A clamp meter is an electrical test tool that combines a basic digital multimeter with a current sensor. Clamps measure current; probes measure voltage. Having a hinged jaw integrated into an electrical meter allows technicians to clamp the jaws around a wire, cable or other conductor at any point in an electrical system, then measure current in that circuit without disconnecting or deenergising it.

Beneath the plastic mouldings, hard jaws consist of ferrite iron and are engineered to detect, concentrate, and measure the magnetic field being generated by current as it flows through a conductor.

The basic features of a clamp meter (Fluke 376 shown here).
  1. Current-sensing jaw.
  2. Tactile barrier (to protect fingers from shocks).
  4. Dial (aka rotary switch).
  5. Display.
  6. Backlight button.
  8. Inrush current button.
  10. Jaw release lever.
  12. Common input jack.
  13. Volts/ohm input jack.
  14. Input for flexible current probe.

More measurement functions

Originally created as a single-purpose test tool, modern clamp meters offer more measurement functions, greater accuracy and in some cases specialised measurement features. Today’s clamp meters include most of the basic functions of a digital multimeter (DMM), such as the ability to measure voltage, continuity and resistance.

Clamp meters have become popular tools primarily for two reasons:

  • Convenience: During a measurement, it is not necessary to shut off the circuit carrying current—a big boost in efficiency.

Clamp meters are preferred for measuring high levels of current. DMMs cannot measure 10 A of current for more than 30 seconds without risking damage to the meter. Clamp meters offer a minimum current range of 0 A to 100 A. Many models have a range up to 600 A. Others go up to 999 A or 1 400 A, and some plug-in clamp accessories such as the iFlex can measure as high as 2 500 A.

Clamp meters are used on industrial equipment, industrial controls, residential, commercial, industrial electrical systems, and commercial/industrial HVAC.

They are primarily used for:


There are three types of clamp meters:

  1. Current transformer clamp meters: measure only alternating current (ac).
  2. Hall Effect clamp meters: measure both alternating current and direct current (ac and dc).
  3. Flexible clamp meters: employ a Rogowski coil; measure ac only; good for measuring in tight spaces.

More info: Contact Comtest,  local representative of Fluke, on (010) 595 1821 or

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