What is a Clamp Meter? Find out!

what is a clamp meter find out

You'll need special equipment to measure things like current and voltage.

You must cut the circuit to insert the instrument's test leads into the circuit in series for instruments like analogue multimeters and digital multimeters to measure current. It's frequently impractical or impossible to achieve that.

Other dangers from cutting the circuit include electric shock.

In these cases, clamp meters are a practical option. This article offers a brief explanation of how to operate a clamp meter as well as any necessary safety measures.


An electrical test instrument called a clamp meter combines a current sensor and a simple digital multimeter.

Voltage is measured through probes. Current is measured via clamps. An electrical meter with a hinged jaw enables personnel to clamp the jaws around a wire, cable, or another conductor in an electrical system. After that, measure and check the current in that circuit without disconnecting or de-energizing it.

Hard jaws are designed to detect, focus, and measure the magnetic field produced by current as it runs through a conductor and is made of ferrite iron below their plastic mouldings.

A clothespin-shaped tool is called a clamp meter, and you can use it to clamp around a live wire and measure the current it is carrying. Clamp meters use the magnetic field created by current flowing in a wire as a measurement principle to determine the current value.

This design has the benefit of being able to detect current without needing to interrupt the circuit being measured, unlike devices like multimeters.





Modern clamp meters offer more measuring functions, precision, and in certain cases, specialized measurement features than their predecessors, designed as a single-use test tool. Most of the fundamental capabilities of a digital multimeter (DMM), including the capacity to detect voltage, continuity, and resistance, are present in current clamp meters.

The two main reasons why clamp meters have gained popularity as instruments are:

  • Safety. With clamp meters, electricians can avoid the traditional procedure of severing a wire and placing a meter's test leads into the circuit to measure the inline current. The clamp meter's jaws don't have to contact the conductor during a measurement.
  • Convenience. Turning off the circuit carrying current during a measurement is not essential, which greatly improves efficiency.

High current levels are best measured with clamp meters. 10 A of current cannot be measured by DMMs for longer than 30 seconds without endangering the meter.

The minimum current range for clamp meters is 0 A to 100 A. The range of several versions can reach 600 A. Some plug-in clamp attachments can measure as high as 2500 A, whereas others only go up to 999 A or 1400 A.

Industrial machinery, controls, residential, commercial, and industrial electrical systems, as well as commercial and industrial HVAC, all use clamp meters. They are mostly employed for:

  • Service: On-demand maintenance and repair of current systems.
  • Installation: Troubleshooting installation issues, conducting final circuit testing, and supervising trainee electricians as they install electrical equipment are all part of the installation process.
  • Maintenance: To carry out planned maintenance, proactive maintenance, and system troubleshooting.


  • Facilities, building maintenance, and HVAC technicians
  • Industrial maintenance technicians
  • Electricians – in-house and contractors
  • Control technicians
  • Service organizations


  • Commercial/industrial HVAC
  • Industrial equipment
  • Electrical systems
  • Industrial controls


  • Safety: Using clamp meters, electricians can avoid the antiquated practice of severing a wire and putting the test leads of a meter into the circuit to measure the inline current. The clamp meter's jaws don't have to contact the conductor during a measurement.
  • Convenience: It's not essential to turn off the circuit that is carrying current during measurement, which significantly increases inefficiency.
  • Service: As needed, make repairs to current systems.
  • Installation: Electrical equipment installation involves troubleshooting installation issues, conducting final circuit tests, and supervising apprentice electricians.
  • Maintenance: Carry out planned maintenance, proactive upkeep, and system troubleshooting.


There are essentially two classifications of clamp meters:

  • Loads contemporary measurement models.
  • Leakage current measurement models.

The classification of instruments can be expanded based on additional characteristics, such as whether they measure alternating current (AC) or direct current (DC) and whether they employ mean value rectification or the RMS technique. Normal AC circuits are measured using load current models. Some more contemporary clamp meter models can determine leakage current and load current.

Load Current Clamp Meter

To measure load currents, clamping more than one wire around clamp meters is impossible. Avoid clamping the instrument around numerous wires at once to avoid preventing accurate measurement.

Leakage Current Clamp Meter

Extra caution is needed when using clamp meters to monitor leakage currents. Measurements should be limited to ground wires. Clamp the instrument around all the cables when measuring an AC circuit (two if single-phase; three if three-phase).

