What type of device is designed to be used as current clamps but has open ends for safer measurements?

The correct choice refers to ammeters designed as current clamps, which are specifically engineered to measure electrical current without needing to break the circuit. This design includes open ends that can be clamped around a conductor, allowing for safer and non-intrusive measurements. This functionality is particularly beneficial when dealing with high currents or live wires, as it minimizes the risk of electrical shock and short circuits.

Ammeters are versatile instruments used in various applications to monitor and measure current flow, which is essential in both residential and industrial settings. The open-ended design of current clamp ammeters enhances safety and practicality, allowing users to take measurements quickly and efficiently.

In contrast, the other options do not possess this functionality. Piezo verifiers and verifiers are typically used for different testing purposes, such as measuring pressure or verifying proper function, and voltmeters focus on measuring voltage rather than current, thereby lacking the current clamp capability.