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Clamp-On Current Transformer Probe for Digital Multimeter

Clamp-on current transformer (CT) probes allow non-contact current measurements using a Digital Multimeter (DMM) or other instrument without interrupting the circuit under test. Not all CT probes work for both direct current (DC) and alternating current (AC). Clamp-on CTs are commonly used for one time measurements, rather than long term monitoring.

Clamp-on current meter
Redecke, Wikimedia Commons