter like up to 600 A.
  • Some of the range of the meter is 999 A otherwise 1400 A

Clamp Meter Working Principle

The working principle of clamp meter is the magnetic induction principle to create AC current measurements without contact. The flow of current throughout a wire generates a magnetic field. Hall Effect sensor mainly detects the magnetic field that is caused by the flow of current to cause a less voltage across the sensor.

Clamp Meter Construction

The construction of this meter can be done using different components which are discussed below.

Jaws/Transformer Clamps

Transformer clamps or Jaws are used to detect the magnetic field while the current flowing in the conductor.

Clamp Opening Trigger

A clamp opening trigger is used to open or close the clamps.

Power Switch

The power switch is used to switch on or off the meter.

Back Light Button

The backlight button is used to activate the LCD display to read the displayed value easily at night or in dark places.

Hold Button

Hold button mainly holds the final value on the LCD display.

Negative or Ground Input Terminal

The ground input terminal is used for connecting the ground jack or negative of the meter cable.

Positive Input Terminal

This terminal is used for connecting the positive jack in the meter cable.

LCD Display

The LCD display is used to show the measured value.

Functional Rotary Switch

This switch is used to choose the current based on the range & type being measured.

Different Types

There are different types of clamp meters available which include the following.

  • The current transformer type or ac clamp meter is used to measure AC (alternating current) only.
  • Hall Effect type is used to gauge both AC (alternating current) & DC (direct current).
  • Flexible type uses a Rogowski coil for measuring only AC in tight spaces.
  • DC clamp meter is used to measure only dc current using hall-effect without any contact.

How to use Clamp Meter?

These can be used by using the following steps.

  • First, connect the current probe to the meter
  • Connect the stretchy tube of the probe in the region of the conductor.
  • The distance between the probe and the conductor must be above one inch or 2.5cm
  • Rotate the dial to the symbol.
  • Check the value of the current on the LCD display.

Clamp Meter Uses

The applications of clamp meter include the following.

  • These meters are used mainly for measuring high-level current. By using digital multimeters we cannot measure the current of 10A for more than 30secs without damaging the meter.
  • The applications of these meters mainly include industrial controls, industrial equipment, commercial, industrial, residential electrical systems & HVAC.
  • These are used for repairing accessible systems based on the requirement.
  • These are used to troubleshoot fixing problems, execute last circuit tests, and manage beginner electricians while fitting electrical instruments.
  • These are used to execute scheduled, preventive protection as well as troubleshooting of the system.

Clamp Meter vs Multimeter

The difference between clamp meter and multimeter are discussed below.

Clamp Meter


A clamp meter is used to measure the current A multimeter is used to measure resistance, voltage, and less current sometimes.
These meters measure high current These meters have better resolution and high accuracy.
Suitable for measuring the speed of machine & current drawn Suitable for electronic work
The advantage of this meter is more compact The advantage of this meter is compactness
Number of functions and damage protection The disadvantage of this meter is Battery life

Thus, this is all about an overview of clamp meter. Generally, these meters are safer as compared with a multimeter. But by using multimeters, more precise measurements can be achieved because they have to come in through contact with the circuit. Here is a question for you, what is the function of dc clamp meter?