Clamp meters are ammeters that can measure current without the need to disconnect the wires where the measurement occurs. They provide information about current draw and current continuity in order to help users troubleshoot erratic loads and trends. Clamp meters have both positive and negative leads and feature extremely low internal resistance. They are connected in series with a circuit so that current flow passes through the meter. High current flow may indicate a short circuit, an unintentional ground, or a defective component. Low current flow may indicate high resistance or poor current flow within the circuit.

There are two basic types of clamp meters: digital and analog. Both are designed to measure levels of alternating current (AC) and direct current (DC). Some clamp meters that measure AC current also measure root mean square (RMS) power, which is the square root of the time average of the square of the instantaneous power. Most products include a current sensor built into the clamp around the wire. Different types of clamp meters can measure different ranges of AC current, DC current, and AC current frequency. Some clamp meters are handheld and portable. Others are designed for bench top or shop floor use. Battery-powered clamp meters can be operated without plug-in power and may be rated for outdoor use.

Clamp meters may provide special measurement types or optional features. Some clamp meters can test diodes or transistors. Others can monitor thermocouples or resistance temperature detector (RTD) values. Programmable clamp meters provide internal data storage and allow users to establish activation triggers. They can also interface with computer hardware and software. In addition, products with external storage devices such as disc drives are available. With regard to optional features, clamp meters may adjust sampling rates automatically, display status information as a bar graph, and measure decibel (dB) readings. Mirrored scales make it easier to read clamp meters to a given accuracy by enabling operators to avoid parallax errors.

0.010 High Accuracy for low resistance measurement Data Logging up to 99 groups Alarm Threshold setting from 10 to 1000 Leakage Current measurement from 0.1mA to 20A