A clamp meter is an electrical test instrument that measures current by clamping around a conductor. It senses the magnetic field produced by current flow, so the circuit usually does not need to be opened or the wire disconnected. Many models also measure voltage, resistance, or other electrical properties using test leads.
Clamp meters are designed for electrical work, but some include programmable electronics, displays, and firmware-features that make them small embedded systems as well as measuring tools. In cyber security, this matters because devices with software can have security considerations such as update handling, code quality, and access to interfaces. A hobbyist project running unexpected software on a clamp meter illustrates that embedded hardware may be more capable than its purpose suggests; it does not, by itself, indicate a vulnerability. Defenders should assess connected or programmable instruments according to their actual features and exposure.