You can clamp two wires at once to measure leakage current.

Leakage current, which can be multiple tens of A if there are numerous connected loads, is a current that passes past the insulating resistance of the load and goes to the ground. The slight difference that flows in both directions can be measured using a clamp meter and classified as leakage current.



Leakage Current Clamp Meter


There are a few safety concerns to keep in mind when using a clamp meter, just like analog and digital multimeters. Leaving a clamp-on power meter connected after use, for instance, could result in an overly high current flowing to the clamp sensor, which could harm the instrument.

Additionally, avoid clamping anything to bare conductors. It's best only to measure insulated conductors with clamp meters.

Since they don't involve cutting the wire being measured, clamp meters are quite safe, but it's crucial to use them at or below the maximum rated terminal-to-ground voltage. Finally, never touch anything located on the jaw side of the instrument's barrier because it marks the safety limit.


Clamp meters come in various variants created for specific uses, such as whether they are designed to measure DC or AC, as was previously mentioned. As a result, it's important to select an instrument based on your planned use. For instance, you'll need a clamp meter that can measure DC to test a battery used in a vehicle, an uninterruptible power supply (UPS), or a solar cell.

On the other hand, an AC clamp meter is required if you want to assess load current or leakage currents in an airconditioner circuit, such as lighting or electricity lines in a house, building, or facility. Select a leakage current type of clamp meter if one has to assess leakage currents brought on by insulation flaws, the current flowing through a ground wire for electrical equipment, or an AC load current clamp meter for routine measurement applications.


Clamp meters are handy devices that measure current and other parameters by clamping around a wire without cutting it. They are simple to operate safely. It's because all that's needed is for the instrument to be connected around a wire. But if used incorrectly, these tools could be harmful. Therefore, follow the guidelines and safety measures linked to selecting and utilising clamp meters in this article to guarantee safe use.


A digital multimeter is a voltage-measuring instrument with certain current-measurement capabilities. A clamp meter is a current-measuring instrument with certain voltage capabilities. They are both very different instruments, and each has perks.

You can perform electronic work with a digital multimeter (DMM), which has excellent resolution and measures in milliunits (millivolts, milliamps, and milliohms). Although the current is often restricted to less than 20 amps, it also lets you do electrical measurements. However, you can use a plug-in clamp attachment to measure greater currents on a digital multimeter.

In contrast to a DMM's millimeters, a clamp meter often measures to the nearest tenth or hundredth of a unit. For electrical jobs, this is adequate.

Guidelines for Choosing Between a Clamp Meter or a Multimeter

  • Basic Meter: Use a basic meter if your project calls for the most basic voltage and continuity readings.
  • High-Caliber Digital Multimeter: If your work includes power quality. You'll require the high resolution and cutting-edge features that clamp meters lack.
  • Basic Clamp Meter: You only need to check that the current drawn by each feeder's three phases is equal.
  • Logging Clamp Meter: If you have regular breaker trips that you need to fix, log clamp meters.
  • Multimeter: If you wish to take remote readings more safely and independently, you should use a DMM or clamp meter featuring a detachable display that you can detach from the clamp's body by 30 feet.
  • Advanced Clamp Meter: If you need to measure motor inrush current precisely, use an advanced clamp meter. Additionally, if you want to measure the output of a variable frequency drive, you'll need a clamp meter with sophisticated signal processing.



Special measurement kinds or additional features may be offered by clamp meters. Diodes and transistors can be tested using clamp meters. Others can observe the values of resistance temperature detectors (RTDs) or thermocouples. Programmable clamp meters have inbuilt data storage and let the user set up triggers for activation. They can also communicate with software and hardware for computers.

Additionally, there are models with external storage components, including disc drives. Optional capabilities for clamp meters include monitoring decibel (dB) readings, automatically modifying sampling rates, and displaying status data as a bar graph. By allowing users to prevent parallax mistakes, mirrored scales make it simpler to read analog clamp meters to a specified level of precision.


Clamp meters have wide jaws that clamp around the exterior of an electrical conductor for non-contact current measurements. These meters frequently measure voltage, continuity, resistance, and capacitance, among other things. It can perform studies on live wires without interrupting the circuit.

Clamp meters available at the HVAC Shop come from big and trusted brands known by professionals. We guarantee quality tools and equipment to make your HVAC business thrive. Don't hesitate to contact us today for more questions and concerns.